New to the KLX300R , carb choice MAJOR conffusion , helpppp !

Hi Guys

Am over the moon to say I'm a newbie to the KLX300R '07 , [mines a US Cal bike imported to the UK] ... having raced a WR250F '03 some years back I was looking for a lighter, shorter and great trail bike and looks from whats said here I've found it .... However ... am totally confussed over what carb mods to make [if any] ... so a big shout out from the Uk .. Hellllllp !

Reason for confusion ...

1. Having contacted Sudco and looked at Jerrys [four works] site , am being given the usual choice of

Keithin FCR 35

Mikuni TM33 pumper

Mikuni TM36 pumper

The K being the most expensive and by the sound of it the trickiest to dial in,

but why the two choices for Mikuni ?

2. Having raced the 03 wr250f i checked out what carb this was running and its a Keithin FCR 37 , which in the years i raced it i never had to touch and the bike was crisp from "zero-to-hero" ....

so BIG question here is Why can't I fit an FCR 37 to my klr300r ????

3. Before I go tearing into things , I collected the bike yesterday and bearing in mind its been sat doing nothing [& i mean nothing, its like new] for over 2 years , on start up , it wont run properly from about 1/4 throttle till you nail it wide open , any ideas or should i throw the carb in my ultrasonic cleaner just incase some old fuel has blocked some passage ways ? .. yes it has the stock CV carb .

4. How noisey is this engine generally ? ... seems a bit rattly compared to my old wr.

Any ways guys , treat me like a newbie , feel free to tell me whats the best [cost effective] ways to make the bike even better and if anyones got links to sump-guards , trick parts , workshop manual , etc etc or even old road tests I would love to hear from you ...

All best and thanks in advance of your help

Greg R

[klx300r A7 newbie]

A 37mm could be made to fit the KLX300. But, the KLX300 does not rev like the wr250f so it can't use the extra air/fuel and may be a detriment to the lower rpm range.

Carb choice should be made on deciding what type of use the bike will get. If your riding will be mostly slower, single track, go with the 33mm. If the riding will be mixed, either the 35 or 36 will be good.

You should also consider setting up the suspension, a weak point on the KLX300, for your weight, riding style, and terrain.

Ride on


Hey Greg,

If you do not want to install the pumper right off the bat you could just install a Dynojet jet kit. It will give you great results especially on the Cali model that you have.

Here is a great thread on the install of a TM36-68, there are several long and involved threads about installing the FCR37 just take sometime and use the search function.

If you are looking for the largest rewards with the smallest investment, re-jet the CVK, get some new front fork springs. (The guys at Moto-Pro are great) install a 13t front sprocket and then ride the crap out of it!


cheers for that guys , yes budget is tight at the moment as having to get UK appproved lights , tyres etc etc ... so the big items will have to weight till i've done that and ridden the bike a few times ... thanks again .. Greg

Hey Greg,

If you do not want to install the pumper right off the bat you could just install a Dynojet jet kit. It will give you great results especially on the Cali model that you have.

Here is a great thread on the install of a TM36-68, there are several long and involved threads about installing the FCR37 just take sometime and use the search function.

If you are looking for the largest rewards with the smallest investment, re-jet the CVK, get some new front fork springs. (The guys at Moto-Pro are great) install a 13t front sprocket and then ride the crap out of it!


Agree 100%. While the kick in the A$$ the fcr 35 gives the bike, its pricey and annoying to fiddle with at times.

Hi Dennis , got the bike in bits , been sat around way too long to not check it over fully , petrol stankkkkkkk so odviously new in there after tanks been flushed ... carbs coming off for a clean and to await arrival of a dynajet kit which i may as well fit for a starter . Question though , where abouts do i start with jetting ... how far off will the Cal settings be to say the UK at 300-500 feet above sea level and quit damp at times. ... will i need to go for the biggest main / pilot in the kit or suck it and see ?

Open to suggestions , plus because no manual , need the valve clearances [i presume at cold] and if anyones got a link to the 300r enduro wiring loom would be great .

oh well lots to do before i kick a leg over it for real ,,,,,

all best


Hey Greg,

The cali carb has a non-adjustable needle etc... the dynojet kit will have some pretty specific instructions that come with it so no worries there. I installed one in my CVK before I moved onto the pumper and had zero problems with the install or the recommended settings that will come with it. I was also a 62-2000 ft above MSL.

You might actually have the valve clearance info on the bike, look at the sticker on the left side of the bike just in front of the gas tank on the head tube. All kinds of good info on that sticker!!

Also check out this Sticky at the top of the KLX page go into that, Bill_P has a great section on the rebuild/jetting of the CVK pics and everything!


Bill_P has a great section on the rebuild/jetting of the CVK pics and everything!


I do???/:D:lol::D Some distant memory.....

Greg, the dynojet will help out. Just make sure you NEVER ride a KLX with an FCR on it. :ride:

Then you'll be happy. Get a header or pipe on it and work on the suspension and you're good to go :D:ride:. :lol:

once again thanks guys , just posted another thread re: ider gear & manual lifter , like to hear your comments ... cheers Greg

Ps, bikes in bits already , as i wait for the dynajet kit to arrive and sort the lights out and other freebie mods.

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