Drive Lash and the Cush drive

[agentbad]

I have been getting a fair bit of drive lash lately and was wondering if getting a new cush drive would smooth things out. I mentioned it to my mechanic when I got it inspected a few weeks ago and said my cush drive needed to be replaced and tried to sell me a new chain as well. So as soon as I got home I adjusted the chain to spec, realigned the back wheel, and cleaned/lubed everything. The chain was just a little out of spec and after tightening things up most of the drive lash is gone however I still feel it a little bit in the back wheel. Should I get a new cush drive or just do the mod and shim the thing?

[Trailerboy531]

When you say drive lash...

[agentbad]

Originally Posted by Trailerboy531

When you say drive lash...

Jerkiness when cracking open the throttling or releasing it. I do a lot of engine braking so I probably notice it more then but I hardly notice at speed.

¯\_( ツ)_/¯

[dcj13]

Originally Posted by agentbad

...Should I get a new cush drive or just do the mod and shim the thing?

I replaced my cush drive and found the new one was almost as loose as the old one. I ended up putting in a bunch of shims anyway.

If I were you with what I now know, I'd just put in the shims and keep the old cush.

[agentbad]

Originally Posted by dcj13

I replaced my cush drive and found the new one was almost as loose as the old one. I ended up putting in a bunch of shims anyway.

If I were you with what I now know, I'd just put in the shims and keep the old cush.

I've read that elsewhere too so I guess I'll just shim it and go from there. What did you use for shims I've seen plastic from a milk jug and pieces of tile flooring.

[dcj13]

I used an old one-quart oil container (or two). Dang near anything will work.

[Motofool]

Originally Posted by agentbad

I've read that elsewhere too so I guess I'll just shim it and go from there. What did you use for shims I've seen plastic from a milk jug and pieces of tile flooring.

http://faq.ninja250.org/wiki/How_to_shim_the_cush_drive

[Singh2jz]

Originally Posted by Motofool

http://faq.ninja250.org/wiki/How_to_shim_the_cush_drive

You beat me too it!

[agentbad]

Have you guys done the mod? Does it make a difference?

[csmith12]

I have done it before. On some bikes it made a small difference, others not so much. It was more about the carbs and getting them to react well to the initial shot of gas to not lurch the bike forward.

Shimming is pretty easy and completely reversible if you don't like it. Start there, if that don't work, time to look at the carbs/airbox. Specifically check the sync of the carbs.

[mgentz]

This thread is very informative.

[Me3]

Originally Posted by csmith12

I have done it before. On some bikes it made a small difference, others not so much. It was more about the carbs and getting them to react well to the initial shot of gas to not lurch the bike forward.

Shimming is pretty easy and completely reversible if you don't like it. Start there, if that don't work, time to look at the carbs/airbox. Specifically check the sync of the carbs.

Sorry to thread mine, but I was interested in this line specifically:

It was more about the carbs and getting them to react well to the initial shot of gas to not lurch the bike forward.

Can you elaborate on this at all, beyond the carb sync? I have had the idle mixtures all the way lean and rich, with rich smoothing the transition somewhat but not fixing the issue entirely.

I have no binding/sticking in any mechanical part, and have even raised the idle to 2000 to try and pull the carbs off the idle circuit to see if this helps, but still get quite a surge when opening the throttle. Engine runs fine everywhere but the initial roll on.

[Ninjinsky]

I had a an annual inspection fail on cush drive (UK) and replaced it. Don't know if it is a legal issue in the US but it fails roadworthiness here.
Guess I could have shimmed it, they would never know

[CC Cowboy]

Originally Posted by dcj13

I used an old one-quart oil container (or two). Dang near anything will work.

Do you drane the oil first?

[baxtc1]

Drive lash, how is your clutch housing?

[jkv45]

Originally Posted by Ninjinsky

I had a an annual inspection fail on cush drive (UK) and replaced it. Don't know if it is a legal issue in the US but it fails roadworthiness here.
Guess I could have shimmed it, they would never know

Half of the cycles in the U.S. would probably fail that inspection.

Seems a bit over-the-top to worry about play in the cush drive to me. Big Brother is watching you - very closely...

[greenaero]

As others above have stated : shim it

[csmith12]

Originally Posted by Me3

Sorry to thread mine, but I was interested in this line specifically:

It was more about the carbs and getting them to react well to the initial shot of gas to not lurch the bike forward.

Can you elaborate on this at all, beyond the carb sync? I have had the idle mixtures all the way lean and rich, with rich smoothing the transition somewhat but not fixing the issue entirely.

I have no binding/sticking in any mechanical part, and have even raised the idle to 2000 to try and pull the carbs off the idle circuit to see if this helps, but still get quite a surge when opening the throttle. Engine runs fine everywhere but the initial roll on.

Welcome Me3!

In a nutshell;

Throttle cable slack in spec
Clean carbs
Well adjusted mix screws
Carbs in sync
Idle set within spec
Good spark (blue in color)
Clean/clear air filter
Chain tight and within spec looseness
Cush drive inspection, replace or shim per rider needs

Basically, a well tuned/running 250 can go from idle to pinned without much fuss.

[Me3]

Originally Posted by csmith12

Welcome Me3!

In a nutshell;

Throttle cable slack in spec
Clean carbs
Well adjusted mix screws
Carbs in sync
Idle set within spec
Good spark (blue in color)
Clean/clear air filter
Chain tight and within spec looseness
Cush drive inspection, replace or shim per rider needs

Basically, a well tuned/running 250 can go from idle to pinned without much fuss.

Thnkas for that.

I have checked everything bar the sync and shim the cush drive - the bike has only done 8000ks, so I will look to sync the carbs on the weekend.

[kxpower?]

Originally Posted by Me3

Sorry to thread mine, but I was interested in this line specifically:

It was more about the carbs and getting them to react well to the initial shot of gas to not lurch the bike forward.

Can you elaborate on this at all, beyond the carb sync? I have had the idle mixtures all the way lean and rich, with rich smoothing the transition somewhat but not fixing the issue entirely.

I have no binding/sticking in any mechanical part, and have even raised the idle to 2000 to try and pull the carbs off the idle circuit to see if this helps, but still get quite a surge when opening the throttle. Engine runs fine everywhere but the initial roll on.

Just a shot in the dark that you could try in 20 minutes for a dollar or two I might shim the needles by one washer. If more gas off the pilot helps richening the transition might help too. My 2 cents...


BUUUUUUUUUUUT make damn sure you feel good that everything on Chris's list is good too or you'll be chasing your tail.

[alex.s]

Originally Posted by Ninjinsky

I had a an annual inspection fail on cush drive (UK) and replaced it. Don't know if it is a legal issue in the US but it fails roadworthiness here.
Guess I could have shimmed it, they would never know

we mostly don't have any kind of annual inspection on motorcycles here. the only exception is if it has been salvaged and you are registering it again... you have to have a brake and lights inspection and they also check the vin to make sure its not stolen.