Engine rebuild tips? - Wrist Twisters
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post #1 of 6 Old 03-26-2020, 03:58 PM Thread Starter
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Engine rebuild tips?

Hey everybody! New member here. I have a 2003 9er, black (the fastest color). I recently laid her down and cracked the engine case. I thought about selling it and getting a new bike but I just love the 919 too much so I’m going to fix it. I’ve ordered a set of case halves and I pulled the motor out today. My question is: has anybody here rebuilt one of these engines? I’m just looking for any tips or tricks, or special tools needed. I’m a mechanic so I have lots of tools and mechanical aptitude, but this is my first motorcycle engine job. Any input is appreciated!

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post #2 of 6 Old 03-26-2020, 09:40 PM
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RTFM

the manual is pretty comprehensive and available here if you don't have it.

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post #3 of 6 Old 03-26-2020, 10:05 PM Thread Starter
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Thank you. I do have the manual, I’ve read through it a couple times. For the most part it seems pretty straightforward, but sometimes it’s hard to get the scope of things just by reading the manual. I was just kinda curious to hear from people who have done it. I’ve rebuilt loads of auto engines but never a motorcycle engine, so it is a little intimidating, but I’m sure I can get it done

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post #4 of 6 Old 03-28-2020, 12:13 PM
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Quote:
Originally Posted by Jacob Zawadzki View Post
Thank you. I do have the manual, Iíve read through it a couple times. For the most part it seems pretty straightforward, but sometimes itís hard to get the scope of things just by reading the manual. I was just kinda curious to hear from people who have done it. Iíve rebuilt loads of auto engines but never a motorcycle engine, so it is a little intimidating, but Iím sure I can get it done
Not lost on me is the FSM's absolute silence on cylinder wall prep for the new rings.
I'm decades from not being current on this stuff, but given the cylinders have a nominal 10 thou' boring allowance for the one only oversize pistons available, suggests to me that a properly selected and used ball hone might be OK/good to use.

Past that, the valve head angle specs are very rudimentary.
Depending on what you are out to do, some extra angles and minimized seat width might yield an undetectable improvement - but you'd know you'd done it!

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post #5 of 6 Old 03-28-2020, 08:38 PM
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I would not hone the cylinders unless the piston to cylinder clearance is less than the specified 0.015mm, or 0.0006". Yeah, it's that tight. In my years working on thousands of Hondas when replacing a cylinder block / engine cases the bores were already precision honed to the proper depth and crosshatch angle, and judging by my '02 with 80,000 miles on that has yet to use more than about 10cc's of oil between changes I'd say they know what they are doing. Of course they need to be thoroughly cleaned with very hot water and Dawn dish soap, followed immediately by thoroughly oiling the bores.

You will find this motor is pretty much the same inside as a four cylinder car engine, just smaller and with tighter clearances.

How many miles on the motor? It would be a good idea to check the valve clearances on the bench before tearing it down. That way you will know what shims you may need in the unlikely event that they need adjustment. You're already there, so why not?

One last thing: where is the case cracked? If it's one of the front engine mounts were there sliders attached there? It's common for a slider in that location to cause considerably more damage than would be the case with nothing.

Have fun!

Rob
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If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
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post #6 of 6 Old 03-28-2020, 10:19 PM
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Quote:
Originally Posted by robtharalson View Post
I would not hone the cylinders unless the piston to cylinder clearance is less than the specified 0.015mm, or 0.0006". Yeah, it's that tight. In my years working on thousands of Hondas when replacing a cylinder block / engine cases the bores were already precision honed to the proper depth and crosshatch angle, and judging by my '02 with 80,000 miles on that has yet to use more than about 10cc's of oil between changes I'd say they know what they are doing. Of course they need to be thoroughly cleaned with very hot water and Dawn dish soap, followed immediately by thoroughly oiling the bores.

You will find this motor is pretty much the same inside as a four cylinder car engine, just smaller and with tighter clearances.

How many miles on the motor? It would be a good idea to check the valve clearances on the bench before tearing it down. That way you will know what shims you may need in the unlikely event that they need adjustment. You're already there, so why not?

One last thing: where is the case cracked? If it's one of the front engine mounts were there sliders attached there? It's common for a slider in that location to cause considerably more damage than would be the case with nothing.

Have fun!

Rob
You got me good.
I was thinking used cylinder block getting new rings.
He's got a new set of halves, so the cylinders should be ring ready and likely be within tolerance re the used pistons.

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