slipping under hard accelleration?

[droptail]

Is there something typical of this bike that feels like it slips momentarily when getting on it hard from a low speed?

I put a new clutch in not too long ago when all I needed was a master cylinder service.

This slipping has happened at least once or twice before, some time ago.

It feels like the tire is slipping for a second, but I don't think that is what it is.

Any thoughts?

thanks

 

[SkooterG]

That doesn't sound normal to me. But it's hard to tell from your description. Hard to believe the clutch is slipping at low rpm, and not at higher rpm.

How many miles do you have on the FJR? Are you inventing things that are not there?

 

[azitlies]

Agree with Skoot, kind of hard to tell from so little info.

Another possibility, and hold onto your butt tight for this one, possibly bent gear dogs? It's under hard acceleration when that shows up, and it's usually precluded by 'hard shifting' (which is what results in the bent dogs).

what oil are u using? it is motorcycle specific right?

 

[bramfrank]

I agree with azitilies - the key is in the term 'momentarily'.

Bent shift forks and rounded dogs in the transmission. Lots of verbiage on the forum already. Here's a search on the subject:

https://www.google.com/search?q=site%3Awww.fjrforum.com+bent+shift+forks+dogs

 

[droptail]

Low speed, climbing to redline, I'd say rising around 6-7krpm. Only happened 2-3 times over 3 yrs, so its very inconsistent.

I'm using Shell Rotella dino.

Bike has about 55k miles.

Newish 200 rear tire, past break in time (1k miles).

I suppose it could be hitting something slippery for being so inconsistent.

I thought damaged shift dogs would cause trans to pop out of gear, or make it hard to engage?

Maybe I have a slipper clutch prototype?

I didn't change the clutch spring, but it should be fine?

I'll look at the links.

ScooterG: Although I am an inventor, I can't claim credit for this one.

Thanks

 

[Bungie]

Low speed, climbing to redline, I'd say rising around 6-7krpm. Only happened 2-3 times over 3 yrs, so its very inconsistent.

Gen 1 Powa!

That inconsistent, pretty much guaranteed it's tire slippage. Wanna feel how hard it really accelerates with no slippage, put a car tire on it.

(Just don't try to turn or you'll die in a ball of flames and molten aluminium)

 

[rogdeb]

Low speed, climbing to redline, I'd say rising around 6-7krpm. Only happened 2-3 times over 3 yrs, so its very inconsistent.

I'm using Shell Rotella dino.

Bike has about 55k miles.

Newish 200 rear tire, past break in time (1k miles).

I suppose it could be hitting something slippery for being so inconsistent.

I thought damaged shift dogs would cause trans to pop out of gear, or make it hard to engage?

Maybe I have a slipper clutch prototype?

I didn't change the clutch spring, but it should be fine?

I'll look at the links.

ScooterG: Although I am an inventor, I can't claim credit for this one.

Thanks

Pretty much exactly what I just went through, except mine was slipping consistently. Mostly low speed in 2nd with quick acceleration to 65K, slipped like crazy. Roseville Yamaha (my dealer) found a bent shift fork and rounded dogs on 2nd and 3rd gears. Mileage was 60,000.

Gonna cost ya if yours turns out the same ---- sorry

 

[wfooshee]

If it's forks and dogs, the gear engages but is not held tight enough by the fork, and the worn ends of the dogs don't mate firmly enough. High torque causes them to slip to the next engaging hole, or the next or the next, till they finally seat. Of course each slip just exacerbates the problem by wearing the dogs and forcing the already bent shift fork back out of the way.

If it's traction, then no big deal.

You'll know which it is if it starts getting worse over time . . . . .

 

[droptail]

Well, at least it hasn't happened more than a few times in as many years. And I do run up the RPM to around 7k every once in a while to hear my exhaust cutout open up and roar.

Good info to know and watch out for, thanks.

 

[Bustanut joker]

Fish on!

 

[supertankerm60a3]

If you are truly wondering, try accelerating hard from a stop sign doing a right turn... in front of an oncoming car during a very rare, marginal break in traffic. IF it is the tires breaking loose, it WILL tell you in no uncertain terms!

Disclaimer: The above post is a joke. Do not try hard acceleration in a tight corner in front of a car from a stop, it can step out on you and pull a groin muscle, then stay up just to let you know it is unhappy with you

 

[ekms377]

Mine kind of does the same thing. When it gets hot, the play in the clutch lever goes away. Then it will slip under acceleration. Its the slave cylinder not letting the rod back all the way. If I bleed it for a sec. I get my play back in the lever. I need to take the slave apart and see if there is dirt in there or back up in the master.

 

[droptail]

Mine kind of does the same thing. When it gets hot, the play in the clutch lever goes away. Then it will slip under acceleration. Its the slave cylinder not letting the rod back all the way. If I bleed it for a sec. I get my play back in the lever. I need to take the slave apart and see if there is dirt in there or back up in the master.

Very interesting, keep us posted.

I'll monitor the play.

 

[Donal]

Mine kind of does the same thing. When it gets hot, the play in the clutch lever goes away. Then it will slip under acceleration. Its the slave cylinder not letting the rod back all the way. If I bleed it for a sec. I get my play back in the lever. I need to take the slave apart and see if there is dirt in there or back up in the master.

That just doesn't sound right. The hydraulic fluid shouldn't expand that much. When did you last replace the fluid? Are you sure there's no water in there?

Don

 

[ionbeam]

Now we have two issues going on the same thread. OP's issue -- almost all the time the popping out of gear happens in second gear due to bent shift forks. A slipping clutch is most noticeable in the higher gears on hard acceleration.

Second sub-topic of intermittent clutch operation -- the hydraulic system should be very consistent. If relieving pressure via bleeding fixes the problem it is most likely that the problem is in the master cylinder or a hose that has internal damage. Something you really should check first (because it's so darn easy) is to pull the clutch lever off and check the bronze bushing for wear or galling then clean it real good and lube it up. This is a known wear item that gets neglected when doing routine maintenance, along with the shift lever pivot behind the foot peg and the rear brake pivot. A sticking lever could also cause similar symptoms.

 

[ekms377]

Mine kind of does the same thing. When it gets hot, the play in the clutch lever goes away. Then it will slip under acceleration. Its the slave cylinder not letting the rod back all the way. If I bleed it for a sec. I get my play back in the lever. I need to take the slave apart and see if there is dirt in there or back up in the master.

That just doesn't sound right. The hydraulic fluid shouldn't expand that much. When did you last replace the fluid? Are you sure there's no water in there?

Don

I did flush the system and bleed it about a month ago or so. I may have overfilled it or maybe clogged the vent. I am going to take the cover off today and inspect that. Water...I don't think so but will ck it when I have it apart.

 

[NMRoadRunner]

I have found that during very hard accelaration my rear tire slips, then starts to smoke, but then thats on purpose! :yahoo: :yahoo: :yahoo: B)