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Post by pxguru on Dec 17, 2014 17:31:21 GMT
If we are looking at exactly the same set up but 2 years apart then its not a tweek but something bigger. After seeing this comparison and knowing all that you have done, the first thing I would do is try a different exhaust. I take it from the beer can packer it has a habit of slipping on the manifold (you know SIP sell real ones?). This could mean something. I wouldn't touch anything else until I had seen it run another exhaust.
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Post by vespasco on Dec 18, 2014 1:09:55 GMT
The sip shim (for £10)! cant be much more than ali or copper or ? (What very thin material would tolrate such heat)? Beercans are free! I thought id give it a go. It doesnt actually slip off anymore altho the shim helps, (so far), its more overkill. But i am worrying a beercan will not tolerate too much heat, especially around that particular point.
As for a plan.... Ive adjusted timing to 19° , where it (usually) needs to be but ive not actually ridden it, so thats first on the list (ride it). Then advance timing further/as far as possible/as required (and check the crank/fly but I like to think i would have spotted such 'scratches') Then, if still not quite right, swap exhausts! Its possible! Its also possible, after studying my microdyno runs, that i will revert back to no base gasket. To keep the transfer duration as low as possible. The dyno results seem to sway towards the 0 packer.
Ive noticed that with the ports fully open @ BDC (using 0.5mm packer) the rev range increases at top end a little.
My main worry is, with no packer the exhaust duration is quite short (around 170°)! and dosent quite fully open the ports. The exposed piston ring at BDC being a bit of a worry too but i dan get over that. Are you hinting that the EGT could be too high at the stub guruji?
Placing the importance of the transfer duration aside for a moment.... I figured out the exhaust is probably/maybe restricted by the exhaust duration (whivh is 170° with no packer) Or is it just coincidence that my max revs are 7350rpm? which if i look back at duration/rpm guides tells me is also 170°! So if, for example , my exhaust duration was @ 173°, and my set up/exhaust allowed it, would it max out @ no more 7750rpm?
If i raise the height of exhaust port, this will make the gap between the crank inlet closing and the exhaust port opening shorter but would that actually affect anything? Or is it only when they're closing that it would have an affect?
And the more i think about raising the exhaust port, the more it makes sense and the more i want to do it. Yet, somewhere in my brain it keeps telling me its quite, no, very important for the nikasil lining to 'wrap' itself into the ports. Once that 'wrap' is gone, then what!? Unless its done right, perfect, its not going to last as long. Which is a high priority for me.
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Post by pxguru on Dec 18, 2014 4:08:36 GMT
The beer can will be ok but the SIP shims fit really well with no gaps. An exhaust leak increases the EGT which is fine if you set it up while its leaking The kind of power loss you have seems a bit too much for timing. You need to try a different exhaust. If everything is exactly the same just 2 years apart then it could be a blocked exhaust. I have seen this a few times before and would like to eliminate it from the investigation. The typical symptoms with a blocked exhaust are that, it goes great until mid range then loses power. Sound familiar? Keep the packer where it is for now. There is no issue with sanding out Nikasil ports. If the plating was going to come off with the heat it would come off anyway. Rounded into the port or not. Once the ports are sanded to shape the chamfer should be polished in (takes a while). The plating only needs to be where the rings and piston touch it. My next barrel is a chipped Malossi 210 I brought off ebay. The small chip is just below a boost port, will just be sanded smooth and left. Won't make any difference to reliability or performance. Once I have finished with it every single port will have been opened out for the most power (I have been designing this one for a while) Certainly wont be getting the bore re-plated before running it
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Post by vespasco on Dec 18, 2014 10:31:32 GMT
Ok. Id agree that adjusting the timing will not give me the miraculous results im after but it may just make it more of a pleasant ride! I dont believe its the pipe thats at fault as one of the first things i done, after finding out i had lost power after the rebuild, was to clean the exhaust,,, (petrol, bent coat hanger and a match) but will not rule it out.
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Post by pxguru on Dec 18, 2014 10:53:07 GMT
Just did an edit above
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Post by henri on Dec 21, 2014 11:35:58 GMT
whats wrong with spud up tailpipe an caustic n warm water ,gave up the lit petrol method after shooting 1 too many exhausts across the yard ,if its not a chrome 1 sitting it on a fire or using a blow torch an re-painting after shifts the most congealed 2 stroke , an if your worried about your shim leaking i'd use high temp copper gasket goo , loctite 207 or permatex ultra-copper , there designed for turbo's n exhaust joints an are reckomended on smallie headgaskets ,they will handle the temp an pressure i would of thought . had a thought yesterday ,have you considered a base gasket leak lowering ya initial compression , since testing youve had barrel off an on gingerley,as ya dont trust studs,lower initial comp is more noticeable/trouble as ya get to mid-high revs maybe giving you the feeling somethings lacking , that an the absence of your packer could explain your mid range flat spot ,but then could a lot of things eh, H
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Post by vespasco on Dec 22, 2014 17:51:45 GMT
Yeh! Ive seen an exhaust fly across the yard before while im still holding the gas torch fun tho! For now ive taken the shim out. I used to stay on, just. But im gonna look into your suggestions h. As for a leak, well, i done a leak test when i stripped it, found 3 x leaks in gearbox, 1 x near the crankcase. Ive never really ruled out a crack in the crank case tho. Ive done what i can to find any cracks/leaks but found none. At low pressure, during my leak test it was ok, but at higher pressure....who knows? This is why im still hanging on to my 'stockp/x200/efl Ive made a couple of alterations recently, recorded some more dyno runs after each change...i just need to sort the results out into something i can refer to confidently. Theres one problem ive found with the MicroDyno, well its not a fault of MD actually...and thats the weather! Ive found it difficult to compare the curves when curve 'A' was recorded on a still sunny day, and recording 'B' recorded on a different, windy day. I had to make sure i recorded on the same stretch of road, going the same way, without too much wind!! Heres where a dyno shop has an advantage. Results will be very consistant, as there is no wind or different gradient roads to contend with. I will post the results and minor changes ive made as soon as it all makes sense!
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Post by henri on Dec 23, 2014 17:01:23 GMT
best 1 ive seen is my mates matchless megaphone trumpet shaped shiny chrome exhaust trying to get into orbit an landing in a neighbours shed roof 2 doors down, impressive but best bit was the perfect smoke ring it left behind . the leak test was just a idle thought as i agree with pxguru when he said the minor tweeks ya done shouldnt of had a negative impact ,tho i'm waiting to see ya nxt dyno results since timings been corrected . but what does the "seat of ya pants" tell ya ,as your concerns about weather n wind on micro dyno results are why i had reservations about it to start with . i'm going to go all "victor meldrew-ish" on its ass , n say no american whipper-snapper with a fancy-dancy computer 1/2 developed app can replace experience/knowing ya own scoot/"feelings"/a human brain that can allow for variables unconsciously etc n etc . an now "breathe" ,Aahhh , thats better , i'm wondering if you can get more consistent results by positioning the mic closer to exhaust outlet ,but out of wind noise ,say on a px on the battery tray ,on a rally with enclosed nearside panels (if there same as super/sprint) gaffer taped to underside ,a bit risky to the phone but for consistency a "clean signal" for the app to number crunch ,am guessing as its set up for rucksack recording you'd have to re-calibrate .youve been in touch with the designer maybe another e mail will get an answer . did he say or you know where in usa he lives ,as if it somewhere like arizona/texas i doubt he's had much variation in humidity/temp/wind to develop with.tho if he's californian round frisco bay ive been told its like cardiff on a wet day with added gays , not quite sure what the guy who said it meant ,but. mark twain said "the coldest winter he'd had was 1 summer in san fransisco" so if he's from there should of had conditions to calibrate for sunny old england , H
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Post by vespasco on Dec 23, 2014 18:06:32 GMT
I think that during the winter months when its a lot windier/gustier, its not going to be so accurate. Its the gusts of wind that make a little difference to results. Being indoors thats the thing you dont get on a dyno. The actual recordings are ok. Phone mic is ok. The signal is clean enough to get accurate results. The wind is no problem in the recording stage with the phone in a backpack. The problem is.... if you have a sudden back/side/head wind gust it will make you faster/slower and give a different curve.... In the summer months, when its a lot quieter (no wind) i believe it would work really really well... You can set the weather pressure and temp, just as a normal dyno but you cant set the gusts of wind tho'! Now that im confident in the use of the MD i would really like to compare/calibrate it with a real dyno to find out which stretch of road i should be using so to speak. With that info the MD would then be invaluable (in the summer)! The developer is from Norway? Germany? Cant remember now! European anyway. Im certainly not relying only on the dyno results to tell me what to do next. Seat of the pants is always no.1 sensor. I know exactly how it should be/used to be. Its getting a little closer to that.. I used to able to quickly and confidently overtake at 55mph..... Hard acceleration would make me slide backwards on my seat if i relaxed..... And at WOT i used to have to hang on tight! A couple more experiments, fine tuning and i think it will be close enough. I dont think it will as nice tho'. Im not planning on thrashing it everywhere this time anyway. That experiment is over! Lots of fun! The dyno is just another tool to help me get it back to how it was....or better... The accuracy of the SIP speedo/rpm also helps a lot. Conclusion is its best on a day with no wind!! On the same stretch of road, going the same direction. Then its simple. At least I now know what id need to do if i decide its still too slow
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Post by pxguru on Dec 25, 2014 11:53:14 GMT
Vespasco, Still need to see a dyno run with a different exhaust on!
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Post by vespasco on Dec 28, 2014 19:08:41 GMT
I getting somewhere.. Heres a couple of fairly typical curves to compare exhausts. (Even although they are similar)! Sip road mkl and sip road mkll Theres still a bit of jetting to do. Its not 'quite' right but getting more ridable But because i didnt realise my timing was out wgen i had 0 base packer, I'd like to try it without again, although likely I'll go back with 0.1 or 0.2mm packer. The dynos gave not bad results with 0.0mm packer, even with the wrong ignition timing and jetting. So im certainly going to keep it low My seat of the pants mild tuning is getting, more, er, seat of my pants! (Thats a good thing)!
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Post by vespasco on Dec 28, 2014 21:30:24 GMT
Its a fair comment Gaz Its like this. The MD is just a bit of fun/time pass. Ive just been learning how to use reliably. I dont need a dyno to tell me what i need to do to my motor. The figures themselves dont mean anything to me really. What have i accomplished? Admittedly not a huge amount. Yet it has helped me realise exactly where the power is, so now i can relate that to my rev counter when riding. Thats about it on a practical level. (Yes i know, feel tells you that too)! Suprisingly, on a still day like today it still actually gave comparable results. I doubt ill use it much more now anyway. At least not until ive got the motor running nicely. Now that im confident of getting comparable results with the MD i will use it again... but only when ive finished finely tuning the motor (the old fashioned way). The results will give me something to compare to later should i need to, thats about it. And if i swap exhausts at a later date MD will certainly come out again.
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Post by pxguru on Dec 29, 2014 9:45:43 GMT
The numbers on MD and GSF may be a bit dodgy but the shape of the curve showing the power band is a big help. I think very useful. Well, from this comparison it shows there is nothing really wrong with your SIP Road mk2. The results are too similar to be exhaust pipe related. I would think it feels faster with the mk1 exhaust on? The height of the exhaust port and how well the exhaust pipe works combine together. With your below minimum exhaust port and a decent expansion pipe, your engine as it is now will have much more power than could normally be expected from just adding an expansion on another engine. The curve being much better shaped on the mk1 shows up the exhaust port issue. Do you not know anyone who could port your barrel? This will really fix it
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Post by henri on Dec 29, 2014 11:46:51 GMT
i'm in agreement with the sentiments of last few posts , its not the "holy grail" but used with care an attention to detail/variables can be a valuable tool to diagnose an tune with , an its always nice to have a second opinion to the seat of ya pants without the cost of a dyno session ,an if all out tuning could see myself using it to get rough settings before fine tuning on a dyno ,could save a lot of expensive dyno-time,H
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Post by pxguru on Feb 9, 2015 8:52:01 GMT
Vespasco, How many mm did you raise the exhaust port? Sounds like not so much yet but going in the right direction if the HP is going up. If the plug is running rich when up to temperature and still pinking at WOT then its not jetting. Do you have pinking marks on the piston? Is it only at WOT?
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Post by vespasco on Feb 9, 2015 12:20:56 GMT
As im a virgin cylinder porter i didnt go mad. Left plenty of room for mistakes and to see the differences 1 x 1. One thing im not too happy with is the radius edge at the top of the exhaust port that i ended up with. I would have much preferred a square edge with slight chamfer. What are your views guru ji? Is a rounded edge going to be ok? Or do you think those rings are going to push into the port?
Its turning into a bit of an experiment. As my transfer duration is so high (127* - (would suit 9500rpm)) and i cant do much about it. I dont even want it to rev that high. so i concentrated on the next best thing, - BlowDown. Using BD (and exhaust duratipn) as my 'De-restrictor'. Im happy to achieve peak power at less than 7500rpm. But i also need to try and match the 9500rpm rev range of the transfers?! A happy medium of aiming for around 7750rpm with BD was/is the goal. A bit at a time. This gives 25* BD. Which when added to transfers gives 177* exhaust , (which is ideal for above 8250rpm). I dont really want it to even rev over 8000rpm tbh. And its unlikely to with my stock carb and SIP road. I prefer the power lower down too, where it will get used. These figures are not ideal but its a comprimise.
At this stage its likely to be my BD thats restricting it. And if i want the BD to match the transfers then id be looking at a high revver. New carb, new exhaust. Which i dont want. So using the BD, i can limit my peak power. Is that correct?
Exhaust port was 37.3mm from top of barrel Now its 36.7 to inside of port but with quite a large radius on the edge of port. (Meaning the start of the radius is around 36mm) Not much i know but i have noticed the difference already. Better too little, not too much! I may have to square off that port better, which will give me a couple extra degrees on exhaust and BD.
Pinking. Yeh! I was hoping never to hear that dreaded noise ever again! Ive a few things to try, i just ran out of time: But would still like to hear all your views ..... Which would be best place to start. MJ is large enough. Showing rich enough.
I have larger ratio idle jets to try Larger atomizer (an E2)! Different slide (from T5) Large air corrector (190) Different (altho' similar - slightly lower CR) cylinder head Different exhaust Timing adjust but i really dont want to go any lower than the 18* im using now. Id really like to advance that by a little if anything!
The fact im now using a 140MJ worries me a little. I will change the idle too (as its easiest) It now has a 55/160 at the moment. (Before it used to run 50/120) I noticed when i had the 135 MJ in (with timing @ 20*) that after a blast at WOT it would idle high for about 10 seconds or so. Air leak? Small MJ? Hmm!? Im still wondering if it has a crack in the cases! But a larger MJ stopped that.
I have richer ratio idles to try but my brain cant make up its mind which is richer. In my head, on an idle jet, a 160 air corrector is the largest size. And the fuel jet @ 55 is also largest size. So this is the largest idle jet!? Allowing most air and fuel.
Then on the other side of the coin is the fuel/air ratios. With the 55/160 ratio considered quite lean when compared to a 52/140 for example (which i also have at my disposal) I thought id figured it out once! Swapping them over and trying them will give me a better answer!
*Summary of that mixed up jigsaw of words above ....
yesterday morning was like this: 135MJ @ 20* ignition and was pinking quite bad from 1/2 throttle onwards
Yesterday afternoon like this and still pinking but not as much; @ 1/2 throttle it improved but still pinking after this, and at WOT.
140MJ 55/160 idle 18* ignition 127* trans 22.75 BD Giving exhaust @ 172.5* CR, guesstimate (i forgot to measure new volume) but v likely at around 10.3:1 CR) a little high??
Aim for around 8000rpm with BD.
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Post by pxguru on Feb 9, 2015 18:27:43 GMT
So you raised the exhaust port by 0.6mm I wouldn't worry too much about the chamfer yet. There is still 1.9mm more to remove yet. A high chamfer is best but a some barrels (see sime's new barrel) run without any and get away with it. If you do run a 190 air corrector on the main jet stack then that will make it pink! Its way too much air for yours. And messes up the mid range atomiser too. After raising the exhaust port the rest of the way try the jetting at; 135 main jet 160/BE3 55/160 pilot I.T. mark timing And go from there. Its all about plug colour and engine temperature. As the transfers wont go any lower 8,000 rpm has to be the target. What packer is needed to cover the dykes ring at BDC? And how many transfer degrees is that? 10.3:1 compression is not really so high. With good squish angle it is possible to have more compression and still not pink or overheat. The SIP Road II should be fine at 8,000 rpm. When its finished it will have more power with an expansion exhaust but its not compulsary! If you like the SIP Road II then will be better round town
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Post by vespasco on Feb 9, 2015 22:47:25 GMT
Maybe its time for a kryptonitronic cdi add ignition timing on thingy. Now theyre programmable! As its a dyno thread i thought id better add some results. The grey curve: was very typical on the 'test track' i frequently used. The other curves were done on a flatter stretch of road and as such show a different story. They also match my gps readings. Green curve: on the flatter road, before porting. Dark blue: on the flatter road again. After porting. Bright blue: the type of curve im aiming for, but with peak at 6800rpm. 6800 because on ALL my dyno results, (now and previous ones) it cuts off at that point. Im going to prepare to take off another 0.6mm. Which will also get rid of that dodgy radiused edge i made. Then ill see if it still pinks. I wont be fitting a larger air corrector to try and get rid of the ping! Its just an option to go with the E2 (which i think is same as a BE2) should i need to try. Thats more of a last resort. The jetting ^^^^ is pretty much how i have it. Lower ignition ° and higher MJ and its pinging. Not good. Pinascos have are notorious for pinking. Squish angle...the head angle is slightly larger than piston angle!! Not what i asked for when i had it made but none-the-less it has been ok for years. Compression has changed (higher). And squish is slightly smaller. With a base packer to fully cover the ring @ BDC the transfer° is far too much. With a stock 0.2mm gasket trans° - 128° With the 0.5mm packer trans were 129.5° !! (0.0mm packer - 127°) I do also need to do some plug chops My CHT readings will be higher to begin with as i modded the head and sensor. And they will read faster! When it was really pinking temps went just over 300°f (dont panic! The sensor is very close to the combustion bowl)! So i think 300°f should be a warning for me. Im happy with the SIP pipe. Its good for long and short runs. Although ive got the use of a welder now so i may try and bring 'my' old pipe back to life....or sell it?
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Post by henri on Feb 10, 2015 9:38:37 GMT
i think i'd retard as far as ya can , remembering nik sayin he was runnin at 15 but had needed to file slots so am guessing 16 is bout most a unaltered stator will do. coincidentally 16 degrees is where sip reckon most of the kits they sell should be timed at , if this doesnt radically improve stuff most likely culprit is altered squish band by the addition/subtraction of a packer , in a rush to get on now,so will read in depth the above posts n see if anything jumps out at me , nice sip copy pipe by the way , H
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Post by vespasco on Feb 10, 2015 19:06:36 GMT
Ill try retarding it further but it will be slow! I never had a problem at 19° which, if i need to retard to 16°, makes my alarm bells ring! Its masking something else thats not quite right. I dont want to hole a piston. I dug out my other head, with a larger combustion chamber too. But i seem to remember using this on my previous, well running set up and it did pink a bit. It could also be fuel related as i drained the tank to fit the bgm FF tap.. Drained it into an old petrol container, maybe that was contaminated?! Ill ride it (gently) some more and drain it out while testing different things. I want to try things one x one to eliminate this n that. I also need to re check my squish, squish angle (i know its slightly larger than the piston) and combustion chamber volume, as ive changed a few things. I also went through my notes for some clues, as from the beginning it used to pink, as did a lot of pinascos. I tweaked the carb, spark plug and timing and almost stopped it. It stopped at around 3/4 throttle + where it used to pink but I could still make it pink whenever i wanted and put up with it for a few hundred slow/running in miles, then it stopped, kinda by itself!? Which made me wonder if its something ive used to clean the head/or its the coolant/sudge from the lathe when it was profiled?? Basically, it seems to get better when theres a slight build up of carbon!? Weird i know. Which thing should i change first?!?? *Edit.. btw ... Henri, i got the do dah whatsit. Thanks very much .
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Post by henri on Feb 11, 2015 7:48:44 GMT
no probs mate ,wire brush n 2 coats of rust killer an its lookin fine ,thanks , a drop in pinking on carbon build up could mean a slightly too large squish , the pinasco pink was usually a side effect of the different squish dynamics coz of dykes rings , or so i was told , it made sense as the guy explained it but ive never got my noggin round it again/since, so i'm not much help now sorry , H
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Post by pxguru on Feb 11, 2015 16:06:18 GMT
The pinking could get better once the blowdown is raised to minimum. Might be something to do with the trapped exhaust gas at higher rpms
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Post by vespasco on Feb 11, 2015 19:59:51 GMT
Hmm!? Do you think its the dykes ring thats trapping some of the mix!? Along with a possibly dodgy squish? The pinasco, out of the box, had a squish of about 3mm! Similar to stock Piaggio.
I deliberately got the squish angle 0.5° larger as this was the conclusion i arrived at, at the time. Next time however, id try and get a head with a proper domed squish band, exactly as the piston dome. The Polini looks very interesting! Although it looks like there's zero squish on the head. I think they're based on the same piston too??!! If they are virtually the same piston then i may have got my CR figures wrong!!, giving me closer to 11:1 CR (Im going to be aiming for 10:1CR, 6.5CCR) this will give me more 'tolerance' with lower grade fuel, should i finally get off my a$$ and go on another trip somewhere "egg-zo-ik".
Maybe with the lower compression the squish was acceptable. Now there's a higher CR the squish is more crucial. Ill have a look for signs of pinking when i take off the head next (this weekend)!?
So now, the plan is to finish off the raising of the HMS exhaust port. The transfers are what they they are. 127° (suited to 9500rpm) Ive decided on trying 36mm height over port. This wil give me the following:
24°BD (suited to 7500rpm) 175.27° exhaust duration (suited to 8000rpm)
For 8000rpm i need 25.5° BD (35.3mm) This will push the exhaust up to 178° which is more suited to just under 27° BD (8500rpm)
This is the reason im doing it little by little And also because i noticed the power band kicking in a slightly later than normal....i dont want to loose too much power in low/mid range. Im sure theres still room for a little dremel work without drastically changing the low range too much. The low end already improved after raising just 0.6mm (As did all rev range tbh)
I think I've just talked myself into cracking on with the porting and ignore the pinking! (For now at least) Thanks guys
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Post by henri on Feb 12, 2015 10:47:41 GMT
pull the plug n inspect with magnifying glass/jewellers loupe under strong light ,ya looking for very small shiny ali balls , welded to plug nose ,if there there thats pinking damage as they use to belong to piston crown , then check piston crown ,damage under plug =timing/jetting pink, at edge/squish = compression/squish pink, tho if you reckon ya comp is 11-1 an 3mm squish my moneys on that as the cause , do the porting if ya minds made up but i'd def try n suss the pink aswell or all that work could self-destruct when piston holes , ouchy doesnt get close ,H
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Post by pxguru on Feb 12, 2015 15:35:09 GMT
Keep an eye on this as H says. Running in this c**p state could make it go pop. For a fast road or sporty tune on your transfers of 127 you need something like 185. This doesnt suit what you are after and like you say, as low as possible exhaust is best for you. About 177 will be about your minimum for power to peak near 7500. Once this is sorted the pinking should reduce. The reason your power drops off at 6500, yet the transfer ports could do 9500, is because the exhaust gas can't get out in the time (degrees)available. With higher compression and so much old exhaust fumes in the new mix it will overheat and detonate. Once you raise the port to get up to minimum blowdown of 177 degrees (max being about 190 degrees!) I expect this pinking to get much less. And a whole load faster
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Post by vespasco on Feb 12, 2015 18:26:06 GMT
Ill be having a very close look at crown n plug n head when i strip the top end to do the porting. This weekend hopefully. Im not going to be riding it when its pinking! Not like this. Looking back its probably the worst ive heard so there'll no dount be a bit of work to do! (Its ok upto 1/2 throttle, @ lower temps). Ill probably not ride until after i do the porting tbh, other work is getting in the way! I dont have 3mm squish, this is just how the pinasco 213cc kit comes if you were to bolt it on a stock motor. My squish is around 1.5mm but as i lapped the head quite a bit recently i need to measure it all again. Plus i have no base gasket now, so its even less than before....and raises compression. Im hoping, as above ^^^, that by raising the exhaust port more, it will help combat the pinking. This is why im going to plough on ahead and raise the exhaust port some more without trying to get rid of the pinking first. Im 1/2 expecting it to pink now anyway, as its a common trait of the Pinkasco. If it does still pink after that, i still have, amongst other things, a lower comp head to try. Dont worry, it wont be going far or fast until its sorted. I know only too well the drastic effects of pinking from a previous life....Sliding down the A3 at 60mph+ on a busy bank holiday weekend, on the back of a pinking, highly tuned Sportique was my nearest death experience ever. I still see that white van coming for me
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Post by henri on Feb 12, 2015 19:25:22 GMT
60+ on a sporty ,thats some tuning ,or a big downhill/following wind+belly full of cabbage n beans =rocket power.H
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Post by vespasco on Feb 12, 2015 20:17:10 GMT
My mates sportique was highly tuned and on 8" wheels too, gearing changed etc. He said his speedo was showing over 70mph (maybe not so accurate!) when it locked up and went wobbling, down on its side, (with me riding pillion). All tuning done in the days with no internet. Hey, I bet you know the road Henri?? Just after the hogsback on the A3, or just out of guildford anyway, big downhill with big bridge over the road, it was downhill too yes. Pinking shenanigans! I seriously thought my time was up. Did my life flash before me? No. Not really. Although it was in slow motion. If there wasn't someone/thing looking after us that day then my last words, mumbled to myself, as i watched this van coming right for us, would have been... "Ooh fuuuu". Bang! No-one knows, not even the van driver, how nobody got hurt ऊँ It was good to watch apparently! And we soon got on our way again (damage= heat seize only!! snapped front brake lever, scuffed loafers!! And the shock of still being alive, whats more with no internal bleeding! Hahaha! Needless to say, i then rode pillion on another scooter that day. Had a fag, had a joke, on onwards.
Well, apart from riding in India, thats my nearest death experience on a 2 stroke. Im sure we all have 'em!?
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Post by vespasco on Feb 13, 2015 19:55:14 GMT
Konstantly Fin Closed
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Post by vespasco on Feb 15, 2015 20:41:00 GMT
I made some progress over the weekend. Exhaust port raised to 36.1mm The power curve has edged along a little up the rpm, The torque has flattened out more rather than paeking to early The pinking dissapeared. I cleaned everything, found no visible signs of pinking. Plus i had fresh fuel this time. The carbon deposits were quite sticky Me thinks i was a little slack on getting the grinding dust out from the previous porting work??! And i made a little slip with the tool, nothing major, nothing that 600 grit couldnt remove! O F! this really is all i had, thats my excuse! Bad craftsman blames his tools, i know! It was a little too windy for dynos. Seat of the pants tells me i dont want to loose any more torque in the lower/mid range, which means i probably wont be raising it any more! Not until the time comes if/when i want a bigger pipe and carb too! Thats unlikely on to happen on the Vespa. I took it for a quick test... Decided it was good enough for quick spin to my local city, 50 mile round trip ... I got 1/2 way there , it started to die!. ...??.. Ah! The new BMG tap has a bigger reserve so needs switching much earlier! It took a while to cut in again! Plus id been trashing the pants off it up and down some dual carriageway, that didnt exactly help with the mpg. Thrn i realised i had no oil with me, i only went out for a quick spin, no tools, oil, nothing. £14 for a bottle of oil at the garage! Ouch! CHT temps, with sensor threaded into the head, are now around 300°f WOT, slowly dropping the longer i hold it wide open. Cruising with a little back wind was a little scary to begin with...it was only just on the main jets @ 55mph! Temps rise a little but i think its mainly becase im just getting used to the more accurate and faster readings. (And hopefully no more cht ring breakage) Theres a little fine adjustment to do on the ignition timing and jetting as yet. Ive got a sip road mkl and mkll to play with, once the current combination has been tweaked. Overall, its alive once more! Happy bunny
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