250R Cylinders

[arakyle]

I bought a cylinder to use as a spare. It came with a stock reed cage. When I took it out, I noticed that the two fins inside the intake port where the reed cage sits are not there. Are some cylinders like this? It doesn't look like it has been cut on, they are just not there. Someone let me know if I've got a piece of junk before I spring for a bore and piston.

[j28d]

85-86 jugs don't have the bridge, and some people cut them out of newer ones for a drag port.

[arakyle]

Thanks. I was worried there for a minute. Are the unbridged any better?

[bushwesl]

Most would actually say that they are worse, but this all depends on who you talk to. The reason behind the bridge is that it acts as a guide for the piston/rings, and doesn't allow for as much wear.

[wilkin250r]

Originally posted by arakyle
Thanks. I was worried there for a minute. Are the unbridged any better?

It depends on your goal.

I dont' know if I've ever seen any actual side-by-side comparisons with all things identical but the bridges, so I can only provide theory, not hard fact. But the general guidelines are that the bridges help with reliability (for the reasons that bushwesl posted), but cutting them out will allow more airflow for high-revving engines.

[arakyle]

Yea, with it acting as guide for the rings I could see these being worse... pretty large opening for the ring to cross. One more thing... when these are bored, I need to make sure that the exhaust bridge is recessed and the ports are chamfered... right? What is involved in this, or do you guys have any one you recommend.