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Discussion Starter #1
Hello!!

I'm a new-to-me Grizzly owner, and happy to be here! I recently got my hands on a 2005 Grizzly 660 with a locked up motor for next to nothing, and decided it was high time to embark on a gearhead project.

So, I'm tearing the motor down to the crank case and removing it, then building it back up on a workbench as a glorious 686!

She will be reborn with a Hotrod crank and all new crank bearings, seals and gaskets, then moving up, have the 102mm bore cylinder and 10:1 piston.

She'll be topped off with a brand new, fully assembled cylinder head, new timing chain and Hotrod cam.

Also, since I'm already there, I'm replacing the water pump, starter, radiator hoses and other inexpensive parts I see that might look rough.

Here come the pics!


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Welcome and congratulations on your new project. I look forward to following your rebuild.
 

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Discussion Starter #3
Here are a few pics of the teardown! The destruction in the top end of the engine was epic, lol


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Wow. That what happens when it runs out of oil.
 

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Double wow!
 

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Discussion Starter #7
So..theres this annoying, externally threaded LH bearing retainer nut that you need to remove in order to tap out the middle shaft from the crank case. Yamaha wants you to use a specialty tool from them, but I used a 1.5" deep socket that I "modified" with an angle grinder. :)


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That cylinder will be fiiine with a light hone....

Here I thought I was good at breaking stuff, the guy you bought it from sure got his money's worth.

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He didn't muck around with that one did he!
Don't forget the oil pump & bearings.
 

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Discussion Starter #10
He didn't muck around with that one did he!
Don't forget the oil pump & bearings.
New bearings are coming as part of the bottom end rebuild kit. The oil pump is perfect looking but will be stripped down and cleaned in solvent. Water pump and starter are being replaced as a preemptive measure!

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Sounds like your right on top of things, should be a great rebuild.
 

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Good project you have there. Are you going redo the clutch parts? If it was a old problem it might need a complete redo. I would get with Brian Farr from BF Clutching to make sure you get all that 686 to the wheels.
 

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Good project you have there. Are you going redo the clutch parts? If it was a old problem it might need a complete redo. I would get with Brian Farr from BF Clutching to make sure you get all that 686 to the wheels.
I haven't yet measured the wear on the wet clutch shoes, but if they're outside the service range I'll replace the wet clutch. I'll be putting in a new belt just because I'm there already, and I also plan on doing the shim mod to the sheave.

Do you have any recommendations or thoughts on this plan?

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That's a whole bunch of Niche industries parts...or at least they look like them.
 

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Is that good or bad?

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It's been in my experience that they make excellent products. I have all 4 axles and front driveshaft in my Grizzly, and I have installed multiple clutches of theirs. All have been perfect. The axles have stood up to my 30" tires no problem. So I would suspect their cylinders and engine components to be the same.
 

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Discussion Starter #18
It's been in my experience that they make excellent products. I have all 4 axles and front driveshaft in my Grizzly, and I have installed multiple clutches of theirs. All have been perfect. The axles have stood up to my 30" tires no problem. So I would suspect their cylinders and engine components to be the same.
Gotcha. The cam and crank are from Hot Cams in California, and the cylinder and cylinder head assembly are from BP Racing in Rancho Cucamonga, but I dont know the exact manufacturer

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Discussion Starter #19
Cleaned up the oxidation on my bezel. The corners need more work the second go round but I'm happy with the progress!


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Got one half of the crank case pretty well degreased, and the crankcase internals inside now also. Going to give them a solvent bath before they are reinstalled.


Next up is pulling the crank and degreasing the other side of the crankcase.

After that I'm considering having whole exterior of the engine painted in some high temp paint like you'd see on an old muscle car.


After that I will sweat in the new bearings. I bought all of them. Crank bearings, transmission bearings and the counterbalance bearing (both ball and needle bearing) plus all the seals.

Once that's done it will be time to install all the new crank and reassemble the newly cleaned transmission, driveshafts, new high flow oil pump, etc. So I can RTV the crankcase back together and get to the piston installation. Progress is good!


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