83 GPz550 won't rev past 6,000

Hey everyone, this is my first post here. Just really looking forward to riding this bike and I can't keep depending on google searches for help. I did a couple of searches on this site and went through the results but couldn't find anything like the problem I am having. I'll try to keep it short.

I got this bike (83 GPz 550) last october for $400, and probably shouldn't even have paid that for it. The airbox was ruined, all kinds of stuff broken...Probably no need to list it all. It now has pod filters and has been rejetted, and it ran well for a couple of weeks in mid november until all of a sudden it wouldn't rev up past 6,000 rpm at all. It would sputter and make all sorts of noises and sometimes backfire if you twisted the throttle enough. I had the top end off over the winter for various reasons. One thing I discovered is that the timing was set wrong by the previous owner, just by one link. I have it set as per the manual I have and the camshafts line up nicely at TDC. SO, it still won't go to redline. You can get it to about 9,000 in neutral, but if you're riding the bike it won't happen. What could be causing this? The only thing I can think of is that the valve springs are bad, but it doesn't seem like something that would happen in a thumb snap and all of a sudden you can't rev it up. I'm not very savvy with electrical systems, so I don't have any ideas here. it had a new battery in it back when I was riding it. I think it's bad now though because I'm getting a battery signal on the dash. It sounds good at idle, with minimal valve noise. Any ideas? I really appreciate your help. I have put over a hundred hours of work into this over the winter and I can't stand not being able to ride it now that the weather is turning.

Many things can cause that symptom.

Might as well start at the beginning. Since you had the cam cover off, are you aware that you cannot replace the cam cover without releasing the camchain tension? The details are in the valve train warning link in my signature.
In that link, you will also see a bunch of details regarding cam timing and valve train in general. You may want to review the drawings to make sure the cam timing is where it should be, as the manuals were a little sloppy with their drawings.

If the valves are set correctly, then the next thing to do is a compression test. That will tell a lot about the engine.
There are several different manuals if you follow the other link in my signature. Get all of them and check out the sections on compression tests.

Next would be to check the ignition and ignition timing. That is in the manuals as well. Specifically, make sure the timing advancer is moving freely. If it's frozen at the idle posiotion, the engine will not rev past about 6000.

chem_biker wrote: ........ You can get it to about 9,000 in neutral.....

9,000 in neutral? Good Grief! Why not just try this trick; it worked so well for him. :laugh:

Pics of plugs?
Steve

Haha. i only tried it once after I realized that I was still having this issue. Just to see if it would rev up in neutral.

That's interesting about the tensioner being a one way device. I had no idea. I definitely installed it incorrectly. Could that alone be the source of my problems? I will start in on these other tests as soon as I can but i will need a compression tester and will have to read more about the ignition timing. Thank you!

Here are the spark plugs. Number 1 cylinder on the left.

Lots of oil. Hopefully you didn't damage the cam chain guides putting the cover on without taking off the adjuster. I'd check that out.
Steve

I agree with loud. Check valve adjustment straight away and compression next. I also wonder about your jetting. Any time pods are installed a Dynojet kit is in order. They come with more tapered needles which are very useful in fine tuning the mixture.