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Old 07-16-2012, 01:56 PM
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Default Splitting case and replacing crank assembly

     

How involved is it to actually split the case and replace the crank assembly. I have the engine out and the clutch basket out. Is it as simple as pulling the case halves apart and installing the new crank assy, bearings and seals, checking tolerances and bolting it back together??? Judging from the looks of it, it appears it will require removing all the transmission linkage and all in this picture in order to separate the case? If it requires significant dismantling of the transmission I'm going to bring it to a local shop and have them do the work but at $90/hour I'd like to save some money and do it myself as I am fairly competent mechanically. I have the yamaha service manual but its actually pretty vague in its ability to describe the removing and installing procedures.

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Old 07-16-2012, 02:15 PM
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Ok, if you have the manual it should not be to bad for a first time do. You will need a flywheel puller and a case spliter to do the job correctly. It is possible to do this job with out removing all the trans parts, but to do a first class job , clean and inspect all bearings etc. it really needs to taken out too.
You will need to heat the cases and freeze the crank bearings to get them in the case so having all out is better.

Your call.

Paw Paw
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Old 07-16-2012, 02:15 PM
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Its quite easy but you need a case splitter and a flywheel puller.
You can freeze the new bearings and heat the cases they should drop in. As for the gears lst time I did not even take those out. I built myself a press and that did it.
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Old 07-16-2012, 02:24 PM
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Ok, there are some great videos available for you to watch on you tube supplied by Rocky Mountain MC. Look up crank replacement and you can watch to see if this is something you think you can do.

Paw Paw
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Old 07-16-2012, 02:33 PM
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Thanks guys. I'll check out those vids. Didn't even think of that.
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Old 07-16-2012, 03:09 PM
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You have another post and I said on that one:

You don't need a case splitter for Suzuki engines. It won't hurt if you do use one but it is not necessary. The main reason that you would need one, is to press the crank out of the case. I used a homemade press out of some bolts at the hardware store and a harmonic balancer puller (cheap).
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Old 07-16-2012, 04:08 PM
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Quote:
Originally Posted by Randog Leader View Post
The main reason that you would need one, is to press the crank out of the case.

Right on the spot
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Old 07-17-2012, 07:52 AM
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Thanks guys. This is a Yamaha YZ engine. The RM videos make it look awfully easy with the Tusk crank and crankcase tools but I'm guessing a regular puller set that I have like this one would work fine for doing the job??? I'll be saving a couple hundred dollars by doing the work myself so it may be worth it to invest in the tusk tools. Other than that it looks pretty easy so I'm probably gonna just do the work myself.
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Old 07-17-2012, 07:55 AM
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I think you will find that the puller set you have will work on some items, but the case splitter tools of Tusk are the way to go.

Paw Paw
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Old 07-17-2012, 02:56 PM
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That will work but you may need to get some bolts from the hardware store. That set is probably standard and won't have the metric bolts that you need. I think that it is M8 that you will need. Hardware store, cheap.
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Old 07-17-2012, 05:06 PM
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I agree with paw paw on the case splitter. I have a splitter and crankshaft puller/installer. I have done a few without these tools, it is not that hard, but once I have used the splitter and puller, it would be hard to go back. The tusk ones paw paw mentions are what I have (from rocky mtn atv). They are $60 apiece and well worth it. These tools used to be very high priced but are now in just about anyones budget. You'll want the flywheel puller too. If you take your time and have a nice clean area to organize the different assembleys it is not that difficult. I like to break everything down into different assembleys myself, clutch, stator, kickstart, shift drum/fork, etc. If anything looks like it may be confusing later I just snap a few pics with my phone. Good luck.
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Old 07-18-2012, 09:14 AM
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Thanks guys. OK, I ended up buying a hot rods bottom end kit for $250 that comes with the crank assembly, bearings and a full athena gasket kit from Motosport. I am also shipping my cylinder here to have it cleaned, plated and honed. I have heard good things about their work and its closer than MT. Gonna go with OEM piston kit too.
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Old 07-18-2012, 09:59 AM
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Buy a "D" piston at Yamahasportsplaza can't beat their OEM prices
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Old 07-18-2012, 10:48 AM
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Nice! The piston kit is $79 there and thirteen bucks cheaper than the best price I've found so far. Thanks.
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Old 07-18-2012, 01:17 PM
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you are welcome
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Old 07-31-2012, 05:57 PM
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Got some new pics. Bought a new bottom end, top end and had the cylinder repaired and re-plated at PowerSeal Usa. They did a tremendous job. It looks like brand new. The case splitting tool and the crank installing tool worked great. Made the tear down and the crank install very easy. Case halves are still apart. I'm debating on ordering a full set of replacement seals. Has anyone put their engine back together only to find out that one of the oil seals like the shifter or front sprocket gear seal started leaking??? I know its cheap insurance and I wish i would have added it to one of my orders. I've already dropped close to a grand in this rebuild. Are seals notorious for leaking or do they usually do fine? Its an 02 and they are likely the factory seals. Thanks for any opinions.



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Old 07-31-2012, 09:22 PM
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Wow Contamination much did you say in another post that this thing ran fine before putting it in to storage for 2 years ?
Where did all that crap come from ? maybe you should add a air filter to your list as well as the new seals while you are in there you may as well do it right and I would also replace the "o" ring in that bottom pic
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Old 08-01-2012, 05:39 AM
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Yep, ran fine. Thats what I don't get. Ran fine when I bought it used. Always took a few kicks to get it started but it idled OK once it was running and warmed up. Granted, I didn't ride it all that much before storing it so I'm guessing that there were maintenance issues with it by the previous owner. I couldn't believe the amount of "crap" that came out of the engine when I opened it up.

I really want to get this thing back together and running again so I can ride it.
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Old 08-01-2012, 10:32 AM
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I would recommend replacing ALL seals, gaskets, and bearings. Yes, you are correct about discovering one stupid component being defective after all of the hard work. It's called "Murphy's Law" and the best way to avoid it is to remove all possible scenarios. I always replace everything when I tear it down that far, even if it doesn't seem "worn". For one thing, it avoids the heartache mentioned above, and another thing is that I have a good baseline on how many hours are used on the components. It's easier to know that the whole Bottom-End has "X" number of hours than to guess about how much the crank bearings have versus the transmission bearings and when was that gearshift seal changed, etc.
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Old 08-12-2012, 09:00 PM
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I one time spent 14 hours straight just to get a bike ready and finished of course I skipped two little seals around the oil pump that never go bad. I finished the bike @ 3:00 AM because I was heading out for a race the next morning. Fired it up just to find out that the pump wasn't spinning and was shooting out all my oil everywhere because that seal decided to blow. Well I would always just replace the seals... They are inexpensive and worth not having to pull the engine out again because a seal blew. Let me know what you decide to do... I think Wiseco offers a bottom end and top end and Bearings for the job. Sweet deal and pretty inexpensive seeing how much time
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