Your previous posts are all about synching and how to adjust the mixture screws. Your first post only describes a problem of the bike stumbling slightly at 2-4K rpm's. You mention no other symptoms.
Now it appears you think you have an intake leak. An intake leak has a very classic symptom; the rpm's rise significantly as the motor fully warms up.
If this is your scenario...hard to start, takes a long time to warm up. As it's warming up, the idle (if set to factory spec) is around 900 to 1,100 rpm's. As soon as the motor warms up completely the rpm's are much higher. So high that you decide (depends on the rider I suppose) to lower the idle to factory spec by backing off the idle adjuster knob. The bike idles fine now but after you turn it off and it cools completely, you find that the bike will only start again if you turn up the idle adjuster knob again or give it some throttle. Even with throttle (which by-passes the choke circuit) starting is difficult. This cycle continues every time the bike goes from cold to hot.
That's the classic intake leak symptom. Spraying water mist (lowers the rpm's) to expose the leak doesn't always work. Spraying something flammable will cause the rpm's to increase but is bad for rubber parts and is messier and more dangerous to use than water mist and will also not always expose the leak. If you have this symptom, I guarantee you have a leak and the manifold o-rings (if used on your model) or the manifolds themselves are failing. If your rpm's do not rise as I said above, it's doubtful you have an intake leak...at least an intake leak like I've ever seen. Any air leaking into the fuel stream between carb and cylinder WILL result in a very lean mixture and irratic combustion that results in the rpm's increasing "on their own". The only time an intake leak won't have this symptom is if the leak is so large that the bike simply stops running or won't start at all.
You can of course make sure the carbs are "popped' into their manifolds correctly and try tightening the clamps better before checking the manifolds/o-rings. The clamps must be the factory style too. No general purpose hose clamps should be used because they don't clamp and apply pressure to the exact area needed to seal correctly. If you have o-rings, replace them all, coat them with some hi-temp bearing grease and torque to about 6 ft/lb unless your manual states otherwise. I always replace the stock Phillips manifold screws with Allens so I can torque them and the Allens make future maintenance easier too. Removing the manifold bolts can be difficult sometimes so use a GOOD fitting bit to avoid stripping the heads off.
Now it appears you think you have an intake leak. An intake leak has a very classic symptom; the rpm's rise significantly as the motor fully warms up.
If this is your scenario...hard to start, takes a long time to warm up. As it's warming up, the idle (if set to factory spec) is around 900 to 1,100 rpm's. As soon as the motor warms up completely the rpm's are much higher. So high that you decide (depends on the rider I suppose) to lower the idle to factory spec by backing off the idle adjuster knob. The bike idles fine now but after you turn it off and it cools completely, you find that the bike will only start again if you turn up the idle adjuster knob again or give it some throttle. Even with throttle (which by-passes the choke circuit) starting is difficult. This cycle continues every time the bike goes from cold to hot.
That's the classic intake leak symptom. Spraying water mist (lowers the rpm's) to expose the leak doesn't always work. Spraying something flammable will cause the rpm's to increase but is bad for rubber parts and is messier and more dangerous to use than water mist and will also not always expose the leak. If you have this symptom, I guarantee you have a leak and the manifold o-rings (if used on your model) or the manifolds themselves are failing. If your rpm's do not rise as I said above, it's doubtful you have an intake leak...at least an intake leak like I've ever seen. Any air leaking into the fuel stream between carb and cylinder WILL result in a very lean mixture and irratic combustion that results in the rpm's increasing "on their own". The only time an intake leak won't have this symptom is if the leak is so large that the bike simply stops running or won't start at all.
You can of course make sure the carbs are "popped' into their manifolds correctly and try tightening the clamps better before checking the manifolds/o-rings. The clamps must be the factory style too. No general purpose hose clamps should be used because they don't clamp and apply pressure to the exact area needed to seal correctly. If you have o-rings, replace them all, coat them with some hi-temp bearing grease and torque to about 6 ft/lb unless your manual states otherwise. I always replace the stock Phillips manifold screws with Allens so I can torque them and the Allens make future maintenance easier too. Removing the manifold bolts can be difficult sometimes so use a GOOD fitting bit to avoid stripping the heads off.
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