Anyone big bore their Rap 350 to a 400?

[blstr88]

I guess the title says it, any of you guys big bore your Rap 350s to a 400? I was lookin at the maxpower kits for my YFZ and I saw that they make a 400cc kit for the Raptor and really it just made me curious, Im wondering if they actually make the Raptor match up to the 400ex/Z400s?

I've been seriously considering selling my YFZ when I get home next month and picking up a 400...I dont want the Rap 700 because of its size, so I was kinda limited to the 400ex/Z400 but now Im wondering if I got a Rap 350 and bored it to 400 if it would be comparable to those guys? Any info would be great, thanks guys!!

 

[courchaine]

you don't need to go that big to keep up with a stock 400 with all the mods on my bike I can keep up with a stock predator wich is I think faster then a Z

 

[blstr88]

Hmm ok so you've got a 366 and some other stuff...I guess what Im wondering is, how much more would it cost me to get a Rap 350 then do it up to put it on par with a 400 versus just buying a 400....?

 

[jasonp]

you don't need to go that big to keep up with a stock 400 with all the mods on my bike I can keep up with a stock predator wich is I think faster then a Z

Predators have like 42 hp stock, which is faster then a z, the Z has about 28-32 hp.. With all my mods I got beat by a Predator (the bike did have a pipe and air filter/jetted). I kept up pretty good for a 366cc. But he had a good 5-10 bike lenghts on me every time. We raced a bunch of times.
I did race a raptor 660 and that was much closer, still he would pull a 1-3 bikes by the end.
I would guess that with a high compression piston and cam with good exhaust and airbox mod you would be up there with a 400. Once they spend a little money on upgrades I bet you'd have a lot of trouble keeping up.
Suspension you'd have to upgrade if you wanted to keep up in the woods.

 

[dave76]

You can go the big bore 400 route but the motor will be more rev happy and not very torqey (remember it's a two valve head). It's a 89mm bore and the stock 64.5 mm stroke. However the cases have to be split and sent out and bored to fit the bigger cylinder sleeve in the spigot. At this point I'd recomment the Hotrods 400 kit as you will gain the torque back plus it's the same dimentions as a 400EX 84mm bore and 71.5 mm stroke. Its the same amount of work (labor) plus the cases don't need to be bored, and the motor dosn't have to work so hard to make the same power.

 

[courchaine]

believe it or not JasonP my friends got an 03 and when he was running the 18inches scorpions tire I was beating I'm top end by a couple bike likes maybe 3 or 4 and now that he is running 20inches Knarly I'm about exactly as fast as him and my friends 440ex with 16/36 gearing and 18inches klaw tire is about 6 or 7 bike lenghts in front of us. I'm wishing that when I'll do the webcam .430 and Kibblewhite valves I'll be as fast as the 440

 

[jasonp]

believe it or not JasonP my friends got an 03 and when he was running the 18inches scorpions tire I was beating I'm top end by a couple bike likes maybe 3 or 4 and now that he is running 20inches Knarly I'm about exactly as fast as him and my friends 440ex with 16/36 gearing and 18inches klaw tire is about 6 or 7 bike lenghts in front of us. I'm wishing that when I'll do the webcam .430 and Kibblewhite valves I'll be as fast as the 440

Yeah, I'm not talking about top end speed more like acclerating. I could put a 16t and beat them on top speed but why. I'd rather out accerate them. Which I can't.
I'm willing to bet that if you switched bikes that you would win on his??

 

[jasonp]

You can go the big bore 400 route but the motor will be more rev happy and not very torqey (remember it's a two valve head). It's a 89mm bore and the stock 64.5 mm stroke. However the cases have to be split and sent out and bored to fit the bigger cylinder sleeve in the spigot. At this point I'd recomment the Hotrods 400 kit as you will gain the torque back plus it's the same dimentions as a 400EX 84mm bore and 71.5 mm stroke. Its the same amount of work (labor) plus the cases don't need to be bored, and the motor dosn't have to work so hard to make the same power.

+1
if your going to bore to a 400cc then you might as well put a stroker in. Money better spend and engine will last longer, be a lot more fun to drive.

 

[klutchbuster350]

If you have the money I would go ahead and buy a 450, or the 400. Well actually, it depends on what you plan on doing. When I started off I rode my warrior. Now I do motocross and ride a 400, but whenever I go mudding, I take the warrior.