Well ever since around November or December I have not been able to start my beloved 400 http://forums.atvconnection.com/hond...estions-8.html.

At first I thought it was just being cold blooded, but I realize now that is not the case. Before spring gets here I would like to make sure it is up and running. It cranks over just fine, gets fuel, gets blue spark, has compression (135psi), I pulled the head and checked the cam timing is spot on. The only thing is will do is backfire once in a GREAT while. When it does it is like a cannon fire. Shot ether at it and no change. The only thing I have noticed is that it seems that it sparks like 4-6 times per stroke. Could the stator have went bad maybe?

Any thoughts?
PLEASE HELP!!!

 

Have you tried replacing the plug?
It may also be your CDI

 

I tried a new plug, still same deal. I read some where before that if it is getting spark, a nice blue spark, then it is not the CDI.

Starting to wonder if it is the pickup coil. That is the only thing I can come up with.

 

Sounds like a timing issue to me because you mentioned the backfire every once in a while Great while. How was it running that last time you had it out? When you pulled the head to check the timing did you try using a timing gun on the flywheel marks too? Has any work been done to your quad before this started happening? You are right about your CDI If it has spark your CDI is good (they either work or they dont).

How about having BAD GAS? Dump some out into a clear water bottle and check the color, if its clear your good. The more color it has the worse it is.
A lot of people underestimate this one the affect of having bad gas. Also it will gum up your carb pretty good.

 

I think it is timing also just don't understand why.

Last time it ran was Late October early November. It ran like a top like always before. Didn't miss a beat, riding wheelies and all. I pulled it in the barn let it cool down and shut it off.

I guess I haven't actually dumped any gas out and looked at it, but it was fresh gas in the end of September at the latest, I am sure I put a little Stabil in it too.

I tried to start it one day in December when it started to get cold and it would just crank and crank and crank. Hit it with ether and nothing. Tried warming it up first with a salamander and it sputtered a little but still wouldn't fire, but that was the closest it ever came.

As far ask work done, it is pretty healthy. White brothers pipe, K&N air filter, and new last year 12:1 compression piston 60 over, stage 2 Hotcam, Jetted carb, and FST cooler mod. The cam and piston have MAYBE 30-40 hours on them tops.

I think there is something up with the pickup coil but don't know how it happened. I haven't put a timing light on it yet but when I crank it with the plug out it looks like it sparks probably 4 times per stroke (just going off of sound of the piston moving). At least that's the way it seems. I will put the light on it tonight when I get home and see for sure.

 

Are you running pump gas in it with a 12:1 piston?

 

Yea give the timing light a try on the flywheel. I know what you mean with it sparking more than once in a stroke. Ive seen that before too when i had a timing issue with my buddies quad. I figured "well better to be sparking too much than too little".. I Made sure it was firing when it past the "F" mark on the flywheel and the cam sprocket mark lined up with the mark on the head then put it back together and all was good.

Im not sure about the pick-up in the stator (the way it functions) so i dont want to say anything about it. I know it tells the CDI that tells the ignition coil when to fire but i dont know how to tell if theyre bad... i do know it wouldnt hurt to check it out and see if its positioned correctly and maybe hit it with some fine sand paper if rusty. you could always use a multimeter and check resistance on your coil and stator.

Check your compression. I know you dont want to hear that since its fairly new piston... Another crazy far out possibility is maybe your timing chain jumped. Your Auto timing chain tensioner could have failed. I doubt it but you have to cover everything...

FUEL/AIR+COMPRESSION+SPARK+=COMBUSTION always check to make sure you have those three first

 

My mistake I was looking at some stuff the other day and it is 11:1 wiesco piston I put in. But the answer is yes and no. I run 93 octane then put Mr Gasket Blend no. 9 booster in it.



I havent had a chance to put a light on it yet but hopefully tonight or tomorrow. If not friday for sure. I printed out the numbers for the stator to check them also.

Compression I can guarantee is good. I have no tester since I some how lost the adapter, but cork the plug hole with your thumb and turn it. It1 is at least 100-110PSI to knock your thumb off the hole. I do that it is like a gunshot blowing my thumb back off. Timing chain is tight enough that even with the tensioner backed all the way off I still can not get it to move a tooth. Marks are lined up perfect.

Wish I had more to report, but I ended up having to work my last 2 days off.

 

Wow... youve got me stumped too. Electrical parts can do strange things without obvious physical damge, so i guess thats whats left to mess with. I thought of 1 more thing then i'm out of ideas... I know you said its getting fuel but did you mean the carb is getting fuel or the combustion chamber? Clogged jet maybe? Spray some carb cleaner into the spark plug hole, quickly put the plug back in and try starting it. Just 2 quick shots of it. If you get combustion your timing is good and you probably have a clogged jet.

 

WELL..... checked with a timing light Friday.... Seems to be sparking at the right time. So now looking at other more serious things. Slightly concerned at this point.

When I was trying to check the timing I noticed something that seemed kind of bad, but, seems to me like it could also make sense. When I crank it over there is pressure coming out the top plug where you check the timing marks. Like air blowing out of there. So I am starting to wonder if there is not enough compression and if I am getting a lot of blow by like maybe I have a stuck ring or something of that sort.

But I can also understand why I would be getting wind out of that hole because of the cylinder coming back down making an air pump kind of deal. Anyone else ever noticed this?

In any case yesterday morning I picked up a brand new compression gauge so hopefully I can get that checked in the next couple days. Weather seems to finally be turning around so I want to have it ready to play!