Very fast lawnmower question

I need to know the model of the bike for any better info.
an 80 tooth #50 sprocket is 16.5 inches in diameter. you'ld only have an inch or so clearance under the sprocket.


A jackshaft only takes as much space as the largest sprocket plus a little for chain and guard clearance.

Mine only uses a roughly 5"x 5" area 12" wide, and it could be narrower, I could have used a shorter shaft.

I will do some measuring. I have a good amount of room where the sprocket will go. Thanks for all the help man.

Video of the engine and most of the frame
https://www.youtube.com/watch?v=EUa4rqWrtDI

That an XS400 motor, Should have the electric knee.

Use the XS400 motor speeds I posted above for a rough guess as to your speeds.

Probably another stupid question but would I use a go kart sprocket or a motorcycle sprocket? Or does it not matter? I was just wondering as chain size might differ? I did some measuring and the closest point to my axle is on the back where the hitch goes. I have about 4x3/4 inches of room on one side for a sprocket. The next closest is the bottom where the sprocket might hit the ground which is about 7 inches away. I took a video. Should I go with a 60 tooth or a 75? I found this sprocket on Ebay.
60 tooth= http://www.ebay.com/itm/NIP-Northern-Industrial-Tools-Go-Kart-Drive-Sprocket-60-tooth-35-chain-4-hole-/200855076391?pt=Go_Karts&hash=item2ec3e53e27
80 tooth http://www.ebay.com/itm/GO-KART-HORSTMAN-2-PIECE-SPROCKET-GEAR-80-81-TOOTH-35-CHAIN-CART-PART-/261134349292?pt=Go_Karts&hash=item3cccd1f3ec&vxp=mtr
75 tooth= http://www.ebay.com/itm/75-Tooth-Go-Kart-Sprocket-35-Chain-Sprocket-Go-Kart-Racing-Sprocket-Aluminum-/200847000290?pt=Race_Car_Parts&hash=item2ec36a02e2&vxp=mtr


I also need to know what kind of chain to use? Just any normal motorcycle chain?
Video of me measuring. https://www.youtube.com/watch?v=-oYJbXGLf84

Electric start and kick start?

The sprocket on the engine is a 530 chain, which is the same as #50 chain. 520 chain is the same pitch (5/8") but is narrower and won't fit a #50 sprocket.

You'll have to use a motorcycle sprocket on the engine but any #50 sprocket will do for the rear.

The only way to get the top speed down to 55 or so is with a 90 tooth sprocket on the axle. Unless you go with the jackshaft.

I watched the video and you have ample space for a jackshaft in the tunnel. Another pair of Flanged bearings and a shaft midway between the engine and axle would be adequate.

Also since your tire is only about 16" tall, the biggest sprocket you could go with is a 70 tooth.

With a 16 tooth stock front and a 70 tooth rear and no jackshaft, you will see approximately 85 mph in 4th gear, I'm sure thats a six speed engine with 5th and sixth being overdrive gears, so your top end would probably be closer to 110mph

Remember that engine stock put out 38 hp @ 8800 rpm

I used this calculator http://www.compgoparts.com/TechnicalResources/SprocketCalculator.asp

Is there a number on the engine?

I am scared if I toss a Jackshaft I will not have room for my shifter set up, electronics, and exhaust. I also wanted to keep the engine close to the middle of the tractor as possible to balance the weight. What size sprocket did the stock motorcycle have on it? I am not going to be pulling with the tractor I am just going to use it to ride around so as long as it wont stall out every time I go to take off.

The numbers I found were 2LO-O11219

CraftsMAN wrote:

I am scared if I toss a Jackshaft I will not have room for my shifter set up, electronics, and exhaust. I also wanted to keep the engine close to the middle of the tractor as possible to balance the weight. What size sprocket did the stock motorcycle have on it? I am not going to be pulling with the tractor I am just going to use it to ride around so as long as it wont stall out every time I go to take off.

The stock bike had a 38 on the back IIRC, and a top speed of 105

That number shows up as eaither a 78 xs400E, or a 79 XS400F

The E/F models had a electric start and 13 Amp charging system. Take note that this engine will probably NOT run without a battery. Check the XS400 forums for more info on electrical mods etc

So that 60 tooth sprocket would be ok? Or which one should I go with?

Would this sprocket work? http://www.ebay.com/itm/RLV-HARD-ANODIZED-GO-KART-SPROCKET-219-CHAIN-70-TOOTH-/200375336601?pt=Race_Car_Parts&hash=item2ea74cfe99&vxp=mtr

Gp tith the Biggest #50 sprocket you can get

I have been looking on ebay but cant find the right sprocket. Can you recommend a website? Or a sprocket that will work? If the sprocket does not give me enough low end then I will install a jackshaft. Your help is very appreciated.

whats your axle size?

1x32 inch.

I found a 70 tooth sprocket but am unsure about fitment. Check it out and let me know what you think..
http://www.ebay.com/itm/281031482464?item=281031482464&viewitem=&vxp=mtr

you are better off finding a #50 sprocket with a 1" keyed hub. The misery of trying to adapt a bike sprocket isn't worth it.

Check out www.princessauto.com.

I picked up an adapter for it.

Sorry bud. Sl70 used #420 chain, or narrow @40 chain, That sprocket is a different pitch than your engine.

What about this sprocket?
http://www.ebay.com/itm/50B60-NEW-60-TOOTH-SPROCKET-FOR-50-CHAIN-50-B-60-/290703279945?pt=LH_DefaultDomain_0&hash=item43af440749

The size tooth count and pitch are good, just need to make sure it has a 1" bore. The one in the pictur looks like a 2 inch
It may be possible to get an adapter sleeve to mate the two.

So I had a 60 tooth sprocket and it was WAY to big. Holy cow. So I am looking at a 40 tooth one. I figured with gears I will still have good low end..

40 tooth is not much bigger than a stock sprocket, but your tires are shorter so it will help some.

You won't have a real pulling gear, but it should pull OK