450 Speed/What Am I Missing?

First off I know the 450 is "SLOW". But I've spent a small stack of bills to try and get from the flats to the trails a little faster. Here is a quick run down of what I've done to try and make that happen. Hot Rod Sheave; tried 10 & 12gr, greaseless/greased OD weights, 12gr performs best. OEM & Blue spring on secondary; both perform about equal on top-end, Blue spins the tires better on low-end. Left the Blue spring on. Dyna CDI with Iridium spark plug, K&N Air; still only hits 37-38 mph on the flats. Pulled the wet clutch, clutch shoes look good, plenty of pad, and doesn't look like it's slipping. Serviced, old spark plug looked good, so I didn't adjust the carb any when I installed the Iridium plug. the next thing I can think of is to check into the carb jetting. The bike has been ran in high altitudes since new so I just assumed it was jetted right, It doesn't seem to run or idle like there is a problem with carburation; the altitude I ride at is from 5k - 8k feet. I'm in no way a mechanic but I think this bike should hit 42+ mph, so does James. Any ideas from you Rhino Bros would be great. The mods and additional parts I've add to this bike are listed in my signature. Thanks in advance. Let-Em Buck. I'm all ears.

Kenny, You may need to open it up and let it breath a little more.(exhaust and or intake mods). An A/F gauge would tell You a whole lot on what Your carb is doing. If You don't want to do exhaust, You could add a tip. I put one on my 660 and I hit the rev limiter a little better.

Larry, when you say intake mods, what are you thinking? I've thought about a tip and looked at exhaust but was to wild about the additional noise, tip would be okay.

Not real familiar with the 450 intake, but I think its similar to the 660. On the 660 it's common to take the short factory snorkel off or replace with a bigger inside diameter. You can also run with no lid(use adapter) or You can go to an open style intake. All of these allow for more air, thus more horses.

Thanks Partner, I'll look into that. Add more intake and a tip would require re-jetting of the carb, right?

Most likely !

let 'em buck, kenny!
my stock li'l fo-fitty hit 42 when i first bought it. now it only hits about 37.
until you dump more fuel and air into it you're not gonna get a whole lot more speed. a cam would allow you to get more mechanical efficiency out of your motor, but you would also need to get a more open exhaust and do some more tuning to maximize a cam change.
if the cdi is tuneable you could try and give it more advance.
a lot of people will laugh, but premium fuel will give you a little more oomph for relatively little money.
i spent over 5 grand building up a harley motor and wasn't satisfied until i spent over 7 grand more for a 40% bigger motor.
"there's no replacement for displacement"

Thanks for your input 08/450; I'm thinking more air down the throat and a bigger dump out the back-end. I roll with premium only. Didn't get all jacked-up until I found a bunch of Rhino junkies. Now the old turd just isn't the same.

i have a air fuel gauge you can borrow to tune

With that KN and at the elevation you may need to rejet anyways. Jets are relatively cheap to buy. With James A/F guage you could experiment a little and see what you get. You can see in my signature what I'm currently using. I hit 37 mph with a plexiglass windsheild, cage extensioon and rear seats in mine. I figure I may be able to hit 40 if I got rid of those things. 40 to me is fast enough trail riding. I would rather speed up the time it takes to get to 40. That's why I was looking at a cam.

I think the 27s are hurting you. I had 26" mudlite XLs on itp wheels on my 450, it ran 43 on flat paved road. I had Hot Rod sheave with I believe 12 gram ODs and a blue spring with no other mods. Didn't have a cdi in it, I didn't think it would have the power to pull more on top end with it as long as I had 26s on it. After the clutch work, it would run better everywhere than it did all stock with stock tires.
That 43 was done with 190# driver and no windshield. I was going to try a cam in it, then I got the $5k trade-in offer on the new 700, so I said goodby to it.

Hump wrote:

I think the 27s are hurting you. I had 26" mudlite XLs on itp wheels on my 450, it ran 43 on flat paved road. I had Hot Rod sheave with I believe 12 gram ODs and a blue spring with no other mods. Didn't have a cdi in it, I didn't think it would have the power to pull more on top end with it as long as I had 26s on it. After the clutch work, it would run better everywhere than it did all stock with stock tires.
That 43 was done with 190# driver and no windshield. I was going to try a cam in it, then I got the $5k trade-in offer on the new 700, so I said goodby to it.

I seen a local dealer here that was offering a 2012 700 for $9800. If I thought they would give a trade in of $5000 I would look hard at it.

I agree the 27's are probably a bit heavy for the 450. I've already decided the next new set of rubbers will more than likely be sized down. On top of that I'm run 32oz of High Lifter tire sealant in each rubber, that probably adds another 3+ lbs per wheel.

Does windshield very much affect on speed ?

I pulled the shield off thinking it might and only seen about 1 mph difference.

On these 1 mph is a good gain. They just aren't built for speed.

0 to 40 is where its at for me

I agree. I want to work on getting it to pull as hard as it can up to that 40.

I have James A/F Meter coming, guess I'll find out whatzzzzup with the turd. Let-Em Buck; lets go riding!!

While prepping for the A/F meter, I've stripped the complete back of the bike off, (bed, cage, rear bumper) took it out for a spin. It had a quicker response up to about 33 mph, then just planed off. Guess I thought there would be more there with that much weight removed. Got the exhuast off today and down to the muffler shop to weld in the bung. Hope the 15" of snow melts down enough to try and tune it in this weekend.

Sprung weight (cargo, cage, passenger, etc), doesn't hurt you near as bad as unsprung weight, (wheels and tires). Spinning that extra weight and adding taller tires making it geared higher really kills us.

If you had some short 26" light tires to throw on there you would see a gain. I had 25" Mudlite XLs on aluminum stock grizzly wheels, then went to the same tire in a 26" with itp wheels. It killed my 450. I wish I had still owned the 25s when I got the sheave. Tire size and weight is a huge trade off. After all the tires/wheels I've had on atvs and utvs, I've decided to run a tall 25 or short 26. Lightest radial I can get. If I ever want big tires, I'm going to go all out and get 29s or 30s.

That's good info to know, thanks.

Well, after being bull-headed and thinking there was more piss-n-vinegar in this 450 than there is, I'm satisfied with the ole girl for putting up with my dumbass, rough ridin attitide. She took it well and came out smellin like a rose. She'll still only run 38-39 on the flats, but she gets to the middle 30's in a hurry; compared to what she was doin. After opening up the air intake and exhaust, I end-up dropping the main jet 10 points, played with the needle jet some and might still go in and drill out the slide for a little more fuel throughout the low-mid throttle response. But she is what she is and by dang I found peace with it. Want to thank the JBS crew for their support and you Rhino Nuts that shared your advice. "Let-Em Buck"

Well, if it gets to the mid 30s pretty well, that means you have made great improvements since that was the original stock top speed. Sounds like it runs good to have that tire on it.

If you ever get the chance to bolt on some 25s, give it a run and let us know what it's like.

i would say what your are missing is about 210 cc's LOL...sorry i had to

Im glad you are OK with what you have now...this way when you grow up you can get a big boy toy like 660 or 700