www.zxrworld.co.uk

Recently just did all my valve clearances, changed the cam chain and checked the guides in one fell swoop, now between 3.5k and 4k revs there is a horrible grinding noise, ive pulled the cam cover off again and re-checked all the timing marks, TDC, and valve clearances again and all seems spot on and i cant see any sign of grinding or damage in that part of the engine, it seems like its coming from that area though.

Ive been using it still for a month and has no perceived change on throttle response, power or anything else and is kept between the above mentioned rev range, any higher or lower than that and it all sounds sweet as a nut.

I did however re-set all my mixture screws back to standard at the same time so am wondering if its anything to do with my carbs.

The only thing I can think of is that there is something loose round that area and the resonant frequency of whatever is loose is the vibrations caused by the engine at 3.5k-4k revs So i am pulling it all apart again this week to triple check.

And before anyone asks no I did not drop anything inside the engine, I have also had my friend who is a Helicopter engineer and also owns a ZXR400 and ZX9R pull it all apart and check everything again and he couldn't find anything.

Any help guys would be a massive help.

Cheers

Sounds like a cam chain problem to me...............

At a guess you have failed to reset the tensioner ? ?

I dont think so, i pushed the bit that extends right back down into the housing, is that what you mean?

Also if was that wouldnt it make that sound all the time not just at specific revs?

understanding that this is an older post from 2011 did you find out what was cuasing the rattle as am having the exact same problem with my zxr400

I'm also having this problem. It makes a rattling noise that starts at 3500rpm, peaks at 3750rpm, and stops above 4000rpm. Anybody have any insights? I just have one month left in my riding season, so I was going to start tearing things down to search for the problem over the winter.