Thought I Was On The Home Stretch?

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#1
So I went to put the case back on the KX85 tonight. Its the left side case that I had removed to inspect the crank area for piston debris after the rings went south.

Everything seemed to be in order and the case went on about halfway and then I met resistance. I convinced it on with my rubber mallet going in a little more than gentle sequence around the case. I got it down to about .5mm of being together and then inserted the bolts in hopes of drawing it together the final .5mm ---------- No Dice.

Once the case was drawn together, neither the crank nor the counterchaft would spin freely, something got cocked up.

So now I am at that moment of having to take it apart again which is going to fun and figuring out why it didn't go on properly.

My question now is have I shagged any of the bearings by it not going on completely straight?
When the case came off the last time, the crank bearing stayed in the case. If I heat the case, the bearing will probably come out of the case this time you think? Then it will be stuck to the crank where I guess I can heat it some to remove it there.

This is all pretty frustrating. My son is supposed to race this bike on Saturday night to open the series. I had thought for sure that we could have this bike done by then......now I am not!

I have never had much luck with 2-strokes it seems. I have built 6 streetbikes over the last 3 years and never ran into these types of issues. I feel like a total newb when I get to working on 2-strokes. LOL
I thought they were supposed to be easier?

Cheers
Bernie
 

IndyMX

Crash Test Dummy
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#2
I had a similar issue when doing the bearings in my nephews KX85 a couple weeks ago.

I had the engine all back together, everything seems right, but even with the engine in the frame and chain on, I couldn't spin the counter shaft with the rear wheel.

So, I took it back out, split it again, and inspected. I couldn't find anything wrong. Nothing. It all looked perfect.

So, I put it all back together, took my time, making absolutely sure nothing was wrong, and put it back in the frame.

Same issue. Very tight feel.

I figured it must be that the bearings & seals and whatnot needed to seat, so I just let it go.

Got everything back together, fired it up. Engine sounded fine. Ran like a cut cat..

I took it out in the yard, just to test it's pulling power.. felt great.

Put the bike back on the stand, gave the rear wheel a good shove, it turned nice a freely.

So, something must just have needed to seat properly after splitting the cases.

I'd say if you put it in the bike and it runs fine, let it be. Just my guess..
 
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#3
I think I may know where I screwed it up?

There was a small o-ring that came off the countershaft assembly when I removed the case.

I think I may have inadvertantly placed that o-ring on the inside between the bearing and the gear?
I couldn't remember exactly where the o-ring went and from looking at the Kawi parts fiche, I think I got confused and placed it wrong.

Now that I am looking at the fiche again, is it possible that the little o-ring goes on the outside of the bearing, sandwiched between the bearing and the spacer?

If that is the case, thats where I messed up.

Cheers
Bernie.

BTW - Indy, I appreciate all of your help. If you ever have a turbocharged motorcycle that needs any info, I'm your man!
I own 4 of 'em!
 

IndyMX

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#4
Dont' think I'll ever try my hand at Turbo's.. But your welcome..

Mine had 2 of those orings.. Both went on the counter shaft after the cases went together, then the spacer sleeve, groove side in and then the counter shaft sprocket.

It should not go between the gear and the bearing.. That'd be a bad thing. Not sure how much of a problem it would be in the long run, but I wouldn't want it there.

Just a note, when I took my nephews engine back apart and checked everything out, it only took about 3 hours from there to getting it all back together and test riding.

There's just not that much to it.

Do you have access to a service manual?? If not, email me, I may be able to help you out on that.. ;)
 
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#5
Hey Indy,

No, I don't have the service manual, just the owners manual. Thats been one of the hiccups in getting this done.
Trying to find out the proper info.

I think the o-ring is what caused the problem as it is not letting the cases mate up flush. Having a bitch of a time now getting the case split again.

I'll keep my chin up here in hopes of having this thing ready for Saturday but I am sure I will be back for more info before it is done.

Cheers
Bernie
 
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#6
Bernie.

Did you use heat on the cases? If not, the bearings will not seat all of the way down in the case. They will bind in the bearing boss and cause the crank to bind. You may want to try to install the main bearings on the crank. Drive them all of the way down on the shaft with a deep socket that fits the inner race. Don't drive on the outer race. Then place the crank in a sealable plastic bag and put it in your freezer for a couple of hours. Lay the case on it's side and heat the case evenly until you can sizzle a drop of water on the case. Then, take the crank and drop it in the case. If done right, the crank will drop all the way into the case. Then heat the other case and drop it over the crank. It should seat all of the way down.

If you do it without heat, the bearings will bind part way down the bearing boss and will remove a small amount of material from the bearing boss. If the bearings are removed and replaced a few times without using heat, it will wear the bearing bosses and the cases will be junk.

Having the C/S o-ring in the wrong place will bind the gearbox but it should not bind the crank if the cases are bolted tightly together. It is usually an improperly seated bearing that causes that.
 
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#7
No, I did not heat anything when reassembling the case.

Just to be clear, I only removed the left side case. The right side is still in place.
When I got the left side off, the bearing stayed with the case. It came off of the crank.

To reinstall it again, the only option I have for heat / cold, is to place the entire motor in my beer fridge (if it will fit) and then try to gently heat the inner race of the crank bearing (I say gently because the crank seal is still in place as well). I don't want to risk destroying the crank seal. It cannot be replaced without removing the crank bearing from the case.

The other option is to get the bearing out of the case and install it to the crank prior to putting the case on.

I am thinking that option 1 might be the best way to go but you'll have to tell me?

Thanx For Helping!
Bernie
 
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#9
Thanx Heaps Indy....
Thats a great help!

BTW Guys,

Since the crank bearing stays in the case on this motor, is it ok to put a little heat from a heatgun or my propane torch to the inner race of the bearing to open it a little for putting it back on the crank? I am worried about the crank seal on the other side but I want to use less violence on the case when I put it back on again.

Wife says that I cannot put the engine in the freezer...lol

Cheers
Bernie
 

CaptainObvious

Formally known as RV6Junkie
Damn Yankees
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#13
IndyYZ85 said:
So, something must just have needed to seat properly after splitting the cases.
Ah yes, the hope that it will wear in before it wears out :nod:
 
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#14
Whew!

Got it back together.
I hope it is all well? The countershaft sprocket rotates freely. The crank turns smoothly but I am not certain how easily it is supposed to spin by just my hand spinning the flywheel?
Sounds like it is probably not unlike what you had going on Indy so hope that it all settles in once I get it all back together.

Yea, the wife....lol
Actually the problem was that we had nowhere else to put the frozen goods that were in there and she wasn't thrilled about having meats sitting on the counter for a couple of hours.
We don't have a stand alone freezer, just the one above the fridge.

Anyway, I have you guys to thank especially Indy who has more than tolerated my barrage of questions.

Hopefully, it will be smooth sailing from here on in?

Cheers
Bernie