XC Setup Questions

[quadmad]

Setting my R up for Cross Country and have some questions.

What is the best gearing with a 20" Rear tres ?
With the sprockets Alloy or steel the best?
What is the best size carby to run, it's a CT310 non pv motor currently running a 40mm carby.

[FL-R]

I run 13-39, steel sprocket, I eat aluminum ones up to much, And a smaller Carb helps in the woods, but with a 310 I'd run a 38a/s

[quadmad]

What size rear tyre are you running?

[FL-R]

20" razrs. Xc is all about suspension. And a good reliable and rideable motor. A Nice smooth power band so it doesn't tire you out.

[tbone250r]

Originally posted by FL-R
20" razrs. Xc is all about suspension. And a good reliable and rideable motor. A Nice smooth power band so it doesn't tire you out.

100% agreed with FL-R.

Steel sprockets, I run 21" GBC X-REX up front and 20" in the back. I actually don't even know my gearing right now.

Suspension is king in the woods. And not just slapping on good suspension, having them properly sprung and valved for your weight and riding condition is even more important.

Smooth, predictable power is the key to a good woods motor. You'll be worn out after half a lap if your motor is jerking you all around the trails. 40mm carb is probably too big. You gain good top-end for that motor but bottom end and throttle response is probably sacrificed.

Check out the Andy Lagzdin build thread here, you can really learn a lot from the way he sets his quad up for GNCC's.

Andy Lagzdin's build thread (http://www.exriders.com/vbb/showthread.php?s=&threadid=381413)

[quadmad]

Got my 20" razrs today, ordered chain and sprockets, thinking about taking off the a arms +1 and Works shocks and moving to to Fox shocks and a arms that will work with the Fox shocks.

Thinking about the CR ignition also. Is it worth the bucks?

[FL-R]

I'm running +2 max ground clearance arms, with pep shocks and Douglas shamrock beadlocks which puts me at 46.5" up front and a. Dominator XC axle and I'm about 45" out back.

[quadmad]

What to best +1 or +2 ?

Who makes the a arms for xc ?

[FL-R]

+2 will be more stable in the high speed stuff, mine are jd performance arms

[Meat]

Don't do the CR ignition for XC. You wanna go the opposite way. Old XC 250R's had flywheel weights on em.

[tbone250r]

I wouldn't hesitate to put the CR ignition on. I'm currently looking for one on my XC bike. Laz @ GTThunder recommends one for added reliability, and even though the flywheel is heavier the performance of the new ignition more than makes up for it.

[Meat]

I thought the flywheels on the CR setup are lighter than stock. And the stock ignition setup is very reliable.

[tbone250r]

Yes the CR ignition's flywheel is lighter, but the added performance of the ignition itself makes up for it.

All these trx ignition components can only be as new as the last date that Honda discontinued them. Having brand new CR ignition parts gives good piece of mind.

[Meat]

"but the added performance of the ignition itself makes up for it." I disagree. But before I ramble on with my reply, I wanna make it clear that I have never run the CR setup and that I know some stuff about the CR setup, but I could have the wrong idea about the CR and I'd like to learn more about the added performance gains from the ignition.

So, from what I understand, the CR setup does two things... it gives ya a stronger spark and it allows the engine to rev faster because of the very small & light flywheel.

The stronger spark produced by the CR is comparable to products that companies like Dyna-tek sell. Aftermarket CDI, stators and coils.
Now I know plenty of guys, myself included, that have done ignition mods(on Banshees) and really couldn't tell much difference between the different ignition curves. I had a setup with the handlebar mounted switch where you could switch between two ignition curves. The difference between the two curves was negligible. The difference between the two curves compared to the stock ignition curve is also negligible, altho I do think I that I could feel perhaps some power gain, it was very small.

The lighter CR flywheel. This is where you guys are feeling the performance difference. It should make your motor feel like a fresh new one. The motor will rev faster. This is where the physics comes in... Just so everyone is clear, a lighter or heavier flywheel will not give or take away horsepower, they just change the shape of the power curve. With the CR setup, the RPM's will increase faster because of less rotating mass on the crank, while on the same note... the RPM's will decrease faster because of the lower rotating mass on the crank. A faster revving motor will get though its power curve faster and hit those higher HP numbers faster than a slow revving motor. The opposite is true for putting more mass on the crankshaft. The power curve will be broader than a CR flwheel's power curve. Now here's where the opinion comes in... I believe that a faster revving motor is not the best setup for a quad running a cross country race. I believe the idea is to setup a XC based motor to be smooth. We don't want our quads to have that high strung "light switch" type of power curve that a freer revving motor will produce. This is part of the reason why the new 450's are easier to race XC compared to a two stroke, you can lug em around the track. This is the reason why 2 stroke guys ran flywheel weights when XC racing. This is the reason why even the new 450 guys use flywheel weights for XC racing. Installing a CR flywheel is going the opposite direction of what we want from an XC motor. We want tractable power. Smooth, "get you out of the mudhole and then straight up a big hill", kinda power. Power that is not going tire you out doing a two hour XC race. There are MANY times during a XC race where you're racing in a single file line, with 30 guys in front of you and 50 guys right behind you, so there is a lot of stopping because of bottlenecks. Again, I believe this is harder to do on a high strung, fast revving motor. Now I can see XC style porting work done to compliment a CR flywheel.


The CR ignition mod seems much better suited for a motocross quad.




I could be wrong...

[fx4pitrone]

I believe there are some that do the CR ig. upgrade and add weights to the CR flywheel

[Meat]

Originally posted by fx4pitrone
I believe there are some that do the CR ig. upgrade and add weights to the CR flywheel

I learn something new everyday. Good reply.

[deathman53]

you can get the cr flywheel in a heavier weight and then add weight to it if you want. I seen them for sale, don't remember where. I have cr ignitions and love them, coupled with a pv 295 "310" cylinder, fiber reeds and mid range pipe it pulls from bottom to top easily.

[tbone250r]

Meat I agree with everything you said about changing the power curve, not total HP. As well as wanting a smooth controllable power delivery rather than fast and hard hitting for XC riding.

I just think the added performance upgrade of the ignition itself would make the power curve better in every way. And if you can add a flywheel weight to that CR ignition I suppose it could be even better.

Laz @ GTThunder strongly urged me to put in a CR ignition when I talked to him about what he would do to my motor. Maybe i'll pick his brain about why he so strongly suggested that.

[quadmad]

Back to the A arms, 1 inch or 2 inch wider ?

[tbone250r]

What rims are you running? And is it a stock frame?

[quadmad]

Stock off set with stock frame. I brought Fox long travel shocks so all I need to do is pick what a arms.

Making a choice for Arms has been harder than I thought it would be.

[quadmad]

Does anyone no if Houser make there xc long travel with caster adjust for the 250r ?

they look really good

http://www.houser-racing.com/products/category/atv-a-arms/long-travel-a-arms/cross-country-width

[killer_yfz]

Houser doesn't offer any new stuff for the R. If you want that style castor adjustment Laeger offers it on their new arms.

[deathman53]

you know that the a-arms have to match the length of the shocks you buy also. Different a-arms use different length shocks, also the valving can be quite specific to a-arms. Measure the shocks you bought and that will help you with what a-arms to buy. After you get a-arms to match the length of shocks you have, then get them re-valved to match the leverage ratio of the a-arms. There is alot more to GOOD suspension than getting a-arms and any set of shocks. As others here said, long travel, really long body shocks can vary between 19" to as long as 22". Spend the time to get the matching stuff and get it working right together, you will like it alot more in the end.

[FL-R]

Call jd performance, he built me a set of +2 arms, +0 forward, and the Max ground clearance ones for 750$ with the upgraded bearings,

[FL-R]

Old pic.

[sameltoe]

I use +4+1 on +1 arms an love it, I too have a cr ign on my xc quad and dont have any problems lugging it around or hitting the tight sections , but I also have a 340pv... I was too worried about the smaller flywheel and thought about weights but haven't seen a "need" for it.

Fl-r thats a beauty of a quad! And Dave makes an awesome set of arms!

[FL-R]

Thanks, I'm running 4:1 shamrock beadlocks up front, which are actually 1/4"-1/2" narrower then any other 4:1 rims.

[quadmad]

Wow! This is great, this is what these forums are all about helping others.
Sounds like Dave at JP Perormance is worth talking to.

Thanks for all your input guys.

[FL-R]

No problem. And +1 or +2 all depends on your riding. Some states are more wooded and tight trees, and some are more open spaced trees, our xc series here in Fl run 50" wide cut trails and some wide open runs and jumps, so I went with +2 arms for alittle more stability and I can still play around on a mx track if I'm feeling froggy.