Land Speed XS400

[aaronxs400]

Figured I would go ahead and get the the thread started for my summer/fall build. This will be my first solo build, and my first frame build. The bike will run in the ECTA here in the Altered OHC Twin 400 classes, the races are now ran here in Ohio. My personal goal is 115mph unfaired, 120mph with a fairing. The debate right now is SOHC Xs400 powerplant or DOHC xs400 power plant. I have both, so I am now just trying to decide what I want to run. Im not sure if there is that much of a power difference between the two, and when you factor in the 6 speed vs 5 speed and kick/electric start vs. electric only, the SOHC is winning out in my opinion.

The specs should be as follows:

Frame:
Custom Construction
Wheelbase:
64-68"
Rake:
40 Degrees
Weight:
Goal is 225lbs
Front Wheel:
18x2.15 RC Comp Imposter
Rear Wheel:
17x2.5 RC Comp Imposter (originally a front wheel as well)
Forks:
Ceriani or pitbike forks
Brakes:
Single rotor up front with single piston Grimeca caliper, Sproter set up in the rear
Controls:
Clip ons
Fuel Tank:
Small fuel cell
Engine:
XS400 SOHC or XS400 DOHC
Carbs:
Mikuni Roundslides, size to be determined
Exhaust:
?
Misc:
Airshifter, charging system and electric start removed, small LiFePo4 battery

Attached are two images i came up with in paint, not sure if i want to do the vintage drag bike look or something a little more modern.

 

[bentwrench]

DOHC comes in a 6 speed if you get one from a Seca.

Good luck! Post lots!

 

[FUBAR]

im looking forward to see where this will go!

 

[aaronxs400]

i need to find out which one mine is...not real sure!

 

[aaronxs400]

looks like its a seca. I am now leaning towards the seca. It has 6 more cc, 4 points higher compression. However, Megacyle DOES offer a higher lift came for the DOHC. im sure i can get a custom grind from webcams though for the DOHC

 

[xschris]

Very cool! I think you will find that you will get speeds of more than 130mph with the right gearing and striped way down weight, my stock (other than jetting and plugs) 79 2-f has been over 100mph with more to go. Where do you think you will run it? I think the dohc makes like 5hp more than the sohc stock.

 

[aaronxs400]

ECTA which use to run in Maxton NC, is now running Willimington, OH. Thanks for the tips! I think I am going to go with the DOHC.

 

[drewpy]

I think the dohc runs counter weights too, so sups a bit of power.

I'd remove them get the crank welded and re balanced. would also need to widen the crank breather system or you will force oil out of the engine due to the excess pressure!

 

[aaronxs400]

im going to weigh both motors as well. I may be just getting too nit picky about it..

The project is being put on hold, well, kinda. In a week or two ill be paying for my frame jig kit from travis. his kit is way better than what I came up with out of the scrap i had laying around.

 

[aaronxs400]

Small update. So i have a pair of RC Comp drag race wheels. The problem was they are both front wheels, one is a 17 other is 18. Plan is the 17 on the rear, 18 on the front.

Problem with all this was they are both single disc wheels. So i was going to run a "sprotor" set up on the rear and a single front disc. Well, i have stumbled onto a dual disc adapter for the RC Comp wheels. So now the plan is to get the dual disc adapter and use one side for sprocket, other for rotor. I may not even run a front brake as they are not required in land speed racing.

Here is what the wheels look like.

 

[FUBAR]

this is cool, different then alot of others. ill call you Burt Minroe

 

[bcware]

You're going to crush 115 mph. In fact, I suspect my build may be able to come pretty close and it's relatively tame. I need to go for a run and do some math (my tires are over-sized).

 

[xschris]

With no question you will have the fastest xs400 out there!

 

[bentwrench]

Pardon my odd question, but are you running the quarter mile? How far do you have to get up to 115?

 

[bcware]

Trapping 115 mph would be fast for anything, let alone a vintage bike!

 

[drewpy]

get the nitro out

 

[aaronxs400]

Having crewed on a nitro bike before, id love to, but I dont think thats gonna happen!

Ive been out of town this week for work, I hope to post some pictures up here shortly of parts..nothing exciting.

 

[aaronxs400]

ive hit 90mph in the 1/4 mile on a 90% stock bike (parts removed, mac 2 into 1, pod filters). this bike will be ran in the standing mile. im thinking 115 at least

 

[aaronxs400]

also may be planning on supercharging it..more to follow.....

 

[bcware]

If you supercharge it I want to see 130 at least in the standing mile.