know any cheap mods for a 300ex

[barrup]

i want my quad to be faster but dont have a lot of $. i already have exaust and jet kit air filter as well widened axle and a-arms any ideas ?????

[300exOH]

You could modify/remove the airbox lid and rejet to gain a little bit more.

The next step would be a higher comp piston, cam and aftermarket CDI.

I have also heard some have had success with upgrading to the 400ex carb but it may work best on a modded engine.

[YAZ43]

400EX carb is a great upgrade. They are cheap on Ebay.

[barrup]

does it just bolt on? (the 400ex carb) or do you have to modd it and rejet it?

[300exOH]

You will need a 350x air boot or some say you can heat up the 300ex boot and stretch it to fit the 400 carb. From what I have read the jetting can be tricky but you can start off with stock jetting and go from there. I haven't tried the 400 carb yet but I have researched the idea. I was thinking about trying the 400 carb but I'm going to wait until a have a higher comp piston and cam first.

[bwamos]

Originally posted by 300exOH
You will need a 350x air boot or some say you can heat up the 300ex boot and stretch it to fit the 400 carb. From what I have read the jetting can be tricky but you can start off with stock jetting and go from there. I haven't tried the 400 carb yet but I have researched the idea. I was thinking about trying the 400 carb but I'm going to wait until a have a higher comp piston and cam first.

I have a 400ex carb.

I would not use it on an unmodded 300ex.

The 350x airboot does not fit, contrary to popular beleif. It's at a bad angle and intereferes with the cross member for the shock mount. I stretched the stock boot to fit. The ID of the carb end of the 350x boot wasn't any bigger than the 300ex's and the 300ex's boot is much more stretchy.

[300exOH]

Originally posted by bwamos
I have a 400ex carb.

I would not use it on an unmodded 300ex.

The 350x airboot does not fit, contrary to popular beleif. It's at a bad angle and intereferes with the cross member for the shock mount. I stretched the stock boot to fit. The ID of the carb end of the 350x boot wasn't any bigger than the 300ex's and the 300ex's boot is much more stretchy.

Thanks. Good info. I'm guessing you heated or boiled the air boot to get it to stretch? I didn't think the 400 carb would work well with a stock engine which is why I gave up on the idea for now.

[bwamos]

Yup.. I used a soldering heat gun at a distance to warm her up. (better wear gloves). It's still a heck of a stretch. The difference in the size of the intake flange is massive.. lol.

Once I got her on.. I clamped her down. When I rejet, I remove it from the airbox flange not the carb. Boiling also works.. that's what I did first, but when I went to rejet the first time I removed it from the carb. Bad idea, lol.

Everything else is a perfect fit though. I'd like to find a way to fit a better boot, but the cross member for the rear shock support is very obstructive. Not a lot of room between it and the seat.

[barrup]

thanx, i think i am just gonna have to break down and get a high comp piston and cam. then i'll try the carb.

[2muchquad]

thanx, i think i am just gonna have to break down and get a high comp piston and cam. then i'll try the carb

The 400 carb made a HUGE difference stock with just a pipe and a kand n filter.You'll be surprised,i was like you i wanted to wait:)

[Kickstarts-suck]

i have one on my 250x and didn't notice a difference

the 400ex carb will fit the carb to head boot good but the air filter boot is the one that is hard to get to fit. I ended up tearing the air filter boot and just bought a UNI clamp on filter.

[exrider4130]

the 400ex carb doesnt make a difference on a mostly stock engine (stock internals). you have to jet it down from stock and its pretty much lik erejetting the 300 carb. the only difference really is th eamount of fuel it holds. throttle response is a little better, buts its really not worth the trouble of having to dial in the 400 carb. one mod that will cost u about 10 bucks and will help prolong the life of your engine is eliminating the crankcase breather system. this system dumps the air that builds up in your crankcase back into your intake system. over time, this will cause carbon build up in the cylinder and can cause gum to build up in the carb. if you want to see whats going into your engine, just pull the rubber intake boot thats between your air filter and card and rub your finger inside of it. the inside will be covered in oil. thats because as the pressure from the crankcase passes through the pcv system, it carries oil particles. the best way to bypass this system is to simply unhook the hose running from the white catch bottle and the intake tube. just plug the hole with some silicone in the intake tube and goe to a local auto parts store and purchase a breather filter. its a small 2 inch cone style filter. install the on the catch bottle so no dirt can be sucked into the engine and the crankcase can still vent properly. damn this is long. lol so to make a long story short, less gum and carbon means a more efficiant engine. hope that helps

[bwamos]

Good call.

Disconned the breather tube from the air intake.

My 98' and I think the 99's and older dont have a smog box. Our breather tube jsut runs up under the tank to the steering stem area. No feeding hot, thin air into the motor.

[barrup]

sweet, iam leaving know to do so peace

[hondaracing0144]

how do you stretch the boot on the 300ex? i need to stretch mine so itll stay on

[Kickstarts-suck]

Originally posted by hondaracing0144
how do you stretch the boot on the 300ex? i need to stretch mine so itll stay on

Heat gun ;)

[hondaracing0144]

is it easier to get a 400ex boot?

[300ex&RZR]

The best and cheapest way to make a 300ex go faster is a new front or rear sprocket. To go faster get a bigger front sprocket and a smaller rear sprocket.

[Tyler01]

yea i would have to agree with "300ex&RZR" If you want faster just go change up your gearing.

[Kickstarts-suck]

Originally posted by 300ex&RZR
The best and cheapest way to make a 300ex go faster is a new front or rear sprocket. To go faster get a bigger front sprocket and a smaller rear sprocket.

All that will do is increase your top speed and decrease your acceleration. ;)

[stroked 400ex]

if you ride on trails, feild or track thats when you change your gearing... and like people said use a heat gun to stretch the boot... i dont think the 400ex boot works or i would have used it, i believe the air box side is a different size... have to cheak my 400ex dont remember for sure...

[hondaracing0144]

the best upgrade i probably did was my fll hmf exhaust and open inbox, all of this cost me $80 haha i got my exhaust off craigslist from a guy which is not my good friend