XR400 carb replacement

[kristian1ify]

So, loads of talk on the web about putting on a Mikuni flat-slide or Edelbrock pumper carb on the XR400, and transforming the beast.

Not that I have much problem with mine, seems to start reasonably well, and no real problems with hesitation (other than my own of course!) . However, lots of people swear by this as the best thing to do with your XR. Does this apply equally to the UK XRs, or is it mainly the California (restricted) machines?

Anybody on here got any experience of this? I may treat myself if it's worth it, but we're talking the best part of £300, so I need to know that it's going to be worth it.

Be honest now, don't try to justify your purchase if it really wasn't worth it!

Ta for any advice,

[416cc]

I read an interesting article in an American dirt bike magazine, about just such a conversion. I'll see if I can find the article.
I had thought about doing such a carb swap on my XR400, but with the advice that I was given, I was able to modify the standard carb and got some very good results. I posted up these modifications in the sticky at the top of the XR page.

[boney]

hi
ive an eldebrock carb fitted to my xr 250 /280 i have to say its a pig to start when cold although once warmed up she starts fine

[Gotham]

...
Anybody on here got any experience of this? I may treat myself if it's worth it, but we're talking the best part of £300, so I need to know that it's going to be worth it.

Be honest now, don't try to justify your purchase if it really wasn't worth it!

I put Mikuni pumper carb on my XR4. I wont regret it and think it's worth the bucks. Didn't want to play with jets as you have to change them when the temperature changes to get the better results. I like simple solutions.
I purchased it because they claimed you will gain better torque at low revs. And yes I think it's noticeable better. I don't have to play with clutch so much any more, just whack a throttle and it wakes the beast.
And it starts much better than with original carb, especially when bike is dropped. Have started it within temp ranges +20 to -15C° and there is not much difference, it starts with one or two kicks.

[Warthog]

My XR came with an Edelbrock.

Can't comment on stock carb as I've never tried one, but power delivery on my XR was great: nice and crisp and starting was always pretty straight forward: pump fuel with throttle, find compression, a bit of decompress at the lever, big kick and job done.

Edelbrock also has a lot of needle height adjustment, achievable through a dial on the carb, without removing the carb from the bike: great if you want to change filters, exhausts or both....

[boney]

hi warthog
is your eldebrock carb fitted with a choke mines hasnt, i follow the instructions supplied two pumps of the throttle and then kick but most times it takes a lot of kicking any tips ?

[Warthog]

hi warthog
is your eldebrock carb fitted with a choke mines hasnt, i follow the instructions supplied two pumps of the throttle and then kick but most times it takes a lot of kicking any tips ?

well, I don't have the XR anymore, but this is some background:

Mine had a choke. It was a little lever on the carb (right side IIRR). Choke Off was the lever pointing at "3 or 9 o'clock", On was turned to "12 or 6 o'clock".

However, I never needed the choke. To start the bike I opened the throttle wide twice (to pump fule into the carb). Kicked the engoine over until I reached the firm TDC, pulled the decompress lever in, ease the engine over a tiny bit further with the kick start, release the decompress lever, big kick with a twist of the throttle and it usually started first or second kick.

Is you bike otherwise standard? Any accessories that would require you to change the mmixtures? May be you bike is running lean... Either way difficulty starting could also merit a valve adjustment check, and a compression check just to be sure...

[boney]

hi warthog
thanks for the reply my bikes a xr 250 witha 280 big bore on it just had new rings, valves and carb serviced like you say it might be running lean ill check the plug or maybe i havent learnt the nack yet
cheers