Excel III buzz

jjmoneysauce

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Joined
Jan 13, 2018
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157
Location
Saskatchewan
1985 Excel III has a weird buzz that sounds like it's coming from somewhere in the middle of the engine. Has anyone ever experienced something similar? Here are a couple short videos of it.

Video 1

Video 2
 

Yeah it has a tach. I disconnected the tach cable and the noise remained. I was going to pull the oil pump and check it all out, but my clutch removing bolt isn't the right size. I'm topping up the battery to see if that affects it, since I found some threads where low voltage to the starter relay was mentioned. I'm really scratching my head on this one.
 
Could you use a piece of large diameter hose, direct it down to the oil pump / tach drive area to try to pinpoint the source / area of the noise? Does the noise (rpm) increase with an increase in motor rpm? Something behind primary clutch? Something in fan housing?
 
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I tried that with a paper towel roll, and it was inconclusive.

I disconnected the primary, thus disabling both the oil pump and tach, started it for a couple seconds, and the noise was still there. While driving it this weekend, I noticed that the buzz stays at a constant frequency regardless of engine speed. It also doesn't make noise when cranking the starter or pulling the recoil. This to me suggests that it's something electrical. The tick of the buzz, if that makes sense, sounds a lot like when I tap the starter housing with a screwdriver.

It does not appear to affect performance at all, so I will keep scratching my head.

Another curiosity, on this machine, is that when it's been running for a while and then is shut down, a few minutes into cooling down, it will make a "pop" sound like those pop guns at Cabela's.
 
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hmm that is weird. i have heard buzzing from hood parts while idling.

as for the pop, the idle sounds too high or it is hanging up a bit. seen that a few times before.
 
yup that might be the problem. i know my dads viper venture needs to idle right down or it pops through the exhaust every time.
 
My VK540 has similar sound , in fact all my quiet sleds have it since I cant hear any muffler note or air box noise .. is this sled new to you ? or this is a new noise ?
..
A broken skirt packed into the port might rattle and amazingly enough they still run well... cracked / broken cyl head fin ? loose nut and washer on head bolt ?
You might want to look inside the engine with a scope for scoring , foreign parts in ports , if this engine is piston port also can get a got view in the ports of
the pistons and crankcase ... some free air sleds had similar rattle unless rubbers added between fins...
I'm hoping for a loose head nut or bolt . as that can be simple to fix.
Ron
 
Sounds like an electrical relay? I’m no expert, but I think a bad relay can buzz, and even possibly pop once cooled ?
 
relay sounds interesting as the cutout relay tries to hold around 12-14volts and shouldn't change rpm ... this sled have electric start ?? a good battery in place , maybe cable hanging
near ground ? Headlight work etc ... But it seems to be such a loud noise .... the pop may be a separate problem completely ....
Hope it is something goofy and not mechanical.
Ron
 
Yes sir, the sled has electric start. I'm still puzzling over it. The sled works completely fine otherwise, except for the buzzing/clicking noise when it's running. The click isn't there when cranking it or pull starting it, only after it starts running. I will take a closer look at the electrical stuff.
 


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