XR400 boging right off idle and hill climbs

[gixer]

Hey Gang
I have a 98 XR400. I am the second owner. I am really enjoying this bike. There was I think a supper trap on it. Not sure if it was that might have been another brand. I checked the main jet size in the carb with the service manual and it seems to be the right one. The problem I am having is that when idling if I whack the gas she bogs down. I was told that is what thumpers do. I don’t know but I had a 200cc thumper and it never did that. Also on hill climbs every one says to take them in 2nd gear. Well she runs out of steam in second gear. If you guys have gone to paragon and go near Rubicon Lake if I take those steep hill in second I am sure not to make it. I can do it in first but would like some extra steam some times to get up the hills if ya know what I mean. Any ideas where I should start looking?? Other wise she is running great. Starts up pretty easy. The first start after she has been sitting a for a while is always the a struggle but after that its fine. I know she sat for a little bit and I was told the carb was cleaned but I am not sure how well if at all. I threw a smaller front sprocket on but would like to get some of the pep back in her. I used to see my buddy on his when he had it do wheelies and stuff and his did not have this problem with the hills and what not.
Thanks for any help.

 

[Pantaz]

You say it "had a SuperTrapp" -- as in previously, but not now; I'll assume the bike is back to stock configuration, along with jetting and needle setting. Best guess is the idle mixture is too rich, and/or the float level is incorrect.

The XR's have a pretty heavy flywheel, so they don't respond well to "whacking" open the throttle. By design, two-strokes are more responsive (I'm generalizing here, so don't flame me)
due to lower frictional losses and the simple fact that they fire on every revolution.

As for gear choices for hills, you need to learn how to feel what the bike is doing. You can't choose a gear because "everyone says use 2nd". If you need more speed, upshift! If it bogs, downshift! I rarely stay in one gear all the way up a hill.

 

[gixer]

From what I can tell its back to stock. I am going to double check that one again. I have been playing around with the gears when on the hills and when I get to the top I always here you have to get out of first hit second. Well if I do that I wont make it. Its the same story with who ever I am ridding with. Even guys who have a XR. I am planning to take the carb appart and soak it in some carb cleaner. I saw at pepboys this cleaner that comes in a gallong container that you soak it in. I will do that and blow it out and try to recheck every thing as best I can. I did not think about the needle setting I will have to take a look. Thanks for the input.

 

[Ol'89r]

I am planning to take the carb appart and soak it in some carb cleaner. I saw at pepboys this cleaner that comes in a gallong container that you soak it in. QUOTE]

gixer.

Be sure to take all of the o-rings out before you soak the carb in carb cleaner. Most carb cleaners will expand your o-rings to about twice their normal size.

Changing your needle position will usually help your throttle resopnse. Also, Honda makes a 'Power-up' needle that improves response. I will see if I can find the part # for you.

If you really want to improve your throttle response, go to a Mikuni pumper carb. These make a major difference in the XR400's.

Just my $ .02 :thumb:

 

[TheJunkMan]

I would like to know that part# for a friend that has an 03 and it runs similar to what gixer said and it is bone stock, I also would be interested in more info on that mikuni carb upgrade.

 

[gixer]

Hello
Yes I knew about the O-rings. I did a set once that was really nice. Real nice painted black set. When I went to get them I was like he who took the black carbs out of the cleaner. I did not know the cleaner would eat the paint off. But man were they clean. If you can get the part # for the power-up needle I would appreciate it.
I have hard of the pumper carbs before. I have seen allot of Klein carbs available. I would like to do this but man the cheapest I have seen is 325 for a klein carb. I have bought 4 smooth boar carbs for a little more than that. So that will have to wait a bit as there are some other things I want to do first.
Thanks for the help