[flyboy]

Hello All. Looking for some other possibilities which may be the root of my problem. My ride is a '99 Iron 500ks, stock except for TM32, Ace Air Can and shorty exhaust.

Problem: This just started. I feel a bad vibration, mostly on deceleration...coming off throttle when shifting between gears, or just slowing down while in gear. Do NOT feel the vibe when excelerating or steady throttle at speed. Do NOT feel it when reving in neutral. The vibe is definately down low, coming up from the footpegs.

Since I can't feel it when reving in neutral, I'm imagining it's coming from the gearbox?

Here's what I've done so far: Tightened all bolts around the gearbox. One was finger loose, others were tight. Checked gearbox oil....good. Checked all enging mounts, head steady and all bolts on frame and wheels...all good. Opened the Primary Case, tightened the primary chain to about 1/4" deflection in either direction. (It was very loose). Removed clutch pack, but not hub, and cleaned all friction plates and spacers while in there with brake clean. Clutch pack looks good. Checked the 20mm bolt that holds hub...it was tight. Adjusted clutch. Filled Primary with Type F, fired her up, still had vibration...actually, seemed a bit worse. It feels so bad, I'm worried to ride it.

Could something be coming apart in the gearbox? Other suggestions to look for?? I've had a RS Shift Kit on order from our hosts since Feb. Was recently notified it should be in within 2 weeks, so I didn't want to open the gearbox to check things out, since I'll be doing this when kit arrives.

The only remaining thing I can see or think that needs tended to is the main drive chain seems loose. Could this cause that sort of vibration....only on decel? Regardless, i'll be tightening that up tonight and give it another go.

Any advice would be much appreciated!

Tim

[ace.cafe]

Could be the drive chain.
Don't over-tighten it. Just  adjust it normally, and see if you get any improvement.

Check the head steady. I know it's on top, but it can have big effects if it's loose, so it's worth checking.

[cyrusb]

Main bearings rumble on deceleration. When you have your primary cover off you can check for looseness by trying to shake the rotor.

[rvcycleguy]

I've had the head steady fastener come loose and it's a strong vibration.  Got worse the farther I rode home.  Thought the motor was coming apart. 

[Kevin Mahoney]

What he said. That is the first thing I would check

[flyboy]

Thanks for the input.
I did check the head steady, but not with a wrench, only felt for finger-looseness. I'll put a wrench on it. And still to tighten drive chain.
I'm hoping it's something simple like that, and not what cyrusb has suggested....although, I'm thinking he may be correct.
I'll keep you posted of my findings.
thanks!

[ace.cafe]

Thanks for the input.
I did check the head steady, but not with a wrench, only felt for finger-looseness. I'll put a wrench on it. And still to tighten drive chain.
I'm hoping it's something simple like that, and not what cyrusb has suggested....although, I'm thinking he may be correct.
I'll keep you posted of my findings.
thanks!

Always check the easy things first.
It could be bearings. That would not be anything unusual for a Bullet to have bearings go bad. The engine bearings are a known weak point.

[Phlakaton]

I've had a similar thing happen as well - ended up the drive chain was a bit too loose.  I never fully lost the vibration but it was mitigated a lot with a slight tighening.  Chain was loose enough to slap on the frame just enough to be a menace

[flyboy]

Just thinking....IF this was to be the main bearings, is there any reason it would be more prevalent while riding?? As I said, I do not feel any vibration when reving while in neutral. Wouldn't bad bearings present themselves either riding or stationary?

[cyrusb]

Flyboy, what i have found is that the engine has to be transitioning from a loaded state to unloaded to get that rumble. It lasts only for the short time it takes to go from loaded to unloaded. I don't think just revving freely will cause it unless they are really shot. As ace suggested, do all the easy things first and hopefully you will find the vibe. I can tell you that my 05 with 10k is beginning to do that for maybe a half second between shifts. A short Brr sound. If and when it gets worse i'lll have to dive in.

[Kevin Mahoney]

On an iron barrel there was one bearing that would normally go bad. 99% of the bikes have never had this issue but it does happen. Normally it would happen pretty early in the engines life. It can sound like a crunching. You are getting some pretty good advice here....don't panic and look for the very simple things

[ace.cafe]

Just thinking....IF this was to be the main bearings, is there any reason it would be more prevalent while riding?? As I said, I do not feel any vibration when reving while in neutral. Wouldn't bad bearings present themselves either riding or stationary?

Having a load on the engine often makes the symptoms more noticeable.

[guss,guss]

please keep us posted flyboy.
 have you found anything loose that may have caused it?
 i am particularly interested because i also have a 99, and waiting on the RH shift kit. are you going to go with sealed bearings? i haven't decided yet. i may just put the RH kit in and use 00 grease for a while.

[flyboy]

Here's where I'm at...
Today, Tightened drive chain about 1"-1.5" and lubed well. Head steady and all motor mount bolts checked and tight, none were loose. Fired her up, and still have the vibration. Extremely noticeable, immediately from start out, when shifting from 1st to 2nd. ALTHOUGH, I noticed if I keep constant, steady speed in 1st gear, the vibe comes back....say, around 1500rpm. Didn't try it in 2nd.

Cyrus, I had the primary back together before I read your post of checking the rotor for slop. Thanks for the suggestion...I'll pull the primary case again tomorrow and check for any looseness. Seems like we both have the same problem, but mine may be worse. (try yours at that steady 1500-2000 rpm in 1st and see if you get the rumble)
QUESTION...should I remove the stator when checking the rotor? Or can I just get a socket on the nut and check? HOW MUCH play is too much...any at all is bad?
Thanks all,
Tim

[flyboy]

guss, yes I did get the sealed bearings...why not while you're in there. I've had those since the end of Feb, along with the kickstart pawl (get that too), which got shipped on time, but still waiting the RS kit.

Could there be a chance there is a problem within the gearbox and not the big end, which is causing this rumble? And it can be solved while doing the RS kit....with the close-ratio gear set!?

[ace.cafe]

When you open the primary case to check for shaft wobble, check both the crankshaft and the transmission shaft. Neither one should have any perceptible wobble.

[flyboy]

Thanks Tom. Do I need to remove the stator too...or, do you think I can get a good feel of it from working the rotor inside the stator?

[ace.cafe]

Thanks Tom. Do I need to remove the stator too...or, do you think I can get a good feel of it from working the rotor inside the stator?

You might be able to.
But it's such an easy matter to just take all that primary stuff out, it might be worth it to get a good handle on those shafts for checking.
Also, this crank wobble test on the drive side will only test for drive side 6305 bearing problems. If it is the main roller, the shaft may still seem supported if the 6305 is not bad. And it won't test for the timing side roller because that's on the other side(unless it is really really badly wiped out).

But, by removing the clutch and primary gear, and checking the transmission shaft for play, at least you can determine if the transmission bearing is bad, which could be causing the sound and vibration.

[flyboy]

Ace, It's positively the gearbox. Stripped down the primary innards to access each shaft. Crank end is tight, trans shaft has play. Not terrible, but definite movement.

Would this be a countershaft bearing on the primary side? Is there a mainshaft bearing in the gearbox?

How should I go about continuing to diagnose this? I'm concerned I may get too deep...should this be done at a shop by someone with trans experience? Or is this not too difficult? I will be receiving (hopefully) the RS shift kit in a week or two, once our host receives, so I'll be getting into the gearbox side soon.
Thanks for the help!
Tim

[ace.cafe]

Ace, It's positively the gearbox. Stripped down the primary innards to access each shaft. Crank end is tight, trans shaft has play. Not terrible, but definite movement.

Would this be a countershaft bearing on the primary side? Is there a mainshaft bearing in the gearbox?

How should I go about continuing to diagnose this? I'm concerned I may get too deep...should this be done at a shop by someone with trans experience? Or is this not too difficult? I will be receiving (hopefully) the RS shift kit in a week or two, once our host receives, so I'll be getting into the gearbox side soon.
Thanks for the help!
Tim

It is most likely the output shaft bearing that is pressed into the case.
It's not real hard to do it, but you have to have the courage to decide to dive into it. You could get the sealed bearing kit, and do the tranny at the same time as the right shift kit. The close ratio gear set would complete the package, if you can afford to do it all at once. The CR gear set gets rid of that huge ratio gap between 3rd and 4th, and makes the bike much more rideable. But it costs a fairly large sum.

Anyway, if you don't feel up to it, and can remove the engine/gearbox from the frame, you can send the gearbox to Chumma to do it for you.

[flyboy]

Thanks for the input.
I think I'd like to dive into it, providing it doesn't need any special shop eqp....ie, press etc. Can it all be done with the gearbox in place?
Is the CR gear set a Hitchcock or Nfield item? Do you know how much $$?
I do have the sealed bearing kit for the 90wt, if that's which you refer to.
As for the output shaft bearing, is that a Nfield thing? Is that the only bearing in there, that can be bad?
Sorry for all the questions. I do appreciate your comments.

[ace.cafe]

The bearings you need are in the sealed bearing kit.
You can do it in the bike, but you will need to use a torch to heat the side of the gearbox case to change that bearing.
The CR kit is an Nfield Gear thing, and you need to check out price and availability with them.