Check all the bolts & screws when you buy it.
My brother had his about 15 minutes when the tire came off !
All the little screws... take them out & loctite them. My brother also lost his fuel ****. It just fell off too! Plus the scews in the handlebar ends back out. Other than that I don't think he had any other problems, of course wheels coming off isn't good! Oh yeah, like 75% of Hondas below 50 degrees it doesn't like to start.
c-ya,

 

The stock tires are very prone to sidewall punctures other than that the thing is rock solid. I've checked mine over and over for loose bolts or nuts and have yet to find one, maybe I'm just lucky. I also did a real mean tumble backwards down a hillclimb, the bike endoed quite a few times. After brushing myself off and licking my wounds I hopped back on the thing fired it up and rode the rest of the day with absolutely no problems, nothing broke, nothing bent, on me or the bike. As I said maybe I'm just lucky.

 

The cold starting problem is cured with a #40 low speed jet and 3.5 turns (from bottom out) of the fuel/air screw. You need to check the screws on the fuel valve and the two that hold the black plastic fuel tank cover on each side. Both are prone to come loose. Since the Ohtsu 501's are radials, they are less likely to get a hole in the center. But since they are so soft, they may get sidewall punctures instead.

 

Ive had my 99 400ex for 1 year now getting ready to buy some new rubber for the rear and rear skid plate. Lots of trips to the nut and bolt store. I have had no other problems.

good luck

400ex K&N W.B. E-SERIES 168MAIN JET CDI BOX

 

Hmmm, hard to start problem, change your pilot jet, even your owners manual states that this bike is jetted lean, emissions crap.

Doesn't have any torque int the mid to upper range??? That's where this engine runs best, esp for a stock 4-stroke. Sounds like you need to check your throttle adjustment, 'cause that's what they feel like when they don't get full throttle...

Hard to slide??? See above...

Need help with the throttle adjustment??? gellett@earthlink.net

 

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</snip> Sorry for that little outburst, the forum was having serious trouble and timing out...

 

Without a doubt you will want to change your tires to a Holeshot because you can get a larger profile tire without sacrificing performance.(XCT) I to have had a sidewall blow out from racing But not once have I had trouble with the Holeshots. Also whether the temp is cold or hot or the altitude is low or high, starting your 400 will always bring some dissatisfaction.

 

Without a doubt you will want to change your tires to a Holeshot because you can get a larger profile tire without sacrificing performance.(XCT) I to have had a sidewall blow out from racing But not once have I had trouble with the Holeshots. Also whether the temp is cold or hot or the altitude is low or high, starting your 400 will always bring some dissatisfaction.