bsr65
High Number
Posts: 114
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Post by bsr65 on Sept 1, 2014 9:17:49 GMT
looking for ideas to cure my px200e spark plug being sooty black. The engine is standard apart from sip road 2 exhaust, drilled air filter, b8es plug and 120 main jet. Iv'e changed the plug, cap, ht lead and cdi and checked the stator with a meter. Ive had the mixture screw out from 1.5 to 3.5 turns out and the problem persists, apart from this the scoot runs well??
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Post by partanen on Sept 1, 2014 9:39:20 GMT
While waiting better answers I wonder why b8es? Wouldn't b7es be better. Generally If spark plug is too cold it cannot clean itself and will become sooty.
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Post by pxguru on Sept 1, 2014 9:57:13 GMT
It should be running better than that but reading this a few things come to mind for you to try. A near standard PX200E should have a B6ES plug for normal use and maybe a colder B7ES if you do mostly motorway riding and only if the B6ES plug is showing signs of burning up. Second I am wondering how you set up your air screw. If you have one of those new fangled brass nut screws, a top tip is to take it out and hacksaw a slot in the top for a screwdriver This is how I do it on an SI carb. Start it up and warm the engine fully. Then with it not running, gently wind the air screw all the way in till it stops. Then out half a turn. Start up the engine. Adjust the idle so its revving a bit quicker than usual (about 1300rpm). Wind the air screw out a little at a time until the rpm picks up very slightly. Out a little more till its smooth, then Stop winding there. Adjust the idle back to normal. Blip the throttle to make sure it doesn't cut out (too weak). Rubber bung back in and thats it. Not so complicated edit: took too long with my quick reply!
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Post by vespasco on Sept 1, 2014 11:12:38 GMT
Put in a new plug Simples a b7 !!! B8 is too cold especially if you only pop into town every now and then. You may want to clean inside the head too as thats going to be the same as your spark plug. If everything is ok but just your plug is sooty then check you are using the correct oil mix 2% A hotter plug should also help considerably. Clean the air filter Take it for a long run and burn off some of that black stuff And make sure you have the mix screw adjusted correctly
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Post by henri on Sept 1, 2014 13:56:34 GMT
try a 118 main jet , mates px200e leccy start with sip road 2 an b7 plug an drilled filter does fine on that in town an his 12-15mile motorway commute everyday , depends on ya use of scoot , if all in town maybe even a stock b6 plug ,but doubt it ,i run allmine on b7 never mind what manual says ,it was written 30 years ago an petrol is different now ,unleaded for a start, H
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Post by vespasco on Sept 2, 2014 20:06:44 GMT
Im suprised that a px200 autolube with drilled filter and sip road only needs a 118! Id have thought thats well lean for that set up!? Unless it doesnt ever get riden above 1/2 throttle?!
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Post by sime66 on Sept 2, 2014 20:52:38 GMT
Mines DR180, 24mm carb, drilled filter, Sip Road 2, 120 main, B7, 2% mix - luvvly jubbly!
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Post by henri on Sept 3, 2014 9:20:37 GMT
he's only got 1 throttle position ,WOT, an i was well surprised aswell ,annoyed 2 as i had a 118 an had to order in the 122/120's we tried first, it use to crack/pink/ping as it cooled after his commute/thrsash an smell overhot on a 116 n standard pipe ,now its steady at 150 degrees , tho i want to stick a 120 in for safety as winter an variable temp/humidity/pressures coming an i feel its on the ragged edge of lean with a 118, that an the 120 cost me a fiver an i want me's moneys worth, H
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bsr65
High Number
Posts: 114
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Post by bsr65 on Sept 3, 2014 9:57:44 GMT
I fitted a 118 jet and a b7es plug, took head off and cleaned the head and piston crown, did notice a fair bit of side movement in the bore. (piston slap) settled on air mix screw 2.5 turns out. Took for a good 5 mile thrash on A road then checked plug, it was a chocolate brown colour, Put it back in started scoot up for a minute then checked again(sooty black) do you think the worn cylinder is causing it. Ive had piston slap before on another p2 but that had no effect on plug colour .Cheers for reply's
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Post by henri on Sept 3, 2014 11:20:11 GMT
at tickover an less than 1/3rd/ half throttle plug will show sooty as it aint up to temp to clean/burn of the carbon ,only colours to check/trust are from a proper chop, kill switch n clutch in at same time from over half throttle an coast to side of road n pull the plug, its mandatory to burn fingers atleast twice aswell. if plug really sooty from tickover i'd wind ya mixture screw in half a turn ,its at 2.5 turns out , dont spose ya know wethers its a fine or course thread 1 as piaggio changed em a few years ago ,for fine 2.5 is a good starting point ,1.5 for course , warm it up an wind out screw til the tickover hunts up/down revs then go back in a turn til it evens out, course ya got to be sure of timing/plug gap n engine state first as carb tunes the last/end not the start , never simples is it, H
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Post by pxguru on Sept 3, 2014 17:30:34 GMT
If it starts by 3rd kick when cold then the bore isn't that worn. Its still running too rich at low revs which is not the main jet. I would put the 120 main back in with that pipe. Even from new there might be some random friday afternoon pilot jet fitted. With autolube running yours should be a 50/120 pilot jet.
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bsr65
High Number
Posts: 114
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Post by bsr65 on Sept 5, 2014 12:37:54 GMT
If it starts by 3rd kick when cold then the bore isn't that worn. Its still running too rich at low revs which is not the main jet. I would put the 120 main back in with that pipe. Even from new there might be some random friday afternoon pilot jet fitted. With autolube running yours should be a 50/120 pilot jet. 120 main jet back in, checked pilot jet that is 55/160, it does run the autolube and it does start on 3rd kick, so it seems the pilot jet is too large. cheers
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Post by vespasco on Sept 5, 2014 17:29:55 GMT
If it starts by 3rd kick when cold then the bore isn't that worn. Its still running too rich at low revs which is not the main jet. I would put the 120 main back in with that pipe. Even from new there might be some random friday afternoon pilot jet fitted. With autolube running yours should be a 50/120 pilot jet. 120 main jet back in, checked pilot jet that is 55/160, it does run the autolube and it does start on 3rd kick, so it seems the pilot jet is too large. cheers The 55/160 pilot jet is actually leaner than a 50/120! Theres gonna be black soot in there. Especially if its just idling away for a few minutes. As mentioned, you need to trash it to heat the plug up enough to.be efficient. If you dont ever ride hard and fast try an even warmer plug Without actually seeing exactly how sooty the plug is and depending on how you rode, ie..WOT for a few minutes, or town riding.. Post a pic of your plug
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Post by pxguru on Sept 5, 2014 18:34:40 GMT
the 55/160 is why it is running sooty. 55/160 is the standard idle jet for a non autolube P200E. Change it to 50/120 and it will all spring into life at low rpm. When the pilot jet is too rich the airscrew doesnt seem to do anything unless its wound right in. Get the 50/120 in and it will run better right away. This is the jet that should have been in yours from new. Vespasco: the 55/160 is richer at idle than the 50/120 and leaner through the progression stage. Just dividing one number by the other is just some some old wives tale. The SI pilot jet is acutally pretty smart. It does two jobs. The small number is the pilot jet for idle till just off the throttle stop. The large number (bigger is weaker)is top hole air inlet for the progression jet atomiser, which kicks in next, up until the main jet atomiser comes in before 1/4 throttle. The boring old SI is no dumb carb
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Post by vespasco on Sept 6, 2014 18:48:45 GMT
Nicely put Ive often wondered about the idle, especially when I wanted to fine tune this part of the circuit. Its the same as the main jet stack really but built as one component. I came to the conclusion that, for my needs, I wanted to try something like a 180/65, rather than something of a similar ratio, like a 120/50. These are not commonly available so I ended up with the 120/50 which I had anyway but have to screw out the mix adjuster screw a little more to compensate. But I'm m not entirely sure I've got that right?! Its tuned by ear/feel anyway. Im always looking at ways to improve my set up. Thanks.
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Post by pxguru on Sept 7, 2014 15:09:16 GMT
Tuning by feel is certainly the best way. With a kitted or tuned engine the slow running must be slightly rich. Most mild tuning works fine with the standard jets but if disabling the autolube and putting oil in the tank instead, then bigger jets are required to allow for the oil now going through the jets.
When the pilot jet number is about right the airscrew will be responsive. From mid position, wind it in it will rev higher, not smoke, run terrible, then cut out and wind it out from mid and it will start hunting and smoke. The pilot jet air inlet number adjusts the mixture when the throttle is just open (one or two mm). Keeping the pilot jet number the same and reducing the air number until it splutters a bit (when riding it) at just open throttle, then increase the air number one jet to run ok. And thats it. The pilot jet will not need to be redone again if going on to change the main jet or main atomiser.
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Post by partanen on Sept 7, 2014 18:50:47 GMT
I've been told (by SIP) it's mixture screw in these SI carburettors. Wind it in gives leaner mixture. Wind it out gives richer mixture.
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Post by vespasco on Sept 7, 2014 19:03:35 GMT
Yeh thats it.. It controls the amount of mixture coming from the idle jet circuit.
And I tried something today, to block off the air feed on the idle jet at tick over. It made only minimal difference if any and it still ticked over ok
The more I think about it, the more it makes sense. Now I just need to find my bag of idle jets to experiment some more.
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Post by pxguru on Sept 8, 2014 4:59:50 GMT
I've been told (by SIP) it's mixture screw in these SI carburettors. Wind it in gives leaner mixture. Wind it out gives richer mixture. The naming of the airscrew, didnt Shakespear write a play about that? Very good point though. In British we (me) tend to call everything airscrew but technically if the airscrew is after the progression diffuser (I say atomiser) it is then a mixture screw. On any carb if the airscrew is near the carb mouth it is a true airscrew and near the engine side it is a mixture screw. And just to complete the confusion, if you have a true pilot airscrew on your carb, it will work backwards too (wind out for weaker and in for richer)
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Post by pxguru on Sept 8, 2014 5:01:04 GMT
Yeh thats it.. It controls the amount of mixture coming from the idle jet circuit. And I tried something today, to block off the air feed on the idle jet at tick over. It made only minimal difference if any and it still ticked over ok The more I think about it, the more it makes sense. Now I just need to find my bag of idle jets to experiment some more. Good work Did you ride it blocked to see if you could feel it too rich?
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Post by vespasco on Sept 8, 2014 15:28:48 GMT
I will but have a base gasket leak to deal with first!
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