I have 93 900rr. Bike runs fine (but not perfect) when it is cold, but when it warms up it shuts off, sputters, and will not take any throttle. I have to be very easy with it to get it home. When cold it will not go past 7k rpm. I have replaced coils, plugs, and took off the fuel pump to see if it made a difference but it did not. I did however find out that the fuel pump was not working but it is running just as bad without it.Any helpwould be greatly appreciated

 

Clean your carbs,check your choke cable out,and check all your vac lines.

 

I'm no mechanic but it sounds to me like a fuel issue.

Good luck and I hope you can find the problem and fix it soon.

 

It might be coincidence that she is ok when cold and sputter when warm. Check out your choke cable and throttle cable first.

 

I cleaned the carbs last night and checked the choke cable last night. All good. Also drained thetank just in case of water and nothing. It is almost acting like an electrical problem. Could this be the rectifier shorting out? I also checked battery voltage and it was 12.97 When I said it ran good when cold I misspoke. It will take throttle but only until 7000 rpm then it breaks up and misses. This problem started very minor and has progressively gotten worse.

 

it could be a vacuum advance problem. triple check your vacuum hoses, also check your coils, could have one trying to go out.

 

Vac lines son!!!!!!!!!!!!! That's what their good for,to **** you off.

 

I just cleaned carbs again and still same thing. I found not 1 vac line on it but it ran fine before. Where should there be vac lines because my petcock valve has no space for a vac line so where would it pull from?

 

When you cleaned the cars did you check the diaphrams on each carb carefully for small tears. These will kill your engine performance. Also, have you synched these carbs recently, they could be fighting eachother. Also, people have different definitions of cleaning carbs, did you visually incpect the main jet and its passage into the bore? I ask because the rev range your having issues in is the secondary/primary circuit and if even one of the jets is clogged or its passage then you bike will run like ****. Cleaner and compressed ir will get the passages clean. How about the floats, if one of those is shot then you will have one carb running lean. If the carbs are truly tuned and cleaned then start with the fuel system again. Any pinched lines when you install your tank? How is the filter? Have you hot wired the pump to check its operation (and make sure it has fuel going in and a vesselt o catch to output, never run pump dry!) If all these check out then your onto the electrical. First check the connection at the reg/rec and the main fuse for the ignition (a few inches forward and down from reg/rec) for any melting. THe bike should run fine, it just won't charge but lets be thorough. If this is good then double check spark plug gap and when you pull each plug make sure it has a light brown color to it. Any wet or white plugs will tell you the problem cylinder. This should keep you busy for the next few days so good luck and if everything on this little list checks out then let me know and you can tackle the next wave of diagnostics. DO NOT throw any more parts at this thing, use it as a learning experience at diagnosing your own problems.

 

Lmao!!!!!!!!

Ok they run off your tank not the petcock. When you "cleaned" your carbs dd you check the jets or just drain the bowls????????