OK, here's the real deal to me from what I found. I had that bad banging noise and people kept telling me it's the valves. Then I read about the lack of oil in the CCT housing, which I find hard to believe, because when I take mine off, oil ozzes out of it. I found out that the spring won't keep enough tension on the tensioner. How do I know? I popped the housing off, got a folded up paper towel and held my thumb on the shaft that pressed agains the tensioner. With a little force, enough to make the thumb a little sore, the noise completely stopped!!! Backed off a little and there it was again. (Do this with the engine running and DON'T let go of that rod). Now to fix this......at your own risk, is I got a 1/4 20 screw and cut this thing to a lenght so that it slided right into the center of that rod where the spring was. When I put the housing back on, I had to push just enough to make the seal that the noise stopped. Whala!! manual cam chain tensioner. I just took the spring out and replaced it with the screw. Cut the head off naturaly. If I was to guess about how much clearance I had before the housing was pushed in was........oh maybe .020. make sure the rod is pushed in as far as ya can before you start cutting this screw to make sure all the slack it taken un in the chain, so it will be a true tension on it when you bolt it back together.

Do you all get my drift on what I did?? If it gets a little loose again...then judgement call on replacing the chain, you can put a thin washer up under there to take up some slack.

 

Can a person use a longer and stiffer spring to compensate for the lack of tension?

 

I am personally a big fan of manual cam chain tensioners. There is a lot less to worry about in the long run. Just make sure to check it every time you do a valve service.

 

I tried some "American engineering" to shim the spring with no luck. If you wanna try what I did, just be careful getting the length of the screw. Just remember to make sure all the slack is out of the chain before you start cutting the screw to length. You want the knocking to stop just as the housing seats. Sometimes that bearing doesn't wanna seat right in the housing and can get ya a little [:@], cause it has to be in there before the housing will seat. Sorry I can't do any better for instructions. I also loosened the scew on the side of the housing til I was done and then tightend it up against the screw.

PS I don't think they make a manual for that 250, but I could be wrong. I asked on the Ninja 250 board and all I got for an answer was "what for".[sm=lame.gif]

 

I just replaced the tensioner Fri night. It seems to be the spring that gets weak, looks like you can order just the spring. Im not sure about doing the manual tensioner. A follow up post after a few thousand would be helpful.

>>>>CAUTION: Anyone messing around with the tensioner out or not secured needs to be aware that they could mess the engine up pretty good by causing the chain to jump on one of the cams and throwing them out of position. You should never turn the engine even a tiny bit withthe tensionerout even by hand. Unless you are fully aware of what you are doing and very careful. Pretty much just dont do it.

EA6BMECH
The manuals (there are 2, base and supplement) are available at your local dealer, ron ayers or bike bandit. The digital crap on ebay is incomplete, however you may be able to find used manuals there. Its very important to have them because just about every bolt has a torque value you have to look up. I use both manuals just about every time I work on the 250.

Edited to say... There are no aftermarket manuals for the 250, besides I have the aftermarket for my Katana and it is severly lacking, the pictures are helpful though so it was worth it for the pics, I plan on getting the OEM one soon.

 

I replaced the tensioner a while back on my KZ750 with an APE manual tensioner. I've had great luck with it so far.

 

10-4 on the messing with the CCT. Mess with it with the stock in place and you can do some damage, make it so there isn't any slack either side, you're better off. I have the manuals too, but books are only as good as the people that write them, or are told to write them. I believe the replacing the spring might do some good, but not a better solution. I just ran my 250 pretty hard after work in the twisties. If what I did was not a good thing, I wouldn't have a bike left. Sorry no one else has ventured out to do this. I'm comfy with it[sm=icon_rock.gif] I think this bike was made to run the **** out of it, So everybody some "lug nuts" and go fer it!!!!!![sm=icon_guiness.gif]

By the way, I have a Factory Pro stage 1 kit in the carbs. I put on pods and had to up the jet size to 108, raise the needle to the last clip(bottom ring) and run the idle mixture out 3 turns. Works for me!!!

 

The warning wasnt to anyone in particular. I have learned that in forums someone with not as much knowledge comes along and reads an idea then grenades their engine because they didnt know any better. You knew to hold the tensioner down when running the engine, others may not.

My reply to you was to your questions about the manuals was because you said this:
PS I don't think they make a manual for that 250, but I could be wrong. I asked on the Ninja 250 board and all I got for an answer was "what for".[sm=lame.gif]

So why would you say that if you have them???[sm=dontgetit.gif]

 

dam where is my popcorn!
alright, my spring question may have not been the best. Look at the fiche. Mechanically, how can you improve this?

 

You're correct mnosbor. And ya never know, I might grenade the engine later on, but I do ride it pretty hard. I got extremely frustrated looking for a remedy for my problem and all I got was "it's the valves". I knew better. It's just when someone replied to me on the manual CCT saying "what for", I just got a little [:@]. So as not to offend anyone, this was the solution I came up with. If you don’t feel comfortable doing this, by all means, do it by the book..
eeeeshhh, didn't mean to sound like a "know it all" but there is a hard lean to "shade tree mechanic"

Gonna be a nice day, go for a ride everybody!!