FJ2400 - Bonneville Land Speed Racer

[racerrad8]

That's it. The gearing is something that would have to be calculated. Of you leave the engine and jackshaft input sprockets the same then its still 1:1. Without diving and not knowing desired final drive ration, but I think if you add an 18 to the engine and say a 16 to the jackshaft output sprocket you now have a 1:1.25 ratio.

The jackshaft must be rigid mounted to the frame so the engine chains stay taunt.

I understand the space concern, I would think you can get the jackshaft done for the difference of basically the shaft diameter. Maybe there is space to run the jackshaft between the engines and have a longer chain to the rear wheel.

Just throwing out ideas...

It's going to be interested in how you are going to control the hydraulic clutch.

I'm thinking two throttle cable boxes. One for pull and if a push cable is required one for that as well.

Randy - RPM

[fj1289]

More of my hair-brained jack shaft ideas ...

Fabricate a swingarm that runs on the outside of the frame (kind of similar to the old club man style swing arms).  Use roller bearings to run  the jack shaft concentric with the swing arm pivot (the way some turbine engines run some compressor sections and/or turbine sections on separate concentric shafts).  

I haven't thought much about the multiple throttle cables - interested to see what the "normal" solution is.  

Multiple hydraulic clutches could be a pain in the butt though.  A way around that - if you can find a lock up clutch for the second engine, just install that with no clutch springs on one engine.  Or, even modify it with light springs to keep the pressure plate separated until the centrifugal arms over ride it - slipper clutch style.   This would not normally work with an old-school lockup that relies on the output shaft to drive it - - but with the two output shafts joined by a chain, the second output shaft would be turning with the other engine and would begin to lockup as you gained speed by engaging the hydraulic clutch on the other engine.  

This would require clutchless shifting on that engine.  I assume (always dangerous) that rolling out of the throttle for a clutchless shift is suitable on the salt?

[RPM - Robert]

More of my hair-brained jack shaft ideas ...

Has the smoke gotten so thick in Colorado that everyone getting a contact high...

[freakhousecustoms]

HAHAHA!!!
It's funny because it's true!



I just drove back from Commerce City and I swear you can get a contact high just driving around with the windows up!

[freakhousecustoms]

Getting Artsy with the camera:

[freakhousecustoms]

Some fun/funny shots:

#1:  Serially... what have I gotten myself into?!?



#2: Lined up and looking pretty ok, if I do say so myself. 

[racerrad8]

Since you are going to build a custom frame, you can definitely get away with using half of the factory engine mounting points. You can eliminate the top rear mount and you can move the front engine back at lease 3-4 inches. That way you can get the top back edge of the front engine back to the headers of the second engine.

Randy - RPM

[giantkiller]

Even farther if he just runs the exhaust on the back engine out the sides.

[freakhousecustoms]

Since you are going to build a custom frame, you can definitely get away with using half of the factory engine mounting points. You can eliminate the top rear mount and you can move the front engine back at lease 3-4 inches. That way you can get the top back edge of the front engine back to the headers of the second engine.

Not only that, but I can take out about another 3" from where the neck extends out on the factory frame.  I can get it so the forks are closer to the engine/headers by moving the neck "back".

[fj1289]

Since you are going to build a custom frame, you can definitely get away with using half of the factory engine mounting points. You can eliminate the top rear mount and you can move the front engine back at lease 3-4 inches. That way you can get the top back edge of the front engine back to the headers of the second engine.

Not only that, but I can take out about another 3" from where the neck extends out on the factory frame.  I can get it so the forks are closer to the engine/headers by moving the neck "back".

If you lower the forks, you aren't going to have nearly as much space between the front tire and header as you think.  And you can lower it quite a bit - especially if you go with a side exit exhaust. 

I lowered the drag bike enough I had to cut and re-weld the sidewinder headers to gain an inch or so clearance.  I also reduced the triple clamp offset 10mm so that decreased clearance too (but increased trail).

[freakhousecustoms]

If you lower the forks, you aren't going to have nearly as much space between the front tire and header as you think.  And you can lower it quite a bit - especially if you go with a side exit exhaust. 

Oh no sir, I do not mean LOWER, just move backwards, towards the rider.  If you at where the neck sits in the frame, you can move it backwards, on the horizontal plane keeping the same rake and trail.  Since I'm already effecting the wheelbase (dramatically), getting back a few inches this way shouldn't really change anything in my world, except to make it easier for me to reach the handlebars.

[fj1289]

If you lower the forks, you aren't going to have nearly as much space between the front tire and header as you think.  And you can lower it quite a bit - especially if you go with a side exit exhaust. 

Oh no sir, I do not mean LOWER, just move backwards, towards the rider.  If you at where the neck sits in the frame, you can move it backwards, on the horizontal plane keeping the same rake and trail.  Since I'm already effecting the wheelbase (dramatically), getting back a few inches this way shouldn't really change anything in my world, except to make it easier for me to reach the handlebars.

I just assumed you would be shortening the forks to lower the bike to give a smaller front profile and reduce drag.  That moves the front tire not just up, but also back.   I think you may end up with about the same wheel position as you are looking for, but without the frame fabrication.   I know the salt gets rough.  Is three inches the specified minimum ground clearance?  Is that enough for most salt conditions?

[freakhousecustoms]

As with every other thing in any form of racing, there are many (MANY) different approaches and many (MANY) different camps.  The thing I enjoy the most is the diversity of the builds when I get to the Salt Flats.  You could spend the entire week just sitting and staring at the bikes and all the different ways folks have chosen to build them.

My, personal, philosophy - at this time (because it's ever-evolving as I grow and learn), is a variation of the K.I.S.S. principle, my version is:

Keep It Simple (Because I'm) Stupid

So that means, while I am building my own custom frame from scratch, both engines will be pretty much stock, front suspension will be stock (with the addition of HD springs) and the rear suspension will use the stock rear shock & spring... just TWO of them. LOL.  For me, and again, this is just MY approach, the "stock" ride height looks pretty good right now.  I've got 2 4x4's holding the bike up... so that's about 7" of ground clearance - I'd be happy with 6-7".  Would it be better if I was lower?  Probably.  But when I look at guys running bone-stock Hayabusa and going FASTER than my target speed, I think I'm pretty ok.  I mean, look how high Mr. Elrod was when he SET the record! LOL!



But yes, to answer your question, 3" is plenty for the Salt, again - some guy run even less.
In fact, my buddy Marc doesn't run any front suspension at all:



He's the current 2000-A-AG record holder at 203.740mph 

[fj1289]

That looks like an evolution of one of the bikes from "Out of Nothing".  Very cool build.  I'll be studying the front steering for a while trying to figure it out!

I also had assumed (once again proving dangerous!) you were going to essentially splice together the front of one frame with the rear of the other with a bit of distance and a lot of structure added.  Building your own frame from scratch opens up a lot of possibilities!  Very cool!

[racerrad8]

What class will you be running in and what's the record?

Randy - RPM