Rear end slack

[cowboybob998]

At least i think it may be rear end slack, you give it some gas and let off of it and you can realy feal the slack going down the road, I can think of three reason there is slack, rear end, drive shaft or midel gear.
This is a parts bike that i am going to use the motor out of, took it for a test ride today, the only reason I am consernd is that it may be the middel gear and it would be better to fix it out of the bike

1980 xs 11 special

[XSokieSPECIAL]

Bob, that slack you speak of is probably in the main drive chain and we've all got it.

Nature of the beast.

Someone who types better than me will come along and explain it in more detail. Nothing to worry about.

[cowboybob998]

Bob, that slack you speak of is probably in the main drive chain and we've all got it.

Nature of the beast.

Someone who types better than me will come along and explain it in more detail. Nothing to worry about.

Gess i will just put the motor in the outher bike and see if there is any deference, I am kind of compareing it to my 86 venture that i ride witch has hardly no slack, are they not the same drive train, or some what simlar.

[bikerphil]

Yep, these bikes normally have slop in the drive train. Operating the throttle/shifting smoothly is key. Once these techniques are mastered, the slop will be almost non-existent.

[cowboybob998]

Yep, these bikes normally have slop in the drive train. Operating the throttle/shifting smoothly is key. Once these techniques are mastered, the slop will be almost non-existent.

Will be a week or so before I get the motor swaped out, will let you know how things turn out
thanks
bob

[TexinMaine]

I really dont understand the term slop or slack. When I drive mine about town at lower speeds if I let off the throttle there is like a rapid deceleration and I am pitched forward a bit. Is this slack? And is it normal?

[DGXSER]

The slop or slack mentioned is more of a pause in the power applied in either direction. All of the gears involved to go from the engine to the rear wheel have some minute amount of play involved. They will add together as you get on the throttle or let off.

The "try to throw you over the handlebars" feeling you mention may be one of two things. First, the bike has alot of low end torque and if you let it engine brake (release the throttle without pulling the clutch) it will decel much quicker. Now, if it REALLY feels like it is about to throw you over the bars, then you may have brakes that are locking up on you.

[TexinMaine]

Thanks DGXSR I think it is the torque thing, it does feel like an engine brake. So I assume this is normal?

[petejw]

hey tex,
stick the bike up on the center stand
and put it in gear, then rock the wheel back
and forth, thatll give you an idea of the slack in the driveline.

[DGXSER]

Obviously it is a guess as I have no idea for sure what your feeling. But yes, I have dropped two gears on my XS1100 while doing 60 MPH and with no throttle, it will skid the back wheel.

[cowboybob998]

slack for sure

Ok, had the bike up on the center stand today, moved the rear wheel back and forth while in gear, about three inches of play in the wheel and could hear clunking noies, sounds like in the area of the middel gear, maybe the motor, not sure, this I dont think is right.
I have another middel gear on the motor I am going to take out of the outher bike, gess I will compare the two and see the deference.
Any ideas ?

[bikerphil]

There will be a bit of slop in the transmission gears (dogs and slots) which is normal. Barely any slop in 5th gear though. Make sure the 3 allen bolts on the back of the middle drive under the boot are tight.

[XSokieSPECIAL]

The main drive chain that runs from the crankshaft to the middle drive WILL have some slack no matter what.

The only adjustment is in your right wrist.........LOL

[cowboybob998]

The main drive chain that runs from the crankshaft to the middle drive WILL have some slack no matter what.

The only adjustment is in your right wrist.........LOL

I am allmost sure that the slack is from the motor out ward not inside the motor, the motor sounds to good to have primary chane noise, its got to be in the shalft comeing out of the motor or in the middel gear, I will take the rubber boot off tomorow and look at the u joint and the bolts in the end of the middel gear, 3 inches of play in the rear wheel is no way normal.

[cywelchjr]

I am allmost sure that the slack is from the motor out ward not inside the motor, the motor sounds to good to have primary chane noise, its got to be in the shalft comeing out of the motor or in the middel gear, I will take the rubber boot off tomorow and look at the u joint and the bolts in the end of the middel gear, 3 inches of play in the rear wheel is no way normal.

If your in first gear that sounds about right for the amount of wheel movement at the out edge. I have had two motors with about the same, and with the thing open you can actually see the slack back and forth. It's a combo of the slack in the dogs and slots of the tranny gears, the primary chain (which will have some slack even new) and the middle and final drives (all of which add a little slack to the drive line). I'd have to play around with one again, but IIRC all my standard tranny cars has that much slack in them (or something close).

I don't remember the gear ratios on these beasts (actually don't think I ever knew them) but you generally will get the least slack in the most direct gear, on a car tranny it will often be 3rd for 3 speeds and 4th for 5 or 6 speeds (typcally 5th and higher on autos are overdrive gears). If the gear ratios are anything like other XS models my XS400 doesn't have any gear that is 1:1, they are all either under or over, with IIRC 5th and 6th being overdrives (in that the final output shaft of the tranny does more than one revolution per engine revolution). This does not take final drive ratios into account, since those are almost always a reduction ratio with multiple turns at the engine for each one at the final drive wheel. I think from what I have seen, that the majority of the slop is in the dogs and slots of the gears in the tranny, with just a little bit being added by the other parts of the drive line.

I think part of the slop is to allow shifting to occur without too much trouble since these trannys don't have any syncros to help them mesh. And since the clutch never really 100% disengages (seems to always be a good bit of drag between the frictions and steels), there has to be enough slop especially in first to let the dogs get fully into the slots while both gears are moving in relation to each other.