125cc motocross engine for BSR

[TJS]

I found a YZ 125 in the local paper. It is an older machine and not water cooled which I think is better for this application (BSR) than water cooled. The owner wants 500.00 for the complete bike (running and rideable). I can take controls and exh. off of it as well. He wants 500.00 for the bike. It is a 1981. What do you think.

I know I have to fabricate a shifter assembly so I can shift this thing with my left foot but I have to make a bell crank or something like that. Any ideas.

Later.


T.J.

[Mike Bean]

I like the idea of having the extra power and gears.You might have to get a shifter sproket instead of the standard go-kart sproket.

The only other problem I would see is your build cost is going to go up a bit. I got my motor new for $189.00

If you don't really have a budget then go for it. I would at least ride the bike a bit before you purchase it to be sure your getting a good running engine.

Now are you going to have to run pre-mix gas? Or does it have oil injection? If you use an oil injection unit you will also need a place to mount it.

Mike

[TJS]

It requires a mix for the gas. Yes I will ride it a little bit if I get it. What is a shifter sprocket (please explain or post a link). I also am thinking of using the front brake off the bike and utilizing it on the rear axle. I know I would need to machine an adapter of some sort but that is no big deal.

Later.

T.J.

[Mike Bean]

Hey T.J.,

A shifter sprocket is (from what I have seen and understand) used on go-karts that have gears like the motorcycle engine. The shifter sprocket I think is thicker and smaller (due to the gears) and will match up to your motor cycle sprocket on your engine.

I came across some of these on the American Power Sports web site at: http://www.apskarting.com/

Mike

[mini me]

hey about the shifter you could weld up a long extension on the stock one and hold it up with a spring. might work? just an idea

[sweav]

Hey Tj go to www.mfgsupply.com. They helped me out on mine. Tell them what you have and what size axle you are going to run. I got a mini hub from them and a 44 tooth 428 sprocket. All I did was told them what I had and they told me the part #s. Great place to deal with, have gotten alot of parts from them. On the shifter it's no biggy, check out rubicons, if I had mine set up I would show you, a couple linkages and your done. The only thing is having to deal with a clutch, a handull to drive in first place then throw a clutch into the mix and also a 2 stroke power band! Just my opinion and opinions are like a-holes, everyone has one.

[RUBICON]

Great idea...I have a 90cc Honda ATV clone on mine...I really wanted a water cooled Kawasaki 90....just for the fabrication challange of a radiator and cooling fan....If you don't find the pics of my shifter..wait!..I'll try to attach one...maybe not great pic but a start...you saw the shifter arm off short ( 2" ) and drill a hole for a linkage...then fab a new shifter forward where you want....link with a rod...look at sport bikes...just like that...as for the clutch...great fun....lean forward and pop it for a short wheelspin....or real torque wheelies in all gears....mine is an auto clutch...when I shift at full throttle the wheels lift in all 3 top gears....and with the nitrous on it carries them farther....

[RUBICON]

Pic of stool ...maybe shifter can be seen

[InsaneSpeed]

I wanted a newer water cooled 125 or 250 for a stool. Once I was the prices those things go for, I picked up a complete 600 minus the radiator for about half the going price of a 250. I put it on another kart b/c I still need to figure out how to make it fit a stool.

[WarPaint]

Hey RUBICON. You have got a nice ride there. I printed out some pics and put them on the shop wall where i work. Everyone there has rode my BSR but yours is a Bat out of hell. Everyone just stops and looks at your pics. If you have video that I could download that would be great. I bet the guys would love to see your BSR run.
Thanks.