I know that the 500HOs and 425s share the same head, but the HO has a slightly more aggressive lobe pattern on the cam. I was curious if anyone knows what else might need done to make the HO camshaft work on my 425? I'm pretty sure the carb jetting will need to be changed because of the increased flow, but would there be a spark advance issue to worry about too? I'm assuming the stock piston wont be an issue?

I was hoping to use the HO cam to get a couple extra HP out of my Magnum 425 2x4 as it sits. I'm rebuilding the self-destructed top end now, and figured I might as well upgrade it if I can since I'm already shelling out a couple hundred for a new cam anyways.

 

It is a easy swap.You may want to find a 500HO intake manifold and carb.40mm is what you have and the HO has a 42mm

 

Awesome! Appreciate the info. Thanks!

 

I was just doing some digging on the carb specs, seeing what other carbs might work in this application from different models. So I randomly decided to double check the specs of my current one because I was thinking I might be content with 40mm just to save a buck... well the Owners manual says mine has a 34mm!

Definitely need to upgrade that... This is a '95 425 Magnum btw. I'm assuming they started putting in larger carbs later on in life since this was the first year these were made?

Oh well... its just money, right? heh..

 

The Non H.O used the 34mm carbs and the H.O used the 40mm. I would think just the high duration H.O cam with the stock 34mm would still offer a performance increase,may need a jetting change at most.

The Kawasaki 300 Lakota has more power then the 300 Bayou and there the same motor and 32mm carb but for the Lakota having a hotter cam also.

 

Okay. That's good to know. This way I can at least spread out the cost of upgrades instead of hemorrhaging it all at once if I choose to go that route.

 

Ok... this may or may not end up being a dumb question... But, I see that the Predators, and Outlaws also have 42mm carbs, but they are physically built different than the Sportsman HO's. I've been looking all day and can't figure out what the difference is, other than one is on a racing quad and one is on a utility quad. I'm assuming it would work just as well as the sportsman HO 42mm carburetor. Am I wrong? Are there fundamental differences? Am I over-analyzing this? (probably) lol

 

Ive done this, they wont run right without the 40mm carb I'm guessin a 145 main jet for starters, look on e-bay for thr carb, the 42mm is probably too big and finding the right boots would be hard, you can buy the correct boots for the 40 off of a 2002 or newer 500 ho.

 

Diffrent motor altogether. The Fuji built 500 used in the Scrambler and Sportstman is a dry sup, 35hp SOHC motor.with a 3.62in bore X 87.9mm stroke.

The 500 motor in the Predator is a wet sup, 42hp DOHC motor .3.91in bore X 99.2mm stroke.

The H.O high Duration cam and larger 40mm carb was added to the Sportsman in 2001 while the Scrambler got it in 1998.

The Fuji 500,425 and 455 are the same motor just sharing a different bore and stroke,so the H.O cam should fit.

 

All good info to know.

Kirbbirds, did you try re-jetting the 34mm? I was kind of hoping to delay buying a bigger carb until a pay day or two later.

Do any of you know the difference between these two carbs?

http://webservices.motorsportdealers...6/6446D007.Gif

http://webservices.motorsportdealers...0/5480D013.Gif

I'm thinking the first one must be the 42mm, and the second is the 40mm. They seem to match up with the Sportsman HO and Outlaw/Predator time lines that you mentioned TLC. But I don't want to spend the money and time to end up with something I don't want. I've seen both types on ebay, and they're pretty similar on price too.

Even if I have to re-jet a 42mm, I think I'd rather go that route just in case I want to get a 500 jug/piston at some point.