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Hi all,
I'm new to the forum. I recently acquired a 75 cb750, with only 12,000 miles on it. The downside was that it had a frozen piston. I've torn it down, had it honed lightly, and have bought a rebuild kit.
Here's the question. I've found some rings, they come in various oversizes. 1.0mm, .75mm, .50mm, and .25mm. I cannot find a set of standard rings. Does anyone know if the .25mm oversized rings will be a huge difference? Can I get away with using them, even though I have not bored out the cylendars?
Thanks,
~Keith
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i have a 75 cb 750 and just rebuild the motor i had a hole in a piston i think u will have alot of trouble trying to stuff those rings in the jugs i got new stock OEM rings on ebay 10bucks a set thats cheap so 40 bucks i had all the rings i needed to get the job done good luck ,Wes
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Wes,
I managed to get stock rings for my bike. I took the cylendar head down to the local Parts Dealer and he spec'd them for me. I had a heck of a time getting the pistons back into the head, and had to have the help of two other sets of hands. It was a real pain trying to get two pistons started at a time. But i did it. Rebuilt the engine entirely, put on new front master cyl and caliper. New clutch cable, rear brake assembly, and lights. I decided not to paint the bike, as I think a custom paint job wouldn't be as cool as the original paint. I couldn't get the exhaust back on and lined up because the muffler was frozen to the pipes. I cut the muffler, got some baffles from ebay, and put on 13 in cut off's. It's still loud, but man does it have some serious power.
If you're rebuilding your entire engine, don't forget to replace the crank bearings and seals. Otherwise, for some reason when you replace the rings, it makes the crank leak oil. Maybe that was just mine, but my buddies did the same thing.
God bless and merry Christmas.
~Keith
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Good to hear u got her together its a pain to get them two pistons started with the stock rings i got mine together and put it in the bike and she fired up first time it rolled over its a very good motor it runs about 70hp at 8000rpm go tit set up cafe style keep the rubber side down. , Wes
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Try David Silver Spares in England Only Honda Parts
Classic Motorcycle Supply - cmsnl.com out of the Netherlands.
Old Bike Barn, New York, Quebec
You can not use over bore rings in a stock cylinder. When you go to the next size piston and rings, say 25 overbore, you have to match the rings to the pistons and have your cylinders bored out so they fit. If you take first over pistons and rings and try to jam them in a stock bore you will get them stuck and then you'll be looking at alot more money spent on a machine shop or mechanic getting it out. If your stock bores are not rusted and you said it was froze up? You may get by with having them honed and not bored. But cylinder boring is cheap. Check E-bay as well but I'm almost certain that one of those suppliers I mentioned has stock rings. How are you pistons? If they are in bad shape do you really want to spend all that time and effort to put them back in the bike. Buy new ones and be done with it.
rm56
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Just for future reference, a trick I learned on fitting pistons on inline fours is to use wood forks under the pistons. It holds two pistons in place and keeps the crank from moving so you can slide them into the cylinders. Cut a 1 by 4 piece of pine with a slot in the middle so the connecting rod will fit in it and the piston skirt will rest on the sides, a great cheap assembly tool.
rm
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Locked
