only running on 1 cylinder need HELP!!

[mynameissean]

i just got my bike all wired up and started it up, both sides have spark, but the bike is only running on one cylinder.. i did a compression test on the cylinder and the right side near the kick start has alot of compression about 120 psi and the left side has about 50-60 psi. i cleaned the carbs thinking that it was maybe gunked up , but still the same thing.
when the bike is running and i give it gas it seems like the left side cylinder get stuck wide open and then backfires alot.

i dont have any idea what is wrong with it. im so close to finishing

 

[rickieh]

try some cylinder lube and system fuel cleaner?i dont know a while lot but id try that

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[jchrisk1]

Sounds like you're lean. Probably have an air leak or your carbs are still dirty. Or both. Did you clean the carbs as per the carb guide? So, it's running on both cylinders when you raise the rpm's?

 

[mynameissean]

I don't think its running on both cylinders, it just back fires a lot whe I rev it up, but only from the left cylinder.. I dont no where the air fuel mixture screw is.. but when I did a compression test it said I only have about 60 psi in the left cylinder

 

[HooliganCycles]

Is that with the throttle wide open? Pour a little motor oil in the spark plug whole and check compression again, if it gets better its rings, or if u have a leak down tester that will tell you exactly whats wrong

 

[littlebill31]

What cylinder is not firing? 60 psi is terrible. That's about 100 psi too low.
Did you read www.amckayltd.com/carbguide.pdf so you can find the major parts on the carb.
Again, if you don't study the parts, and know how they work, it will never run correctly. Getting "lucky" does not work on these bikes.

 

[grizld1]

OK, one more time--you can't raise compression to spec by screwing with the carburetors. Step One: buy or download a manual. Step Two: read it.

 

[CDNTX650]

sounds like a valve problem to me.

 

[mynameissean]

That was not with the throttle wide open I didn't no you had to do that. I'm going ti try that then the oil.
Its the left side. The side with the stator .
I'm ordering a manual tonight

 

[XSLeo]

It probably doesn't run on the side with the low compression. The compression should be with in 10% from side to side. Yours is 50% difference.
If it comes up with a tablespoon of oil down the spark plug holes, then the rings are the problem.
You need to do a top end job. While apart check the lower end according to the book.
Leo

 

[littlebill31]

There is a lot of info in the "tech" section on here about "Not running right" and other important stuff to check, and how to check it properly.

 

[5twins]

I wouldn't throw the towel in on the top end until I checked all external possibilities. Check the valves. A tight one could leak compression. If this is a long dormant motor just brought back to life, some run time might start bringing the compression back up on that low side.

 

[gggGary]

What 5twins says I have brought em back from lower than 60PSI. Not every time but sometimes it can be revived. A chunk of carbon on a valve seat or a valve seat that's kinda rusty from sitting open will do that, stuck rings can give low readings. I like to hit cylinders and valve stems with PB blaster let em sit try it again. As others are saying STOP! investigate the cause, when you know that. report for suggestions on possible fixes before it's tear down time. Sticky valve stems are also common on long time sitters. OR the PO may have run it for a long time with a bad float valve and ruined a cylinder. That happens a lot too.

 

[xjwmx]

Guys guys guys. He didn't do the compression test right, so he has more compression than that. Plus the the side runs but wide open.

 

[PHeller]

The big thing is if the compression test was done with oil or not.

I've got the same problem, 60psi dry, but I also did mine with oil, which evened my compression on both sides to 150.

Tried it a little later as the oil dried out and...back down to 100psi and lower.

I'd think if it were the valves, the wet/dry compression test wouldn't show any differences.

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[PHeller]

Check the valves. A tight one could leak compression.

I know that I may have made my clearances a bit tight...this may be my problem.

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[mynameissean]

I did a compression test with the throttle wide open n it was up to 150 ish.. now its just not running right poppin a lot and it takes a lot of time to go back to the idol. And when i ride it it pops real bad n after u left off the gas it still accelerated alittle

 

[xjwmx]

Ok so you have good compression.

Your symptoms could be caused by a lot of things, from bad relatively expensive parts to a simple maladjustment. What have you checked so far?

 

[littlebill31]

Sounds like a real lean mixture to me and carbs need to be synced.
But first, it's time to go through that guide I posted and read it a lot.
You have to make sure that the cam chain tensioner is adjusted, then the valves, then the timing, then, and only then, go to the carbs.
They need to be done in that order only!!!