SB50P

[stl450rider]

a friend of mine got a 89 sb50p.. First of all,Im assuming it is restricted (p). Second, Where are the restrictions? I know that they are single speed, this one barely pulls up a hill though. It has a 68 main jet in it. What can be done for relatively cheap to increase the acceleration, if anything. Or should he just sell it?

Thanks

[eliteguy50]

Hand port the cylinder and shave the head.

[stl450rider]

are there specific port numbers to go by? or just opening the intake and exhaust ports slightly? get the head shaved like 10,000th of an inch? and is the power to be gotten out of this even worth the trouble?

Thanks

[Bear45-70]

Cut the head at least .0020" and in my opinion, no. But then I only have a Spree and an Aero 50 in 50 cc scooters. The rest are 80 and 125s.

[eliteguy50]

are there specific port numbers to go by? or just opening the intake and exhaust ports slightly? get the head shaved like 10,000th of an inch? and is the power to be gotten out of this even worth the trouble?

Thanks

If you have your own equipment, you can do the mods for just the cost of the gaskets. If you hire it done, a swap or selling it and buying something else is the better way to go. Shave 25 thousandths. Don't open them too much, you need to keep ring surface for reliability.

[Dio89Elite]

if you're looking at a lot of time going uphill, i'd sell it or consider an engine swap for more power.

[stl450rider]

what are the gains like out of a big bore kit? or is it a waste of money?

[Bear45-70]

The old saying in Hot Rodding is "There is no replacement for displacement." As far as I know, no one have ever dyno'd and engine before and after a BBK install.