running problems

[STAN]

Hi my problems are
when bike worms up it now rev es out.
History
this started off while riding when rev es went over 4000rpm it was holding rpm ; then started to Rev out at start up so I've got carbs checked out a new diaphragm was fitted all else was OK' and I've put new carb holders on bike .
still I have this problem can some one give me light on whats wrong here.
thanks .

[ross]

welcome friend...

hey there stan...you have arrived at the holy grail of knowledge of your motorcycle....first off, if you could, fill in your signature with the type of bike you have....model, year, standard or special....helps us members know how to address your problem.....there could be a multitude of issues that you may be facing....idle screw...sticky throttle cable..float height, carb cleaning, sync-ing....etc.....best off is to describe what has been done 2 the bike and why.....us XS11 members really like photos to describe what is going on...really helps with the cure....welcome to the family....ross

[Ken Talbot]

First off, it sound like you've got a vacuum leak somewhere. Could also be broken pick-up coil wires that all of a sudden reconnect, so all 4 cylinders are firing, which would cause big RPM rise. 99.9% chance your carbs are also dirty.

First thing you might want to do is spend a bit of time going through some of the tech articles here to see if some of the symptoms there match whet you've got. That would narrow things down a lot.

When you say you've got carbs checked out, what does that mean? Did you strip them down and clean out every orifice, jet, and passage, or did a buddy look at them from a distance and say they look okay. It really does make a difference who did what to it. Likewise, why did you need a new diaphragm and carb holders?

[STAN]

well thanks KEN
I will check out possible vacuum leaks and broken pick-up coil wires .as i have a spare pick-up coil , witch i have replaced with one on bike before & made no change but will try again. now I've got new carb holders on.

and i will look at the tech articles here to see if some of the symptoms there match and will let you now thanks.

When i said I've got carbs checked out;
they went in to a bike repair shop to check them over the number 1 carb diaphragm had where cracks and some small holes on crease lines;
and carbs were cleaned I'm tolled and blown out a by air line, ie
needle & seats etc will find out more about the clean.

as for the new carb holders i put on to replace old cracked ones as to correct possible vacuum leaks from old ones.

[skids]

Any time you replace "carb holders" , and I am assuming they are on the head side, you should do a synchronization. You could turn the idle down once it warms up to that point. In fact, I would try that first and see how it runs, and if it won't hold a steady idle, like it is searching or hanging at higher rpms, do the synchronization and do it near 1100 rpms (not midrange).

[STAN]

well thanks ross

At the holy grail That's a good way to describe the site .

model, 1980 xs1100 standard .
idle screw have tried it backed off .

sticky throttle cable carbs seam to close off when throttle is backed off,

float height, was checked in shop and i was tolled was fine ,
carb cleaning, was done in shop also as to needle & seats jets etc blown out by air will find out more about clean.
one new diaphragm was put in number 1 carb as it had wear patches & some holes on crease lines as i new of that all ready.

sync-ing.... was set up by shop as to get bike to run before proper set up in shop with bike .

the bike was a unfinished project a guy gave up on the head was off along with some other small items so Ive had cam shims x2 replaced and i have put bike back together, when 1st road it was back firing only when going around corners so other than that went well for about 170km on test runs .

will have to more work on vacuum leaks somewhere & pick-up coiL.

The shed not a happy place 4 me when its like this but ill get there hay

[ross]

hey there stan... to check for vacuum leaks, use a propane torch....do NOT lite it...just turn it on while the bike is running....check all possible areas for vacuum leaks with the torch leaking propane....if the idle goes up, you have found your leak....knowledge learned from here...ross