'77 R100S: Finally running!

[zombiepotatosalad]

I took it out for a test ride. It's actually idling (more or less). I have to try to find the sweet spot with the carburetors. There's a lag between throttle and acceleration, and after a while of running it will want to die at idle.

I also hear what sounds like a buzzing (like a weedeater) coming from the right exhaust pipe when I'm under acceleration. I hear it over my right shoulder.

 

[20774]

Sounds good! Do you have a set of procedures for synching the carbs? This sets the idle speed and mixture as well as ensures that the throttle cables are under equal tension as you begin to open the throttle. Could be the lag your feeling has to do with proper setup.

Definitely look over all attach bolts for the muffler. Can you duplicate that buzz while on the center stand in the driveway?

 

[manitou_commando]

I also hear what sounds like a buzzing (like a weedeater) coming from the right exhaust pipe when I'm under acceleration. I hear it over my right shoulder.

If you take off the right side muffler and shak it about, do you hear rattling? Perhaps a baffle has corroded off and is floating round in the shell.

 

[zombiepotatosalad]

Sounds good! Do you have a set of procedures for synching the carbs? This sets the idle speed and mixture as well as ensures that the throttle cables are under equal tension as you begin to open the throttle. Could be the lag your feeling has to do with proper setup.

Definitely look over all attach bolts for the muffler. Can you duplicate that buzz while on the center stand in the driveway?

Will having the air filter out affect the quality of the running and lead to the issues I'm having? The air filter is dented on one side, like it was squished. That's how it looked when I got it.

 

[20774]

Will having the air filter out affect the quality of the running and lead to the issues I'm having? The air filter is dented on one side, like it was squished. That's how it looked when I got it.

Hmmm...maybe in a small way I would think. The track of the air that enters the engine was part of the design process by the engineers, so change the path can have some effect. Note that people who put those "cones" on the carbs rather than rely on stock air intake system usually have to end up changing jets and other settings.

 

[kinterridge]

Belated welcome form SC. I've had my '77 R100S out quite a bit lately. +1 on everything Kurt has mentioned, haven't read all your postings, but I would add to pull the tank, drain it then pull your petcocks and check for blockages, such as sludge, tank liner bits, etc. i.e. anything that might cause fuel flow issues. Air flow is important, get a new filter. Check your fuel lines, especially if old. Pull the carb bowls again, look for debris. Definitlely do a carb balance after you do a valve adjustment, lots of info on how to do them. Sounds like a lot of things but they are not too time consuming.

 

[zombiepotatosalad]

Hmmm...maybe in a small way I would think. The track of the air that enters the engine was part of the design process by the engineers, so change the path can have some effect. Note that people who put those "cones" on the carbs rather than rely on stock air intake system usually have to end up changing jets and other settings.

Looking at the manual, it says to adjust the screw on the bottom "without using force." I assume that means stop turning it when it shows resistance.
Another video I saw shows turning the screw all the way in until it won't turn anymore, then backing it out to what your bike needs. Which is correct?

 

[20774]

Well, the mixture screw that I think you're talking needs to be set at some starting point. Usually that's done by turning it in so that it lightly seats and then backing out the required number of turns. Provided the carb is clean and the threads are clean, then it should turn in easy enough until you feel some resistance...that should be lightly seated.

 

[zombiepotatosalad]

Well, the mixture screw that I think you're talking needs to be set at some starting point. Usually that's done by turning it in so that it lightly seats and then backing out the required number of turns. Provided the carb is clean and the threads are clean, then it should turn in easy enough until you feel some resistance...that should be lightly seated.

I set it as close as I can to the manual. I hook up my carb synchronization meters to the vacuum ports, and I get no reading at all.

There's also a fine line on the top mixture screw between idling, and shooting up to 4,000 RPM. As far as I've tested, there are no vacuum leaks.

 

[kbasa]

If you over tighten the screw, it disrupts the seat it fits into, so go easy there. Just until it touches and you feel resistance beyond overcoming the force of the threads.