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A friend and I bought a modified camshaft for his ninja 300/EX 300. After installing and checking/adjusting valve clearance everything seemed ok. After a few laps on our local track the bike started making a noise similar to when the valves are a bit lose, so we went back and opened her up. Measured everything and everything is good so it's not the valves, closed her and there was no noise again. After an other run on the track the noise came back. So it seems like something that occurs when the engine is hot My theories are:

  • Drive chain too tight (I observed this but do not know what the correct tension is)
  • Mixture of hot engine and poor lubrication when hot

My friend already ordered a manual chain tensioner to see if it helps, so I will come back and update the thread if something changes.

What are your thoughts?

  • Quick update, the manual timing chain tensioner should be coming in on Monday so we will be installing it Monday night and checking again.

New update

We put the manual tensioner in, and until now that seemed to be the problem, we still have to test this and make sure it doesn't happen after some laps on the track. But we let the bike run for a few minutes and it was all Ok.

Final Update

After a full race weekend and a full track day the bike is great and no further weird noises where found, so it was definitely the chain tensioner. Seems like after modifying the camshaft it puts more stress on the chain and the stock tensioner is not good enough. Thanks to all for pointing us in the right direction.

Manual chain tensioner

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  • I don't see anything in your post related to plastiguaging the connecting rod bearings. I'm under the belief that your mains are rollers, right?
    – DucatiKiller
    Apr 12, 2016 at 19:34
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    Also, if you can upload a video that has audio into youtube, or something like that, and post it in here we can have a listen. That will lead to less speculation. I keep leaning mentally to connecting rod fluid bearing because I didn't see that you measured the connecting rod ID and the offset journal OD.
    – DucatiKiller
    Apr 12, 2016 at 20:15
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    That cutaway doesn't show the chain tensioner. It might be useful for you to share the profiles for both stock and aftermarket cams (lift, duration). I wouldn't be surprised if the current chain tensioner is not providing adequate tension
    – Zaid
    Apr 12, 2016 at 21:24
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    You got me to look up the procedure... indeed they should be adjusted cold according to this link. ... but wait just a second.. that link shows screw type adjusters with rocker arms. You image doesn't show that. What's up? Do you have rockers with screw adjustments (to be gapped when cold) or shim type direct path to valve type (measured who knows how?) What EXACTLY what procedure and reference did you use. What clearances did you target? Something doesn't sound right here... (model = 250 or 300??)
    – zipzit
    Apr 13, 2016 at 18:57
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    It looks like the 250 had screw and locknut valve adjustments but the 300 switched to a shim under bucket system. You title clearly says Ninja 250, the the first sentence in the content says Ninja 300 (Well that's clear as mud.) I'm curious.. how many shims did you have to buy to get this right? new shims are $9 each. Please share the exact valve gap measurements on this posting.
    – zipzit
    Apr 13, 2016 at 19:05

1 Answer 1

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since your getting your tensioner in, I'll throw in

I'm rollin with the tensioner. ALL IN!

Valve ticking can sometimes sound like a tenionser. Your description of valve lash setting makes feel good about it, I can see hours of double checking.

The stock tensioner is admittedly a POS. A manual one can make things better or it can make them worse, it's up to you

I highly recommend not over tightening the cam chain. Sometimes it sounds better but only because you can make the so tight they sound like a jet but that's not what we're trying to do here. we want an nice even flow, even just a hair loos, if the manual can push it rod further in against the tensioner without intervention.

AND THIS IS THE KEY...non intervention. Let it idle and run it and turn the manual scew in a 1/4 turn at a time. Be patient and you will find your mark.

Manual is they way to go. Please let us know how it turns out!

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