1991 RM250, need a cylinder. What fits?

I recently picked up a 1991 Suzuki RM250 for $100. It's nearly complete other than the cylinder (and PV's) are missing. From my research I can only use a 1991 or 1992 cylinder due to the o-rings vs gasket, as well as the exhaust pipe flange not physically fitting. However, I was told that this bottom end was the same up to 1995. I'm having a hard time locating a 91/92 cylinder, much less a complete one loaded with the valves, and the 93+ ones are a bit easier to come by. Would I be able to use one of these cylinders instead? I'd imagine that I'd need matching year valves at least. Or is there anyone that manufactures a big bore kit that may come with a cylinder? I don't care about power curves or getting the most out of this engine, I just want to make it run again without dumping an unreasonable amount of money into it. Thanks in advance for any info!

RM from 91-92 should have frame mount to front of the head. 89-90 cylinder and corresponding head (using conventional head gasket) could be fitted but need to confirm exhaust pipe flange diameter.

RMX cylinder is also compatible with your 91RM bottom end in case you find one of them in your search.

Likewise, if you find a complete 93-95 cylinder with PVs you could use that with your 91-92 head.

 

Post here with links before buying anything and I'm sure folk will keep you right.

RM from 91-92 should have frame mount to front of the head. 89-90 cylinder and corresponding head (using conventional head gasket) could be fitted but need to confirm exhaust pipe flange diameter.

RMX cylinder is also compatible with your 91RM bottom end in case you find one of them in your search.

Likewise, if you find a complete 93-95 cylinder with PVs you could use that with your 91-92 head.

 

Post here with links before buying anything and I'm sure folk will keep you right.

 

Thank you for the reply. Is the RMX cylinder compatible with the exhaust/head I currently have as well? And what year RMX? (My bike is 100% complete minus the cylinder and valves - I still have the stock head and full exhaust)

 

And to confirm, I CAN use a 93-95 RM cyl as long as I buy it/use it with the 93-95 valves all as an assembly? This would be very beneficial!

Thank you for the reply. Is the RMX cylinder compatible with the exhaust/head I currently have as well? And what year RMX? (My bike is 100% complete minus the cylinder and valves - I still have the stock head and full exhaust)

 

And to confirm, I CAN use a 93-95 RM cyl as long as I buy it/use it with the 93-95 valves all as an assembly? This would be very beneficial!

 

Sorry for delay in responding, had internet connection issues.

 

The O ring type heads used on the 91-92 & 93-95 cylinders will not fit on the RMX cylinder as the headstud PCD is different. It's larger on the O ring types as the studs are moved outwards to leave more room for the inner O ring groove.

 

You need to measure the diameter of you exhaust header where it slides into the cylinder as there are two different sizes, and on bikes this old there is always a chance parts have been swapped or interchanged over the years and are not original. This means you need to confirm exactly what you have first before buying replacement parts that might not be compatible.

 

A complete 93-95 cylinder with PVs will fit your engine. You would use your 91-92 head so the frame mounting lug is in the forward position.

 

Again I'll state that you can post links to parts you are thinking of getting and people will chime in to confirm they are compatible with your needs. :thumbsup:

Edited by rmxdan

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