300ex Build up

[fmftrx300ex]

I Have an 01' 300ex. I plan to do a cam and piston...My dad has a Z400 And i would like to have the ablity to pass him not the other way around. so any ideas suspention wise and gearing...we ride fast trails some rough and some smooth. thanks

[300ex mxracer]

Your probably not going to be able to fly past him without some extensive mods.

[fmftrx300ex]

can you help me now?

[TRXRacer1]

Originally posted by fmftrx300ex
can you help me now? You can make a 300ex pass a z400 but you'll be spending over a couple grand to do it.

Yea man you will need at least a grand put into the motor if not more so just go talk to an engine builder and see what he has to say becuase its not worth someones time on here to tell you everything you will need to do it when they personally arent going to be doing the work. If you think a few bolt ons will make it faster then the thread is pointless becuase it wont.

[fmftrx300ex]

it dont have to out run on the line and not in like fith gear my dad weighs 200+ and never ever has his z400 in 5 gear so...ok maybe we dont want to pass a z400... I want ideas on how to make it as fats as posible and i know im not gunna get there with bolt ons.... i plan to do a piston, a cam a carb....what can i do to my gearing ? whts gunna give me the most bang for my buck you guys get wht im asking?

[TRXRacer1]

Originally posted by fmftrx300ex
it dont have to out run on the line and not in like fith gear my dad weighs 200+ and never ever has his z400 in 5 gear so...ok maybe we dont want to pass a z400... I want ideas on how to make it as fats as posible and i know im not gunna get there with bolt ons.... i plan to do a piston, a cam a carb....what can i do to my gearing ? whts gunna give me the most bang for my buck you guys get wht im asking? What's your budget now?

[fmftrx300ex]

my budjet is prolly 1000 now idk depends if i get a job this summer... just give me ideas on parts i would need

[m.h.s.c.#527]

all that would take is skill i race against a guy his name is tucker wyatt he smokes 450s all day long in the woods hes just good so just work on your skill z400s arent that fast

[fmftrx300ex]

there is always room to improve my skill but my quads set up needs some improvment big time...i have a fourm for my suspension so tell me good engine work i can do ...im tapped out a 65, i need a new rev limiter...ill list whats done at bottom of post... its speed me and him are close to same skill, i can do every thing he can and then some(jumping and high speed tight trails)




Whats done...
Engine internaly is stock
FMF Powercore 4 (with no spark arestor)
No airbox lid
UNI air filter
Jetted (duh)
thaTS REALLY IT

[fmftrx300ex]

OH AND I KNOW ITS NOT SKILL BECAUSE THE 4 WILL DO 80 AND THE 300 WILL DO 60 BOTH STOCK...sry caps

[kawiefan]

the z dosent go 80 stock. it goes about 68 -72 stock

the 300 will go about 55 max depending if its beat or ot

[TRXRacer1]

Dude.......... I just realized you're the guy I helped a week or two ago on this exact subject. How many times are you going to post about the same topic?

[ALAMX37]

The biggest power gains will be achieved through headwork. Prot and polish will give you more power than any other mod you can do. I would do a port and polish, cams, and piston. I have personally rode a TC 300ex and it was very quick for a small bore bike. Either way get all the work done by the same person, matching cams to porting and so forth.

[fmftrx300ex]

Originally posted by TRXRacer1
Dude.......... I just realized you're the guy I helped a week or two ago on this exact subject. How many times are you going to post about the same topic?



Its not the exact same im gunna call it quits after this one....Idk If can afford porting how much and to get it all done by one person out of the ? for me (to expensize) OK....

[fmftrx300ex]

heres what i plan to do as of now im open to adjustments/improvments...

11-1 wiseco piston
bore to 297cc
Hot cams stage 1
400ex carb
Amr Stage 3 CDI
Amr Monster coil







Whats everyone think? and the rev limiter is deff open for ideas

[ALAMX37]

Don't waste your time with a 10 cc bore you wont gain enough to notice. If your getting a carb then get at least a 38 mm.
Stage 1 cams are for rec riding not racing. I understand its expensive but if you dont do it right you will wish you had after you realize how much money you dumped on such a minimal performance gain.

[fmftrx300ex]

Originally posted by ALAMX37
Don't waste your time with a 10 cc bore you wont gain enough to notice. If your getting a carb then get at least a 38 mm.
Stage 1 cams are for rec riding not racing. I understand its expensive but if you dont do it right you will wish you had after you realize how much money you dumped on such a minimal performance gain.




Wel stage one is all the make for the 300ex and i cant go to a web cam... unless someone is selling hardend rocker cheap for a 300ex.......

[TRXRacer1]

Originally posted by ALAMX37
Don't waste your time with a 10 cc bore you wont gain enough to notice. If your getting a carb then get at least a 38 mm.
Stage 1 cams are for rec riding not racing. I understand its expensive but if you dont do it right you will wish you had after you realize how much money you dumped on such a minimal performance gain. First of all He's talking about 25cc bore and although it won't be a big gain it will help. The added compression is where the most power will be found. I don't know if you've looked into it yet fmftrx300ex but the 330 kit from FST isn't a huge expense. If you don't want to go there now and you're willing to resleeve next time then go as big as you can now with what you have. Now putting a 38mm carb on a machine less then 350cc makes no sense at all unless it flows like a monster and is build to run only on the top end. It's way too much, tuning will be more difficult, and that's big enough you will see a drop in the low end. The 35.5mm 400ex carb is more then enough. It's a good carb and cheap! The stg 1 cam for this machine is not just a recreation cam either. It's about as big as you can go without performance valve springs and to be honest I would put the springs in anyway to prevent any float on extra top you'll get with that CDI. Power gains with this cam are strong from the mid to top and proves to be the smartest choice for the money.

I'd say you're on the right path fmftrx300ex. If you can though talk to FST about just a low budget blueprint port to get rid of that horrible exhaust restriction. Once you look in down the ports you'll see what everyone is talking about. Call and price it before you dismiss it.

[300ex mxracer]

Originally posted by fmftrx300ex
heres what i plan to do as of now im open to adjustments/improvments...

11-1 wiseco piston
bore to 297cc
Hot cams stage 1
400ex carb
Amr Stage 3 CDI
Amr Monster coil


heres what id do.

11-1 piston(depending on how hard you ride you might need 50/50 93 and race gas)
cam
ported head

the ported head will get you more power than the carb, CDI and coil.

[fmftrx300ex]

I ride hard tht mean im gunna have to do a blend? gas is so expensive!!!!!!!!!!! and my dads weird and says no porting... any one do it cheap as crap super basic?

[morse250r]

fst my buddys kid and the 295 kit on a 250x which these are basicly the same engines it rocked then he went to the 390 stoker in motocross he was up with the 400s and 450s runs well but had porting exhaust fst cam 400ex carb it was a well running kit very reliable give mickey dunlop a call and ask questions pick his brain great guy and reasonably priced

[fmftrx300ex]

English? sorry tht post was hard to understand....ND DOES ANY ONE KNOW IF IM GUNNA NEED RACE GAS WITH 11-1?

[300ex mxracer]

Possibly. Mine started pinging when i was ridin hard out in the field in snow, so we just started mixed 93 and 110 50/50 when i raced so it wouldnt be a problem.

11:1 is about on the line as far as fuel goes on an air-cooled engine. if you had a liquid-cooled engine it would be different. my 450r comes stock over 11:1 and only requires 93

[fmftrx300ex]

ok... then idk if i want to do high compreesion (i cant afford race gas!!!!) we ride every weekend and do about 30 miles so race gas would just cost to much

[fmftrx300ex]

so any more ideas?

[TRXRacer1]

Originally posted by fmftrx300ex
so any more ideas? Well you did say a grand this time so call or email Four Stroke Tech (fst) and see if they have a 10 or 10.5:1 comp 330 kit like Powroll does. When I did the fst 330 kit it did not require case work so the machining costs were not that much. Figure a 330 kit and machining for around $500, a cam for $140, 400ex carb for $65 and a basic blueprint port for $200 from AAEN Perfomance (check with fst they may be able to do a blueprint port for the same). That's about $900 so you have a little left over for odds and ends.

As far as the porting, once you look into the exhaust side of the head you will see that there is a LOT of work needed. I mentioned AAEN Performance because the owner is still hands on and he's been around for ever and knows how to make power out of anything that has a spark plug. You won't find a Honda specific area on their web page so just give them a call. Blueprint porting is basic and what you need here. Like I mentioned already, check with fst too.

[fmftrx300ex]

one last question... should i put the 1000 bucks into my 300ex or save it up for 2 years and geta 450 when i turn 16?

[TRXRacer1]

Save your money.

[bwamos]

You won't need race fuel to run 11:1


Originally posted by fmftrx300ex
one last question... should i put the 1000 bucks into my 300ex or save it up for 2 years and geta 450 when i turn 16?

IMHO, save the money unless you are racing it in a series.

[300ex_#387]

Originally posted by fmftrx300ex
heres what i plan to do as of now im open to adjustments/improvments...

11-1 wiseco piston
bore to 297cc
Hot cams stage 1
400ex carb
Amr Stage 3 CDI
Amr Monster coil







Whats everyone think? and the rev limiter is deff open for ideas


Back when I races my 300 I had basically that set up.

12.5:1 compression piston
297 bore
Hot cam
400ex carb
Ported&Polished
Aftermarket CDI

To be honest I really don't think it was worth all the money I put into the motor work. Sure it was faster, but that motor is over 20 years old, and it just doesnt have a huge reaction to modifications. If I were you though I would put most of my money into the head. Over sized valves, a good cam, get a GOOD port job, and a piston.

[fmftrx300ex]

ok thanks alot evrone, but i have desided tht i am gunna put some sprokets on it and thts it, when when i turn 16 im gunna go out and find a 450, 2 years aint to long of a wiat