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Hi all, I am having a bit of a problem with a 3.5 Morini and I was hoping you could advise me on a way ahead. The small end bearings/piston pin bushes have been replaced and now there is no way in hell that the pins will go through. Bushes and new pistons from NLM.

How were the new bushes inserted in to the rods?

I had to do a small end on a Gilera single last winter. After being made to the dimensions in the workshop manual I pulled it in to place using a long bolt, nut and spacers. As expected the pin wouldn't go through. As it was all a bit of a make do and mend job I used an adjustable hand reamer (£7 off Ebay) to ease it very carefully bit by bit until the pin could be pressed through by hand. Amazingly I kept it in line well enough that the pin also then went through the piston OK and it ended up running quite well.

That was a very simple "phosphor bronze" bearing and quite 'thick' though.

The service manual says:

I think I may try and do it your way. I just don't have the time, or inclination, to pull it all apart again.

Tim Louth wrote:I think I may try and do it your way. I just don't have the time, or inclination, to pull it all apart again.

Best of luck. I can imagine it being trickier with the 'cross oil grooves' in a Morini small end bush. My custom bush had plenty of 'meat' on it as I had it made to use a piston that takes a 13mm pin with a rod that originally used a 15mm pin. Also just two oil holes - though they were a game to drill and then get in line while pulling the bush in !

You need to adjust the reamer in TINY increments and then cut by rotating in one (the correct) direction which I found didn't seem to be the one I expected!

Keeping the reamer perfectly in line is really difficult working in situ. At least a Morini small end protrudes above the crankcase mouth further than on a Gilera 98.

If you can eventually get the piston back on without brute force you won't be far out, but worth popping the cylinder back with no rings in place and see how the piston 'lies' and that it reciprocates perfectly freely.

You can probably get it to the point it will run OK - but for how long?

Well. I like a challenge!!!