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A little bit puzzled...

  • Thread starter Thread starter dw200
  • Start date Start date
D

dw200

Guest
MY 82 650G project is finally running but not right. The pipes off of Cylinders 1 and 2 are cool enough to put hands on after idling for 10 minutes or so. I was told by the previous owner that gave me the bike that it had a burnt valve. Compression check (without carbs in place) was ~150 PSI on all 4 cylinders. New plugs in 3&4 were good, new plugs in 1&2 looked dirty already. New dyna ignition and boots are installed and showing good spark. Carbs have NOT been rebuilt yet.

Any thoughts??
 
Sounds like it's time to rebuild the carbs with a kit from cycleorings.com and change the intake boot O-rings. The airbox needs to be installed and properly sealed, or if you are using pods the carbs will have to be rejetted before the engine will run properly. While you are at it test the petcock to make sure it's not leaking fuel down the vacuum line. And of course adjust the valves. All basic maintenance for a 28 year old motorcycle.
 
The petcock is not leaking fuel thru the lines. The airbox was installed and but I cannot say how well sealed it was. The bike had sat for over a year in a shop with the carbs sitting on a shelf so I know they are dirty. This bike (and me) just had other priorities that had to be dealt with before dirty carbs. But at least it does run (sort of) and that is a beginning.
 
Even if the bike started and ran okay (unlikely), the carbs would still have 28 year old O-rings inside that could start leaking at any moment. It's always best to deal with maintenance issues up front so you don't have to deal with it again.
 
Never said the bike ran "OK", just that it did run which was an acomplishment for it right now. Yes, the next step will absolutely be a carb rebuild.
 
Umm.... well, you ask for thoughts. The casual review of your post shows a good ignition system and no burnt valve (wonder why, exactly, the PO suspected this?).

1 & 2 are running rich enough to soot up the plugs and likely not running at all (or intermittently) such that you can touch the pipes.

I'd say just what you and Nessism already know - carbs fully stripped and cleaned, reassembled with new rubber bits, float levels checked and set, carbs bench-sync'd then vacuum sync'd on the bike, then idle mixture screws tuned (and people really swear by the Colortune system for positive, spot-on idle mixture setting. I have yet to pick one up).

If it's still bad, rethink the compression check (still wondering about that burnt valve...) and then back to ignition.

Kirk
 
dw200 said:
Compression check (without carbs in place) was ~150 PSI on all 4 cylinders.
Click to expand...


No burned valves here...but please learn from what Dale (Rusty) has linked - adjusting the valves is on the short list of required maintenance that needs to be done no matter what!
 
rustybronco said:
Mine "ran" also... http://thegsresources.com/_forum/showpost.php?p=1238313&postcount=64

please add a valve clearance check on your list of things to do.
Click to expand...

+1,000,001! I was just down the road you're on essentially, rebuilding carbs and replacing 0-rings - only to find a valve hanging open, all clearances tight - it's lucky for me I didn't burn a valve. I'd think if you really do have 150psi in your cylinders then you're okay valve wise. Here's a link to my recent thread, in case you find it useful.

http://www.thegsresources.com/_forum/showthread.php?t=164509
 
rustybronco said:
Still, just a small step away from where I was at. ;) and the reason I posted...
Click to expand...

Oh I meant as far as them not being burnt, sorry. Yes they certainly could be in need of adjustment with good compression. All it means is that it's not 'too late' yet :)
 
The bike was given to me by a friend. It had quit running for him ( he said it just wouldn't start one morning) and he let an airplane mechanic that we both knew look at it. His diagnosis was a burnt valve and he never could get it to run. The gut didn't remove the head so not sure how he figured out the burnt valve. He never fooled with the ignition as far as I could tell. But using the wealth of info and people here, it was quick.

I figured up front that the carbs may be an issue but the ignition would be a deal stopper if it would not start of now that I know it will run I can go further and hopefully get the bike on the road.
 
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