right, as i stated in my project im having a few running issues. my bike is a bit of a mis-match of parts, so bare with me here, i really need another opinion on this.
my old engine cases were model "3BN" (replaced)
my current/original CDI is also "3BN" (kept this)
my original barrel is 3MB, as is the head (kept these, rebore)
right, now. my current engine cases that i bought to replace my old were marked "3DB" but there was not any difference from what i could find.
Onto my actual question, im having running issues with my carb setup, BUT my carb has a flat slide type with the 210 main jet. Acording to the haynes manual, this jetting is ID'd as "3MB". Aparently 3BN is a 180 jet, i am just not sure if the carb i have for my engine is right.
the bike runs, it will only run on the idle, then i can turn it off and it will run for a bit, stall and wont start again unless i turn the choke back on. it's also smoking quite badly. i have done my best to keep the carb factory set, float height etc.
-- Edited by MartZ0r on Monday 30th of May 2011 09:11:18 PM
right guys, i found ze problem. basicly i had 2 carbs, my original had the air screw rounded off and right in, so i bought a supposidly exact copy. both flat slide, both 210 main jet etc. so i asumed the carbs were infact identical. i have just teared both carbs down to compare them, i stumbled on 2 problems.
one is, the jet needles on the slide in both my carbs are different sizes, the one is 2mm longer and a bit fatter. the other is more pointed and narrow
second problem is the pilot jet in the carb i had in the bike was 17.5 instead of 22.5
it was a noob mistake and is a lesson learnt, always check, dont assume!
i will let you guys know how it goes tomorrow when i fit it back in.
EDIT: carb is off a DTX. hence the different pilot jet.
-- Edited by MartZ0r on Monday 30th of May 2011 11:02:23 PM
That is smoking quite a lot, probably just needs warming up and taking for a good thrashing.
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keep an eye on your oil levels, one of your crank seals might be seeping oil. I've had this before but it was bad, I had a massive stinky cloud billowing out the bike!
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mine does that to when its cold clears up in about 5 mins tho. I always thought it was supposed to smoke a bit, iv done what youve said tho m8 kept an eye on my oil levels its stayed fine tho , an the seals from what iv seen so far ,all looked good..
They always will smoke a little bit, that's part of being a 2-stroke!
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i dont have a bad crank seal, i already checked for that, it's definitly 2 stroke burning.
but i have made a worrying discovery. i tested y'day with a compression tester, it gave 20Psi. it was cold so i thought id try it today warmed up properly, thats how it should be done... no luck, 25Psi max. if i add oil into the barrel it gets nearly to 50Psi with a good few kicks. fresh builds have to bed in, but that is too low for sure.
something wrong with the top end, that would cause oil not to get burned up. rings look fine from under the exhaust port, so unfortunatly its a head/barrel off job :(
took the barrel back off, piston rings are definitly in the correct order and i cant see any issues with the bore/piston that would cause such low compression.
i thought maybe my gauge is a bit naff, but to be honest i can turn the flywheel over by hand fairly easy.
right, my gauge has been sending me crazy. there is jack wrong with the bike. i got it running great now and starts first kick every time, very responsive on the throttle. i put my gauge on theother day after doing some work on the bike, it was reading 15psi, the bike had been running perfect.
there is no way the bike could run with the 25psi figures it was giving, let alone 15. i have left the engine alone now and carryed on getting it finished. i will update my project page.
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DT125R Forum -> Tuning -> few questions related to engine numbers and CDi's and carb models
