TOPIC:

Yeah, bend the little tab, so frickken arcane I know. Just got finished bending my little tabs on the geep so it isn't leaking gas anymore but the auto shutoff that ceased shutting off needs a rebuild kit or better yet get pitched into the trash and replaced with a real shutoff.

Okay so enough bitching from me. Any crud in the bowls? What happened on mine was there was crud in the middle 2 bowls and that likely held the float needle open. I'm not running a fuel filter at the moment and that is going to change.

And your right, the float level while important and part of the mix isn't going to affect the running as much as other items on the list.

Oh, and if you planning to maintain your motorcycle yourself, which I highly recommend then purchase, download, borrow or steal a manual.

The other question I had was how does the bike run off idle, like at 30 mph with the throttle open. The carb sync affects mostly the idle and the just off idle responsiveness of the engine. When those slides are open it matters not that much. I'm thinking it best to start with a good bench sync because I just went through this not long ago with my LTD. The manual will tell you how to do a bench sync.

Do me a favor when you get chance. Go to YouTube and type in Bruce Lee - water- teapot and report back

There is something I failed to mention with regards to leaking fuel and its important. When this occurs there is the possibility that gas is getting into the cylinders. My bike was parked on an incline but I stuck my nose into the oil fill hole anyway because the consequences of fuel in the oil may well result in engine damage.

You'll want to check yours.

Togoster wrote: The other question I had was how does the bike run off idle, like at 30 mph with the throttle open. The carb sync affects mostly the idle and the just off idle responsiveness of the engine. When those slides are open it matters not that much. I'm thinking it best to start with a good bench sync because I just went through this not long ago with my LTD. The manual will tell you how to do a bench sync.

The bike runs okay at like 30mph. It is a little sluggish with acceleration - not very torquey in any gear - but I was attributing that to the carburetors and poor cam timing, but maybe it's something else? I don't notice a lick of difference in torque at half-throttle vs. WOT; the only thing that changes is the noise coming from the exhaust.

There wasn't any crud in the float bowls when I checked them last night, but I purchased an inline filter anyways. I guess I will do a bench sync and make sure the floats are at the right level. I will also check for fuel in the oil.

TexasKZ wrote: One inch from what????
I am not familiar with the 750 specs, but I'd bet the fuel level should be +/- 3mm from where the float bowl and the carb body meet.

26mm from the gasket to the top of the float. Measuring the fuel level doesn't really help since you have to put the carbs on, fill em with fuel, take the carbs off, adjust, put the carbs back on, fill with fuel, check, and readjust. Sounds like a pain in the ass if you ask me.

It is a pain, but it is the most accurate way to measure. The dry measurement will get you in the neighborhood, but not as close as the clear tube method. It can also identify a failing float valve.

I get the sense that we are not looking at one specific problem here but rather a list of things that are either wrong or at least not quite right.

Even the bench sync won't affect running at 30 mph with the throttle open and if you feel that the motor lacks the torque then I would suggest establishing a basic engine health baseline. Check compression would be the first. Timing, check for a strong spark...etc, etc.

Rather than trying to pinpoint the problem by assumption, start eliminating the possibilities for a poor running engine.

That's my best advice.

Oh, and pull the plug and see what they look like. Make sure they are the correct plug gapped properly.

It's time to put this thing to bed

Woo, more work! haha! By the way, I was able to download the 300+ page Clymer Manual and I can't seem to find any information on the Keihin float height. It mentions the Mikuni height should be 18mm, but doesn't go into detail on the Keihins which I have.

I'll get the carbs bench synced, just to start since they are already removed from the bike. Then I will check compression, spark plugs, timing, valve clearance etc...

I really appreciate your help with trying to figure this out! I will keep you updated on my progress.

Have you checked under the Articles tab near the top of this page to see if the factory service manual for your specific year and model is available to download?

Hmmm, thanks for that TKZ, I'll have to try that for my650.

Let's face it these aren't the torqueist bikes in the barn anyway.

I'm happy to "help" but all I've done is make more work for you but I stand behind what I'm saying. You've shown a great patience with this and that coupled with the fact that i love troubleshooting things in general makes for a good combo. It's not easy to figure out what it's wrong and so it should be relegated to procedure when you can't rely on experience. It's even harder when the motorcycle is not right in front of you.

I posted that YouTube video of Lee because to fully understand basic concepts it helps to clear your mind get back to square one and start again. Basically you need 3 things for combustion, compression , fuel and air. Basically. But we not only want combustion, we want performance so we need to fine tune things.

We need to be the fuel, we need to be the vacuum.

And yes, I'm as much of a unit as Bruce was.