New bike for me

[mnferwerda]

Hi,
Last fall I purchased a 1983 GR650. It needed quite a bit of work but I have it working now but I do have an issue with it not idling correctly. I've lurked on this site and believe I covered everything but my carbs are schizophrenic! Sometimes it idles nicely (@ 1000rpm) and other times it will idle @ 3500rpm and some times in between. Things I have done so far:

• take carbs apart, soak in carb cleaner for 24 hours, run compressed air through the various openings and inlets
• replaced the main jets with the proper size - 132.5 (It had 142.5 but the bike came with air pods filters)
• replaced pilots jets
• replaced o-rings that looked bad
• checked the float levels (one need just a slight adjustment)
• put the original airbox back on and sealed it, and put in a new air filter
• replaced intake pipes and associated o-rings and clamps.
• replaced throttle cable
• check choke cable and it and the throttle cable work properly
• the connectors from the airbox to the carbs seems to be good, no obvious cracks or holes.
• adjusted the valves as needed. 2 of them are barely within spec (i.e. tight). Is it better to have them a little loose or tight?
• I've adjusted the idle mixture screw to about 1.5 - 2 turns out.
• I've checked the carb synch. It is a little bit off but I really don't know how close they have to be.

The bike seems to accelerate ok. It has been a long time since I had a bike so I really don't have a good grasp on that. I did take it to a shop and the mechanic rebuilt the petcock. He did take for a ride and noted that the the idle does hang a bit but he said it may just need to be ridden some more and may settle down (and also implied that today's gas with ethanol is partly to blame). Anyways, I ridden through a few tankfuls and the problem seems to be getting worse. So I've missed something. There has to be a logical reason. ANy thoughts would be appreciated

Since we all like pictures, here are a few...

• bike with rattle can paint job (PO did it)
• brake master cylinder with (really) old brake fluid (cleaned and replaced)
• worn front sprocket (also replaced)
• Carb synch at @ 1700 rpms... (is this OK?)

Mark

 

[mnferwerda]

next pic?

 

[mnferwerda]

Another one

 

[mnferwerda]

last one

 

[Big Rich]

Cool GR!

The sync should be done with a lower idle. But do the valves first (the exhaust valves are generally better off on the loose side - which valves of your are tight?). I can't help too much with stock carbs / intake.....I haven't run stock in years.

If you decide to get rid of the rear rack, I know somebody who is desperately looking for one!

Edit: search around for a tutorial about cleaning ALL that sludge from your brake system. If it's in the MC, it is in the caliper too. And you can use a master cylinder from a GS500 if yours is too far gone.

 

[mnferwerda]

So on 1 cylinder the intake is .03 and on the other the exhaust is .03. (spec is .03 to .08).

I got the front brake all cleaned up and it works well.

I found the rack at a swap meet. I had to bend it a bit to fit, but it turned out nice.

 

[Big Rich]

I would do the exhaust valve to get it on the loose side of the tolerance, but check the intake after a couple thousand miles. They will only get tighter...

 

[mnferwerda]

FYI: Old vacuum lines was the culprit of my idle issues. They didn't seem to be bad but when I pulled them off and plug the vacuum inlet with my fingers the idle immediately went down... Went to Napa and spent $1 on new tubing and voila!