• Enter the March CB750 Supply gift certificate giveaway! It's easy... Click here, post something, and you're entered into the drawing!

81 CB750 First Startup

grepper

Old Bike Nerd
Messages
467
Reaction score
1
Points
18
Location
Lowell, MI
Just thought I'd share my success.
I'm building a bike from basket cases. The engine, carbs, everything completely rebuilt. She fired right up. I have some tuning to do and a lot more work to finish her off, but I'm way ahead of schedule for being able to ride it next summer.

 
Nice job bud!! Who built the motor?

I did. I combined the bottom end of an 81 CB750K and the top end of a 82 CB750SC. The cases for the bottom end were vapor blasted. I checked all the bearing clearances and primary chain lengths. As for the top end, I cleaned the crap out of it, painted it with engine enamel and cured (backed) it in my oven. New cam chain tensioners, honed the cylinders, lightly lapped the valves, new piston rings, gaskets and seals. When it came to the valve stem seals I ordered the viton seals, and a better bolt kit for the cams. I let her run for a bit and no leaks!

I rebuilt the carbs over Thanksgiving weekend. Runs pretty good for just a bench sync.
 
I did. I combined the bottom end of an 81 CB750K and the top end of a 82 CB750SC. The cases for the bottom end were vapor blasted. I checked all the bearing clearances and primary chain lengths. As for the top end, I cleaned the crap out of it, painted it with engine enamel and cured (backed) it in my oven. New cam chain tensioners, honed the cylinders, lightly lapped the valves, new piston rings, gaskets and seals. When it came to the valve stem seals I ordered the viton seals, and a better bolt kit for the cams. I let her run for a bit and no leaks!

I rebuilt the carbs over Thanksgiving weekend. Runs pretty good for just a bench sync.

Never knew about that "baking" process but it sounds sweet. Excellent work. Hope I have the same success.
 
Never knew about that "baking" process but it sounds sweet. Excellent work. Hope I have the same success.
Well you can't just use regular spray paint to paint an engine. Especially if you want it handle the heat and to stand up to gas and such. Engine enamel requires curing. I tried just running an engine to cure, but not all parts reach the required temperature. The can says 200 degrees for 1 hour, hence baking it.

 
Back
Top