Rossi .21 6 Bolt Head Piston and Sleeve

[jaxracer]

Hey guys, do any of you know if the current Rossi 4 bolt head piston and sleeve will fit into the old style 6 bolt head case? Are the bore and stroke numbers the same? I know one is a 3 port and the other is a 5 port but I was under the impression that the bores were the same.

Thanks

 

[Martin Hamilton]

The bore & stroke are the same on the 2 motors 16.56mm bore x 16mm stroke, liner dimensions are the same as well so their both interchangable in the cases other than 1 being 5 port over 3 port. The 3port outboard liner does have lower timing on the ex & transfers though, from memory when i last checked them both together the 3 port outboard timing was 5 or 6 degrees lower than the 5 port one on both ex & transfer timing. Part number for the outboard p/liner is 1010, they do have a new 3 port p/liner with the same dimensions which has higher timing on ex & transfers which also has a billet cnc piston of much better material than the older cast pistons.Part nunber of this p/liner is 13411,youll find this isnt a commanly known part to most. Its a 3 + 2 ie 3 transfers + 2 bypasses through both the piston & liner. Martin.

 

[jaxracer]

Awesome Martin. That's exactly what I was looking for. I knew the ports and port timings were going to be a little different, nothing a little dremel tool couldn't fix Now this new piston and liner they have out, do you think Hyperformance Products would have it or where would I be able to find it at?

Thanks man,

-Mitch

 

[Martin Hamilton]

Mitch i found out about this p/l by accident really around 2 years ago before they had released anything about it.Im in the UK & was buying direct from rossi as their wasnt a uk importer. I was ordering some of the 1010 p/l & in the conversation with them they mentioned this new p/l they had made & were getting good test results with it, So i bought one to have a look at but i never got round to trying it.I beleive you can now get them in the US now from SG Model Engines,Go to their site click on all items in the top left then go to page 6.About half way down the page youll see them,listed as Piston/Sleeve,7 port, Marine 21 outboard, 13411 at $85.They call it a 7 port but its a 3port they include the 2 bypasses in the port count as well as it has 2 slots through the liner below the ex port for lube so making 7 holes in the liner + exhaust. Theirs some really nice pics of this p/l on this site. Martin.

 

[jaxracer]

Sweet, yeah I found it on the SG Engines website. That looks a lot better than the liner than the liner was in 4 bolt engines. Well thanks alot man. I'll have to see about ordering one sometime here soon.

Thanks again,

-Mitch