[Psyco Diver 69]

Well I have a 1980 Yamaha MX175 laying around cause I blew the tranny after years unpon years of abuse (greatest dirtbike I ever owned by the way) Any ways I was thinking of stuffing a nice 2 cylinder in there and making a cheap club bike or cafe racer. I have the bike down to 215lbs with fuel and oil in the motor so I figure this will make a nice light wieght racer. Anyways The stock wheels are 21" front and 18" rear and I was thinking of changing to smaller wheels and I know I can fit pretty wide tires since theres plenty of clearence for the nobbies it has.I was going to swap a different set of forks so I can have disk brakes up front Heres the basic geometery

caster 60 degrees
trail 4.96" (126mm)
wheel base 53.1" (1350mm)
road clearence 10.4" (265mm)
overall lenght 82.5" (2095mm)
overall height 44.1" (1120mm)

What 2 cylinder motor should I go with. I was looking for something I can find cheap, but makes good power and is still reliable too?

21/m
1980 Honda CB750 Custom
1972 Oldsmobile 442
1985 Oldsmobile Cutlass

 

[Geeto67]

quote:
Well I have a 1980 Yamaha MX175 laying around cause I blew the tranny after years unpon years of abuse (greatest dirtbike I ever owned by the way) Any ways I was thinking of stuffing a nice 2 cylinder in there and making a cheap club bike or cafe racer. I have the bike down to 215lbs with fuel and oil in the motor so I figure this will make a nice light wieght racer. Anyways The stock wheels are 21" front and 18" rear and I was thinking of changing to smaller wheels and I know I can fit pretty wide tires since theres plenty of clearence for the nobbies it has.I was going to swap a different set of forks so I can have disk brakes up front Heres the basic geometery

caster 60 degrees
trail 4.96" (126mm)
wheel base 53.1" (1350mm)
road clearence 10.4" (265mm)
overall lenght 82.5" (2095mm)
overall height 44.1" (1120mm)

What 2 cylinder motor should I go with. I was looking for something I can find cheap, but makes good power and is still reliable too?

21/m
1980 Honda CB750 Custom
1972 Oldsmobile 442
1985 Oldsmobile Cutlass

I vote for a suzuki T500 two stroke motor. Makes about 50 hp with the right tuning, and it is compact in size and light. If you really want to go large, put a kawi triple in there (lots of hill climbers do this with dirt bike frames).

 

[Psyco Diver 69]

I was looking from something in the 4 stroke style, cuase I still have the title to this bike and if the bike is civil enough I may want to run it on the street too. I'm dunno yet, mainly just trying to get ideas, but the suzki motor would be nice, 50hp with a 215-230lb frame would make for a pretty quick bike

21/m
1980 Honda CB750 Custom
1972 Oldsmobile 442
1985 Oldsmobile Cutlass

 

[Swagger]

I've stull got my 1980 YZ400 and another spare engine. Still runs great, just lost interest in dirt biking but I've thought a couple times really hard about turning it into an ultra light 2 stroke roadster. IIRC it goes at about 240lbs and around 55hp with the goodies I've got (pipe, head, carb, reeds etc.)....
It's also got 38mm forks.

Hmmmmm......toss on some 38mm street forks, some clip ons and an 18" disc brake front end with some good street tires and bodywork apropriate to pavement....hmmmmmm

Lead, follow or get out of the way!



**edit for really crappy typing**

Edited by - Swagger on Nov 08 2006 1:40:07 PM

 

[Geeto67]

quote:
I was looking from something in the 4 stroke style, cuase I still have the title to this bike and if the bike is civil enough I may want to run it on the street too. I'm dunno yet, mainly just trying to get ideas, but the suzki motor would be nice, 50hp with a 215-230lb frame would make for a pretty quick bike

21/m
1980 Honda CB750 Custom
1972 Oldsmobile 442
1985 Oldsmobile Cutlass

The T500 is a street bike and is one of the most reliable two strokes to come out of the 70's (yes there were 2 stroke street bikes back in the day) and with stock pipes is pretty quiet. A 4 stroke motor will add a lot of weight to your frame, don;t be surprised if you find yourself in the 300 lbs range quick.

 

[robertob]

I once had a TS400 that someone before me built into a road racer. The steering geometry might be funny - mine had a GS550 swap. The cool thing about dirtbikes-as-roadracers is the ground clearance. You won't scrape anything...

 

[ROSKO]

There are a ton of articles at: www.eurospares.com
I know someone built an XR250 based roadracer, info is on the site somewhere. Also, you may want to subscribe to either the VintageRoadRacing or MotorcycleChassisDesign lists at www.Micapeak.com

Also, in the same vein, there was a KTM LC4 powered RoadRacer for sale on ADVRIDER.COM

Thats all I've got. Good luck, keep us up to date.





BORN TO LURK, FORCED TO WORK.
www.NYCvinMoto.com
www.VinMoto.org

 

[Psyco Diver 69]

my friend let me know about a XS650, its striped down but the wiring harness, the motor and the front end is still there including the disc brake set up. I'm going to check into it this weekend. I wonder what type of power those engines produce. I need to look into local race tracks and see what engine limits they have and stuff like that

22/m
1980 Honda CB750
1972 Oldsmobile 442

 

[robertob]

XS650 engine has a ton of potential. They were (are still?) used by dirt trackers a lot.

 

[texmawby]

and sidecar powerplants too!

tex