Hello guys, it's good to be here, thought I'd find something like this around here on the internet somewhere (It hasn't failed me yet)

Anyways, I'll jump right into it here. I recently purchased a 1986 Ninja 600 as a project for the winter. I got it at a really good price. It ran, and shifted, and everything, but has a few issues that I'd like some opinions on.

The main problem is the bike will idle, but is a cold blooded starter for sure. Once it gets to idle, it won't rev up normally past 3-4K RPMs, where it begins to stutter and will eventually die. If you manage to get it past 3-4K it will rev to 7K in gear, and all the way to redline in neutral, but it feels like it's running out of fuel or spark the entire time. Here's what I've done to troubleshoot.

1. I disassembled all of the carbs, inspected the jets, needles, floats, and diaphragms. All of them were good. The floats seemed about the right level, but I don't know because I don't have the right tool to measure it, and everything was clean. The jets had some varnish on them, but nothing too bad, and all of the diaphragms had grown a very tiny bit, but still sealed and seated into their groves and none had any pinholes or tears. The mixture screws came out easy enough, and the screws on carbs 1 and 2 were leaking. Upon inspection the o-rings were not in the best shape, so new o-rings are on the way. The fuel filter was clear of debris, as was the primary filter inside of the tank on the petcock. The tank did have a bunch of crap in it though, old varnish particles from sitting, however, none of it was on the petcock meshing and none of it was inside of the carburettors. I'll be cleaning the tank as soon as I can.
2. I've checked the resistance of both ignition coils on primary and secondary sides and they're all within specs. I'll be checking the pickup coil tomorrow when it's not so cold/wet/rainy out. I also checked the resistance of the spark plug wires, all of which are fine.

I plan to change the oil and the spark plugs as soon as I get a long enough extension to work around the coolant pipes and the right sized spark plug wrench, but my main problem is what I'm assuming is a fuel issue right now. If anyone has any ideas I'd love to hear them.

Thanks a lot guys, and sorry for the long first post.

-Gary

 

ride it again, and as you are accelerating and hit that "dead" spot begin to apply the choke and see what it does. If it picks right up then you have some fuel restriction.. another obvious thing is air.... how is the filter?

 

I have tried to use the choke before but I think I was still running on the low speed circuit, it didn't really help or harm anything, but I've never done it while rolling on the throttle. However, right now the bike is in pieces and I can't really put it back together until I've at least cleaned the tank and the carb jets.

The air filters are all K&N Filters, one for each carb, and they're clean.

 

ok. I had one of those (an 85) that someone gave to me and I tore it all the way down and rebuilt it. Then gave it to my daughter for her first "real" bike. It was gloss black imron, it looked great. That starting thing sounds like maybe your low speed air screw is maybe too lean?? worth a look.

 

I think it might actually be too rich. The idle mixture screws were backed waaay further out then supposedly they were supposed to be.

 

welcome to KF. keep us posted on the progress PETC

 

hmm, 1986 gpz. No mention of all of the rubbers being in good condition or replaced. Good area for air leaks. Without knowing this, .....? Carb issues and foul running will always be asked.

 

PETC,
double check your manual on those screws and make sure they werent AIR screws, in which case you were way too lean. most bikes have the idle mixture screw set somewhere around just 1 to 2 turns out from fully seated