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Could it be as easy as....

  • Thread starter Thread starter Sasquatch
  • Start date Start date
S

Sasquatch

Guest
Okay, I understand that I should bite the bullet and replace the boots and rings between my carbs and motor (the bike is an '81).

Quick question for everybody. When I start the bike, with just the barest amount of throttle, it will run smooth at 1000 rpm, but if you let go of the throttle, the tach will slowly move down to around 800rpm then die. Could I just increase the tension a little on the throttle cable?

Could a small leak in those boots discussed above cause the bike to actually not idle at all?
 
Use the idle adjust screw...

Use the idle adjust screw...

Sasquatch said:
Okay, I understand that I should bite the bullet and replace the boots and rings between my carbs and motor (the bike is an '81).

Quick question for everybody. When I start the bike, with just the barest amount of throttle, it will run smooth at 1000 rpm, but if you let go of the throttle, the tach will slowly move down to around 800rpm then die. Could I just increase the tension a little on the throttle cable?

Could a small leak in those boots discussed above cause the bike to actually not idle at all?
Click to expand...

It's a big knob between the carburetors that opens all the throttles a little bit without using the cable. There should be small amount of slack in the cable.
Vacuum leaks cause the most problems at idle or very low power, if yours are leaking it's an easy fix.
So what size/model is the bike?
 
It's an 81 650L. The previous owner says that he thinks one of the boots was cracked (I presume he met the boots between the carb and motor and not between the air box and carb) and so he put some silicone on there. Though I can't see the silicone fix, I haven't taken off the tank. I was told by another member today that silicone won't work and I pretty much should just spend the $100 and get new boots and o-rings.

HOWEVER, given that the bike runs smoothly at 1K w/a little throttle, but won't idle at all, I was thinking, why shouldn't I just tighten the barrel adjuster on the throttle cable a little bit...wouldn't that work? I'll still swap out the boots, but it'd be nice if the bike would idle now.
 
Symptoms of an air leak are an inconsistent idle - mostly where the idle increases and hunts around. From the way you describe your bikes problem, you should increase the base idle - using the knob on the bank of carbs, not with the throttle cable adjustment nut since that is just to reduce the free play in the cable.
 
Will give it a go..I presume that once I pull the tank, the idle adj. knob is probably in the neighborhood of the throttle and clutch cables?
 
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Sasquatch said:
Will give it a go..I presume that once I pull the tank, the idle adj. knob is probably in the neighborhood of the throttle and clutch cables?
Click to expand...


YOu dont need to remove the tank or anything to adjust the idle adjustment knob. It will be a metal knurled knob between the #2 and #3 carbs. On some models, the knob is facing downward, on others it may be more upwards. From the left side of the bike, reach your palm up, right hand underneath and between the #2/#3 floatbowls, then reach up with your fingers about 3 inches.
You should be able to feel it with your fingers. Clockwise rotation will increase idle rpm.

Earl
 
adjustments w/o disassembly? SWEET! I tried looking at it in my garage (it's night w/o a lot of light in there) and I couldn't see it w/a flashlight, but tomorrow I'll take it outside...my Clymer shows it in the schematic and you would *think* to look at it, it shouldn't be hard to find.
 
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#82 is the adjustment knob. It's a tight fit to get at, but should rotate easily enough.

Brad bt
 
Thanks. That is the same schematic in the old Clymer that came with my bike I believe...I looked it up after Nessim mentioned it but you see how in the schematic they just have it floating in space? Thanks to you and earlfor for saving me time by more accurately describing where to find it and how to get to it.
 
Sounds like you've got the info you need, but don't be afraid of removing the tank. I've done it and it's an easy job, unless of course it's full. I was really intimidated by the idea of doing it, too, but once I did, I realized it's a really easy job and easy to put back together. Study the Clymer, take some digital pics to remember where the connections go underneath if you need to and git r dun. These bikes in a lot of ways are designed with the idea that home mechanics will do their own work on them, which is one of the many beautiful things about GSs!
 
Ride or run the bike until its at normal operating temperature before adjusting the idle. If you adjust/increase the idle on a cold engine, idle rpm will increase further once the engine is warmed up.

E.
 
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This morning I wheeled the bike outside. Idle knob located and adjusted and bike is now holding a steady idle at 1.1K. I took it for a couple spins around the block keeping it under 4K didn't seem to miss though the power did seem to come on suddenly about 2.2K...bike was likely still not fully warmed up though. I didn't want to do more though as I can hear a little tapping noise coming from the cam area. I haven't flushed the oil yet as I have to put in a new stator as well, so until I can vouch for it's coolant, I don't want to take it any distance (and there is that pesky motorcycle endorsement I have to go get :-D). thanks to everyone for their advice and encouragement so far.
 
Sasquatch said:
Thanks. That is the same schematic in the old Clymer that came with my bike I believe...I looked it up after Nessim mentioned it but you see how in the schematic they just have it floating in space? Thanks to you and earlfor for saving me time by more accurately describing where to find it and how to get to it.
Click to expand...
make sure your bike is warmed up good when you increase the idle and dont burn your hand.i usually put a cork glove on to do it.Have you cleaned and oiled your air filter and made sure your airbox lid is on good and tight?This could all make a difference.
 
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