XS650 With Big Twin Transmission? 6 Speed?

[pa-powerstroke]

Many guys think that the close ratio transmission in the XS is a huge problem. Im planning on taking my build on longer highway trips and dont want the rpms through the roof so I decided to re-sprocket. Many guys try the Mikes overdrive 5th. But I was looking for other options, a transmission from other yamahas of the same period that would possibly fit with minor machining or someone to make a 6 speed, this would be the best in my opinion and I know someone out there has the tools and skill to do it. The last option I was brainstorming was a big twin tranny behind a cut down XS engine. Ive seen the transmissions removed on dual engine XS race bikes, any way to make this possible?

 

[racerdave]

Sure all it takes is a big pile of $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

 

[Growl]

I have wondered the same thing. There are a lot of Harley Big Twin trannys out there... with good parts support. Even the 4 speed and 5 speed trannys are wide ratio - which is a beautiful thing. They are not cheap exactly but what's the alternative? They are however strong, long lasting and rebuildable.

How to adapt to the XS 650? It would be complicated. The frame would have to be lengthened also... chopper...

If you cut and weld the engine, which I have seen done on Japanese engines in 2 engine drag bikes... you still have the issue of the drive off the crank being by gear on the right side and the Harley tranny is looking for chain drive on the left side... and then you need a clutch.

Maybe you could keep the engine cases intact, use the XS650 clutch and simplify the internals of the XS650 tranny to get a drive output on the existing output shaft to drive the Tranny via chain.

Then you would need an even longer frame.

 

[pa-powerstroke]

I have wondered the same thing. There are a lot of Harley Big Twin trannys out there... with good parts support. Even the 4 speed and 5 speed trannys are wide ratio - which is a beautiful thing. They are not cheap exactly but what's the alternative? They are however strong, long lasting and rebuildable.

How to adapt to the XS 650? It would be complicated. The frame would have to be lengthened also... chopper...

If you cut and weld the engine, which I have seen done on Japanese engines in 2 engine drag bikes... you still have the issue of the drive off the crank being by gear on the right side and the Harley tranny is looking for chain drive on the left side... and then you need a clutch.

Maybe you could keep the engine cases intact, use the XS650 clutch and simplify the internals of the XS650 tranny to get a drive output on the existing output shaft to drive the Tranny via chain.

Then you would need an even longer frame.

I thought about running a sprocket off the left side of the crank like I have seen one twin engine xs's but then comes the problem of how to make a spark, where will the power come from.

 

[jbenedict]

For starters, you would have to cut the transmission off the XS and weld something over the hole and then do something to allow for the loss of the oil capacity. Then, take the rotor and stator off and adapt a Harley front pulley. The clutch would be easy. Use the Harley clutch. You could rig up a generator/alternator system to run off the crank on that side because the clutch is gone. Iggy is already running from the cam so no problem there. It would probably easiest to get a Harley frame and mount the XS motor in front of the Harley trans which would be on the mounts on the frame.

Back in the days of pre-unit Truimphs, BSAs and Nortons, transmissions could be swapped around at will. A popular swap was a British transmission behind a WL45. Four speeds worked much better than three. If you want to do this just because you want to do it, nothing wrong with that. It seems like a lot of trouble for what you want out of it.


If you want to change the ratios around, a taller 5th gear is available. If you *really* want to change 'em around, talk to these guys (and bring your checkbook),

http://www.novaracing.co.uk

 

[TwoManyXS1Bs]

Have you looked in here?

http://www.xs650.com/forum/showthread.php?t=20073

 

[chizler62]

Jackshaft?

Posted via Mobile

 

[MacMcMacmac]

Jackshaft through the hole left from pulling the starter?

 

[member3480]

Years ago I was on a project that was two CB750 motors as a drag bike with 2 speed trans. What a nightmare and it was tough getting both motors to run together and the leaks from stress cracks where the back of the motors were welded was a on going thing. The metal that was used on these cases is not easy to weld . You got to be very good and slow. Trans we used was just a two speed made up with a high and low gear. Sprockets were setup on end of crank that went from one motor to another and double sprocket on rear motor to trans. That was easy because there was no charging system. Bike was a DUD and never ran the times the owner wanted but it did look cool.
If there was a single gear (HIGH) in the trans you may be able to go off that sprocket to sprocket but I really don't think the time and money is worth the effort. Tons of machine work here so have deep pockets....

 

[crashcourse]

Another option (not really practical, but this is a brainstorm) - if you could find the guts of a six speed from something smaller (XS400 is a six speed, isn't it?) and just stuff them into the existing case. If the gears are narrower you can fit more of them in a given space. But unless the metal is better quality your gears will be proportionally weaker. Not sure what the ratios are though, so even if it could be made to work you may not get what you want.

Finally, you could always engineer your own transmission. How hard could it be? Answer: really hard. But you would learn a lot.

 

[jbenedict]

Have you looked in here?

http://www.xs650.com/forum/showthread.php?t=20073

Nova makes that sort of stuff. They don't have one for the XS at this time but they develop parts all the time.

http://www.novaracing.co.uk

They also have 6 speed transmissions for CB350s and CB450s which are used in road racing. They do say they will make anything if you can pay for it!

BTW: It is popular to put motorcycle engines in race cars in Europe. Hayabusas and Fireblad Honda and the like. The make a reverser which goes between the engine sprocket and the drive to the rear. When they need to go in reverse, they just put it in reverse. But, since the reverser is after the gearbox, it will go in all 5/6 speeds in reverse. One of these guys got timed in a Caterham 7 going 110 MPH in reverse.

 

[jbenedict]

Years ago I was on a project that was two CB750 motors as a drag bike with 2 speed trans. What a nightmare and it was tough getting both motors to run together and the leaks from stress cracks where the back of the motors were welded was a on going thing. The metal that was used on these cases is not easy to weld . You got to be very good and slow. Trans we used was just a two speed made up with a high and low gear. Sprockets were setup on end of crank that went from one motor to another and double sprocket on rear motor to trans. That was easy because there was no charging system. Bike was a DUD and never ran the times the owner wanted but it did look cool.
If there was a single gear (HIGH) in the trans you may be able to go off that sprocket to sprocket but I really don't think the time and money is worth the effort. Tons of machine work here so have deep pockets....:bang head:

Russ Collins and Vance and Hines had a couple of these which worked really well. They used a Crowerglide clutch and parts of a Lenco transmission. Vance and Hines had a double running on gas and Collins had a triple running on fuel. Both the fastest bikes of their day.