Engine noise

Long · Post by **Long** » Wed Oct 18, 2006 7:21 pm

Hello and thanks in advance for any light you can shine on my problem. I bought an H model zxr 400 yesterday and was told there was some kind of engine problem with it. The price was right so I confidently went for it hoping I could diagnos it and subsequently fix the problem.

Early on everything was fine barring the need to clean the carbs. But later in the evening as I geared down from 3rd to 2nd and hit about 12000rpm the engine began making noise. It seems to be coming from one of the left cylinders. If I had to describe the noise in text(as I seem to have to) it would most closely resemble this...frrmmm(roll the r)...and it was repeating itself at a rate of about every 1.5 to 2 seconds, so kinda like...frrmmm..frrmmm..frrmmm..Now to my limited in experience ear, it sounds like a valve fluttering and it's pronounced when the engine is in negative load(as in when slowing with the throttle off-engine braking).

Any ideas??

Post by **masterofinsanity** » Wed Oct 18, 2006 8:42 pm

eerrrmmmmm eerrrmmmmm eerrrmmmmm no!

does it do it at 12000rpm in neutral?

Long · Post by **Long** » Thu Oct 19, 2006 1:56 am

No, No, No, you got it wrong dude.

It's frrmmm..frrmmm..frrmmm..and it does it continuously at any rpm, in any gear. The sound is pronounced when engine braking.

Post by **masterofinsanity** » Thu Oct 19, 2006 8:35 am

are you thinking its definitely from internals? could it be a loose header pipe?

Long · Post by **Long** » Thu Oct 19, 2006 9:57 am

Well hell, I guess it could be! Actually thanks for the direction as I'm a bit of a cynic and always believe it's the worst case scenario.

I'll take the plastic off tonight as I need to clean the carbs and get a closer look at the engine exterior and do a couple odds and ends. I'll most probably be back here soon enough to pose another query or two after I've had a look.

P.S. I hope you're right about the header pipe!

Post by **masterofinsanity** » Thu Oct 19, 2006 10:18 am

sounds like a plausable answer as the bolts may have come loose and the noise you are hearing is the vibration through the pipes?

Long · Post by **Long** » Fri Oct 20, 2006 2:43 am

Sadly, it is not loose header bolts. Having taken the fairing off and firing it up the noise is def coming from the cam chain. I can hear it slapping the case inside. I'll be opening the valve cover and cam chain lower sproket cover to have a look at the damage. Tensioner or chain or both. There is enough information on this site to guide me through this and thanks for that! GREAT SITE!!

The bike sat for 6 months before I bought it, and itâ€˜s in China, land of the muppet mechanics. The first time I test rode it it was lurching and surging above 7000rpm and wouldn't pass 10000. I figured it was carb related and easily fixed. I got it home and took off the tank and airbox and the muppets had left the bolt hole plugs on the airbox off. I slapped some tape over the holes and went for a blast, sorted. It pulled right up to 10,000. it still wouldn't idle but I figured that was dirty, maladjusted carbs. Bingo again! Last night I took the carbs out and opened the float bowls and it looks like the Sahara desert in there.

This leads me to my next query. I read on another site that a guy had put smaller mains in the middle two carbs and I've heard of this before. It's actaully the way my CBR250 mc22 was set up. On this Kwaka 400 the mains are arranged thusly... #1- 98...#2-102...#3-102...#4-98... so the middle two carbs mains are larger than the outside carbs. Is this not screwed up?

Thanks for input.

Long · Post by **Long** » Sun Oct 22, 2006 3:05 am

Update:

Well it's def the camchain as I've pulled it and measured it and it's past the 20link limit even without the 5kg of stress. So I've decided to keep going and strip it to the frame and do a frame up restore.

It's not in terrible shape but the wiring loom is quite messed up. Chinese boys and electrics don't mix well. List of things to do, cam chain, fork seals, wiring loom, massive carb clean. That's what it needs to run. Then the rest is making it pretty. I'm thinking black...frame, swinger, wheels, fairing, calipers, discs etc.

That'll get me started.

Baz, should I move this to the projects thread? I'll keep updating as it keeps me sane and there's noone here to talk to about it. I'll start posting before and after pics once it's down to the frame.

Post by **masterofinsanity** » Sun Oct 22, 2006 9:18 am

glad you've found out what it was before it was too late, yes definitely start a build thread, look forward to seeing it.