I think its bad news at 5000 rpm"s

Yamaha 82 750 Maxim, I've done everything that I have read about to make this engine run correctly but I am getting a really bad vibration and noise change when I hit 5000 RPM, it doesn't matter what gear I am in it does the same thing right at 5000 does anybody have any idea what might be going on

 

Are your carbs synched? Have you checked and adjusted your valves? These two work together in many cases after adjusting valves the synch needs adjusted.

 

What happens after 5K??

 

More importantly, what is your refrence point for what should be happening?
What other motorycles have you owned?

 

Seems like there has been a couple of these lately. I know I get a bit of extra vibration at that RPM, but not excessive. At least one other poster complaining of this found a broken weld on the collector chrome cover that made all sorts of racket when it hit that resonance rpm.

 

Valves are in spec, carbs are in sync almost perfect, valves were adjusted first. After 5k nothing changes other than the rpm's going up. and that bad louder noise keeps getting louder I'm not sure what you mean by reference point k-moe. Do you mean at 5k ? That's where the engine sounds like something is going to come out of the front of it. Up to 5k it sounds like a well oiled machine. Back in 82 i bought a brand new 650 maxim, years have passed but i don't remember this noise. Rooster, what and where is the collector cover ?

 

does this bike have rubber motor mounts? if you bang on the middle of the exhaust collector with your fist, does anything rattle?

 

And that ^^^^. The internal baffles in the collector are also known to break loose.

 

The sound sounds like it comes from the top end of the engine I can hear it in the front like at my exhaust area I have replaced my exhaust Donuts seals whatever you want to call them and tighten the nuts down per spec

 

Re-tighten them, exhaust leaks can often mimic .clicking'.....but second gear only.....weird...

 

X2. My 650 developed a nasty vibration right after I had to unbolt the motor to address a wiring issue. Tightening the motor mounts back up corrected the issue.

 

I'm pretty sure I've a problem with mine as well, though it's at 3500rpm for me. Rattling/ringing noise,have thought I fixed it a bunch of times but it keeps coming back. Figure it's got to be in the collector or it's cover plate.

Door dude, it sounds like this: https://photos.app.goo.gl/DbWed415rIccyyBq1 really noticable at 20 seconds in.

That what you're getting?

 

Double check their torque.
Don't discount the collector underneath. Sound waves move.

 

Yeah, can be really hard to know where a sound is coming from if you can only get it to happen at speed while riding.

 

It happens just if I'm sitting in the driveway revving it up. I think the first thing I try is to loosen up my header pipes and readjust just to make sure that they are flat on the donuts and then retighten and torque the nuts

 

I just looked at the video you sent Winters dark no mine sounds like it could be internal and on the top end of the engine it happens at the same vibration 5,000 RPM if I go faster the Rattle and noise is still the same but it just gets louder because the RPMs are going up. I really don't hear a rattle it's more of a stronger vibration that is louder

 

I went out for a ride this evening, 5k same thing. It just doesn't feel good to ride that fast

 

I have the same 5,000 problem. Makes me feel better that it's not 'my' bike, but it's something with these 'bikes'.

Here's my thread;

http://www.xjbikes.com/forums/threads/vibration-only-at-5-000-rpm-up-and-down.114531/#post-572933

Just out of curiosity, did you let your bike sit a while before it started the problem?

Thank you,
Chris.

 

By refence point, I mean what other motorcycles have you ridden. What engine type, how recently, and for how long?

Since you describe it as a rattle, I'm goin to agree with the others and lean strongly toward it being a exahust issue. Loose heat shield, broken weld betwen the inner and outer header pipes (the heades are double-walled), or broken baffle in the collector.