As my SP500 H.O. sheds semi-groovy parts, the 425 EXP is there to reap the rewards. First the H.O. cam, now the 40mm Keihin carb. A new manifold and airbox adaptor are the only new parts I'll need to put this big carb on the EXP.
Put your wallets away boys, she's spoken for.
While the H.O. gets the 42TM Mikuni Flatslide pumper, which will hopefully install just as easily. (fingers crossed for both projects).
I'll let you know.....

 

fourlix,

If you really want to wake the Xped up go and get a 500 jug and the high compression piston from Wiseco. It will increase the displacement from 425 to 465 and raise the compression from 9.2 to 11.5. I have done this to mine and I can pop the clutch and ride wheelies in second gear with 28 x 12.5 Outlaws on all for corners. I have not done the cam or carb yet. Still cannot get anygood info about the torque curve differences between the two. Maybe this spring when I put the 25's back on I will do the cam and carb.

 

Cool 425,,By "Jug" do you mean the cylinder itself? Any problems with rod length etc? Evidently not! I wonder how tuff this EXP crank is compared to the Scrambler/H.O. crank. Boy, with your brains and my looks I think we're gonna have us a couple of Hot EXPs!! How much $$ was the cylinder and piston? Were they just a 500 cylinder with a high compression Weisco piston? Any other parts?

 

fourlix,

The only different parts needed are the cylinder from the 500, head gasket for a 500 and the Wiseco piston. I think the cylinder is close to $300. I got a deal on mine. The piston is $149 from HPD. The head gasket is not cheap either $48 from Polaris. The rest of the gaskets add up to about $30. It is an easy swap. Everything bolts right up. So far the crank is holding up just fine. The motor has been together for a couple of weeks now. Been thrashing on it and no problems yet.

 

fourlix & 425xpedition-

how much difference does just a k&n filter make?

does the whole kit gain a lot more?

 

What? Maybe half a horse? K&N filters flow a little more air and keep it clean, and they are washable/reusable. If you are running a tiny bit rich, a K&N might be just enough to straighten you out, maybe a horse. Jets are jets. If they're wrong they need to be changed. If they're right, leave 'em alone. One companies jets aren't better than another, and aren't going to give you more horsepower. Jets are cheap, get some. Check your plug, how's it run? Rejet if neccessary. Remember that change in altitude will affect your jetting. More air at sea level means larger main jet and vice versa. If you live at 6,000 ft and are going to the dunes at Pismo, plan on rejetting. 2-strokes are much more
finicky when it comes to jetting. Get it right or it'll run like a dog (too rich, black sooty plug, too big a jet) get it LEAN and it will run too good, but have funny throttle response, plug will be white, or white with little tiny beads on it (that's your piston melting!) Piston will seize in the cylinder, actually melting to the cylinder wall, then breaking loose, then scraping
up leftover pieces of melted piston into the ring groove, losing compression. This all happens in about a tenth of a second. Cool, huh??