Engine Vibration
 

Hi everyones.

Ever since day one my EC300 has been a real viber. But of late a bit more noticable in the mid range as it comes onto the pipe. I checked the engine mounts and slightly nipped up the front lower, which reduced some of the vibes while on the stand but the bike still gets a real buzz on right before it explodes into band.

My rear pipe mount is broken and has been removed. The front one is looking pretty shagged out. The O-rings and springs are good though. Would these create extra vibration? I have removed the lower front pipe mount (rubber part) and solid fixed it. I will be taking it for a test ride to see if this reduces the vibes. Either way I know I'll be up for a new rubber mount as solid mounting is a sure way to crack the pipe.

Any other ideas why the bike buzzes so much?

I noticed that when i reduced squish and leaned jetting, my bike got a lot less vibey. i did change how the pipe is attached also - i removed the 'tank' attachment...and reworked the lower front mount. not sure which made it much smoother....

Put your foot on the pipe when you hear vibration to see if that makes a difference. If it does, then it is probably related to the pipe mounting.

I use 43x3.5 viton orings on the pipe header flange. They make pipe installation difficult but really help tighten up the pipe flange. They also seal better.

Just to confirm I am speaking about vibrations that you feel. Not the pipe buzzing on the header. I have experienced that in the past as a side effect of the engine buzz. You know the one you feel coming up through the pegs and the bars. Its very very noticable right as it comes onto the pipe. I know they all vibe to a certain extent but it just feels a bit too much.

I know I'll have to pull the stator cover and check the flywheel and main for play at some point. Main question is though, how much would loosish pipe mounts transfer vibes to the bike.

Every time I crash, I seem to ruin the pipe O-rings. Then the vibrations get worse. However, my bike vibrates the same as yours does right before it comes on the pipe.

I made my own lower pipe mount out of some rubber bushing I had laying around. The metal springs sometimes vibrate really loud too. As long as I don't have an exhaust leak at the head, I'm good to go.

Guess I'll just have to take it for a burn with the pipe hard mounted and see how it changes the vibrations felt. I don't expect silky smooth or anything but it was just a tad annoying. I'm not sure if it feels a bit more noticable due to the smooth transition the NEDx needles have as the powervalve opens. I think the hit the N3 range masked it a bit as there was a more abrupt transition. Will do some testing and report back.

300s tend to vibrate more do to the increased mass. Loosen all the mounts and re-torque starting with the swing arm pivot. Check your crank for radial play. I assume the newer sealed bearings are ball bearings, not rollers like on the '02 - '07, and should have no detectable radial play. I had an '00 with a bad crank that spun in the inner bearing race, causing wear and play, and started to vibrate after some hours. There is always the outside chance that the crank is just not balanced right. This is not common, but there are only so many things that it could be.

Thanks Glen,

Just a few quick questions re engine mounts. Do I have to drain the coolant, disconnect the lines, move the radiators forward to get to the engine mounts? Or should I just be able to sneak a socket in on the RHS and back off the locking nut a few turns before firing the bike and letting the engine find its neutral spot?

It has vibed since day 1, and crank had no play 30hrs ago when the top end was done. The vibration is mostly bareable but a bit of an annoyance when rolling the throttle on slowly the vibes build build build and then onto the pipe it just sings nicely. Trying to ride it just before the powervalve its vibrating quite a bit. I actually wonder if it could be related to the timing. Might try flicking back to rain mode and seeing if that makes much difference aswell.

You should be able to get a socket on the mounts without much drama. You can play with jetting, but if you have a 2K-3 like I'm sure you do, the timing is fixed by a locator insert in the stator plate.

Cranks are balanced with a balance factor that is good for a certain RPM range. Since the 300 is better ridden at a lower RPM than the 250, why should they have the same balance factor? Answer is they shouldn't, but they probably do. This is just a guess on my part being they have the same part#. Thats why it gets smooth as RPMs increase, where you would ride the 250 more. If I were building a 300 motor, I'd have the crank re-balanced for the sweet spot. I talked to a guy once who did this on an old Husky 360 and it made the old paint shaker more comfortable.

You can also send your flywheel out and have than balanced, but all Kokusan flywheels I have seen had evidence of factory balance (material removed in spots).

You're definately the man in the know. Correct with the stator. 2k-3. I was going to test the dual ignition switch just to see what effect it has.

I'll definately give everything a go like you have said by letting the engine and pipe find their own place. Do you suggest also loosening the swingarm pivot aswell? or just the rest and work from swingarm back?