Hitchcocks Forum

Hello, had a 65 since 2004, and it's never been right, on my second top end rebuild in 5000 miles. It keeps on seizing . Love the bike, but want reliability. Has anyone fitted an alternative petrol engine?

Hi, instead of changing the engine I would be looking a bit harder to solve the problem. Engine seizes can be caused by more than the top end! My 350 seized at 5000 miles due to the crankshaft coming loose.

On your second top end rebuild in 5000 miles?, you have one of two problems, either the rebuild is being done incorrectly (piston clearance incorrect or rings incorrectly gapped) or the fuel mixture is too weak causing the engine to over heat. Solving either on of these problems is far easier than an engine transplant.

As the others have said, it shouldn't seize, not ever. The old iron engines are simple and reliable if not thrashed all the time. Not sure what other makes will fit but any RE bullet/twin engine will fit.

Pre EFI

anything is possible.



and you only need two things, motivation and money.



on a less costly note, these engines are a simple set up.

yet amazingly people still mess this up.



like others said, your problem is easier to fix than spooning a complete different engine in the bullet chassis

Hi, Ok. Third time lucky. So it could be a lean mixture creating additional heat, so I will raise the needle a notch, is there anything else? I have not as yet taken it apart to see the damage.

Don't assume anything at this stage! Dismantle the top end of the engine and examine everything with an open mind. You're looking for the cause of seizure and that might be a result of a chain of events, for instance a weak mixture may cause poorly gapped rings to tighten in an undersize bore. See? 3 potential problems any one of which would cause problems in the long run. Don't despair though, the examination and measuring process is pretty straightforward on these engines and you will get a lot of good advice here. The 65 is probably the best developed Classic engine IMO and although quality control issues are not unknown (!!!) it is a rugged design and worth sorting out!

REgards, Mark

The timing being wrong can cause over heating as well. I have in the dim and distance past when I had slightly seized piston after engine rebuild, (Not on an Enfield)cured the problem by removing the high spots on the piston with a scraper.

when you say seized, does your piston look like this?