Sleeper build

[diesel53]

Guys,

My little brother started riding and I want to build him a sleeper bike. Im trying to get to the 60 hp mark, something that will rev quick and be reliable. Im giving him my frame with an 8 over swing arm...

Does anyone know what the stock cylinder dimensions are? I have a ported jug (stock) and a 5mm long rod crank but not sure what I should do or if that will work. Or any cheap build ideas for decent power?

[acecarlos]

No cheap options to get to 60HP on an OEM cylinder, with or without a +5MM stroker crank. Unless you are going to spend a lot of $$$'s, and go with a dedicated Drag set-up, getting to 60HP is not going to happen. Need to be realistic about what you can expect from an OEM cylinder ("sleeper look"); a MX Pro Ported & Flowed OEM cylinder running on Race Fuel with an In Frame Pipe (FMF, PT-HR, TRX5), 38-39MM Carb and a good set of reeds will get you to 52-54 HP, and not easily...this is realistic HP on a conservative Dyno and not inflated numbers.

If you really want 60HP, on Race Fuel, and have a driveable, reliable, non-Drag set-up; you will need to go to a 330CC or 350CC...these are not "cheap builds" for "decent (60HP) power". If you will settle for 42-44HP, an off the shelf ProX310 will get you into that range.

Carlos.

[diesel53]

No cheap options to get to 60HP on an OEM cylinder, with or without a +5MM stroker crank. Unless you are going to spend a lot of $$$'s, and go with a dedicated Drag set-up, getting to 60HP is not going to happen. Need to be realistic about what you can expect from an OEM cylinder ("sleeper look"); a MX Pro Ported & Flowed OEM cylinder running on Race Fuel with an In Frame Pipe (FMF, PT-HR, TRX5), 38-39MM Carb and a good set of reeds will get you to 52-54 HP, and not easily...this is realistic HP on a conservative Dyno and not inflated numbers.

If you really want 60HP, on Race Fuel, and have a driveable, reliable, non-Drag set-up; you will need to go to a 330CC or 350CC...these are not "cheap builds" for "decent (60HP) power". If you will settle for 42-44HP, an off the shelf ProX310 will get you into that range.

Carlos.

Okay 60 was an estimate but 50 plus hp would be perfect. We have a good stock jug with a 68.5mm bore, will it support a 77mm stroke or do I need another crank? I have esr reeds, and a trx 11 pipe. Un sure of the carb but I will get to that later...

Thanks for the help by the way. Ive never dealt with the smaller bores. Only my 370 pro x and 80mmx77mm esr motor. They both ran great. My logic is a smaller bore stroker will do well as an all around bike, with alot more torque..

[250Renvy]

What you want seems to be a complete contradiction. 60hp, rev quick and be reliable. Not sure you can have all of those.

If your brother isn't that big of guy, you shouldn't need to go super big on HP. If he's overweight, tell him to drop some pounds, that might be cheaper than adding ponies.

[diesel53]

What you want seems to be a complete contradiction. 60hp, rev quick and be reliable. Not sure you can have all of those.

If your brother isn't that big of guy, you shouldn't need to go super big on HP. If he's overweight, tell him to drop some pounds, that might be cheaper than adding ponies.

50-60hp to me is not big at all. and he is only 115 pounds so this bike should be quick with him on it. Im throwing the motor in my lightened frame with superlites and a decent suspension.

[acecarlos]

50-60hp to me is not big at all. and he is only 115 pounds so this bike should be quick with him on it. Im throwing the motor in my lightened frame with superlites and a decent suspension.

Sorry to disagree; 50-60HP on an OEM 68.50MM bore on Race Fuel (Methanol is much easier to achieve 60HP) even with a 77MM crank is a big deal. Now, if you find one for those Dyno's or Builders that will tell you what you want to hear, and give you inflated numbers tthen that is a different story. On a conservative Dyno, getting to 52-54HP on an 68.50MM OEM cylinder that is NOT a dedicated Drag engine is a very good accomplishment. The OEM stock Jug will support the 77MM crank, the TRX11 pipe is not the pipe to use with an OEM cylinder at 68.50MM...way too much Pipe volume for a 283CC engine.

Carlos.

[diesel53]

Sorry to disagree; 50-60HP on an OEM 68.50MM bore on Race Fuel (Methanol is much easier to achieve 60HP) even with a 77MM crank is a big deal. Now, if you find one for those Dyno's or Builders that will tell you what you want to hear, and give you inflated numbers tthen that is a different story. On a conservative Dyno, getting to 52-54HP on an 68.50MM OEM cylinder that is NOT a dedicated Drag engine is a very good accomplishment. The OEM stock Jug will support the 77MM crank, the TRX11 pipe is not the pipe to use with an OEM cylinder at 68.50MM...way too much Pipe volume for a 283CC engine.

Carlos.

Thanks carlos, good info. Do you know the exact dimensions of the cylinder?? Agreed on the pipe..

[Langbolt]

Diesel53: READ THIS

TRX250R on the Dyno - 2 Stroke Engines - Glamis Sand Dunes

This is a highly modified stock jug and only made 53.3HP

Look at how narrow the powerband is....Drag motor

Is this what you want ?

[diesel53]

Diesel53: READ THIS

TRX250R on the Dyno - 2 Stroke Engines - Glamis Sand Dunes

This is a highly modified stock jug and only made 53.3HP

Look at how narrow the powerband is....Drag motor

Is this what you want ?

jug with stock bore and stroke. Thats not what Im talking about and no this is not a drag only bike

[acecarlos]

Thanks carlos, good info. Do you know the exact dimensions of the cylinder?? Agreed on the pipe..

I just took your post stating 68.5MM bore x 77MM stroke...283CC The cylinder you said was stock, no porting, therefore; it woul support a 77MM stroker crank.

Carlos.