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Post by 90GTVert on Feb 28, 2010 19:30:40 GMT -5
A valve timing issue shouldn't just come on suddenly like that. You should have had the same trouble when you first started it after your big bore installation unless something came loose like the cam chain tensioner or a valve adjuster.
Check your spark plug, cap, wire, connections to make sure everything is tight and looks OK.
Check your oil to see if the level has risen or if it smells strongly of gas. If that has happened you may have a stuck or improperly set float that is letting fuel dump into the intake and run into the engine. If you find a lot of gas in the oil DO NOT run it until the oil is changed.
Check for intake/vacuum leaks or fuel delivery issues that could lead to a lean condition. If the engine leans out enough the mixture won't always ignite and it can spit raw fuel or ignite it inside the exhaust. Since the GY6 carbs have an accelerator pump, pumping the throttle could be making it push enough fuel to keep running.
If you installed a performance CDI along with your big bore, try removing it to make sure it isn't causing ignition timing issues.
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Post by thatoneguy on Feb 28, 2010 20:06:55 GMT -5
well i checked the chain tensioner and the bolts that were holding it came undone causing the chain to skip on the cam teeth now im afraid my timing is messed up i only hand tightened the bolts on the tensioner cus i used some liquid gasket stuff to reseal it but now i fear the timing is all jacked up and im not quite sure how to fix it.
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Post by 90GTVert on Feb 28, 2010 20:37:06 GMT -5
If the timing slipped the marks on the cam and flywheel probably won't be aligned now.
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Post by thatoneguy on Feb 28, 2010 21:04:59 GMT -5
how do i re align them i would really like to get this thing up and running again if not i will just buy a new motor and put in it.
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Post by 90GTVert on Feb 28, 2010 21:31:37 GMT -5
Wow. Don't go junkin' this motor just yet. Have you found that they are not aligned yet? If they aren't lined up, set the engine so the flywheel's T mark is aligned with the case pointer. Loosen the cam chain by removing the tensioner. Pull the chain off of the cam. Line the 3 holes up on the cam and install the chain. Re-install the tensioner. If it runs fine after that, consider yourself lucky nothing worse happened. I fixed an ATC110 not long ago that bent a valve because it skipped timing and the piston smacked the valve.
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Post by thatoneguy on Feb 28, 2010 22:41:24 GMT -5
does the piston need to be at its highest point if i align it on the T?? becuase i checked it and its not the only point its fully extended is when timing mark on the side of the case is at the top of the arrow on the fly wheel which way it tells you to rotate it?
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Post by 90GTVert on Feb 28, 2010 23:09:04 GMT -5
Yes, the piston needs to be at it's highest point, called top dead center. The T stands for Top dead center. If the flywheel is on T and your piston is not at TDC, something is wrong. The flywheel is attached to the crankshaft and so is the piston. The only way that should be off is if the crankshaft were made incorrectly (in which case your engine should have been running like this from the day it was new) or if the flywheel or woodruff key that positions the flywheel had stripped and things went out of position (very very unlikely). It would be more likely that you are looking at the wrong pointer on your case.
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Post by thatoneguy on Mar 1, 2010 0:43:48 GMT -5
on my fly wheel i have the letters TF and just before the TF is an arrow and at the very tip of the v on the arrow is where every thing lines up/top dead center or so it seems and thats how it all lined up before i put the new piston and stuff in so im not too sure whats wrong with it. i got it all put back in ima try and fire it up tomorrow if that dont work i can provide pictures if that might help figure things out. idk im pretty sure i have it lined up with the right mark on the case theres only one... IE it ran just fine before i did anything to it i just wanted a lil more bang when i stepped on the gas
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Post by shiftless on Mar 1, 2010 12:45:04 GMT -5
I happen to be redoing a top end today and took a pic or 2 for you timing indicator on case  hard to see the marks in the pic , but the flywhel should be marked like this  piston at tdc  I visually confirm tdc with the head off and mark the flywheel with a sharpie tdc on this engine is right at the top of the arrow on the flywheel install your cam as previously mentioned ( a tooth or few off will make a difference in timing) The conrod, crankshaft and flywheel are fixed and there is no adjustment there I'm guessing your cam isnt aligned properly EDIT: I noticed in your other thread that you switched to a 32mm carb That might too much carb for your engine I run a 28mm flatslide jetted at 38pilot, 130 main on a 61mm bbk and it seems to be a good combo |
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Post by thatoneguy on Mar 1, 2010 16:02:21 GMT -5
thanks for the help ill either try toning my carb down or i might just try my old one and just rejett it but i was pretty sure i almost had it i went back through it and realligned every thing and every thing lines up exactly so im donna try and fire it up keepin my fingers crossed..... on a side note i was running the 32mm carb onit before i did the big bore kit and it was runnning fantastic but i had it jetted to 125 ill just do a lil trial and error until i get right
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