Valve Timing issues

jazzyrigged

Jazzyrigged
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Over this past winter I tore down the engine on my 78 special and replaced all of the gaskets on it. I have reassembled everything and found that air is blowing outward from the carbs mount and sucking inward from the exahust, completely opposite of how things should work. Could I have the timing on the camshaft completely off when I reassembled it. Is there anything else that could cause this to happen. I followed the instructions from 650 central and thought I had everything reassembled as they described, but I have an obvious problem with the backwards running valve system. Any help would be greatly appreciated. Pretty sure I will have to take the head off and figure this all out. I had to walk away from the project this morning and now I am calm enough to try to rationaly figure things out. Thanks all!
 
I have also had problems with valve timing. It sounds like you may have the camshaft in backwards, i.e. the threaded part on the wrong side. The threads/the advance mechanism should be on the right side and the points on the left. :thumbsup:
 
Over this past winter I tore down the engine on my 78 special and replaced all of the gaskets on it. I have reassembled everything and found that air is blowing outward from the carbs mount and sucking inward from the exahust, completely opposite of how things should work. Could I have the timing on the camshaft completely off when I reassembled it. Is there anything else that could cause this to happen. I followed the instructions from 650 central and thought I had everything reassembled as they described, but I have an obvious problem with the backwards running valve system. Any help would be greatly appreciated. Pretty sure I will have to take the head off and figure this all out. I had to walk away from the project this morning and now I am calm enough to try to rationaly figure things out. Thanks all!

Welcome to the site man. I am from Jerseyville and will be up there in a week or so (not that I could help). Any pics of the ride?
 
I have also had problems with valve timing. It sounds like you may have the camshaft in backwards, i.e. the threaded part on the wrong side. The threads/the advance mechanism should be on the right side and the points on the left. :thumbsup:

I thought about perhaps the camshaft on backwards, but the points are connected and on the left and the advance mechanism is on the right. Do you think it could be out of sych 180 degrees or something along those lines? Just trying to get to the heart of the problem, but very appreciative for all suggestions. Thanks all!
 
Even with the cam reversed the valves would work right. I have looked at a cam just for this reason. The question came up a week or so ago. The cam lobes are the same. Or close enough.
How are you turning the engine over to observe this? If you are turing it by the alternator nut you need to be turning counterclockwise. If you are turning it clockwise then your turning it backwards.
An easy way to check the cam position is to turn the engine counterclockwise at the alternator nut untill the timing marks line up at TDC.
Under the points cover look at the position of the points cam alignment pin. It should point straight up or straight down.
If at 12:30 or 11:30 there is a problem.
 
That would make sense. Thinking back on the procedure it sounds like I may have been turing it clockwise instead of counter clockise when I set the timing. Does anyone know of a way to reset the timing without pulling the engine? Thanks everyone for helping with this. Once I get it all back together I will post some pics of my bike.
 
yeah make sure the pin is at 12 or 6 o clock first. if not your cam chain is off a tooth (or more).

not sure what you mean by reset the timing.. turn the motor counter clockwise, tighten the cam chain so the adjuster is flush with the lock bolt. (turning it clockwise probably threw off the chain tension)

turn to tdc (if you go past it do not turn it clockwise to go back to the t mark, go around again), check for the pin location on the cam. if it's 12 or 6 go on to valves
 
there's a pin on the points side too. either one works. if you look at the points side just make sure the advance weights are snapped back all the way
 
Allright folks heres the scoop from work this morning and into the afternoon. Undid all the engine mounts and leaned it to the left, took the head off and put the camshaft into the correct timing position (those damn gremlins in the garage must have messed up the timing the first go around.) Anyway putting it all back together and noticed the auto advance unit has a break where the pin fits in to advance the unit. Well luckily Mikex XS carries a replacement part. Guess I won't be riding this weekend, but maybe next. Thanks all for the advice. I'll post more soon, and hopefully some pics once it's all back together.
 
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