[Fritzer108]

A few days ago, I took my 1994 YZF750R for a spin and couldn't get it to rev above 10k rpm. Just the day before my ride, my dad drove it to his doctor's appointment with no such issues. I figured that one of the main jets must have gotten clogged, so I took it apart and cleaned it out. The main jets all seemed to be clear, but I blew the passages out with compressed air and carb cleaner just to make sure.

After installing the carbs again, I have a horrible hanging idle that hangs at 7k. It revs fine now but will not come down. I checked for air leaks in the boots and the balancing lines but everything seems to be air tight. There are many threads that show up about a hanging idle, but what confuses me is how well it was running before. I will note that the previous owner deleted the EXUP system (I got it as an abandoned bike). Thanks in advance.

 

[Fritzer108]

Update: I fixed the hanging idle. One of the intake boots had a crack at the bike that I could not reach and leaked air like crazy. I patched it with some RTV sealant until the new boots would show up. The bikes idles nicely now and comes back down nicely.

The issue with the 10K rev limit is still present. As soon as I hit 9-10K, I start to feel a slight stumble and it soon falls on it's face. It pulls really nicely from 2-8k. Having cleared the main jets of any clogs, I am going to see if the petcock or fuel pump are not performing as they should. I am fairly confident that this is a fuel problem, but if anyone has experience this before, please enlighten me. While I had my carbs off, I reset the float height to 14mm as I found that it had been set to 11mm.

 

[Fritzer108]

Anyone?

 

[Lesblank]

Have you checked plugs lately. Could have a plug not firing correctly. Had a similar issue years ago and turned out to be a poor wire to boot connection. The spark would travel thru boot with no load on engine, but arch out under load.

 

[Fritzer108]

I took it for another ride today and could not see any arching at idle but the problem still existed. I'm going to replace the plugs, trim the leads , and add extra insulation to the boots and leads.

 

[jbur13]

Sounds like the Exup valve needs cleaning. Or you removed it and unplugged the control box for it