modern board track racer, special design by me

[JohThomas Sorrels]

if i move wheel where my shocks are, would that put me at zero trail

I'm not sure what you mean by this but if you are suggesting that you'd take off the suspension from the fork and mount the tire back directly to the fork, that will help, it may even give you positive trail. Just to make sure, zero trail is still not desirable for your application, you want positive trail. On my motor bike I have about 4", you should at the very least shoot for 2" of positive trail.

 

[JohThomas Sorrels]

Below is a drawing I made while designing my bike that will better illustrate trail, if you look below the front wheel there is a dimension of 5 1/4" that is my positive trail measurement between the line going straight down from my axle to the dotted line running through the center of my head tube. My actual dimensions are a little off from this drawing but are close and I still have about 4"- 5" of positive trail. The head tube angle has a direct relationship with the amount of rake built into a fork, you can have a near vertical head tube as long as your fork angles back to create trail. In your case your fork has a ton of rake with the suspension so you need a very angled head tube to compensate.

 

[jj256]

I need my front suspension where I live has bumps and stuff in the road and I don't want to bend up my.wheel

 

[JohThomas Sorrels]

I need my front suspension where I live has bumps and stuff in the road and I don't want to bend up my.wheel

That's understandable, it's good to have some suspension if you are going to ride at the speed your motor will be capable of. However, you don't need as much travel as you have on your fork, your suspension arms (the two tabs that go from the bottom of the fork to the wheel axle) don't need to be as long as they are. I made a real rough chop of what I'd suggest you do, obviously you'll still need to lean the head tube back (indicated in green). I drew a straight fork with a lot shorter suspension arms in red and also put in construction lines of where your trail would be after all of this...

 

[jj256]

I'm going to redo my front end

 

[iven]

Screw it I'm going to redo my front end

maybe if you flipped the fork around and welded similar mounts back on it?
i donno im not thinking with math right now but could work..

i know what its like, i live near ghetto areas right now.. and the streets suck.. like the past month or two every road i take they are tearing up and messing it up again.. bumps everywhere.. i like springer forks more then for the style i kinda really need them... :|
this one crappy road i usually have to take home is really bumpy and half the time cars run you off the road and theres no sidewalk or anything,.. just dirt,gravle and muck.. potholes everywhere..
dont feel good... :x err

 

[jj256]

I live on a main road and theres hills and bumps all over the place

 

[jj256]

I may think I have zero trail or 1/2 inch of negative trail:

 

[jj256]

update pictures, the drive train:

 

[harry76]

Im fairly certain your gearing is too high, your primary jackshaft sprocket should be smaller then the engine pulley, they appear to be the same size which means you are relying only on your secondary drive for reduction.

A bigger primary jackshaft sprocket (and possibly smaller secondary jackshaft pulley) should do the trick.

 

[jj256]

its a 12 tooth sprocket on my clutch and a 15 tooth sprocket on the jack shaft for higher gearing on purpose and the a medium size pulley for a reason: high power speeds at a low rpm

 

[Beau]

He just doesn't want to listen... :shock:

 

[harry76]

its a 12 tooth sprocket on my clutch and a 15 tooth sprocket on the jack shaft for higher gearing on purpose and the a medium size pulley for a reason: high power speeds at a low rpm

What you are saying doesn't make sense, yes CORRECT your bike is setup for high speeds at a low RPM. I'm just wondering who will drive your tow vehicle everytime you need to take off

 

[harry76]

He just doesn't want to listen... :shock:

I noticed you were giving him advice that could save his life, he seems to just ignore it????

Oh well, we tried!!!!!!

 

[jj256]

Well my bad if it seems if Im being arrogant or disrespectful but I'm low on money and built this thing from nothing if I had the money it would fix all the bugs in the bike but I dont

 

[harry76]

Well my bad if it seems if Im being arrogant or disrespectful but I'm low on money and built this thing from nothing if I had the money it would fix all the bugs in the bike but I dont

My bike was built on a shoestring budget also, but I still took time and listened to some good advice and I now have a bike that has been safe and trouble free. I don't want to talk for Beau but I'm fairly certain he built his bike on a budget also. And generally fixing mistakes will cost you more in time then money, it's up to you though. If you don't fix these things they could come back to bite you in the ass later on.

 

[jj256]

OK cool I have fixed my front end thanks to beau and ill try to get another sprocket

 

[Beau]

The only way to fix that thing is start over.

The sprocket won't help much. Your jack shaft is going to bend or break off sticking that far out. Mine was only about 4" out and I had problems. I just used 3/4" bar, and it wasn't hardened (it should be).

The fork and headtube are still way off.

The rear end is not strong enough, and the pogo stick out back isn't going to help anything.

Buy a Mini bike frame and build it up!

 

[jj256]

Pogo stick? I took the shock out as you suggested. I wish I could start over but that's out

 

[Beau]

If you were closer I'd help you out.

I'm not trying to bust your balls, but you are building a motorcycle, not a bicycle.