FJowners.com

General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: MN Made on December 04, 2012, 02:14:07 PM

Title: Advice on rebuilding/machining motor
Post by: MN Made on December 04, 2012, 02:14:07 PM
I recently purchased a 1985 FJ1100 with 28,000 miles on it. The bike is in great condition. I have gone through all of the mechanicals including adjusting the valves and doing a compression check. I found that all cylinders are at 160 lbs. The bike runs really well. It does show early signs of the "2nd gear issue" in that it is sloppy into 2nd - but does not slip out of gear under load - yet! I purchased a replacement gear set that has had all gears undercut except 1st gear. My dilemma is this - I am on a tight budget but want to do things right. When I have the cases split to install the gear set, what is the bare-minimum amount of machining, etc. that I should perform on the motor while I have it in pieces? I am planning on a full gasket set and new shift forks but what about the pistons, etc.? Absent of obvious damage or cylinder ridges can I just reinstall them in their respective cylinders and call it good? Should I replace wrist pins and clips? Hone cylinders and new rings? Any assistance and opinions would be greatly appreciated. Thanks, Greg
Title: Re: Advice on rebuilding/machining motor
Post by: Pat Conlon on December 04, 2012, 02:28:16 PM
A 28k FJ with 160 across the board is in great shape. Good for you.
My recommendation is to clean, decarbon and with new gaskets and Just do your 2nd gear fix.
Along with the back cut gears, Remember to upgrade the shift forks, that's what caused the 2nd gear problem to begin with..Might as well Upgrade your clutch spring while you are in there, see the clutch files section.

Cheers
Title: Re: Advice on rebuilding/machining motor
Post by: racerman_27410 on December 04, 2012, 05:56:53 PM
I agree with Pat.... also realize you do not have to pull the top end of the engine off to split the case and replace the gearset.



KOokaloo!
Title: Re: Advice on rebuilding/machining motor
Post by: FJmonkey on December 04, 2012, 07:39:55 PM
Greg, welcome to the FJ nut house...
Title: Re: Advice on rebuilding/machining motor
Post by: fj1289 on December 04, 2012, 08:06:05 PM
I agree - just do the 2nd gear fix and be done!  Sounds like the engine is in great shape and doesn't need anything. I'd reuse the crank bearings too - they won't have any real wear on them as long as nothing nasty has gone through the oil system. Likewise with the cams, etc. The biggest issues for FJs is overheating  - and that would have shown up in the compression check.

I've even seen a discussion on how to fix 2nd without pulling the engine - not sure if it was on here or the yahoo list.

Good luck!
Title: Re: Advice on rebuilding/machining motor
Post by: SlowOldGuy on December 04, 2012, 08:40:04 PM
If you're pumping 160 on all the cylinders, then DO NOT TOUCH THE TOP END!!!

That's perfect compression.  Just fix the gears and enjoy. 

DavidR.
Title: Re: Advice on rebuilding/machining motor
Post by: MN Made on December 11, 2012, 10:46:46 AM
Quote from: racerman_27410 on December 04, 2012, 05:56:53 PM
I agree with Pat.... also realize you do not have to pull the top end of the engine off to split the case and replace the gearset.

I've never heard that - but I like the way it sounds. Do you have any links or info on splitting the cases while leaving the top end intact? I would love to leave everything in place since it's so healthy.



KOokaloo!
Title: Re: Advice on rebuilding/machining motor
Post by: Pat Conlon on December 11, 2012, 11:07:49 AM
Greg, we sure do, check out the Files section, look under 2nd gear fix. We have a couple of write ups.
Title: Re: Advice on rebuilding/machining motor
Post by: bigbore2 on December 21, 2012, 05:45:51 PM
160 is great comp.  I just did mine and were 120-m I am at 5000 ft.  What is your altitude there, MNmade?