Oh no. I adjusted it.

 

Been thinking about this today. If you still have that tensioner, can you make it so that it is pushing down on the chain, instead of pushing up?

Since, you're after speed, what all have you done to shave weight off?

So far I've done the following:
- blob removal
- brake rotor shieds removed
- parking brake removed
- headlight removed
- taillight removed
- removed wiring for lights
- airbox removed
- removed bumper
- aluminum grab bar

Things I would like to do
- make the z400 front spindles work, since they are aluminum
- aluminum handlebars
- replace key switch with tether
- relocate decompression lever somewhere under the fenders and use a smaller cable
- use a better clutch lever assembly that does not have the parking brake setup.

 

I can make it push on whatever I want, but it will still be rubbing and slowing me down. Besides, I don't need it. I have a chain guide.

The engine is 50lbs and the frame is 20lbs. That means there is 250lbs in everthing else. I don't know what else to get rid of and most of that is probably tires.

The biggest things are going to be the things that move the fastest... like the chain and the outside of the tires.

If you're riding at 50mph, the tangental speed of the tire is 50mph relative to the hub, but the hub is moving forward with a velocity of 50mph too, so the top of the tire is moving with a forward velocity of 50+50 = 100mph. It takes a lot of acceleration to get up to 100mph and any little increase in mass is going to require much more force to keep the overall acceleration the same.

It might be easier to think of it like this: If you roll a can of soda across the table with your hand, your hand may be moving at 10mph and the table is moving at 0, so the can is moving at 5mph. You have to move your hand at 10 to get the can to move at 5. You'd have to move your hand pretty dang fast to get the can up to 50 mph in the space of a an arm's length.

That's why I'm a big fan of shaving lugs off my tires. 1lb of tire weight is like 2 or 3lbs of frame weight.

Chain weight and friction play a big part too. If you keep your sprockets small, the chain moves slower. And the smaller the front sprocket, the more leverage it has on all that friction in the chain and the less meaningful the friction is.

Now all those rotating things are out of the way, the rest is just F=ma.

If you have a total weight of 500lbs (quad + rider), which would be 15.54 slugs of mass, and you accelerate up to 50mph in 350ft, then the acceleration is 7.68 ft/s/s. So F = 15.54 x 7.68 = 119.4 lbs

Under full-bore power, your quad can apply 119.4 lbs of force on average which will accelerate your total weight of 500lbs up to 50mph in a distance of 350ft.

So what happens if you shave off 10lbs?

Right, so, 500-10 =490. Which is 490/32.174 = 15.23 slugs

119.4 lbs = 15.23 x a. Then a = 7.84 ft/s/s. By shaving off 10lbs, you can now accelerate .16 ft/s/s faster. Which means instead of going 50mph in 350ft, now you can get up to 50.5 mph. That's barely even significant. So, if you can't find at least 10lbs to remove, its really not even a measureable difference.

 

I had some spare arms laying around, and a little bit of time today.

First question. Does anyone know what model LT250R this lower arm is from? I don't know if it's from the 85-86 models, or the later models where they improved the front suspension. Based on pictures from ebay, I think these are the later model arms.



I cut the ends so that they would fit into my frame as far forward as possible. Then I took a LT250s upper arm and cut it so that it would fit as far back as possible. Here is the result.


Camber is a lot closer to 0 then it is with the stock setup. Although it's difficult to say for certain, since the quad is not sitting level. The other side is just a little higher so it's leaning just a little.


The big change is there is now a lot more positive caster. I assume that is a good thing.

I like this setup a little bit better than what I have seen with using the LT250S arms. Those arms do not have replaceable lower balljoints and these do. These arms will require some adjustment of the shock mounts though.

 

Not to change the subject. I just found out how bad the stock timing chain tensionor is. I just rebuilt an 85 Lt230. Have the jug bored .5mm over. Used stock crank and cam. On start up I was getting alot of timing chain smack/lash. So I was looking at buying a manual one. They don't have one that fits(as far as I found). So I made one out of the stock timing chain tensionor. If you want pics and the few steps to make stop this issue let me know. I also have a widening kit. Bolt on tat I have been making.

 

Show us what you've done. Both the tensioner and the widening kit.

 

Got some more time in the garage tonight.

I had previously purchased a swingarm from a '90 quadsport, which is about 1" longer than the stock one.


Got it installed easily enough.


I've decided that I'm going to change the color scheme, which sucks because I should also change the color of this swingarm. But it's already coated, and since P/C is so ridiculously hard to get off, it's going to stay this color.

I'm going to get orange fenders, keep the frame blue, and coat the front arms and hubs orange. This swingarm will probably be the only grey piece left.

I also found that I need to grind away a little more of the upper spring mount to allow that raptor shock to rotate freely. Right now, when the spring compresses it rotates into the upper mount. I only need to remove a little bit of material to fix this though.

 

I can never remember what is positive and negative caster/camber. But the camber you have going on, I don't like. I had that for a while too and I prefer the wheel tilted the other way some... or just perfectly plum.

About the caster, I like it so when I'm going forward, the wheels center themselves automatically. Usually they come from the factory that way and when you lower the back, the caster gets even more so. Mine is so bad, it takes a fair bit of arm strength to turn. I need to dial it back some, but its a lot of work.

It looks like you just need longer front shocks and you'll have the arm angle where it needs to be.

 

In the picture there is just a little positive camber, and I will be getting rid of that. It should only take a few washers on the lower arm to deal with that. Or maybe switch to the 250s steering knuckle, but I think that will go too far in the other direction.

 

You could be right