I recently purchased a 96' XR400 from a guy who had it less than a year. The bike ran great up until I took it to the shop to have the valves checked/adjusted. I also had them check why the bike was hesitant to return to idle. The shop adjusted the valves and told me the throttle cables were bad, which I replaced myself.
Now the bike hesitates off idle, enough that the motor will die if I'm not careful. I didn't check the performance before I changed the cables, so I'm not sure if I screwed something up or if the valve adjustment caused the problem. Also, the change didn't fix the return to idle problem. The idle problem is intermittent, so I know that the idle adjustment is not the issue. I lubed the cables thoroughly before installation, and the throttle housing is clean and lubed.
I'm going to remove the carb and clean accordingly, but I'm not sure if there are any specific areas to focus on regarding the problems I'm having...

1. The hesitation off of idle
2. The slow return to idle

Any information is greatly appreciated.

jeford said:

it is odd that the carburetor was not touched and the symptoms happened after the valve adjustment.

I would chek the throttle cables for tension for the slow return to idle first, but...

Both symptoms, the hesitation and the "hanging idle" are pilot jet related. You can work on the 1996 model carburetor and I would start with the pilot jet, but if it were me I would find a 1998 and later carburetor, which eliminated the cranky jetting issues of the 1996/97 series carb.

I think you're on the right track there with a good carb cleaning.

Also, I've checked my valves enough to know that I hardly ever get it right the first try. Get some feeler gages and check them yourself.

AHRMA17L said:

Sounds like a plan. I have no idea when the last time the carb was cleaned, so it could use some attention regardless. Any tips on finding a later model carb? I ride in the NW and will have some decent altitude changes during a ride, so a pretty versatile carb is most likely the best. I've read some other threads about the Mikuni carb and have seen some differing opinions. Which is best, late model stock or after market?

I have a stock one off a 2001. I went with the Mikuni and think that the price to performance return is over rated. From the sounds of it I had the stocker dialed in for sea to 1k FASL. I never had the dreaded bog after it was good and warmed up. I think I'm running 62/165 or maybe even 65/165...I forget.

I've dug into the bike, attacking on several fronts. I cleaned and inspected the carb, which has a 62 pilot and 162 main, with the needle in the 3rd slot. I've also checked the valve clearances, and they're dead on. I put on new cables, but I'm having a bit of a problem with the grip. It seems like getting the cable body tight enough not to slip equals the grip sticking. I'm also working on Gordon's mods, which has brought up another issue: I can't figure out how to get the muffler off in order to check the header intakes. It is a FMF MegaMax, Model # 1000. It does not have a clamp between the header and the pipe. I would include a picture, but I can't seem to figure that out either. I'm also wondering if the carb jetting is correct for this bike's setup. No snorkel, stock air cleaner, and FMF pipe. I will be getting a Unifilter, so I'll need to take that into account if I have to re-jet.
Any ideas?

Trying to show the photo.