350x/300ex Conversion Question

[rooster300ex]

Alright, When my quad needs to be rebuilt i'm going to put a 350x engine in my 300ex. I'll use most of the parts off of powrolls site. I was thinking meanwhile till my quads needs motor work i'll buy a 350x engine off ebay as cheap as i can, and send it too four stroke tech to install everything that will make the 452cc(12:5:1 compression) kit they have rip as much as possible. My question is will that 452cc kit be reliable if using it for no racing purposes. I know i'll have to get an extended swingy. I'd prolly have to get a +3 one or something. also what kind of power do you think an engine built up as this would put out. I know many might think why don't you just buy a 400 and build it up or etc. The reason is i've rode all the quads that i might like to buy but just don't like them. Mine is unique to me and is exactly how i want a quad to be.

[rooster300ex]

There has got to be somebody that knows about the big bores for the 350x engine.

[Notfast3nuf4m3]

i dont know how the big bores are but i have heard there a pain to kick
i built my 350x with wiseco12:1 high comp piston .40 over web cam springs and hardweld rockers dunno how it runs yet but will shortly

[bwamos]

Incase he didn't already know a 12:1 in a 350x motor will require Race fuel, or at least a mix of race fuel.

Other than that it should be just fine.

[440_Turtle]

check out www.3wheeler.org there is alot of triek info on there.

[rooster300ex]

Originally posted by bwamos
Incase he didn't already know a 12:1 in a 350x motor will require Race fuel, or at least a mix of race fuel.

Other than that it should be just fine.


Yea for sure a mix or something with 12:1. It will be built by four stroke tech so it should be built right.

[dork]

i have the 452 FST bore kit and cam in my 300ex and it runs great. so far its been reliable, and thats one season of ice racing which is WFO all day long. it should be fine for recreational riding, the 350x bottom end is pretty tough. with that kit you have to resleeve and bore the cases for it. i don't have an extended swinger, but i have extended a arms and axle. a longer one would help if you're mx'ing, but for flattrack stock is fine. it will wheelie easily though in the first 4 gears. my kit is 10.8:1, and i had to have a thinner headgasket made to bring it up to that so if you get the 12.5 kit measure all your volumes to see if its really 12.5. i run pump gas, if you go over 11 i 'd run race gas or at least 50/50. if you know how to find tdc and nudge it past then its easy to start(like any kick four stroke). as far as power goes, my friends have a raptor(pipe, open lid, stage 1 hot cam, and biggun cdi) and banshee(pipes, shaved head) and in a straight drag it will beat the raptor by 2-3 lengths and 1-2 for the banshee by the top of 5th gear. around an oval on the ice i have no problem running with 450s.

[rooster300ex]

Originally posted by dork
i have the 452 FST bore kit and cam in my 300ex and it runs great. so far its been reliable, and thats one season of ice racing which is WFO all day long. it should be fine for recreational riding, the 350x bottom end is pretty tough. with that kit you have to resleeve and bore the cases for it. i don't have an extended swinger, but i have extended a arms and axle. a longer one would help if you're mx'ing, but for flattrack stock is fine. it will wheelie easily though in the first 4 gears. my kit is 10.8:1, and i had to have a thinner headgasket made to bring it up to that so if you get the 12.5 kit measure all your volumes to see if its really 12.5. i run pump gas, if you go over 11 i 'd run race gas or at least 50/50. if you know how to find tdc and nudge it past then its easy to start(like any kick four stroke). as far as power goes, my friends have a raptor(pipe, open lid, stage 1 hot cam, and biggun cdi) and banshee(pipes, shaved head) and in a straight drag it will beat the raptor by 2-3 lengths and 1-2 for the banshee by the top of 5th gear. around an oval on the ice i have no problem running with 450s.


Are you using a 300ex motor or the 350x motor, and is your motor ported & polished, bigger valves etc.

[dork]

its a 350x motor. it has stock valves, mild porting, powroll exhaust and fcr41. for comparison, my buddy has a 300ex with a 380 kit in the 300 motor and its even with me til about 4th gear. it runs strong for a 300 plus you still have elec. start and reverse. something to think about...

[rooster300ex]

How does that 380 run in the sand?