Wow cant believe this ones still tricking everyone, but I guess in a way its comforting to see I am not the only one getting his patience tested by continuing problems etc. Anyone have a clutch hub they will sell cheap? [img]i/expressions/face-icon-small-smile.gif[/img]

Lets regroup for a second and review what we know already from whats been posted.

1) its getting some kind of spark
2) its getting fuel
3) its got comp (120psi).
4) its got enough of them to backfire
5) 170 main (Kehin or dyno?)
6) Hotcam w/o de-comp
7) tore the thing down completely just to check it over.
8)Piston was perfect, rings good, cylinder flawless,
9)no broken valve springs or anything.
10)Went through the whole carb and got it cleaned out
11)I've also checked and reset the timing several times and its all good.
12)doesn't fire when I sprayed starting fluid down the chute
13)put in a new spark plug, swapped out my rev-box with a known working one (HN1) and still nothin

I am just going to post some thoughts randomly and am not questioning anyone ability or knowledge etc, but I hope one of these ideas gets her running.

First thing that comes to mind is that any sort of misfire or backfire etc could be caused by the timing being off (just one tooth can make a difference) or from a mechanical problem in the valvetrain (which checked out OK) and lastly the more popular fuel delivery problems. Being your running a 170 main on a stock bore with minimal mods I would be first looking at the carb, and deffinately checking the needle and position, the slow jet, and changing out the 170 main to something closer to what your setup would require (150-165 range, but thats just to start, and you would need to dial it in later). I think this may very well get it running even if it needs a pull start, but it shouldnt.

Another that I didnt see mentioned (sorry if I missed it) is what the valves are set at. I know more than one person who after all the hours of work getting everything torn down and reassembled just got excited to see it all together again and completely forgot to set the valve lash. If its out far enough off it could produce the problems your seeing.

One thing thats hard to figure is starting speed of the engine thru the starter, and unless there is a weak battery or a slipping starter clutch gear etc its really hard to be sure of just how fast it really is turning. That is why so many have suggested the pull starting, and it may not be a bad thing to try if the carb fixes dont help.

Only thing left would seem to be re-checking everything one more time, and hope that you can find that one stupid thing that wasnt right that may be causing it not to run.

I am still leaning towards the carb (hows that air filter by the way?) and think you need to really be sure its 100% and make the needed changes to the jetting etc.

Lots of luck too cause I know only too well how much a pain in the **** it can be

 

I don't think that it has been asked but does it have a stock carb? (Does it have a yellow choke lever?)
Do you have a stock exhaust? (Is it black?)

I'm trying to determine your jetting. You said the motor was stock except cam, is there anything else that looks aftermarket or did he claim anything when he sold it to you? The backfiring would be that you are extremely rich??

You should be able to go to any dealer and they will have a coil tester and should test it for free. Call first and ask. Like the previous guy said, you've got to have a quality spark.


After that it's time to jump start that baby.

 

Yep, its the stock carb. Stock header with a DG Xcellerator slip-on. I'm going to try and snag my buddies coil and plug wire off of his 400ex but probably won't be able to obtain that till this weekend. Just want everyone to know that I appreciate your help with this because when you are dealing with it first hand, it gets rather frusturating as most of you know. So I've got to get some specs for you and I'll update you when I find out. We've received about 15" of snow here in the Twin Cities during the last few days so it would be fun to throw the paddles on and go play in the fluff while it lasts. Thanks again to all for your input and bearing with me[img]i/expressions/face-icon-small-wink.gif[/img]

 

Master fuse near battery...might be the culprit. I think they are 15amp. The bike comes w/ an extra in a lil holder.
Good luck.

 

Forget about the coil till later, and get that carb setup right first. Even if the coil is bad your still going to have to straighten out the carb before it will run right or at all.

Check to see what size slow/pilot jet is in there, check the needle postion and lean out if needed, and swap out that main jet, and then see what happens.

If all the stuff you checked previous was accurate and is ok etc it very likely will run after going thru the carb.

And dont forget to be sure the air filter is "brand new" clean.

 

Yah...after all you don't need a coil to to run the engine, right? [img]i/expressions/face-icon-small-wink.gif[/img]

 

I thought I had posted this in my initial description of what was going on but before I even tore it apart, I did have it running for about 10 seconds and it was smooth (with the exception of the cam chain slap). It did NOT shut off on its own; I turned the key off because the slap wasn't sounding too healthy. This was with the airbox off completely, and after I had initially taken the carb all apart and cleaned it out. It was idling high, but obviously running lean because I had no airbox on it at all so that explained itself. Since then, all I get is the occasional backfiring BOOM, and that is with the new plug. Reason I bring this up is that I feel the carb shouldn't be the issue, but it was cold out, 35-40 degrees, and might have needed that 170 main just to run. However, being the main doesn't control the pilot circuit, it really shouldn't have an effect on starting, correct? I will check the pilot and confirm the main, and we'll see what happens then I guess. Thanks

 

Just sounds like a timing issue to me.

 

This may sound stupid, but if you open the drain on the float bowl, does fuel come out?
My 400 has a problem of the float getting stuck. Then when trying to start it, it has most of the symtoms that you described. Just a thought.

 

Sure you do [img]i/expressions/face-icon-small-smile.gif[/img] but when you look at what has been posted so far it looks like the coil isnt bad, and the two issues that stand out are the carb and the timing. Remember that he didnt take the coil out, or disassemble it for inspection like was done on the carb and top end of the engine so there isnt a chance of something being missed etc.

I am not saying that it couldnt be the coil, or even that there isnt any chance the timing or valve lash is wrong, but its a lot easier to remove and inspect the carb, and it can produce the results he is describing.

I have seen personally all three of these issues (fuel, elec, timing) be the problem for a non running 400ex, but the carb seems to be the most common, and easiest to check.

Hope that clears things up a little