TOPIC:

I am going to start the rebuild of my 81 1300. Looking at some good head work, port/polish/flow bench work, some regrind cams and possibly some bigger pistons. Also replace the cam chain guides and rollers and rebuild the water pump.

I am no stranger to turning wrenches, but I have never had one of these apart.

The bike has 65K on it, it runs with no bad sounds, but it sat for a long time. She smokes pretty good, and I think the valves may have been run too tight.

I am planning on going through the top end, but I am curious if I should split the cases. This bike has the deep sump, so I am not worried about the mains and rods, but that plastic gear that drives oil pump concerns me. Is that something I need to replace? 30 year old plastic is not the most reliable stuff...

Best of luck to you on your rebuild! Definitely let us keep tabs on your progress. I for one would follow that intently .

Not sure on the service life of the bevel gears, but that would be the only reason to go through the bottom end unless the transmission has been abused.

If you do wind up splitting them I'd like to suggest looking into seeing if undercut gears would help your performance build. No idea if anyone has considered it for this bike lol. If you replace those nylon gears maybe we can look into having metal ones made like we recently have been able to do for the cam chain idler gear. Otherwise, I would at least get a shift kit since I know those are available .

Even though you may have already considered them, I hope my suggestions help!