Differences between 1986 and 1985 Maxim-X

So I have a motor from a 1986 xj750x that I'm planning to install in a 1985 xj750x. There are a few cosmetic differences between the powerplants, so it got me wondering if there are any other mechanical differences between the two that might crop up during the swap? I'll be putting the starter, stater, most of the cooling system, carbs, most of the controls and all the electronics from my '85 on this '86 donor motor.

Any insight would be appreciated, thanks guys.

-iX.

 

You won't have any problem using the '86 engine on you '85 model.

Starter, stator, carbs and wiring is all the same. The main difference on the engines between the years is the location of the ignition pickup (internal and has the same wiring connector for the TCI box) and the side case covers are black instead of a natural aluminum color. All the other model year changes are not engine related.

Make sure you get the valve clearances set before you swap it into your bike, as that will make things a lot easier.
Also, put new O-rings on the intake manifolds, as you don't want to rely on 30 year old rubber to seal against vacuum leaks.

Tony

 

Ok, sounds good. I noticed the cosmetic differences in the motors and decided I like the 86 better anyway. Is there a source to read about the other changes between years?

Absolutely valves are on the agenda. Checked them already. Almost all the intakes are in spec except one single valve that is a complete zero. On the exhaust side we have three or four to do. Hopefully we won't have to try twice on the zero clearance valve, I'm just going to put a shim on for an additional .008 and hope it's enough to raise it into the tolerance zone on the first try.

The rings are still on the donor motor for the carbs, they look and feel really really good, I don't think they are original. I think I might keep those. The carb to airbox rings would be coming from my existing mill, probably I will replace them as I may already have a vacuum leak on it.

Thanks for the tips!

 

Try the xj4ever catalogue as a reference for changes from year to year. Search a part, and if there's a change, there'll be a separate listing for the changed part. Chacal's site isn't only a good spot to find parts, it's also a valuable source of info.

 

Read somewhere that on a motor that has sat for a bit you should crank it over as fast as you can with a wrench a few times before believing a zero clearance valve measurement. Guess what -- it worked! Showing a gap in spec on the suspect intake valve now. So only exhaust to do.

New question: If I see a bit of very light scoring on the bucket, and can feel (if not see) some imperfection in the cam lobe, what should I use to smooth it out?