I just got my 625sxc on the road and am hearing a loud noise that sounds like its coming from the engine, maybe timing chain or valves. It sounds like it isn't getting enough oil. While moving it is hard to tell where for sure, but I stopped as soon as I started hearing it today and at idle could hear the valves clacking louder than I would expect. If I give it throttle the noise will go away slowly, until all I hear is the engine running normal. Back off the throttle quick and the noise starts back up, ease off and it stays quiet.
Is this normal for an LC4?
Re: Funny Engine noise
Posted: Thu Jun 12, 2014 12:23 pm
by waserman
How many miles are there on it ? Almost sounds like timing chain may be worn and when the bike is at idle there is slack in it and when you give it gas or under load the slack is taken up. Have you pulled the cam chain tensioner to see how far it is ratcheted in towards the front of the bike ? I can't remember the number of clicks before it's time to replace the chain I think if your more than seven in your getting close. This is assuming that you have the standard auto cam chain adjuster in and not one of the aftermarket tensioners , which were available for some but not all models. The other thing that I have read is the valve train rocker arm rollers wear out and need to be replaced also. I think that they are tiny bearings that ride on the cams operating the valves. I also didn't ask when the last time you checked the valve clearance was, I'd start there.
Re: Funny Engine noise
Posted: Thu Jun 12, 2014 1:35 pm
by chasbo
Between 7-8k on the bike. Even though I got it two years ago, a shoulder injury kept me off of the bike until this week. So all I can go by is what it sounded like when I rode it home after I bought it. Valves were checked just before I got it and were fine.
Re: Funny Engine noise
Posted: Thu Jun 12, 2014 6:09 pm
by Rut Row
on the LC8s, there was a problem with the hydraulic tensioner. Not sure if the LC4s had the same problem. Mine sounded something like that.
Re: Funny Engine noise
Posted: Thu Jun 12, 2014 6:17 pm
by chasbo
I was thinking it might be the decomp making noise or the top end wasn't getting enough oil. Tensioner is a possibility as well.
Re: Funny Engine noise
Posted: Thu Jun 12, 2014 11:39 pm
by anotherguy
Cam chain.
Re: Funny Engine noise
Posted: Sat Jun 14, 2014 9:01 am
by waserman
chasbo wrote:I was thinking it might be the decomp making noise or the top end wasn't getting enough oil. Tensioner is a possibility as well.
The decompression mechanism will make an odd noise if the idle is too low not sure what the rpm range for idle is on your bike. I have also heard of the ratcheting paw notches wearing out and allowing the spring loaded adjuster to moving in and back out when the engine is running .
Video of Engine Noise
Posted: Sat Jun 28, 2014 8:33 pm
by chasbo
Here is a couple videos I took today where the noise is pretty easy to hear. Looking back at one of the filters that came out of the bike, it looks like it has a little wave to it. Enough of one that I am going to go ahead and rebuild the water pump. I will be able to access the timing chain and check its tension when I do that as well.