Engine Vibration

[Jakobi]

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?

 

[stainlesscycle]

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....

 

[Eric K]

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.

 

[Jakobi]

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.

 

[Bailey28]

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.

 

[Jakobi]

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.

 

[GMP]

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.

 

[Jakobi]

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.

 

[GMP]

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).

 

[Jakobi]

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?

 

[Neil E.]

In other posts Glenn has said loosen all points, then tighten starting with the swingarm pivot. Solid advice.

 

[GMP]

Yes, absolutely. Its the first to get re-torqued (81Nm) I wouldn't run the bike with a loose motor though. With all the mounts completely loose, take a close look at the mount tab to case fit. If any gaps are present it might pay to shim the clearance. I have not had to do this to a GG but a couple guys here have. Also look at the fit between the swingarm bearing sleeve and the boss in the frame. On my '03 there was some very small weld spatter preventing a full 360 deg. contact, and actually cracked the sleeve when the pivot was tightened. Unlikeky now as the newer bikes are a lot cleaner in detail, but doesn't hurt to check service the suspension while its apart. Good Luck!

 

[Jakobi]

Well I've been down the workshop and done what you said.. Too late here to be starting it up so I won't know how much difference its made until tomorrow.

Loosened the swing arm, and all engine mounts. The tab clearance was pretty good so no shimming done. Worked my way from the swingarm to the lower to the front and finally the head. Then went over them all again to make sure they were torqued up nicely. I also had to remove the front coolant line to get enough clearance on the front mount so fresh coolant and a flush there. Cleaned everything up. Inspected the piston and cylinder through the exhaust port. All nice there.

I'll be throwing the pipe on in the morning and firing it up! Wish me luck..

 

[Jakobi]

Still got a bit of a buzz. Maybe a tad better than normal. I switched out the needle on the carb to see if the jetting was adding to the vibration and I think it is to a certain extent.

Thanks for all the advice

 

[GMP]

If all mechanicals are OK, you may just be dealing with mfg tolerances as far as balance. Have you compared it to other 300s? If all is well on the outside and it still bugs you, have the crank and flywheel balanced. If its the vibration in the bars thats the most annoying, add weights to the ends just inboard of the handguard mounts. This can help in some cases, it did on both of my KTMs which were a lot worse than any GG I've ridden. A simple piece of tubing filled with bird shot, taped for a friction fit in the bar ID.

In the end maybe you would prefer a 250.

 

[jeffs2200]

My 300 has vibed real bad since day one. I recently sent the head to RB and it vibes even more now. I am not sure if the increased compression or what.

I was looking my bike over really well last weekend and noticed that the right side rocker support for the linkage was broken up by the swingarm. I took it all apart yesterday and ordered a replacement. It appears to me that the engine is sitting a little crooked in the bike. I think this is what caused the linkage support to break. The bolt for the swingarm was very difficult to remove as well and you can see that it is not centered through the frame from one side to another. I plan to loosen everything and try and straighten and re-tourqe all the mounts. I hope this will help with the vibes and also keep the swingarm support from cracking again. The support had to be in a bind to crack in the first place. From looking at it I see no other explanation.

 

[GMP]

What year? This is similar to what I had going on with my '03. Put the pivot shaft back in the frame with the swingarm bearing sleeves, brackets, and engine. Slowly tighten things up, looking closely, and you will get an idea what the problem is. You may have to clean/square up the surfaces of the frame bosses.

 

[Jakobi]

Its definately not unbareable and somewhat unnoticable when really riding the bike in the dirt. Where it is super annoying is when rolling on slowly down the road, particularly with the NEDW needle which seems to buzz up just before coming onto the pipe.

I also think that the stiffness of the renthal twin walls tends to transfer the vibes a bit more than the hebos. I have new lower and upper pipe mounts / vibe isolators ordered which I will be fitting before I ride next should help a bit too.

 

[GMP]

They all feel alien on the road, mine too, especially after riding a nice road bike for awhile. Its easy to find that bad spot on the street and sometimes you have to ride it there. If it doesn't affect you in the dirt thats good. Thats why I avoid all the dual sport events with excessive blacktop.

 

[jeffs2200]

Mine is a 2011 300. There really is no excuse for something like this IMO. I am sure I could have gotten the rocker support warrantied but it was only $56 so I decided not to mess with it. I will check everything when putting it back together. I am going to try and be sure it is all lined up square before tightening so I do not break anything again. I have a feeling it had been broken for a long time but it is not a spot I look at often. If anyone is unclear of the part I am referring I can post a pic.