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400ex wont start after re-ring.

9K views 32 replies 6 participants last post by  Helmut 
#1 ·
Hey guys first post on here. I've had my bike for about 4 years and I re ringed it friday. Everything went good and we gotter back together and now it won't start and run. You can hit the throttle about halfway down and it'll will like sputter everytime the motor turns over but it never will catch and run. Can anyone help me with this problem. I'm in desperate need of it to run. We gotta get some cows up. Thanks in advance.

Pitman
 
#2 ·
Sounds like the timing is maybe off or it doesn't have enough compression to fire up.
 
#3 ·
Well I've had the valve cover off a hundred times adjusting the timing over and over and over andit all has the same results. I've gotta new plug in it but we haven't don't a compression test yet. It ran perfect before we tore it apart. Is there any chance it could be the ignition control module I've read up a little bit and I see that it does the timing. I've also tried shooting it with a shot of ether and it won't even run on that?
 
#4 ·
Does it have good spark?
 
#7 ·
According to my manual, 100-128 PSI.
 
#10 ·
Did you put the ring gaps in the proper places? The only other thing I can think of would be the timing.
 
#12 ·
I'm going to have to agree with Helmut.... there is an issue with the rings. a compression test will quickly determine that.
 
#13 ·
Maybe the valves aren't sealing up.You could have a burnt exhasut valve.
 
#14 ·
Oh boy this is frustrating. All the rings are opposite. Of eachother and the cam is timed at tdc with the lobes pointed down and all the lines on the cam sprocket are aligned evenly.....is there anything else that I coulda knocked outta time? Why won't it run on ether?
 
#15 · (Edited)
have you checked compression?? and make sure the key is on and the red slide lever is on.

Do you have a strong bright blue spark?
Did you forget to plug something up?
 
#16 ·
I agree you should check your compression. You can take the spark plug out and put your finger over the hole. It should have at least enough compression to blow your finger off the whole and make a loud pop, this is how i found out my bike didn't have enough compression. I would still use a compression checker though if you have one. If not you could have a burnt/stuck valve or one that isn't seated well and losing compression.
 
#17 ·
Alright I'm definatly gonna check compression and ima take all my wires in the front lose and sprayem with wd-40 and see where I am from there
 
#18 ·
Okay so I stuck my finger over the plug hole and it blew it off but not as hard as I would think so I poured some tranny fluid in there and cranked it with the plug in hopin to gain a littl compression. I cleaned it all out and cleaned the plug up put it back in and it almost ran! It smoke some white smoke and skipped a few beats but soon became short lived and went back to not starting. I'm thinking its gotta be compression. I'm gettin me a ge tonight or tomm to check!
 
#21 ·
IMO it would depend on how bad your rings were that you replaced and what the cylinder looked like. If it were me I would get a little bit bigger piston from Wiseco in the kit that comes with rings and everything and have the cylinder honed and bored to fit it. You may be able to just get bigger rings and have the cylinder honed and board for those which i believe should fix it if it is losing compression through the rings.
 
#22 ·
If you bore it, you will have to get over sized piston and rings, both.
 
#23 ·
The cylinder was scared at all from the rings goin out. It was smooth as can be. We used a cylinder hone to scuff it up a hair and installed the new rings
 
#24 ·
Okay so tonight we compression tested it. It got upto 90lbs and I got another q....we shot it with a small shot og ether and then I smelled the crank case (took the timing plug outta the side) and it smelt like ether. Is there supposed to be pressure in the crankcase?
 
#27 ·
There shouldn't be any pressure in the crankcase, while it's not running. There will be a little pressure if it's running.

I don't like to use ether as it tends to wash the oil off the cylinder walls.
 
#25 ·
You did install the rings correctly didn't you? there is a up and a down to them.
 
#28 ·
IF you ringed it correctly and cleaned the cylinder up good you should have more than 90 on the compression I would think? maybe somewhere around 110 to 130? you may have an issue in the head?
 
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