pecker
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Posts: 65
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Post by pecker on Apr 30, 2016 11:47:17 GMT
Hello everyone great site, what would be a good starting point regarding main jet on this set up using standard carb on a 2002 px 125. Any comments from anyone that has similar set up appreciated. Cheers pek
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Post by jimscoot on May 1, 2016 3:57:13 GMT
115
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Post by henri on May 1, 2016 8:04:26 GMT
the venturi's greedy ,tryin to remember but on simes brief? update thread when he put one on an a ram-air filter his jetting had to jump right up ,maybe 10 numbers .an a pm's a greedy pipe compared to his sip road2 . get a jet set ,go real big n work down .H
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Post by sime66 on May 1, 2016 9:01:17 GMT
Have to agree, H; Polini reckon upjet by 10 for venturi. I’d have thought Malossi 166 and PM must already be about 110(ish)? (on a 20/20?) – So starting safe & high and ten over has got to be at least 120(ish). I don’t like suggesting jetting for others, and I haven’t had a PM or Malossi 166, but there-abouts and checking plug early to see how close it is. Fiddling with jetting with the venturi fitted is a drag too, I did a cut-out in it to get to the jets, so I could leave the venturi threadlocked in place; it’s on my (not so) brief build thread – page 18.
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pecker
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Posts: 65
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Post by pecker on May 1, 2016 11:45:49 GMT
Thankyou guys for the info.
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pecker
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Posts: 65
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Post by pecker on Sept 3, 2016 11:55:41 GMT
Still tweaking with this set up, a few light seizures and one bad along the way, Currently using 3% oil(pre mix in tank) autolube all blocked off/ NGK B8HS/ mixture screw back of carb 2 half turns out/ pilot-idle jet 52-140 and atomiser-mixer BE4 that come with kit/ original 160 correcter/ main jet 128. Currently 180 miles in on this kit, been keeping upto half throttle and below, Started with 130 mj , have been up and down, had a little/slight seize at 124 mj, With 128 mj plug chopped at half throttle 45mph/50mph indicated, the plug is still looking quite light It ticks over very nicely, starts immediately with choke in and out with electric start.
Would it be the way to go to use 24/24 components such as BE3 mixer/atomiser - 55/160 pilot-idle jet to be able to richen the process or just keep fiddling with main jet?
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Post by henri on Sept 3, 2016 16:55:58 GMT
junk the be4 ,thats a t5 atomiser ,i'd of thought a be3 would be better . if your still on half throttle the main jet aint in play yet . H
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pecker
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Posts: 65
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Post by pecker on Sept 3, 2016 17:59:01 GMT
Ye i will try a be3, do you think pilot could be tweaked, ive read there is a cross over from quarter throttle to three quarter throttle, thanks H ?
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Post by henri on Sept 4, 2016 8:31:16 GMT
1/4 to 3/4's its all atomiser mostly , the pilot will still be giving fuel right thru the rev range ,but atomisers in control . you say it starts easy with choke in an out ,is that from cold ,as startin from dead cold without choke indicates a over-rich pilot .H
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pecker
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Posts: 65
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Post by pecker on Sept 4, 2016 12:07:13 GMT
sorry H, i wasnt that clear, from cold starts nicely with choke pulled out then runs/ticks over good when choke pushed back in, then starts well when warm with no choke. pek.
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Post by henri on Sept 4, 2016 17:35:45 GMT
thats how it should be ,so pilots got to be about right/in the ballpark . as above ,i'd be lookin at that atomiser ,the jets with the kit are a average setting , but every engines different as are the riders . H
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Post by vespasco on Sept 4, 2016 18:59:34 GMT
I was wondering if, for your set up, you'd get more out of a complete si 24mm carb rather than just the jets?
The BE4 runs a little richer than a BE3
Stick with one of your larger main jets for now if you are still running it in.
Does it ever stutter or 'machine gun' when at lower revs?
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Post by henri on Sept 4, 2016 19:13:39 GMT
a be4 is the t5 atomiser ,from what i understand its richer at higher revs ,1/2 to 3/4 throttle than a be3 , but at 1/4 to 1/2 its leaner .an on t5's only has 1 airjet the 120 , or a mallosi 185 for there 172 kit . H
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pecker
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Posts: 65
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Post by pecker on Sept 4, 2016 20:10:34 GMT
alright vespasco, it does not stutter, but does make a bit of a loudish ttttttttt sort of sound (the best i can describe) when coming of revs at low speed, could that be machine gunning, is that bad, what would cure this. or does machine gunning happen going up through cheers pek
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Post by vespasco on Sept 5, 2016 19:46:56 GMT
When coming off the revs that ttttttttttt is probably ok. whatever it is ! hahaah
The machine gunning would generally happen going up through the revs
Don't be shy when using a large main jet. You don't want another seize.
When it runs lean it could run quite well, fast, nippy. Feels good. But I would recommend you find the point where it runs rich. Symptoms like the 'machine gunning' will help distinguish the different affects of the different jets. Then fine tune from there.
Sounds like your idle is ok.
Also, at what speed/throttle opening did you have a slight seize?
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pecker
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Posts: 65
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Post by pecker on Sept 5, 2016 21:12:49 GMT
Thanks for the responses from you guys on this matter, i had a slight/ small seize with a 124 mj @ half throttle going about 50mph as indicated after about 150 miles, i also had a bad one after 150 miles (a bit scary,) half throttle sameish speed with 1st try kit using a 118mj that time melted exhaust side top piston ring and scored barrel right up, and decided to get new one rather than re -bore and new piston etc.... Ive orderd the stack that is in a 24/24 to have a play with. also something i have noticed is if going slowish 20-30mph down hill slightly off the throttle , it feels a little like im getting a small bump up the ass coming from the engine, hope you get what i mean, is that a normal sort of feeling you get with kitted/expansion pipe set ups. all the best pek
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Post by vespasco on Sept 6, 2016 16:17:56 GMT
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pecker
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Post by pecker on Sept 6, 2016 22:22:20 GMT
Cheers vespasco, just thought I'd check on the bumping as thought it was a lot more pronounced with kit fitted, just ordered some more mjs, thanks again for advice,pek.
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Post by baldmeister on Sept 11, 2016 20:41:23 GMT
with all you have done to the engine, i would try a 140 main jet . worked well in mine with the polini thingy
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pecker
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Post by pecker on Sept 12, 2016 23:09:05 GMT
Cheers for that baldmeister,currently got a 135mj in along with rest of stack and idle/pilot that is standard to the 24/24 carb,still taking it steady (half throttle)but early indications look good, darker plug,but as you advised I will up the mj as i gradually give it more teddy, it's also starting well when cold with choke pulled out then pushed in,and ticks over nicely, and starts good when warm.pek
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pecker
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Posts: 65
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Post by pecker on Sept 25, 2016 22:24:41 GMT
Hello again boys, with being flat out at work and footie season in full swing i have not been able to test as much as wanted,but i have been able to get out and have a few really good runs this weekend. At close of play today i am up to a 148mj BE3 mixer 55/160 pilot/idle 160 air corrector, mixture screw back of carb 2 1/2 turns out B8HS.
Starts fine by choke pulled out then pushed in ticks over, starts when hot/warm no choke, then ticks over.
On flat level ground it revs out through ok, but now with these bigger mjs 135ers plus it really is very grumpy with any uphill gradient especially the 140s, and when slowing down behind traffic and going back on the revs a really boggie/flat spot at around 33mph - 39mph then when gets to 40mph revs out nicely again.
The more serious problem i still have is a very light plug at the 50mphish mark, even with the last mj tested at this speed (half throttleish) a 148mj i could not believe my eyes what i was looking at the plug colour wasnt that far off the colour of driven snow. VERY CLOSE TO SEIZE i would think.
So with a bit more help of you boys hopefully we can beet this little bugger. I,m thinking possibly air correcter, am i in the right ball park thinking bigger hole means more fuel= Richer, i see there is a 120 that is in the 2424g T5 carb could this possibly help??? and the maybe try BE4/BE5s in conjunction, and would going to a B9or10Hs plug help??? I have noticed the slides for the carbs, hopefully i can get round it before we explore them beautys only 13 of them. Was hoping to get to woolacombe this weekend, never mind always next year. As always any advice appreciated, pek.
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Post by jimscoot on Sept 25, 2016 22:43:09 GMT
Seems like your very close Pek,
keep at it and youll get there
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Post by pxguru on Sept 26, 2016 6:14:28 GMT
Pecker, Seems like you have the same issue as Vespasco. A smaller Air Corrector is the next step here. I suggest an AC140. The AC should be no smaller than needed. After fitting an AC140 hopefully the plug is black enough on the 148MJ and the MJ can be reduced step by step until digestive colour at WOT. Get this far and some of the lower rpm issues will have improved already.
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Post by vespasco on Sept 26, 2016 16:41:40 GMT
Yeh, I'm having this problem too.
Last year it was over heating anything after 1/2 throttle - this was due to the BGM fast flow fuel tap I had fitted. It caused an air lock and halved the fuel supply to the carb. I'm now on a stock tap.
My exhaust also was shot to bits internally and made the engine hot too
I also upped the plug number to a B9
Also I re-torqued the cylinder head and carb and exhaust/cylinder joint.
All of this helped a little but it's jetting the carb that's going to change things.
Have a look towards the end of my thread " Rally modifications"
My motor, like yours, starts well hot or cold now, so leave the idle, for now anyway. I'm going to try a drilled out 140AC, drilled to 1.5mm, to make a 150AC or you can try the 140AC It should feel too rich so will have to come down on the mj
Start with stock jetting and slide etc but with a big MJ. Earlier you mentioned anything bigger than a 135MJ on yours and it bogs...bogging, like you described is what I consider too rich... The key is to find the Mj size where it doesn't bog but if you go up just one size it should stutter or bog just a little. For me, this is optimum MJ size. Going up one size from perfect is obviously safer.
What I'm trying to do at the moment is just to get a brown plug at WOT, despite how it runs getting there. Then make changes to atomizer/slide if needed... but hopefully that won't be required.
jimscoot - tell us more about your set up, looks impressive... maybe in another post
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pecker
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Post by pecker on Sept 26, 2016 20:52:55 GMT
Cheers again lads for the comments, i believe a 140AC is standard in a 20/20 so i have one of those, last night reading late as you do with eyes nearly shut i came across the sip air corrector's web page they say the higher the number AC's go the leaner they get, so using that theory 120AC the richest 140AC and 150AC middle ground with 160 being the leanest. So im going to order a 120AC to have a play with as well, along with a 9er plug. The weathers looking good for weekend, so i will be able to have a good go, and hopefully get the plug coloured up nicely. All the best, pek.
ps. I was parked up @exmouth about a month ago, when two pleasant women approached me and mentioned there other halves were into scooters after a brief conversation they departed by saying if you can master a tuned vespa you can master a good women, i said i havnt tried one of them for a while.....laughs all round.
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pecker
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Posts: 65
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Post by pecker on Sept 26, 2016 21:18:46 GMT
Just realised 120AC only for T5, so 140 it is,pek.
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Post by pxguru on Sept 27, 2016 7:01:09 GMT
There is an 185AC as well and there is an 120AC for the 24/24E. Nice to experiment but these are not really to be played with though. The size of the AC should be the smallest that makes it run ok at all rev ranges. Too small and it will seize, too big and it will seize . Just to make carb setting up simple the AC is not just weaker and richer, it changes the distribution and is both, like a needle in a big boys carb.
A 140 should be the right one for yours.
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Post by jimscoot on Sept 27, 2016 7:31:01 GMT
Where do I start,
You need to ditch the 20/20 carb. Buy a 24/24e carb, even better if you can get the DRT modified top and drilled 1.8mm carb bowl hole.
It's very important to stick to the 160/be3 jet stack. And around a 48/160 or 50/160 idle jet.
Ok this is gonna hurt,
Ditch the Pm pipe and get a sip road or a sip road XL.
The Pm pipe demands a bigger carb like a PHBH28mm , but I wouldn't go there because it's old tech two stroke rotary valve and it likes the SI carb.
Come back here when you've bought the 24carb and we can go from there
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Post by pxguru on Sept 27, 2016 15:27:27 GMT
I like the PM pipe when combined with a standard gearbox It will jet in fine on the SI20/20, the 140AC should be enough to fix that. A bigger carb is always better if you don't care about economy or autolube. With a low gearbox this set up should give more high rpm power/top end than a SIP pipe and overall will feel a bit better (and sound nicer). let's see how he gets on with this first
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pecker
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Posts: 65
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Post by pecker on Sept 27, 2016 21:51:59 GMT
Cheers very much for the responses, all taken on board,pek.
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