First off, welcome to the board!

 

Thank you for the welcome.

After a bit more reading it looks like the carb is the same between the 425's and the 500 non HO. Of course, just jetted differently.

 

I have a 95 Magnum 425 that I'm thinking about stepping up on power.
I would appreciate if you could send some of your finding my way, I saw the video that atvjunkie821 had posted and I was very impressed with what he did to his quad.
If you wouldn't mind keeping me posted, I will be thankfull.

 

i dont think so ZSK... all i did was check the cylinders but the 425 has a different cylinder then the 500, so it definatly just isnt a bored out 425 cylinder

 

A different bore size will be a different part number.

 

haha, you so right...duh! i didnt think that one through....so the camshafts are the same, but that is all i have found so far to match up

 

Hey guys all I did to mine is a k&n filter and proper jetting so far. Jetting made it run like a beast, it runs with stock 500ho's now. The motors are the same and the parts will swap. If you use a newer cylinder as I am going to use, there is a plug you need to remove for the crankcase breather. The 425 had a fitting in the cylinder and the newer models plugged it and moved the breather line to the case. It serves the same propose. I have all the parts to upgrade to The HO specs. With a 500 cylinder and a 1mm overbore it will be a 518. You need a 500 cylinder and piston the HO carb and carb intake. The 425 air box will not work with the HO carb because it's larger so you will need a box off a 500HO. I hope this helps. Drop in a 153-155 main jet and you will be wowed.

 

yea you're right junkie that stroker kit is pricey considering all the other parts youll need plus that kit !

although i am interested in you're 518. along with the piston, cylinder,intake and carb , is the head any different or just the cam? any ideal what the optimal jetting is for that 500 h.o. carb? what years and machines make for good donor parts? where did you get the piston?.....geesh look the noob is all needy with info....ha! but thank you for any additional information you can provide.

 

Please keep us in the loop when you do the upgrade. :tuschel: I've heard of a 500 scrambler kits that works them out to 628cc, but that's also a stroker kit.

 

:wub:628 stroker????!!!!!!:wub:
where do i find info on that?!?!?!?!?!?!

 

Well i think the 518 will be all that this bike needs for me, it already gets me in trouble, haha. I will keep you posted for sure and I will post some new video of it after the upgrade. Hopefully spring weather will be here soon so I can get it done. I can't wait to smoke my neighbor's 500HO like it's setting still. I can pull him on top now but midrange speed is about dead even. He does get a slight holeshot off bottom. Yeah I forgot to mention that a have lighter clutch weights(46grams).

 

96 Magnum 425 Snorkeled

Has anyone ever snorkeled a 96 425 magnum? I snorkeled my air box and it still runs but doesn't have the top end speed it had before. I can't find a jet kit that is actually made for it. I am guessing the stock 500 (non-HO) jets will help? Any ideas?

 

yes those jets will work. The slightest change in airflow will change air/fuel ratio the CV carb is very sensitive to any change. My guess is that the snorkel is choking it down and will need a smaller Jet to lean it back out. My 2cents.

 

What size pipe are your using for your snorkel? IMO and I know some will disagree, but you need at least a 2.5" pipe for enough airflow. Did you vent and seal the PVT case also? Is doesn't matter how much top end you have if the belt is slipping because it's wet.

For the jets, you can buy individual jets from your local dealer or online. I like to have a couple sizes larger and smaller on hand.

 

425 Magnum snorkeled

I have a 1 1/2in snorkel pipe coming out of my air box. That is what size fit snug in the rubber boot on the airbox. I have not snorkeled the belt or anything else. I haven't had it in any water yet. I rode it quite a bit since I snorkeled the air box, and it runs fine, but I noticed the top end power wasn't as good. A atv guy told me to cover part of the snorkel with a couple fingers while I had it running fairly fast. I did and it sped up up alot when I covered it up. So, I was guessing I needed a little larger jet to counter the extra air I am getting now.

 

Hey mud, that sounds right, If you covered up the hole a bit and noticed increase then you need a larger Jet. I tuned mine with a wideband O2 sensor reading from the muffler clean out plug, takes all the guess work out.

 

96 Magnum 425 Snorkeled

Thanks for the info guys. I am glad I found this forum site. I always seem to have a hard time finding info on the web for this bike.

 

hey mud, what wheel, tire package you running on the magnum and to you have any pictures of the snorkel?

 

I have 12in aluminum crushlock wheels with 28in Super Swamper Vampire EDL's. The only problem with running that tire package is I snap stock chains if I get on it on dry ground. I had to get a heavy duty gold chain and it has held up so far. But she will throw some mud....

I dont have any pictures with the snorkel. When I get a chance I will take some and post them.

 

Welcome to Four Stroke Tech.net! Engine Products, Polaris, Scrambler or Sportsman. The price, if current, seems very reasonable. 600cc or 628cc big bore/stroker kits.

I've contacted Aaen and they only offer a pipe, clutch work, and a different carb.

 

sweet thanks for the info!

 

That big bore kit is sweet, but not so sweet of a price!

 

Hey mud, Did you use adapters for the rear wheels or did you find the wheels to bolt up to the rear stock pattern?

 

Crush Lock wheels

Hey junkie, sorry I just saw your question.



A friend of mine works in a machine shop, he made me some adapters that also worked as spacers and the wheels. Another friend of mine races atv's and has an atv repair shop, he also makes the crush lock wheels. They can make them to fit any bolt pattern in 12 or 14 inch wheels. They are awsome, even with deep lugs, they make it easier to steer and you only run 3-6 pounds of air and never have to worry about a flat leaving you stranded. You can drive on them flat. They sure dig in the mud.... If you are interested in some, I can get them alot cheaper than you can buy them from High Lifter.

 

Hey Cam, yes the head is the same. I think the HO cam is all that you can get now, the older cam is superseded by the HO cam. There was a lot of problems with the older cams, not sure if it was not hard enough material or what. I run a Zinc additive in mine because the newer oils(unless it's a specialized oil) has the zinc taken out do to effects on catalytic converters. Zinc has tremendous lubricating properties that all the old oils had. Anyway back on subject.
Any 500 or 500HO cylinder from a Sportsman or Scrambler will work (96-06).
JETTING: I can't emphasize enough that these carbs are very, very sensitive to any change in airflow. The slightest change will affect fuel ratio. I found this out using an o2 sensor to calibrate the Air/Fuel ratio(A/F). For instance, My magnum with airbox and the factory rubber boot that goes up to the gas tank shroud needed about a 153main Jet for proper Wide Open Throttle(WOT) about 14.0to1.0 A/F. Now remove the rubber boot. A/F goes to 23to1 at WOT(very lean) Taches out 1500rpm earlier. So I had to Jet up to a 162 main jet to get it back right. Ok say you use the 500HO carb and 500HO airbox with the unmodified stock lid, in theory you could use the stock 500HO jetting. I will be testing this as soon as I get a 500HO airbox.
PISTON: The piston I bought is a Namura cast 1mm overbore coated piston. I bought it off ebay. Other companies such as Wiseco offer pistons for these as well but at a much higher cost. I thought i'd give these guys a try, about the same or a little cheaper than factory parts. Plus I get the coating, whatever that might be worth. So far I have about $250 invested in: Carb, cylinder, intake, and piston set. All off Ebay! Man I love that place.

 

thank you for the info junkie! i bought my magnum fairly cheap and she had been abused ! i coaxed her back to life and im still fighting some issues. i was thinking about replacing the carb and cam anyway. when i read about your magnum that got me interested in your project ! and you're right ebay is awesome! if i can get the parts ill probably go the 518 route also!

 

Same hear Cam, I bought mine for 250. I have about $1000 in it now. Least I know what is good and what isn't now. I can't see myself spending more on my atv than my automobile, especially when I know it will be buried in mud, flipped over, run into trees and what ever other kind of hell that I can put I through, LOL.

 

I paid 700.00 for mine i got another 300.00-400.00 in it. i think the most expensive thing i have bought so far is the race driven chain and sprocket set ( heavy duty o-ring chain and sprockets) and then there was all the little nickle and dime sh*t like paint, fixing wiring ,ect, ect ! the only issue im still having is with the carb! runs horrible with the airbox on great with it off. ive had the carb apart and cleaned it a few times bought a new fuel pump it gets alittle better the more i tinker with it.i have pics of it as i tore it down if you look on my profile.