strong vibe from motor when going to WOT at 55-60mph

[Bret Morey]

I'm hoping someone here can point me to some ideas or troubleshooting steps to figure out why I have a pretty heavy vibration coming from my motor if I open the throttle to WOT at 55-60mph.  I have a 2015 DRz400S with just under 13,000 miles.  I checked the valve clearance about 200 miles ago and they were all well within spec.  I recently did the 3x3 and installed a JD Jetkit.  That woke the bike up a bit and completely eliminated an issue I used to have where the bike would stumble for a second if you cracked the throttle to WOT suddenly (assuming this was a lean condition that the new jetkit resolved).  I did not notice this new vibe problem after the jet kit install so I don't believe that to be the cause.  I then installed a new Kenda 270 on the rear, and the bike was still fine after that, with no vibes or abnormal behavior at all.  Then two days ago I drained and flushed the coolant system and filled it with engineice, and  changed the oil to BelRay full synth, replaced the filter and cleaned the screen.  The next day on my ride home from work I notice that if I go to WOT between 55-60 mph in 5th gear I get a ridiculously strong vibration from the motor.  It doesn't do this at any other speeds or in any other gear.  It seems to be more pronounced when the motor is heavily loaded like when going up a hill.  If I ease on the throttle (like I know I should) I can go through this speed and RPM range without the vibe.  It seems to respond directly to how much I open the throttle.  If I am at half throttle there is no noticeable vibration, at 3/4 throttle it is a noticeable vibe, and at WOT I get a pretty violent shaking that seems to be coming from the motor.  

Has anyone else ever experienced this, have any ideas what it might be, or have any suggestions on how I might be able to start diagnosing it?  This is not a subtle vibration.  It comes on strong and responds immediately in changes to the throttle.  On flat or downhill stretches I seem to cruise right through that RPM range and it smooths right out, but if I am going up hill it is a crazy vibe that sticks with me until I can get the speed and RPMs up.  This one has me stumped and seriously concerned that continuing to ride with this condition might result in serious and expensive damage to my beloved DRZ.

Any help will be greatly appreciated.

Thank you. 

Edited August 11, 2018 by Bret Morey

[ohiodrz400sm]

I'm hoping someone here can point me to some ideas or troubleshooting steps to figure out why I have a pretty heavy vibration coming from my motor if I open the throttle to WOT at 55-60mph.  I have a 2015 DRz400S with just under 13,000 miles.  I checked the valve clearance about 200 miles ago and they were all well within spec.  I recently did the 3x3 and installed a JD Jetkit.  That woke the bike up a bit and completely eliminated an issue I used to have where the bike would stumble for a second if you cracked the throttle to WOT suddenly (assuming this was a lean condition that the new jetkit resolved).  I did not notice this new vibe problem after the jet kit install so I don't believe that to be the cause.  I then installed a new Kenda 270 on the rear, and the bike was still fine after that, with no vibes or abnormal behavior at all.  Then two days ago I drained and flushed the coolant system and filled it with engineice, and  changed the oil to BelRay full synth, replaced the filter and cleaned the screen.  The next day on my ride home from work I notice that if I go to WOT between 55-60 mph in 5th gear I get a ridiculously strong vibration from the motor.  It doesn't do this at any other speeds or in any other gear.  It seems to be more pronounced when the motor is heavily loaded like when going up a hill.  If I ease on the throttle (like I know I should) I can go through this speed and RPM range without the vibe.  It seems to respond directly to how much I open the throttle.  If I am at half throttle there is no noticeable vibration, at 3/4 throttle it is a noticeable vibe, and at WOT I get a pretty violent shaking that seems to be coming from the motor.  
Has anyone else ever experienced this, have any ideas what it might be, or have any suggestions on how I might be able to start diagnosing it?  This is not a subtle vibration.  It comes on strong and responds immediately in changes to the throttle.  On flat or downhill stretches I seem to cruise right through that RPM range and it smooths right out, but if I am going up hill it is a crazy vibe that sticks with me until I can get the speed and RPMs up.  This one has me stumped and seriously concerned that continuing to ride with this condition might result in serious and expensive damage to my beloved DRZ.
Any help will be greatly appreciated.
Thank you. 

I would 1st check for loose fasteners.

What's your gearing? 55-60 mph seems kind of low to put the engine under load wot in 5th. I confess I am probably used to much taller gearing than you run also.
13k would be pretty early for a bottom end. Especially if the bike has been well maintained and in stock tune all of it's life

[jjktmrider]

Any chance the clutch is slipping ?  Not liking the new oil ?  Maybe a good long mild ride to really work the oil into the plates they'll be fine . Otherwise was thinking same as Ohio , too low rpm and the motor is chugging badly when trying to rev it so quickly .

 

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[Bret Morey]

I'm running 15-41.  Admittedly this is a fairly early shift and I could carry past the vibe point in 4th and shift later.  My concern is that it never did this before, and it is not a subtle vibration, which has me concerned that something is failing or has already failed, or something else is wrong that is going to cause damage if I don't address it.  I'm thinking about changing the plug in case it just not burning clean under that particular load, but the plug has only been in it for 2000 miles so I have my doubts that it is the source of the problem.

[Bret Morey]

Thanks for the idea rider, but I don't get any slip in the clutch jumping on it in first gear, and I would expect that would be more likely to make it slip.  And this is a pretty heavy vibe, almost more of low frequency thumping like I am lugging it, but really really rough and harsh, much more so that anything I have felt form the motor before, and I have lugged it way worse rising offroad.  I know I am lugging it a bit in that gear at that speed when I go to WOT.  My main concern is that this was never an issue before.  I'll probably just toss a new plug in it, and if that doesn't help, I'll take it to a mechanic to have them try to diagnose it.  I just hate asking someone else to do work for me when more often than not I end up being told nothing is wrong only to find out much later when something grenades itself that they missed the problem.

[jjktmrider]

Clutches slip in 5th long before 1st . There is more load on them in the higher gears fighting the leverage ratio than the lower ones so it's in those high gears you'll have issues while 1st-2nd are just fine .

 

 

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Edited August 11, 2018 by jjktmrider

[Bret Morey]

3 hours ago, jjktmrider said:

Clutches slip in 5th long before 1st . There is more load on them in the higher gears fighting the leverage ratio than the lower ones so it's in those high gears you'll have issues while 1st-2nd are just fine .

 

 

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I was not aware of that.  Thank you for sharing that knowledge.  I'll take it for a test drive again and concentrate on the vibe and my acceleration and see if I can detect any slipping.

[Bret Morey]

Starting to suspect rider was right and it had something to do with the clutch not being happy with the new oil bath, and needing some time to get used to it.  I took it for a ride and no matter what I tried I couldn't reproduce the issue I was having consistently the other day.  I'm not sure though because I would have expected the bike to rev up if the clutch was slipping.  I guess it is possible that is was slipping, grabbing, slipping, grabbing with a high enough frequency that the motor never got to pick up it might do what I experienced.  It's gone for now, and hopefully gone for good. 

[jjktmrider]

That slip/grab/slip/grab is what I was thinking of since I don't think your fiber plates are shot which is when the motor will rev . I've seen something like this in the past when a guy used regular automotive oil and the clutch started slipping . I told him to change the oil with a correct oil type he complained of a lot of jerking that slowly got less and less then back to normal . Took a couple hundred miles to get rid of the oil additives in the plates from the auto oil . Hope that is all that's going on with you and it's now fixed . May be a sign your clutch springs are getting weak as mine are . Now that I have my new stroker in if I grab a handful of throttle my clutch will let go once or twice then grab good , feels like the wheel slipping on the rim except I'd have a flat tire by now with a ripped valve stem off the tube .

 

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Edited August 12, 2018 by jjktmrider