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Post by broughton5 on Mar 3, 2013 19:44:01 GMT 1
right chaps got a 12a carb with a 220 main jet (for micron), fitted today for first time run up no probs but idle hangs at about 3k for a while before dropping to normal, also when you give it a quick blip on the throttle from idle it almost dies, am i right in thinking its the pilot jet to lean? standard 20 pilot fitted , if so why would it need changing from standard and also which size would be best to try cheers in advance pete.
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Post by skydemon on Mar 3, 2013 20:01:29 GMT 1
You're not little Pete the Medic are you??
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Post by broughton5 on Mar 3, 2013 20:09:12 GMT 1
no mate im big pete the tarmacer
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Post by looey on Mar 3, 2013 20:21:36 GMT 1
Doubt it will be the idle/pilot jet size. I have had them where the hole size has reduced over the years just through years of fuel drying. Might be worth just checking the bore of the pilot jet is as it should be. I use tiny precision drills and really carefully run them through by hand.
I assume you've got the air screw set as per book ?. If the pilot jet is too small you can reduce the air screw setting by small increments at a time to see if it makes it any better.
After that it could be an air leak which would produce the exact symptoms you have
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Post by noelrdlc on Mar 3, 2013 20:24:34 GMT 1
I would take that 220 main down to a 210.
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Post by broughton5 on Mar 3, 2013 20:47:01 GMT 1
no air leak cos put my old carb back on and everything normal
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Post by ferret79 on Mar 3, 2013 20:58:10 GMT 1
sounds similar to induction leak, could be crankshaft seals, is it starting easy?
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Post by broughton5 on Mar 3, 2013 21:07:28 GMT 1
yep starts fine like i said put my other carb back on and every thing fine only decided to change carb because mines of a 10v dt but with the 10w jets fitted , so thought iwould get a 12a one and see how it ran with that.
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Post by ferret79 on Mar 3, 2013 21:12:13 GMT 1
i would strip carb right down everything out, clean all jets with cleaner blow out with air line if you can, check float height, and try again
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jackup
Thrash Merchant
Of all the things I've lost I miss my mind the most
Posts: 388
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Post by jackup on Mar 4, 2013 9:14:21 GMT 1
sounds like the choke circuit is partial blocked take the float bowl of an clean the tube in it with carb cleaner also whats your needle position
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Post by looey on Mar 4, 2013 10:52:15 GMT 1
Are the Pilot jets the same size in each carb ?. If so, swap em over to see if it makes any difference, if not then you can eliminate the pilot jet.
Have you adjusted the air screw to see if it makes any difference ?. Screw it in to richen the pilot mixture.
It won't be anything to do with the main jet. The main jet doesn't do anything at all until 3/4 throttle and above, which clearly you are not using at idle or blipping the throttle.
Once it has warmed up and the choke is in, it won't be anything to to with the choke circuit either unless there's an air leak in it which will be highly unlikely.
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Post by broughton5 on Mar 4, 2013 17:50:17 GMT 1
yes mate pilots the same swopped them no difference at all, just done a air leak test with wd40 every thing good ,fiddeld with the screw made no difference,only thing i havent done is take screw out completely(next job) one thing i forgot to mention theres no air box snorkel fitted would this make a difference? and needle position is 4 has standard nether thought to change that.
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Post by looey on Mar 4, 2013 18:11:19 GMT 1
Snorkel missing won't make any difference, mine doesn't have one.
Needle position shouldn't make any difference either but for the time it takes you could put it to one clip richer to see (one notch further down when holding it with point downwards).
Might be worth getting the bike nice and warm then take it for a run ?. Wouldn't give it any beans until you know the carburation is good though, maybe just around the block to see what it's like once it's properly warmed up ?.
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Post by broughton5 on Mar 4, 2013 20:06:34 GMT 1
just had a closer look in the carb body theres a angled hole towards the front of the carb(towards the inlet rubber)about 7mm of the pilot hole it looks as if it heads down towards the pilot passage and looks to be clogged slighly with some white cruddy stuff could this be the problem?? time to invest in some carb cleaner and give it a really good do thats me sorted next weekend work permitting!!
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Post by mellow on Mar 4, 2013 22:16:40 GMT 1
Thats the bypass.must b clear and often missed.should get a mist of fuel out of that(or carb cleaner  |
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Post by jollyr6 on Mar 4, 2013 22:18:56 GMT 1
Hi Pete if u get any probs let me know ill dig my carb out if u like hurry up n get it done u have my number mate ;D
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Post by broughton5 on Mar 5, 2013 8:10:01 GMT 1
is that you tone ? shes up and runnig mate got the old carb back on.
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Post by flames on Mar 6, 2013 19:29:29 GMT 1
have you taken the airscrews right out yet? some carbs hav a rubber o ring on them,dont know if yours is sposed to or not,but worth checking.
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Post by broughton5 on Mar 6, 2013 20:29:48 GMT 1
yes mate has got one going to give it another clean, i think it was the bypass blocked ,will give it ago at weekend if i get the time. cheers for the advise chaps keep you posted.
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Post by broughton5 on Apr 1, 2013 13:35:35 GMT 1
well chaps decided to brave the cold today and refit the carb after cleaning the bypass, and hey presto idle comes back down to normal instead of hanging at 3k thanks for all advise and help just need to give her a run now ,still to cold for me yet,thanks again.
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