TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: niterunner68 on October 09, 2014, 06:51:38 PM
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OK for those of you that sent me a few hints on things to check out thanks! But...here is the deal I did a new top end on a fresh bottom end build, have weisco stroker crank n rod set up, LRD ported jug with an 86 piston set up and spacer plate. assembled the monster and wouldnt start(HAD THE BREAK YOUR LEG KICK BACK) so ...majority said CDI box was bad...ok put on a good one and now I dont have the crazy hard kick back but now after about 3 or 4 kicks it back fires...I am so freeking out here...idk what to do next
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Have you checked spark at the plug? What about checking all the electricals per the manual?
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Yes Bowtie first thing I checked was spark, it is all good. I am in the process of going over the wiring...I am comparing it to my other R but problem is the other has the CR ignition set up so idk if that referance is gona be 100%....Could this be a ground issue? have spark but maybe not enuf to fire? My big question is what color is the ground that is usually by the coil? black with white stripe?
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Yes Bowtie first thing I checked was spark, it is all good. I am in the process of going over the wiring...I am comparing it to my other R but problem is the other has the CR ignition set up so idk if that referance is gona be 100%....Could this be a ground issue? have spark but maybe not enuf to fire? My big question is what color is the ground that is usually by the coil? black with white stripe?
I don't have a ground by the coil, mine is up by the CDI but maybe that's not where it's supposed to be. It's green in color.
The engine needs to have a good ground to the frame in order for everything to work right. This is usually accomplished by metal to metal contact at a motor mount. Put an ohm meter between the one of the frame bolts and the head or cylinder or something and see if there is any resistance, should be 0.
What is the spark plug gapped at? Needs to be pretty tight, I put mine at .018".
Are the jets in the carb clean? what does the plug look like after kicking it to try to start? Wet or dry? smells like gas?
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I'm no electrical expert at all so i'll just say the obvious things. First I do is clean every single bit of corrosion off all connectors, flywheel, pickup coil etc.
and I noticed you saud you used a Wiseco crank.......be very weary of that
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First thing I would do is put a new plug in it gapped to .016" if it will not start then pull start the bike, many times the bottom end gets wet with allot of oil and fuel. Jamie drove a couple hours to my house to start Jon's motor and with my electric starter it was running in a matter of a few revolutions. Once you get it started and it cleans its self out more than likely your issues will go away, if they do not then you need to start dissecting the electrical system and carburetor
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Yank the plug and crank it over, make sure everything is free and smooth. Have you done a static comp test just to check where you're at? Leave a rag stuffed somewhere? haha stupid stuff but it happens!
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just go through a process of elimination. try pull starting it if you think the bottom end is full of gas. if that were the case your plug would probly be drenched however, so that would be a clue. try new plug and if its fairly dry you can probly look else where for the problem
couple other things you might want to look at since you say it has good spark. if theres a inline filter or even if there aint a inline filter atleast be sure theres good fuel flow to the carb. went through this very recently on one of mine. filter was not letting fuel to the carb. be sure pilot jet is clear, it should still fire with the choke however but once its running the clogged pilot will cause problems
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Yank the plug and crank it over, make sure everything is free and smooth. Have you done a static comp test just to check where you're at? Leave a rag stuffed somewhere? haha stupid stuff but it happens!
these engines will run on very little compression. might be down on power but they will still start and run. if the kicker has even the slightest resistance, thats plenty enough compression to start it
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I was more curious if it had extremely high compression.