Please!! help me get my bike running for the build off trip!!!

[jonboy-xsbobber]

Hi I have an 81 stock ignition just changed cam chain guid and tensioner new pistons and rings. After it started up second kick but I was having problems with my left cylinder missing popping and back firing at idle I was going to get my stock carbs rebuilt but went with a set of vm 34 round slides from tcbros. Put them on with new uni filters started first kick. Right cylinder runs great with the new and old carbs. Took it down the road and back it seemed to run better but still had a miss in the left cylinder mainly at idel. Went out today and it didn't want to start but when it finally did the left cylinder didn't seem to be fireing at all except for a loud back fire every few seconds that sent smoke out my air filter. I swaped the plug wires to see if it moved to the right and it didn't. The left plug looked wet when I checked it I put a new coil wires and plugs end of last summer. I adjusted cam chain and valves after rebuild.

It just seems to be getting worse could it be a jetting or a syncing problem? (Uni filters and open pipes)
I have looked on here and found some info but would like to get some help directly if possible I am trying to get it ready to take to ohio in August and I'm running out of time and money and help wound be greatly appreciated

 

[TwoManyXS1Bs]

Put in fresh plugs, or, at the very least: Clean the old ones really good (no black porcelin), re-gap, and reverse them (right into left, etc).

Then ride it around for awhile, and when it acts up, pull the plugs. If that left plug is wet again you need to determine if it's gas-fouled or oil-fouled or both. Gas-foul will be liquid wet and smell of fuel. Oil foul will be shiny wet, feel slippery, and look darker. Gas-foul is carb/fuel problem. Oil-foul is bad, maybe rings, or headgasket weepage...

 

[peanut]

if you swopped the Spark plug ,lead and cap over on the cylinders and it made no difference then it would suggest that it is not an electrical problem .

The plug on the cold cylinder should be wet with fuel if not then you have a fuel flow issue with the carb on that side .

I would do a compression test on both cylinders to establish that you have not got a compression leak somewhere . Turn the engine over at least 8x times until the compression reading does not increase and the same number on both cylinders. It should be done with WOT wide open throttle Compression testers only cost a few dollars http://www.ebay.com/itm/ENGINE-AUTOMOTIVE-COMPRESSION-TESTER-KIT-DUAL-SCALE-GAUGE-TWO-ADAPTORS-PETROL-/201102717346?pt=UK_Diagnostic_Tools_Equipment&hash=item2ed2a7f1a2

My guess is it might be a valve seating problem .

Did you remember that the valves need adjusting on the cylinder with the piston on its compression stoke at TDC ? then turn the engine over 360 degrees and do the valves on the other cylinder at TDC.Stone cold obviously .

 

[jonboy-xsbobber]

Thanks guys and yes I adjusted the valves just like that I will go buy a compression tester today and reset my valves and cam chain tension
Any other things I should check?

 

[jonboy-xsbobber]

Won't I flood my engine if I kick it over with WOT?

 

[peanut]

shouldn't do. Vacuum cocks should only flow when the engine is running otherwise they would be continually leaking . If you're worried, clamp or disconnect the fuel lines

Its important to test both cylinders identically to get a meaningful result. Starter motor would be better.... if not just screw the gauge in and put the bike into third gear and push it along the road until you hear the engine turn over a dozen times.

Make sure that the ignition is off obviously

 

[jonboy-xsbobber]

I have gravity fed petcock and my bike is kickstart only

 

[jonboy-xsbobber]

Left just over 160 right 165???? Good bad???

 

[TwoManyXS1Bs]

Sounds okay to me. Maybe the left rings just need to seat more...

 

[jonboy-xsbobber]

So just new plugs and see how it runs?

 

[TwoManyXS1Bs]

Yep, new plugs. Back in the day, we always replaced plugs at the first 500 mile checkup, advised the same on rebuilt engines. During initial break-in the engine will burn a little oil and tiny bits of iron from ring break-in would appear on plugs (not always, but happens enuff to warrant changing).

I used to save those plugs, and later bead-blast them and throw them into my 'maybe' box...

 

[jonboy-xsbobber]

So new lugs started after awile but only if the right carb had the choke on and the left didn't ran ruff back firing and the left pipe stayed cold took it around the block made a puff sound every once and awile

 

[TwoManyXS1Bs]

Sounds like the left carb and/or its fuel delivery needs to be fully examined.

 

[jonboy-xsbobber]

New tank new lines and filter new carbs where should I start?

 

[TwoManyXS1Bs]

Drop the drainplug of that left carb. Catch the fuel in a clear container so it can be examined. Turn on fuel tap and see that it delivers at least more than a dribble...

 

[jonboy-xsbobber]

Thanks a lot will l
Post how it goes

 

[TwoManyXS1Bs]

Close look at your pic in post #1 shows the left carb throttle cable just dangling there. I hope it's hooked up now???

 

[jonboy-xsbobber]

Yes it is that was before I finished hooking them up

 

[TwoManyXS1Bs]

Also noticed that you're running a plumbing-type faucet for a petcock. The seal washer in those may not survive gasohol. Unless it's been specifically designed for that...

 

[jonboy-xsbobber]

Yeah I got it from pandemonium customs