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-   -   XT600 Engine rebuild questions (crank, bearings, valveseals etc) (https://www.horizonsunlimited.com/hubb/yamaha-tech/xt600-engine-rebuild-questions-crank-91963)

Doubleyoupee 30 Jan 2019 13:37

Quote:

Originally Posted by xtrock (Post 595309)
Did you only use a normal 2 or 3 arm puller, was it hard pulling out? Iam thinking if its easy to damage gear. The original bearing was 100% like the new one? Iam still thinking bearing will get more stuck when heating up due to the expansion of metal.

Neither, I used a bearing puller like this:

https://i.imgur.com/WTpk5KQ.jpg

It was quite stuck. I heated it up using a heater air gun (paint stripper). At first I was unsuccessful because I didn't heat the bottom part of the gear (puller was in the way). After that it came off relatively easily.
There's no damage on the gear as far as I can see. It appears to be a very hard material. Harder than my puller (It left dents)

As for the heat. No, both axle and bearing will heat up, but the bearing is a larger diameter so will expand (slightly) more. The diameter of the bearing gets larger not smaller when the metal heats up.

xtrock 30 Jan 2019 13:50

Ok i see, yes metal will get larger and then get more stuck i would think. Was the original bearing bad condition and how many km? I would think a bearing like this would last 150k km at least. Measure and compare the original vs the new, maybe a little difference.

Doubleyoupee 30 Jan 2019 13:51

@turboguzzi

Also to test my theory I'm quite sure you can tap your bearing down all the way on the shoulder with a screwdriver + small hammer

Quote:

Originally Posted by xtrock (Post 595314)
Ok i see, yes metal will get larger and then get more stuck i would think. Was the original bearing bad condition and how many km? I would think a bearing like this would last 150k km at least. Measure and compare the original vs the new, maybe a little difference.

No. Otherwise nobody would heat something to remove it. The bearing does get larger, that's why the diameter will increase and it will be more loose. The old bearing was okay, but i'm replacing all bearings just because I can. Hobby project :)

xtrock 30 Jan 2019 14:11

Quote:

Originally Posted by Doubleyoupee (Post 595315)
@turboguzzi

Also to test my theory I'm quite sure you can tap your bearing down all the way on the shoulder with a screwdriver + small hammer



No. Otherwise nobody would heat something to remove it. The bearing does get larger, that's why the diameter will increase and it will be more loose. The old bearing was okay, but i'm replacing all bearings just because I can. Hobby project :)

Normally you heat one of the metals and cool down the other for them to release and heat makes seized metal easier come apart. I would think its the cooling process that makes metal let go of each other, to different metals shrink different.

turboguzzi 30 Jan 2019 17:32

Quote:

Originally Posted by Doubleyoupee (Post 595315)
@turboguzzi

Also to test my theory I'm quite sure you can tap your bearing down all the way on the shoulder with a screwdriver + small hammer


not in my case, it doesnt move at alll.
i remember using the puller also for the bearing.
sure, not as hard as the gear but was a pretty solid fit. will check today with a micrometer the exact shaft dia, you might be undersize...



remember that unless you have a precise way to put the gear back indexed somehow, you will need to slot your cam sprocket to arrive to the right cam timing.

Doubleyoupee 30 Jan 2019 21:09

Quote:

Originally Posted by turboguzzi (Post 595323)
not in my case, it doesnt move at alll.
i remember using the puller also for the bearing.
sure, not as hard as the gear but was a pretty solid fit. will check today with a micrometer the exact shaft dia, you might be undersize...



remember that unless you have a precise way to put the gear back indexed somehow, you will need to slot your cam sprocket to arrive to the right cam timing.

Interesting..
However you can see this guy here: http://www.youtube.com/watch?v=_HACEfo_gKc&t=3m10s
His is going off exactly as mine - very easy.

I'm not worried about putting the timing gear on. I have enough measurements to put it back exactly where it was. I'm just wondering about the bearing placement. But if I look at everything, to me it's most logical that the bearing sites on the shoulder with the inner race by default.

Stupid thing is that it's not touching the pin anymore if I put the crank upright (in normal position). It's literally the flex from the C3 bearing that is causing it to touch the pin now - it's that close. An extra 0.05mm would fix it. Would put the big-end clearance at 0.60m, which was my initial request.

I'm thinking of going to another shop tomorrow. I don't trust this one anymore.

xtrock 30 Jan 2019 21:24

Seems like there is alot different measurements here, the video says 1mm, Turbo 2,4mm?

Doubleyoupee 30 Jan 2019 21:29

Quote:

Originally Posted by xtrock (Post 595345)
Seems like there is alot different measurements here, the video says 1mm, Turbo 2,4mm?

Yes. This is why I believe the bearing is a floating bearing. It can move slightly when the engine warms up. This is also what David Lambeth told me (XT600 guru) and it explains why you will find the bearing in a different spot for all cranks. Only the timing gear is constant.

However I still think it should be able to travel all the way to the crank, and that this is the default position. Clymer manual apparently also states this, but I don't have it (yet).

xtrock 30 Jan 2019 21:55

Quote:

Originally Posted by Doubleyoupee (Post 595346)
Yes. This is why I believe the bearing is a floating bearing. It can move slightly when the engine warms up. This is also what David Lambeth told me (XT600 guru) and it explains why you will find the bearing in a different spot for all cranks. Only the timing gear is constant.

However I still think it should be able to travel all the way to the crank, and that this is the default position. Clymer manual apparently also states this, but I don't have it (yet).

Ok, clymer says conecting rod to crankshaft side clearence 0,25-0,75mm. the big end side clearence 0,25-0,65 how to know what they talk about? Is it really this clearence between bearing? I cant find anything that confirm it. I quess the bearing circle must make the metal only expand out from center(the easiest way to expand in a ring) and the shaft is not expanding much thats why it can release in heat?There is alot of info in clymer about balancing the crankshaft

jjrider 31 Jan 2019 11:46

I have 4 cranks but just 1 is an e-start and that's unfortunately in a motor that's still together but I popped the flywheel off 2 of the others since the cases were split anyways and both of them had loose bearings on the crank(bearings still feel nice and tight with very little "wobble") and I could fit a .026"/.660mm shim between the bearing and gear with the bearing pushed against the shoulder .

With the bearings against the shoulder they had roughly .003-.005" clearance to the conrod pin (which were both basically flush with the web , not sticking out . If not for your pin sticking out that little extra that the crank is pressed together wouldn't hurt anything , but it sounds like it's pressed more than the .6mm if the pin is sticking out like it is .

btw , measuring from the key slot is a poor place to go by and compare to any others , I doubt they're extremely accurate in placement . To the end of the taper is where I'd go by with a debth mic but before anything was pressed apart. Now it's a complete guess really . If they have the web pressed .6mm too far , where did that come from ? conrod side clearance ?

.

.

Doubleyoupee 31 Jan 2019 11:58

Quote:

Originally Posted by jjrider (Post 595359)
I have 4 cranks but just 1 is an e-start and that's unfortunately in a motor that's still together but I popped the flywheel off 2 of the others since the cases were split anyways and both of them had loose bearings on the crank(bearings still feel nice and tight with very little "wobble") and I could fit a .026"/.660mm shim between the bearing and gear with the bearing pushed against the shoulder .

With the bearings against the shoulder they had roughly .003-.005" clearance to the conrod pin (which were both basically flush with the web , not sticking out . If not for your pin sticking out that little extra that the crank is pressed together wouldn't hurt anything , but it sounds like it's pressed more than the .6mm if the pin is sticking out like it is .

btw , measuring from the key slot is a poor place to go by and compare to any others , I doubt they're extremely accurate in placement . To the end of the taper is where I'd go by with a debth mic but before anything was pressed apart. Now it's a complete guess really . If they have the web pressed .6mm too far , where did that come from ? conrod side clearance ?

.

.

It's hard to measure the clearance between the conrod pin and the bearing, since if you put the clearance tool in, you push the bearing outer edge away. The bearings have a lot of clearance on them (C3/C4 bearing).
Mine has around 0.05mm/0.002" clearance but it's so little that if I tilt the crank sideways, it does touch the pin (because of the flex in C3/C4 bearing).

So i've decided to ship the crank to a known (XT) specialist and have it done properly. I don't think it's properly aligned now either.

I know the measurement I did isn't the best, but I thought it would be easiest to reproduce. I have this one as well which should be more accurate, but it's on an angle:

https://i.imgur.com/ag24wR1.jpg

Finally, yes, it had 0.9mm big end side clearance. Crank was 75.25mm wide too. How? No idea.

Anyway if anyone has the clymer manual and could share it or at least the pages regarding crankbearing/timing gear that would be great bier

xtrock 31 Jan 2019 12:41

I would say, dont start messing with this job unless your bearing is shot for sure. Most of us will problably get this back togheter again, but there is alot of small things on the way that can lead to failure after riding for some time. A cheap fix with a bearing for 25dollars ending up with shop visit for hundreds or broken engine..

Doubleyoupee 31 Jan 2019 13:34

Quote:

Originally Posted by xtrock (Post 595361)
I would say, dont start messing with this job unless your bearing is shot for sure. Most of us will problably get this back togheter again, but there is alot of small things on the way that can lead to failure after riding for some time. A cheap fix with a bearing for 25dollars ending up with shop visit for hundreds or broken engine..

What? The bearing is already removed. At this point it doesn't matter if I put the old or new bearing back on. Please read, this topic is getting really cluttered with corrections and unrelated discussions like this

xtrock 31 Jan 2019 13:46

Quote:

Originally Posted by Doubleyoupee (Post 595365)
What? The bearing is already removed. At this point it doesn't matter if I put the old or new bearing back on. Please read, this topic is getting really cluttered with corrections and unrelated discussions like this

This was a suggestion to others who maybe thinking of doing this, and i cant find anything here that is unrelated or cluttered. If you cant handle that people here want info other than helping you its your problem, i quess biggest problem is that i wouldnt copy my 450 pages clymer book for you!As a new member you should be happy for all help you get, end of story from me!

Doubleyoupee 31 Jan 2019 13:59

Quote:

Originally Posted by xtrock (Post 595367)
This was a suggestion to others who maybe thinking of doing this, and i cant find anything here that is unrelated or cluttered. If you cant handle that people here want info other than helping you its your problem, i quess biggest problem is that i wouldnt copy my 450 pages clymer book for you!As a new member you should be happy for all help you get, end of story from me!

You mean info like heating a bearing/gear will cause it to get more stuck?
Misreading several posts doesn't really make things easier in this thread either.

And I never asked for your entire 450 page copy. One page would be enough - and if you actually cared about providing info like you said, that wouldn't have been such a problem.


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