bike cosentino

Isn't this a beautiful CB350F? The owner spent a lot of resources on it. Powercoating, new paint, re-chroming, the works. Just gorgeous! The egnine was rebuild also, but, well, that is why it came to me. The bike was gobbling up oil like nobody's business. Actually dripping it from both mufflers in fact. Here is my finger after poking it into a muffler. My customer couldn't keep oil in the poor bike.
Oil around spark plug holes. Did the usual tests. Listening for air at the intake manifold.
Listening at the valve inspection cap hole. Listening at the oil filler hole. Cylinder head off, lot of oil all over.
Combustion chambers very oily. And check out these pistons, just swimming in oil. More.
More. Turns out the bike had a CruzinImage big bore kit. By now everyone is familiar with the problems with these kits, particularly in the CB350F. Here is another example of "getting what you pay for". The main problem is the rings are junk. In less than 500 miles The ring end gap doubled, indicating severe wear.
But as bad as that was, and it was the worst of it, it was only the beginning. Whoever assembled this engine left worn valve guide seals in it. They practically fell down the valve stems. The cylinders were bored incorrectly also. The piston-to-cylinder clearance was 0.0015". And it was found that the CruzinImage pistons had 1.2mm negative deck.
Relative to the piston/cylinder deck, here is an OEM piston (left) next to the CruzinImage piston. But that still wasn't all. All the valves were receded badly. More.
More. Remember, this engine had been "rebuilt" only 470 miles previous. Lot of carbon buildup. More.
More. Typical Chinese piston pin circlips. Not good. The first step in correcting all this was to ascertain whether the engine could be properly assembled with the Cruze pistons. Dimensions were taken all through the piston to determine whether this thin-walled cast piston could withstand some reshaping of its crown.
The piston and combustion chamber were also "clayed", further illuminating the amount of area I had to work with. And finally, the valve to piston clearances were mapped out. By now I knew there was room to re-deck the cylinders and even degree the cam, but it would require a very slight amount of piston reworking.
Little bit of valve relief increase. Then the cylinder was properly decked. And some OEM Honda rings were located.
The cylinder head got a good valve job, including hard-to-find OEM Honda valves. Close up. Finished.
New Viton valve guide seals. Moly on the valve stems. All gasket surfaces prepared.
More. More. Everything ready for final assembly.
Using the factory ring compressors. Note the now correct deck. Waiting for the cylinder head to be ready.
Misalignment in the aftermarket big bore cylinder head gasket. This was dealt with. Head on, now cam timing. Fine-tuning final cam position.
More. Bike together and ready for first shake-down cruise. Cylinder compression after first test ride. Yeah!
Inspecting for leaks after test ride. More. More.
No leaks! Job completed, customer very happy! Another pix.