98 EC250 won't start.

[Marki]

Last year I brought a 98 E250 in parts. I've never seen it run but I knew the previous owner and it was fine until he took it all to bits. I've completely rebuilt the engine. New bearings, seals, piston etc. I finally got it all back together but I cannot get it to start, well not 100% true but here goes. I've filled all the fluids and filled up the carb with premix through a remote tank (pop bottle). Changed the plug and I definately have a spark. Choke has been tried on and off but it won't even back fire/pop/bang/anything. It will run for a couple of seconds if I spray carb cleaner into the carb. I've cleaned the carb twice, it's a real simple design and I cannot see any blockage. Air screw is 1 3/4 turns out. Reed were replaced when I rebuilt the bike. I've tried disconnecting the air box but still no luck. I've tried kicking it with WOT and fully closed throttle, and everything inbetween.

Does the fact that it will run on carb cleaner mean that the piston timing, reed valves and everything else after the carb is working ok? Am I missing something obvious?

Any advice is really appreciated, I've worked out that about 200 kicks is my limit for a days exercise!

 

[gasgasman]

You need 4 things to make and engine run.
1)Spark
2)Fuel
3)Compression
4) Air

They all have to happen at the right time.

I think you spark timing may be off. Is the spark a nice blue arc?

 

[pscook]

It might be that you need more gas in the carb to get it to draw properly. Also, did you clean the carb? If the pilot jet is plugged it will not start (or will have difficulty starting). Pull the bowl, pull the pilot, and look for daylight. Also check that your slide is completely down, as a little lift might draw fuel up the main and be drowning the spark. It's a long shot, but there are lots of variables.

it sounds like you are close, just make sure the pilot is clean. If you have cleaned it completely, then i would make sure the pilot circuit itself is clear, from the AS screw to the orifice in the carb bore. Good luck.

 

[Marki]

Thanks for the ideas guys.

Pscook, looks like I'm going to have to clean the carb again .

I think you spark timing may be off. Is the spark a nice blue arc?

Spark looks fine. What makes you think the timing is off?

 

[gasgasman]

If the timing is off, it won't fire off the fuel/oil mixture. But it would the thinner carb cleaner.

The timing would have to be drastically off though. Like a broken keyway on the flywheel.

 

[Marki]

Ahhh ok. If it makes any difference It'll happily fire if I put a teaspoon of premix down the plug hole!

 

[gasgasman]

filled up the carb with premix through a remote tank (pop bottle).

Does the pop bottle have a vent on the top? May not be getting the full flow of fuel.

 

[Marki]

I cut the top off the bottle and hung it from the ceiling. The carb doesn't seem to be drawing any fuel that is why I 'think' it is either the reeds or the carb. I'll give it all another go tomorrow. I need the rest having tried to kick it over for a hour ;-).


Just thought I should check the compression just in case.

 

[gasser]

Do you have a filter between the pop bottle and the carb that could be blocked?

 

[Marki]

Thanks for the suggestions guys, it is all sorted. It was my own fault for not double checking the carb. It turns out that the needle valve was sticking once the carb was assembled.