Engine vibration

[XF650]

I would appreciate advice on possible cause of vibration coming from my 1997 XF650 (Freewind) motor - basically the same motor as DR650. Has had rear baffle drilled, carbs re-jetted & air box opened up (dyno tuned) but vibration doesn't seem to be induction related.
Bike now done 20,000 km's with excellent power & doesn't burn oil or rattle. Have isolated the vibration as internal, being real annoying @ 5,000 + rpm.

I have been told it's unlikely to be balance shaft related because if balancer fails then engine will quit. So if anyone with experience with DR650 / XF650's could advise what to look for, I would value your comments
Thanks

[xwhatsit]

Well, you've already ruled out the balance shaft thing, but I've also got a thumper with balance chains. I've currently got the side cover off for something unrelated, but the Haynes manual for my bike says to check balance chain tension as apparently they can slip a tooth or two, and all you'll know is that the bike will vibrate more and more.

The other thing is checking the engine mounts. I know when I briefly ran my motor without top engine mount (in my garage, just to check if it ran :)) it vibrated the frame like a bitch. So are the engine mounts still torqued right up?

[XF650]

Well, you've already ruled out the balance shaft thing, but I've also got a thumper with balance chains. I've currently got the side cover off for something unrelated, but the Haynes manual for my bike says to check balance chain tension as apparently they can slip a tooth or two, and all you'll know is that the bike will vibrate more and more.

The other thing is checking the engine mounts. I know when I briefly ran my motor without top engine mount (in my garage, just to check if it ran :)) it vibrated the frame like a bitch. So are the engine mounts still torqued right up?

Thanks for your suggestions but balancer is gear driven off crankshaft & engine mounts checked OK.

[surfer]

Is it a lot of vibration or just a tingle in your fingers from the handlebars? Handlebar weights or a bar snake might help to reduce this.

I have an XS650 which vibrates, apparrently this is normal for my bike. But I did reduce it quite a lot by tensioning the engine mounts as mentioned previously, AND by tensioning and adjusting the bolts that hold the front end onto the frame. You might also want to check that the carbs are balanced. Is your cam chain the right tension (if your bike has one)?

You could also find someone with a similar bike and compare yours. You never know yours might be better.

Good luck

[XF650]

Is it a lot of vibration or just a tingle in your fingers from the handlebars? Handlebar weights or a bar snake might help to reduce this.

I have an XS650 which vibrates, apparrently this is normal for my bike. But I did reduce it quite a lot by tensioning the engine mounts as mentioned previously, AND by tensioning and adjusting the bolts that hold the front end onto the frame. You might also want to check that the carbs are balanced. Is your cam chain the right tension (if your bike has one)?

You could also find someone with a similar bike and compare yours. You never know yours might be better.

Good luck

The vibration is more than normal - even some fastners have come loose.
Cam chain tensioner is auto but will check anyway, thanks

[Ixion]

Well, it is a big single. They will always vibrate a lot more than multis. I have vibrated stuff off ffwabbit, and broken mountings etc from vibration. Do you mean the vibration is bad even for a big single (feet won't stay on footpegs, hands won't stay on bars) or just it vibes (mirrors are a blur, odd bits loosen off, tingles through the bars etc). if the latter, it may be just a characteristic of your particular bike. Some are always worse than others.

[XF650]

Well, it is a big single. They will always vibrate a lot more than multis. I have vibrated stuff off ffwabbit, and broken mountings etc from vibration. Do you mean the vibration is bad even for a big single (feet won't stay on footpegs, hands won't stay on bars) or just it vibes (mirrors are a blur, odd bits loosen off, tingles through the bars etc). if the latter, it may be just a characteristic of your particular bike. Some are always worse than others.

Vibration has got noticably worse. Fresh oil doesn't help either.
I'm beginning to wonder if it's related to extra power from dyno tune.

[Ixion]

That could be. Back in the day, it was well recognised that some tuning was unwise, because the extra power came at the cost of an incomensurate loss of sweetness.

[F5 Dave]

Always hard to tell, check the mounts for cracks.
Not trying to scare monger (as is common on these threads); Possibly the crank has twisted out of alignment if over-revved which would vibrate real bad.

[Grub]

I rode a number of CBR600's when I was looking and yes, even though they're inL4's, there was a huge and I mean huge, difference in vibrations at different parts of the rev range in the different bikes.

Mine and two others vibrate from 4,900 to 5,200 (just where u want it smooth for 107kmh touring) but two of the others had worse vibes. One started at 3,900 and the other at 4,300. The bikes like mine all had standard pipes, the other two had after-market ones.

That pretty much confirmed for me that there is a humungous resonance set up in the cans and that's what you're feeling.

[XF650]

Muffler resonance could be the issue, especially as I drilled 12mm hole in rear baffle at time of dyno tune. I prefer that to a twisted crank !! In meantime am re-checking all fastners, mounts etc
Any other ideas?

[F5 Dave]

. . .
Any other ideas?
Never shake a baby.

[imdying]

Never shake a baby.Uh oh... sorry OAB :doh: