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Changed front sprocket... Now tranny is screwed???

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So yesterday my dad and I installed a new pro taper 14t front sprocket on my 07 SM. The install went smoothly but we got done late so I did not get a chance to test ride it. Today after I get home I hop on, warm er up and roll out of the garage out onto the street. AS I first go from nuetral to first I notice that it clunks into gear a little harsh. Never really did that too much before but whatever... it happens. So I take off from 1st and as I shift to 2nd the same thing KLUNK.

Also the bike feels like its almost surging and it is not smooth at all when getting on and off the gas slightly. Almost as if the chain was super loose but we put it to factory spec after changing the sprocket.

So as it is if you have the bike sitting there in neutral and try to go into 1st gear you get the clunk. All the shifts are not smooth. We removed the pro taper sprocket and reinstalled it again and still the same issues. The sprocket shouldn't have anything to do with the shift from N to 1st at a stand still though.

Some notes about the initial install... my dad removed the nut with an impact gun so maybe it was not very tight. Also we did torque it to the specified 80ft/lbs when installing the new gear. The bike has 450 miles on it and at this point I guess im going to have to tow it to the dealer. The oil was changed 100 miles ago. There didn't seem to be any issues before we changed the sprocket. Pro taper lists the sprocket as 00-06 Drz400...

Oh Also I have the TT case guards and I noticed that my shift lever is scraping on the cover a little. You can move the entire lever in and out (from left to right if you are sitting on the bike) a little over 1/8 inch... is this a problem?

Any Ideas? Any help is greatly appreciated.

Mike

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You may have problems you may not. Hard to know what you mean by "clunk". Will the bike creep fwd in neutral or in gear?

There is a potential for binding in the transmission when the countershaft nut is tightened but rare for such a new bike. Lift the chain completely off the sprocket (you can with the wheel forward) Does the sprocket turn smoothly, easily, with no bind in neutral? If so - good. If not - bad. If there is a bind, does it go away when the nut is loosened? Oh yea, is the sprocket on correctly. The raised center toward the engine.

Sure you have the chain slack correct? About 1/2 inch slack with the suspension loaded 1/2 way down.

"You can move the entire lever in and out (from left to right if you are sitting on the bike) a little over 1/8 inch... is this a problem?"-----Are you sure about the 1/8 inch? Some play is normal. About 1/16 inch. If it is really 1/8th, that is too much. Check to see the retaining ring is in place. Right where the shaft comes out of the engine under the sprocket.

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Noble, Thank you for the awesome response :D

Well lets see...

By clunk i mean a harsh sounding shift with a jerking action that tugs the chain a bit. A lot of effort is required to make the shifts and a few times going from N to 1st required me to press down on the shifter 5 or 6 times.

A couple of times there was a grinding action almost like when you shift a manual car without enough clutch...

When in neutral the rear tire spins ever so slightly and you can easily stop it with your hand. Pretty much the same in 1st gear with the clutch pulled in.

The sprocket will turn freely with NO bind in neutral. The sprocket is on correctly with the raised side towards the engine (we checked that when we removed it to see what was wrong)

You may be right on the chain slack. I had a feeling that it was too much and that is what it felt like when riding the bike. Like the chain was jerking me around a little. By loaded 1/2 way down you mean half the travel used up?

I just went out into the garage to double check the play in the shift lever. You are correct it was about a 16th of an inch and the retaining clip was there. I guess thats ok then.

:crazy:

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does the cluch lever have free play?one thing when i got my sm was that the clutch adjustment was out of wack.if its ok then maybe a shift fork is bent.drain the oil and check for exessive metal particals

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Hi mike,

Sorry to hear of your problems with such a new bike...

...like not enough clutch? Hm... do you remember if the bike was in gear when you removed the nut with the electric impact tool? Those can apply a lot of hammering torque without really feeling like it.

This is just a wild guess of a non tech... but does anyone know if that hammering action could be transmitted to the clutch basket? ...possibly skewing the arms and keeping the clutch plates from disengaging fully?

I hope it's not this and is something simple and cheap to fix...

Take Care,

Greg

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Thanks for all the help guys!

We had the bike in nuetral and I was on the rear brake when my dad removed the nut with the (air) impact gun.

I can see how too much chain slack combined with the non rubber dampened sprocket could seem very different than the stock setup and perhaps thats part of the issue. Is there such a thing as a 14t rubber dampened sprocket similar to the stock SM 15t?

There is still the problem with it being hard to shift. I think a good analogy would be that its like having a car with an automatic transmission and you a revving it a little while in neutral and you pop it into Drive. You will get a clunk and the car will jerk a little. The bike Definetly DID NOT shift like this before. I rode it a total of about 30 feet before I knew there was an issue. Went down the block and turned around because I knew I had a problem.

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1) A lot of effort is required to make the shifts and a few times going from N to 1st required me to press down on the shifter 5 or 6 times.----Sounds like something in the way of the shift lever.

2) A couple of times there was a grinding action almost like when you shift a manual car without enough clutch----Sounds like clutch problem.

When in neutral the rear tire spins ever so slightly and you can easily stop it with your hand.------Good

Pretty much the same in 1st gear with the clutch pulled in.-----Well that sounds like clutch release is OK

The sprocket will turn freely with NO bind in neutral.---Good

The sprocket is on correctly with the raised side towards the engine ---Good

You may be right on the chain slack. I had a feeling that it was too much and that is what it felt like when riding the bike. Like the chain was jerking me around a little. By loaded 1/2 way down you mean half the travel used up?---Yes. That puts the chain at its tightest point. Sprocket, swing arm pivot and rear axle in line. Same for all motorcycles. May not be exactly 1/2 way down but you can judge the chain tightest point.

(Chain slack with not cause problems 1 or 2)

I just went out into the garage to double check the play in the shift lever. You are correct it was about a 16th of an inch and the retaining clip was there. I guess thats ok then.---Yes that's OK. Are you sure the shift lever is not hitting something stopping full travel?

It is always recommended to have the transmission in neutral when using an impact wrench. Did you do that?

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Did you take the shift lever off to install the TT case guard on the left side?

In the past, when I have I re-installed the shift lever, I did not get it all the way back on. By mistake, I had it too far out and not deep enough on the shift shaft. I would notice the excess play, and the bike would not shift smoothly.

After re-installing it so that the shift lever was as far onto the shaft as it could go, those problems went away.

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Thats the plan right now... the bike is sitting with no sprocket on at the moment. Tomorrow I am going to put the stock sprocket back on and make sure the chain is adjusted correctly and see what happens.

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OK we just put it back to stock with the stock 15 rubber dampened gear and with the correct chain adjustment the bike seemed fine! Wow I feel poretty dumb for stressing so hard when it was pretty much the chain being too loose. Thanks for all of your help with this issue I was having!

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