i'm in the process of completeting this transition, and from a few people that have done it they say it's well worth it, The information that I have gathered is when it's done it should have no issue with smoking a slightly modified 400ex, (and that's stock) if that's the case I would be thrilled. Some of you long time honda owners tell me what you think. I meen with a little more motor work to the 350x, there may be no limitation..............preadators....raptors..... ds650's....banshees, well o.k. maybe not banshees look out. By the way the motor swap is quite easy to do, the toughest was finding the motor itself....well tell me what you think, or what other mods might really make this thing scream....thanks

 

I'm just wondering what it haves to beat a 400ex

 

if i remember right it has a stock higher compression? I was talking to MDE3 about his setup he had on one of them.

 

I think people give those 350X engines WAY too much credit. You won't beat a 400ex unless it has some serious issues or yours has some serious mods. Hope you like it though, and a torquey 4 stroke in an R frame should be pretty nice.

JP

 

nah the 350x's are pretty fast... not quite sure what MDE3 said he got his pulling at the wheels but i think it was in the 40's? I know for a fact with minor mods they will beat a 400ex

 

Cool. I wish him the best.
JP

 

AS SOON AS THIS BEAST IS READY TO RUN, MY BUDDY HAS A MODERETLY PUMPED UP 400 WE'LL GO HEAD TO HEAD, I'LL BE SURE TO LET YOU GUYS KNOW WHAT HAPPENS, I'M INTERESTED TO SEE MYSELF, BY THE WAY DOES ANYONE KNOW THE STOCK HORSES OF THE 350X OR WERE I COULD FIND OUT?

 

stock there putting around 23 HP gt thunder dyno test said

 

THANKS FOR THE INFO MANUEL

 

Stock horsepower from the Honda manual is listed as 27 horsepower for the 350X.

Here we go again............the 350X engine was the 4 stroke of choice before the 400 ex came out, and the 250X/350X conversion was commonly run on the pro circuit before 1999. As far as what horsepower you can achieve with them....well it's how much do you want to spend? There have been a few TC 550 cc versions I have seen that smoked everything in sight.

We had two and raced them both on flat track, and one was modded for MX later. The smaller one was only 368 cc's and the larger one 423 cc's......... both with stock stroke. TC built or worked on both engines, and his claim was about 42 - 45 hp. for the smaller motor, with porting, mx cam, cdi, SuperTrap/TC pipe (his header and cone, and a modified Supertrap exhaust with no discs(basically a straight pipe that looked like it had a muffler..... for appearances), I added a billet aluminum intake designed to go with the Lectron 44/38 Taperjet carbs, and would say 42 at the rear was about right for the smaller motor and the larger one about 48 - 50 hp. The smaller motor ran a 13: 1 piston and the larger one a 14.5:1 piston.

The smaller bike beat lot's of 440's and piped Raptors on flat track as well as quite a few banshees, and 250- 300 r's, it also lost to some 416's, 440's, 490's and other Raptors and one Banshee. Remember that the torque pull from a 4 stroke on a shorter flat track can a be very important advantage pulling out of the corners, so beating a lot of 2 strokes is not all that unusual in flat track. The 2 strokes hit too hard to use the power while pulling out of the end of a turn, and will spin you out easily, so they have to back off in many cases. Some of the better riders on banshees were able to overcome this but only with the big bore kits it seems.

The larger 350X ran away from most modded bikes, but was beaten by at least one Raptor, a YZ439, and a 330r, and a superfast Banshee. It was about even with some seriously worked 'Dales, and a Trinity built 440 ex motor, but seemed a bit faster than a lot of 350X/460 stroker kits. Again this was flat track racing, not drag racing, and the motor is not the only element, set up and the rider are at least just as if not even more important.

So you figure what's faster.........lol there is no simple answer. It is what is done, how well it's done, and by whom (what tricks they know), and what shape the motor and drive train is in at the time. Suffice it to say you will not be unhappy with the results from your 350X/250X mods and you can take them as far as your pocket book will allow. Properly done and raced in the right class for your ability - if you are into racing - that old combination will not embarrass you.

I am currently having a 350X "supermotor" built, which is targeting 60+ hp. but with durability..........we shall see.