The big 3-0 Hp: Crossing the Line!

Hey everyone, Just wanted to let you know that after being so satisfied with my recently big-bored klx which has a muzzy, kustom kraft, kdx snorkel but still stock carb. I decided to up the power some more. I had it dynoed today and i got 27.18 peak hp. I said to the guy who owns my shop that i use " what can I do to make this thing cross the 30 hp threshold. I asked if a pumper carb would increase HP he said no only throttle response. i do plan to get a fcr sometime soon but i want to work on the power first. So he tells me I can go with some hi-po cams and get either a 3 angle or 5 angle valve job. I opted for the 5. This came out to about $1100. This brings my running total up to 9 grand and thats with me doing a lot of the work. Yes, yes I know I could have just bought a ktm or husky but thats not what i want. I want a custom beast that can't be bought, only BUILT. Half the fun for me is watching my bike grow and seeing the looks on others faces. What good is money if you dont spend it? Anyway the guy said this should bring to to around 29.5 to POSSIBLY JUST 30 but I may have to reshape the C Chamber to get any further HP. I said " sh*t, Thats gonna cost me right?" then I realized EURICKA! I left the quiet core in my muzzy! haha so i took that out and the hp went up another .6 so the guy said I should most deffinatly be able to get 30 hp. I am just so excited and wanted to let everyone know. anyone else done a valve job or cams? how'd it work out for ya?

I also have a 331 and have big money in head and valve work along with Web Cam cams. With out a doubt, I would not touch the head until it at least needs valves. IMO, the best and most noticeable improvement to the KLX was the addition of the FCR35. Although it may not add power on the dyno, it will give you the impression that it has and give the biggest WOW factor. I started with a 300 and not a 250. If I had to choose, I would much rather have my 300 with the FCR35 over my 331 with cams and the CVK. The FCR35 and good suspension are the first two major things I would do to a KLX.

Since the CVK34 was used on the original 250 and you are running it on a 330, it seems like a larger carb might get you some power at high revs. The pump would be gravy.

Also seems like you are after bragging rights rather than making your bike better seeing that you are chasing power over rideability.

I won't lie I will enjoy having some bragging rights but i also ride about 80% street. The reason I am holding off on the pumper is because I was told the pumper carb gives big benefits off-road but is not great for street use. Do you guys think i should go with a bill blue mikuni 34 or spend 700 for the bolt on fcr from fsw?

There's been alot of talk about whether or not a pumper carb makes more power or if the throtle response makes it feel that way. That butterfly valve going across the venturi of the cvk is 4 mm wide. If you subtract the cross section of the shaft when the valve is fully open then the cross sectional area of the 34mm carb is only a little more than 31mm. 34mm cirle has a cross sectional area of 907 square mm. 4mm x 34mm = 136 907-136=771 Thats the area of the 34mm carb-771. A 31 mm circle has an area of 754mm. A 35 fcr has 961 square mm. 36mm mikuni has 1017 squre mm. A 37mm fcr has 1074 square mm. The guys that have these carbs think the power is better and the numbers show potential, what do you guys think?

I just put an FCR35 on my bike last week. Thankfully, the guy i bought it from had it tuned perfectly, essentially i bolted it right on. Took it for the first ride Friday night. powerwheelies in the first 3 gears down the side street in front of my house has never happened to me before on my KLX. I also have a larger header, which accounts for the power as well. But i couldn't get the smile off of my face.:lol:

I'd also agree that the pumper-and-pipe and suspension upgrades are the two most worthwhile big dollar improvements to a KLX. If I bored out the bike, I'd be inclined towards a 37mm FCR just to flow a bit more air. There is nothing wrong with the 35mm FCR, and it installs easier, but you may get more performance with the 37.

Well I have always trusted you guys so.... you think I should spring for the fcr 35mm Or just save some money and go with a mikuni/bill blue 34mm. I hear they are both great but the way I see it is since I am already going all out on this bike why skimp on the carb which is supossed to make the " biggest " difference? What are your thoughts?

Also can anyone tell me if the fcr 35 fsw sells is new or used and does is bolt right on or is it very difficult to install?

I'm partial to the FCR35. It is however, substantially more than the Mikuni's. From what I have been told the Mikuni's are much better than the CVK but there is a reason the FCR style carbs are on all the modern bikes. Once dialed in the FCR35 will rip compared to the CVK. Totally transforms the bike the way it should have come from the factory.

Jerry at FSW sells new carbs. He sets them up to be a direct bolt on and the jetting will be very close if not right on. You will have to use a single cable for the throttle. You can use one of the stock cables and throttle or Jerry also sells a single cable and throttle. With the pumper I would also get a hot start. If you go with a carb from FSW he will also drill and tap the carb and set that up as well.

its a shoehorn fit, but mine fit with no cutting of the frame. You also have to shim the back of the gas take with a rubber spacer so the tank does not rub the carb. shows it i believe.

to give you an idea of a proberly tuned carb, yesterday, I walked out into the garage and kicked my bike, with no throttle, started on the second kick. i also have the hot start mod and a 1/4 turn throttle assembly. i used the stock throttle cable, although it needs about 3/4 of an inch of the rubber/plastic and metal insulation cut back, which was harder than it sounds. I'm told when you are riding and it stalls an the bike is hot, to restart do NOT touch the throttle when trying to restart it. kick it and kick it and if it doesn't start, then open the hot start and try. again, my bike starts with no throttle and actually doesn't like any throttle for the first 3 minutes of warm up, bogs it and it stalls. i've not had my bike in the woods yet to try the hot start, still to dang cold and nasty here.

man... I wish I would've posted this thread before I dropped a grand on the valves and cams. But anyway after reading an extensive thread about CK's fcr 37 install I am deffinatly gonna go with a 35 from FSW. Just wanted to ask you guys do you think +75$ for the choke is a must? I know my bike is a pain to start when its cold without the choke on. also, will a hot start fit with the choke version of the carb? anyone buy the choke version or is the regular sufficient? Thanks for all the help guys.

mine does not have a choke, but does have a hot start. so i can't answer if its needed. starting is not a problem, but i keep mine in a garage and the coldest it gets is about 50 degrees.

the valve job you did should help regardless.

The choke is not needed with the FCR35. I give about 3-4 quick twists of the throttle and it fires right up. I've been in temps as low as the teens and had no problems. The hot start is not needed or used for cold starting. It is beneficial after you dump it and it stalls out on you.

This brings my running total up to 9 grand and thats with me doing a lot of the work. Yes, yes I know I could have just bought a ktm or husky but thats not what i want. I want a custom beast that can't be bought, only BUILT.

Good gas for you for building your own bike! I'm doing to the same with my 00 Dr Z400 kicker... Paid $2000 in offroad only trim and over $5k total now! :p pics in garage

Thanks for the encouragement soup I appriciate it. I don't know why some people have to be so negative on here. I try to live by the term "to each his own" because I know a lot of people ride bikes or do things that I myself would neccessarily not do, but I don't judge them on it. We all find happiness on 2 wheels being propeled by engines right? So why hate on someone because their take on it is a little different than yours? So many people curse me ( not so much on TT) but else where online for trying to make my KLX somthing it's not supossed to be. But honestly what truly is a bike SUPOSSED to be anyway? Last time I checked it's a tool used for bringing hapiness and fufillment into someone's life. at least for me....

Hey CRF,

I agree with ya, a bike grows with the ability and personality of the person. My KLX300 was my first dirt bike and in the begining I crashed it a lot so I had to replace some of the stuff and when I did I replaced the parts with nicer components. So much so the last big ride I went on some of the guys that I only ride with once a year thought that I had gotten a new bike! The Stroker susp, and the big bore kit, pumper carb made a huge evolution in what the bike could handle in the desert of southern california!

I am sure that the future holds a lighted version of a 450, but for now the KLX is where it is at for me!


I agree with you 100%! It doesn't matter what you ride.......the only thing that matters is the fact that we ALL RIDE!:ride: Thats why we buy these two-wheeled machines.:p (And to get away from the wife:thumbsup: )

Does anyone know if keihin discontinued making the FCR-MX 35mm carb a.k.a. the one were talking about... I went on their site and I only found info for the 37 and 41 mm's. It seems like from the look of the site that the carb was discontinued. Or maybe it's just much harder to find since very few bikes use it due to most motocrossers being eith 250s and 450's and the 35mm venturi size is not common? anyone help me out here just wonderin'?

Check with for their part number 016.693


It is a 35mm FCR for Suzuki DR350. It MIGHT be the one.

Ride on


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