Scooterotica

Well I had a talk this afternoon with someone that knows a fair bit about these V4 kits and he said there is a possibility that the barrel is machined wrong, not enough off the bottom and too much off the top.
This would explain the piston crown being below the exhaust and transfer ports at BDC and the boost port window showing in the inlet a BDC.
Also all the V4 barrels are 103mm high, they are done that way because of the head being recessed into the barrel.
I'll post more if I find anything else out.

Out of interest, are all the problems listed on this thread relating to the small block 186 kit, or is the small block 198 kit the same?

I'd finally decided on the Mugello 198 kit for an engine rebuild.......... until I read this thread!

CPH Lambretta wrote:Well I had a talk this afternoon with someone that knows a fair bit about these V4 kits and he said there is a possibility that the barrel is machined wrong, not enough off the bottom and too much off the top.
This would explain the piston crown being below the exhaust and transfer ports at BDC and the boost port window showing in the inlet a BDC.
Also all the V4 barrels are 103mm high, they are done that way because of the head being recessed into the barrel.
I'll post more if I find anything else out.

I worked at a scooter shop and we had our first batch of V4s (the recessed head version) from tino and they were all like this, i.e. boost port showing in the inlet and the piston well below the transfers and exhaust port a BDC (we thought for a while that we had been supplied 60mm cranks by accident for a while). We contacted Tino, sent him photos etc but he told us that these kits were designed this way. I was still convinced that this was bullshit and lo and behold the next batch we received had been machined at the bottom and had a larger shoulder above the top fin. I think someone has dropped a bollock at the cylinder factory but the kits are being sold anyway. The kits like this do work, but they are very hard to set up for low rpm and need lots of throttle to get into the power, not very good really.

This could explain why my port timings are crap...

Maybe a recall is in order...

@ Johnd thanks for the info sounds like thats exactly whats happened

@ Red Ghost if you have one of these barrels I would have thought it would be even worse with a 60mm crank because the piston will come even further down, showing more of the boost port window.

I have a 110mm rod and I've played with different packers and 'wot not' and it all just comes back to well s**t really..

So what is a fix for this then?

:bald:

Shouldn't this all be checked before putting on the market?
The heads on the v3 version seem to be a common problem, swapped mine for a broady one and no more problems, however piston replacement and a new head when you have already bought the kit is not cheap and puts another 150 pound on top of the kit

:bald: