I posted in the klx300 forum area.. but honestly it seemed dead so i figured i'de try here, if thats not ok delete this post.. ill delete the other one in the klx300 forum.

I had a few questions,
-Will an edelbrock pumper carb 38mm for a xr400 fit on the klx300? would it be too big of a carb or not fit without major modifications? Does the pumper carb improve acceleration and top speed or just responsiveness of the throttle?
-The bike has a fmf muffler, I just bought a big gun header for it i've read the header makes more of a difference in low end is this true?
-It was geared 14-50 which was a bit low because i'm dual sporting it. i bought a 47 tooth rear will that help my top speed any? just want to be able to cruise at like 50-60 w/o killing the engine.
-I really like the speedometer on the 07 klx250's is there anyway i could wire that up to my 02 klx300? (pic included so yall know what i'm talking about)
-also picked up aceribis rally pro x bark busters which i'm pretty happy about.


Appreciate any answers or info you guys can give me loving the bike so far its a great little scooter to get from A-b around town.

 

The 38 might be a little on the big side, but I'd think with proper jetting research, it might work. I think the bigger problem might be fitment. There's not a lot of room to work with on the 250/300 KLX. I'm not familiar with the dimensions on the Edelbrock carb. I think you'd be pioneering new ground for that carb on the 300. The carb that's just about a straight bolt-up and has the jetting sorted for the 250/300 KLX is the Mikuni TM36 pumper. I installed one last year, and it's been perfect.

Man, connecting all the wiring and such for that instrument panel isn't worth it or even totally possible IMO. I took that panel off my '06 and replaced it with a Trailtech Vapor. I'd do the same with a 300.

On the gearing I wasn't satisfied with the 14/47 gearing. My '06 KLX250 is a 300 with a full Muzzy exhaust, all airbox mods, and a TM36 pumper. I still needed a 13/47 for really good off road. If you're not running that much trail, the 14/47 will probably work.

 

Heres what i got as a response from a seller about the edelbrock-
"The bore is oval shaped, 38mm x 32mm. The outside diameter of the carb where it goes into the intake boot is 44mm. I don't know if it will fit a klx or not. I doubt the cables would fit, because they are for an XR400."

I'm really excited about modding out this bike.. Got it so cheap and already street tagged i actually have some money left over to buy some decent stuff. Ill post pictures every time i get something done to it i guess.

It has a vapor on it, but its cracked in half. Don't know why or how but it was like that when i bought it.. so i guess i'll pick up one of those too.

So for street gearing.. i'm almost wondering if i should go down a tooth in front and run 13/47.. I'de hate to loose out more of first gear because its already so low. I dont have a speedometer right now though so i have no idea what speed i'm going at.. just stay a few car lengths behind cars.. i bought the bike to be a commuter for just around town.. ride an RM250 for off road.

Has anyone used those renthal twinwall bars? they look nice and i think the klx is in need of some new bars and grips anyway..

 

The Vapor instrument panel is an excellent item. The OEM instrument panel you show in your pic is stupidly heavy and doesn't provide much operational data compared to the Vapor. The Vapor is fairly inexpensive for the data provided. Stay with the Vapor.

If that Edelbrock is not a flat slide carb, I wouldn't mess with it. Here's another thing...if you don't know where you'll start with at least some close jetting on the KLX with that carb, you should be in for some serious jetting time and experimentation. If you want a pumper, I'd really recommend getting the Mikuni TM36-68. I love what the pumper carb did with my 300, and all the work for mounting and jetting have already been done.

On your gearing, the 14/47 should be fine. You'll miss the really low first gear, but it's only necessary for slower, technical off road. I've run with both 14/47 and 13/47. Just keep both front sprockets and swap them out if needed for a dualsport off road trip if needed. A lot of places will require the bike to be street legal out west even if it's all on dirt.

 

Alright i'll take your advice and go for the mikuni.

So for gearing let me get this straight i might be a little confused.
I want the engine to not have to struggle to keep 50mph (currently 14/50)
I bought a 47T rear sprocket (14/47) and was told it should give me an extra 5-10mph on the top end, but i would loose speed off first and second gear.
1st gear and 2nd are already very low so putting a rear sprocket on with less teeth will make them even lower?
Keep in mind i'm riding through the city With roads that average 30-50mph.

if i dropped the front sprocket to 13 and put the 47 on there would 1st and 2nd be pretty much non existent? What comfortable cruising speed for the bike would i get you think?
I know the klx 250s is geared something like 14/42 so they are better on the street but they still retain 1st and 2nd pretty well correct?
Maybe I'm just confusing myself.

 

1 tooth up front is worth 3 on the rear. 13/47 should feel the same as 14/50. 14/47 will lower your overall rev per speed a little, or another way, raise your speed per rev.

 

"Lower" gearing generally means that slow speed control in relation to your rpm is improved so you don't have to constantly slip the clutch in first gear to maintain momentum. By technical off road terrain, I mean places where you can't go fast in first gear because of traction, steepness, and obstacles. A low first gear like that provided by a 13/47 setup allows you to creep over obstacles or maintain forward momentum by using the tractor-like power and speed delivery by a very low first gear. Yes, you have a very low first gear with a stock 300's 14/50 gearing...really identical to a 13/47. Personally I don't want any first gear setup "higher" than 13/47...or 14/50. Your situation seems more pavement oriented, so frankly you could go to the 14/42 OEM setup with good results. I only mentioned the 13T front sprocket in your case because you could keep it handy for easily swapping it in and out for different conditions. I believe another option is to use a 15T sprocket with your 50T rear to give you higher gearing and less rpm on the highway. I believe IDRIDR could chime in on this.

I'm not clear on your statement about your 300 "struggling" to maintain 50mph...unless you mean the engine is spinning too high an rpm to be comfortable on the pavement. For the cheapest, quickest solution, you might look into the 15T front sprocket.

 

Ah yes sorry i was confused thinking a 13 tooth front would give me more top end, but a 13t front would be close to 14/50 gearing... so going up a tooth in front to a 15/47 would be somewhat equal to 14/42... i think i understand now. thanks guys..

Should be getting the vapor, bars and grips soon.