TOPIC:

I have my 81 750H in pieces all over my garage as a winter project. I have a few questions and requests.
The pistons had quite a bit of carbon build up on the crowns so I cleaned them off as best I could. I work in an aircraft maintenance hangar so I have access to quite a bit of equipment. Is it safe to use a plastic media blaster to clean my piston crowns and combustion chambers?
I’ve had experience tearing down automotive engines and transmissions but have never really dealt with complete tear downs of motorcycle engines except for a couple Honda ct 70’s. Is it a difficult task? What should I look for when doing so? Is going to a Kz550 6 speed worth doing while I’m at it?
I will be repainting the bike and the engine and have decided on a metallic green for the tank and side covers. The engine will be done in a satin black but I also want to add some contrasting color there as well, ie; painting the valve cover and possibly some covers a different color. Has anyone done this? We’re the results (painting) what you expected? Pics would be very welcome.
I have had some minor carburetor issues and am considering bringing them to work and using the ultrasonic cleaner but not knowing if the cleaning solution they use for the jet nozzles will damage my carbs has me second guessing it. Maybe I’ll find an old carb and try it out on that first to see what happens.
I also want to ditch the stock handlebars and go with something lower like maybe off a standard model. Will cables need to be replaced to accomplish this? I’m sure as I get deeper into this project I’ll have more questions but for now I’m just at the starting point.

Troubled1 wrote: I have my 81 750H in pieces all over my garage as a winter project. I have a few questions and requests.
The pistons had quite a bit of carbon build up on the crowns so I cleaned them off as best I could. I work in an aircraft maintenance hangar so I have access to quite a bit of equipment. Is it safe to use a plastic media blaster to clean my piston crowns and combustion chambers? Yes, just tape off the wrist pin bore and ring grooves. clean everything really well after. I would also rebuild the head after blasting. Before you go to through the effort of cleaning up your pistons I would measure the bore and pistons to see if is in spec.
I’ve had experience tearing down automotive engines and transmissions but have never really dealt with complete tear downs of motorcycle engines except for a couple Honda ct 70’s. Is it a difficult task? Much simpler than most car engines or airplane engines.What should I look for when doing so? look for wear on critical parts, such as bearings, pistons, cams, etc. get a manual and measure parts you plan on reusing. Is going to a Kz550 6 speed worth doing while I’m at it? There are people who have done it and can chime in and offer their insight. Looking at it objectively, the 550 has relatively close ratio transmission with 6 gears to stay in a narrow power-band. 6th gear is not very much taller. This could be useful if you are road racing when you tune for a specific RPM. when you factor in the new primary gear ratio of the 750 the 550 trans leads to about a 250 RPM decrease at 60mph. You will see a similar effect by just playing around with the final drive ratios. The kz650/kz750 will run all day long doing 80mph no problems and it will not effect longevity of the engine. these engines were designed to spin. seems like a lot of work for a slightly taller high gear and a weaker transmission,
I will be repainting the bike and the engine and have decided on a metallic green for the tank and side covers. The engine will be done in a satin black but I also want to add some contrasting color there as well, ie; painting the valve cover and possibly some covers a different color. Has anyone done this? We’re the results (painting) what you expected? Pics would be very welcome. IMHO this can look really good when done properly, but its easy to go overboard. I think its a nice touch when a bike is performance oriented. kinda like the wrinkle red paint that comes on FCR carb tops.
I have had some minor carburetor issues and am considering bringing them to work and using the ultrasonic cleaner but not knowing if the cleaning solution they use for the jet nozzles will damage my carbs has me second guessing it. Maybe I’ll find an old carb and try it out on that first to see what happens. always can use carb cleaner spray. a little more effort but i have always had good luck doing it this way. the trickis to block off passages one at a time to make sure the cleaner is forced out rather than just spraying the ports and letting it take the path of least resistance.
I also want to ditch the stock handlebars and go with something lower like maybe off a standard model. Will cables need to be replaced to accomplish this?Depends on how much lower you go, but if you change it more than 2-3 inches of rise I would shorten the cables, it can work fine but looks goofy with extra cable length I’m sure as I get deeper into this project I’ll have more questions but for now I’m just at the starting point.

have fun with it.

My wife rides a 1981 KZ550. We bought it as a project and fixed it up and painted it. It's a great bike for smaller people. I've ridden it but at 6 ft 3 in I'm a bit too big for it. For a smaller engine it's a fast machine with good acceleration.

The carbs are difficult to remove and re-install...not a lot of room. The engine is easy to work on and can be dismantled on the bike or off. My only beef is that the shims are under the valve tappets, so if you need to change one you have to pull the cam off, and then re-time everything afterwards. You can still get a lot of parts, and there are a lot of used ones on ebay.

Photo shows my wife's bike.

I only pulled the engine mainly because it’s a lot easier to do the gaskets on the bench. Scraping the cylinder base gasket tools hours. Painting the engine properly can only be done, in my opinion properly when removed from the bike. I have done the shimming on the valves once. It wasn’t too bad but still more work than a job like that should be. When I do my carbs all the boots get pushed into the air box to give me more room to remove them. After a couple of goes at it, things go quite quickly.
That’s a fine looking bike your wife has.

Troubled1 wrote: .........Painting the engine properly can only be done, in my opinion properly when removed from the bike. ..........

Why would you want to paint the engine? Ed

I just want to change things up a bit. Some people like annoyingly loud pipes some like led lighting everywhere.

Troubled1 wrote: I just want to change things up a bit. Some people like annoyingly loud pipes some like led lighting everywhere.

Its all about what tickles your fancy
Dave

It didn't look like that when we bought it. New tires, chain, sprockets, OEM exhaust and paint. Lots of little stuff including many hours of scraping off 35 years of dirt and grease.

You can't see in the photo but the badges on the tank and sidecovers on my wife's bike are covered with little round mother of pearl sparklies. They reflect light, particularly in the dark. It was her bike and her choice. Makes it more personal as you say.

Good luck with your toy!

I took my pistons to work today and used the plastic media blaster. I had already scraped and wire brushed the tops and got them mostly clean but the plastic media made them look almost new.

Engine is back in!! I ended up bringing the cylinder jug, head and cam cover to work and used the plastic media blaster to clean them up. I painted the cam cover, oil pan, exhaust clamps and cam chain tensioner with VHT copper engine paint. The block, cylinder jug, head and side covers were painted with VHT black pearl metallic.