weird screeching noise when driving with engine cold?!
 

Hi everyone,

Winter is here so i´m preparing to do some maintenance on the bike and need some assistance.

I noticed this spring/summer a weird screeching/hissing noise coming from the engine/front of the bike. Best I can describe it is I start the bike everything sounds normal, get on and give it some gas while its still cold and when I lay off the gas at maybe 40 mph the noise is very noticeable. I brake and get down to maybe 20 mph and the noise suddenly stops.
This noise only comes when the engine is cold after I rev it up at speeds before stated.

Has anyone dealt with the same thing and found what the issue was? it does not sound good. Was not able to take a video since its only noticeable at speed.

I feel sometimes the engine does take a while to heat up to operating temp but then again I live in Iceland! Could it be something with the thermostat or is it totally unrelated.

Thanks,
Eidur

Does this noise appear when the engine is ticking over and on the side stand, or only while riding

^^^+1

Try to duplicate the noise with the bike on the side stand. If you can do it, then it points to an engine issue, if it only happens when riding, it points to a drive train issue.

The noise only appears when the bike is at speed off the stand, I revd the bike many times on the side stand but the noise never comes.
Not sure what it could be in the drivetrain since it´s only coming when the engine is cold.

I went through all the electrics, forks, brakes, fuel system last winter, bike runs great other than the carbs need syncing.

I know the noise description is very vague, was hoping someone recognized this.
Would maybe something with the oil pump or stator make loud screeching noises like this when failing?

Like @Hawkwind says , transmission , have you adjusted your chain slack, can get that type of noise from a tight chain

I did adjust the chain slack this summer but the sound was noticeable both before and after. will jack up the rear and see if the sound comes that way and see if I can pinpoint the problem.

Thanks

Discs? maybe a pebble caught in the pads...

I would think that is not the issue since its only noticeable when the engine is cold. Noise does not change when I brake hard after it starts, just goes away when I get back down in rpm and speed

I'm not to familiar with the old 600f, but is there any duct work or flaps in the air box that open or close when the bike is hot? Maybe it has to do with air flow, since it only happens at speed.

No active ducts in the Hurricane. Just low pressure intakes inside the fairings.