All good suggestions guys...so here's the deal. First is that if it was a weak battery that wouldn't start it, then why won't it idle after I pull start it. The battery turns the starter over quick although I'm sure it is nowhere near new, but I really don't see this as the basis of my problem. Second, I stole the whole carb off of the 2001 400ex I borrowed and put it on my bike and my engine did the exact same thing as always (turns over smooth and fast and when I pump the throttle to prime it, it backfires. It does this with the choke both on and off. I will go through my carb again just to be sure, but I'm not real sure that that is the cause either. Whats getting me here is the fact that I drove it for about 10 minutes the other day and it ran perfect in the midrange and upper rpms but would just DIE the second I let it go below 1/4 throttle roughly. Then, with a very warm engine, it still refuses to start or even pop for that matter. Something doesn't make sense here...

 

Mine never liked to idle either, but if I am reading you correctly yours in stalling well before it would be at an idle rpm (is that correct?).

Now that you were able to get her to run with the pull starting etc can we look at this as more of a starting and idling problem rather than a running problem?

I ask that because there are different things I would look at for a starting and idle problem, and others I would not bother with.

In the past the idle problems I have seen that were not from the carb (internally) were mostly from air leaks in the intake (how is the plug now?) and the fuel screw needing a lot of adjustment. There were a few that had float sticking problems too.

Have you tried starting it at half or more throttle? do you pump the throttle before hitting the start?

Also just a long shot but does the other 400 your taking parts from run now? I ask this because I had a problem on a car more than once with borrowing coils to test one in mine that both ended up being bad, so it can happen.

Like the others I really hate to see you have to get into removing parts you dont need to etc, but unless one of the easier things suggested on the last so many replies actually fixes the problem I am not sure that going back to step one and rechecking everything just to be 100% sure would be all that bad an idea. I mean I wouldnt pull the cylinder and the piston, but I would deff dbl check the timing and valve lash etc if nothing else pans out.

Best of luck and keep us posted.

 

Did you get this problem figured out yet?

 

Nope, still boggling my mind. I'm taking the carb apart in the next hour here. The airscrew near the bottom of the carb was completely in however. Just going to check my jets and try to get that dialed in and hopefully the problem is just simply carb related.

 

Run the air screw out a couple of turns then try to start

 

I haven't worked on these engines much at all but if you bike has been backfiring, even one good one, it will throw you carb out of whack and mess up the jets. Another thing to check is your muffler/silencer. If that is clogged up, even a little bit, that can keep it from starting. I would put another silencer on if you can. Use your buddys for a few minutes to try it out. Good luck.

 

If the screw was all the way in it not only could have been the cause of it not starting/idling, but you also want to consider the fact that by overtightening it you can also damage it (the fuel screw) I dont know how to test it, but if you still have problems after going thru the carb again and turning out the screw you should keep it in mind.

Also when you get it back together start with the screw out around two turns and see what happens.

On a side note I happened to be looking at the shop manual for some torque numbers and took at look at the trouble shooting part in the back and it seems you will have addressed all the items listed so unless something tested OK that wasnt there isnt any help from there.

 

I am NOT trying to start anything, but you mentioned that the air screw that was turned all the way in was at the bottom. Are you shure thats not the float bowl drain screw? Just trying to help.

 

This is a classic problem with a rebuilt honda wheeler. everybody rebuilds the motor but does not get new chain guides and a new timing chain. Get a manual their $25 online.

Take off top piece of the engine look at your cam. If you can move the chain at all away from the cam you need to get it tightened.

Another way to check tension on the cam chain tension is to remove the automatic tensioner on the bottom of the head has two bolts that hold it on. if you can put it back in more than 3/4 way in then you need to tighten that chain.

I f your going to do any thing with carb make sure you have at the right float position for your set up. Hell try all positions see what you come up with!!! let me know how that works

 

VD

Curious what your thinking is on the guides only?

Do these wear in a manner that would effect chain operation?

I can understand the problem with any obvious damage, but am not aware of any wear problems that would effect the chain or actuall timing.