KDXRIDER.NET

Sorry Ted I did not know it was you.

We will have to differ on methods. There is enough free play in the conrod side movement for me, I'd rather chase spin.

What is chase spin?

What is the concern/issue with centering the crank on the initial install?

You get one go at putting a crank in. If you can magically position the crank in your cases and the left and right crank bearings are in there centres when resting then you have the beginnings of a very happy motor.

I recall a build thread on here where there was a conversation about how to do the final centering of the crank when cases are together. If you already know how much room there may be from previous assembly, couldn't you make an educated guess to split that in half and use a feeler gauge (as in the video)? Seemed like a good idea to me.

I don't have the manual with me but most two strokes have a gear on the right side that is torqued up. The inner bearing rase is squashed between the crank and gear. This means the crank is pulled into the gear. The only way to avoid any movement from your only go at putting the crank in is to drop it in clunk, hard against the bearing. It will cool down and be the final resting place centered. The left cases/bearing are heated and positioned where they sit as they do no get any further side movement asked of them.

I will have a look at the manual tonight but most cranks are held in place by the right side. So the task is to have it centered when all done up.

There are many ways to put a motor togeather this is just the way I choose.

Tioli- I know what you are referring to with engines that have the crank pulled to the gear. But the KDX isn't one of those. The gear on the crank doesn't play a role on the position of the crank. The only thing that does is where you put it.

And I don't think it is really necessary to center the crank with the KDX. I have now had about a half a dozen KDX engines and most are totally off center from the factory. But since it only takes a few minutes to do it, it can't hurt.

And with any method you use, I would definitely try to avoid moving the crank once the halves are together. If you need to move it, you would need to put something between the webs so they can't move and then push the crank, not pull it into position.

Ok
Talking of off centre both my 200 barrels are off centre. At the top the studs are aligned with the boar but the inside transfer port wall between piston and transfer port are about 2mm different in thickness.
Have you noticed the same?

Post 235 on, there's a whole discussion about this from SS109'S E2 build.

http://162.243.75.126/forums/viewtopic. ... 78#p116678

Have now read the manual so know what you mean Ted. This is not good news Ted. I knew what I was doing with the normal way of doing it. This system seems to be free floating which brings a new to me set of questions Ted.

Crank is my next major job so can Il piggyback the questions if that's ok Friedom?

Like:

I just measured the run out on the spare crank. In mm the tolerance is 0.00 to 0.03mm

Mine are 0.012 each side. Would you have a go at making it closer to 0?
When I dident have the ability to measure them I just took what I was given. When I could measure them they came in nice HRC boxes so I took what I was given.

I'm getting ready to do mine too.
I liked the idea mentioned in the post above of centering them so there's the same gap on both sides (or close to it). I don't really know if it's supposed to be bottomed on either bearing, but it sounds like if it is, it's 1 or the other. I think only the right side gets pulled into the case by the main bolt, the left side is going to sit where it sits.
I'm no machinist, though. Who is qualified to answer this?

Tioli wrote:Mine are 0.012 each side. Would you have a go at making it closer to 0?

If you could get it to zero run-out that would be awesome. But I'm not sure if that is practical with common tools/copper hammer. I think the guys with the jigs can get close, but I'm not even sure they can get it perfect.

Friedom wrote:I think only the right side gets pulled into the case by the main bolt,

Which main bolt are you referring to?

Tedh98 wrote:

Friedom wrote:I think only the right side gets pulled into the case by the main bolt,

Which main bolt are you referring to?

Well I was referring to the right side crank bolt, but now that I think about it - it doesn't pull the crank into the case, does it? I think it just holds the gears on.
Is the crank really floating wherever it lands in the assembly process?

Friedom wrote:

Tedh98 wrote:

Friedom wrote:I think only the right side gets pulled into the case by the main bolt,

Which main bolt are you referring to?

Well I was referring to the right side crank bolt, but now that I think about it - it doesn't pull the crank into the case, does it? I think it just holds the gears on.
Is the crank really floating wherever it lands in the assembly process?

The right side bolt is a nut. Both ends of the crank are threaded. And you are correct, the nut just holds the gears on. The clutch gear only goes so far on the crank and doesn't touch the bearing or anything else.

When I hear "floating" I think of something that moves around. And the crank definitely doesn't move around once installed - at least not on its own.

When installing the crank, the bearings are the only things that provide a definite limit to where the crank is positioned. Or said another way, you can position the crank anywhere you like as long as it is between the two bearings (I believe the crank will hit the bearing before the web touches the case).

Tedh98 wrote:

Friedom wrote:

Tedh98 wrote:
Which main bolt are you referring to?

Well I was referring to the right side crank bolt, but now that I think about it - it doesn't pull the crank into the case, does it? I think it just holds the gears on.
Is the crank really floating wherever it lands in the assembly process?

The right side bolt is a nut. Both ends of the crank are threaded. And you are correct, the nut just holds the gears on. The clutch gear only goes so far on the crank and doesn't touch the bearing or anything else.

When I hear "floating" I think of something that moves around. And the crank definitely doesn't move around once installed - at least not on its own.

When installing the crank, the bearings are the only things that provide a definite limit to where the crank is positioned. Or said another way, you can position the crank anywhere you like as long as it is between the two bearings (I believe the crank will hit the bearing before the web touches the case).

Right. So I guess the fundamental question is should it be bottomed on the right bearing, left bearing, or centered, and does it matter?

Friedom wrote:Right. So I guess the fundamental question is should it be bottomed on the right bearing, left bearing, or centered, and does it matter?

I don't know what the Kawasaki engineers had in mind, but as I mentioned earlier, I don't think it really matters.

I say that only because nothing is mentioned in the manual about where the crank should be positioned and most of the stock KDX engines I've had on the workbench are fully off-center to one side or the other. There was maybe only 1 that was close to being centered.

I don't see the downside to centering it. But I've overlooked the obvious before. . .

I know some people that know this stuff and was going to contact one then realised what there answer would be. I had a go at it and got it to about 0.01 at the factory measure point 8mm out from the crank. Unfortunately when you measure as far out as you can, just before the key ways it's 0.10 so I will keep going.

Ted back to that question of the barrels being bored offset by 2mm. Is that the same for your barrels?
It's a little thing that you can't do much about but it players with the port trajectory and may need to be considered hear.

Tioli wrote:Ted back to that question of the barrels being bored offset by 2mm. Is that the same for your barrels?
It's a little thing that you can't do much about but it players with the port trajectory and may need to be considered hear.

Do you have a picture of where the offset is? I've got a stripped down 220 cylinder and the 2mm offset wasn't jumping out at me.

22 pictures down page 26 from the signature link

Or 22 pictures down
http://www.trials.com.au/forum/viewtopi ... &start=500

Update on diy methods - tried putting a plate behind rotor cap with extended cap screws and a push bolt in the middle. No bueno, could see the shape of the metal plate extruding through the rotor cover.

Then I took a bar of 2"x1/4" steel, drilled holes to use the 6mm and 5mm connections listed in the manual, ground a 5/8 bolt to a cone tip and used it to push on the crank. Bent 1/4" steel, no sweat.
Guess I might have underestimated how much pressure is needed to push the crank out.
I still think a sheet of 1/4 or more metal the diameter of the whole magneto cover bolted on in 5 places would work, but don't have one handy.
If only there was a tool designed for this very purpose. Lol
I did check the local parts store. Didn't have pullers with wide enough arms.