Weird Starting problems orion/dacar 125.

[diff333]

Hey guys i'm stumped on this one hopefully someone has experienced something similar. Btw its the DMJ152FMI motor. I had a previous post regarding the cam timing, just to recap, previous owner changed head and fitted wrong cam gear and bend valves. I replaced the original head, fitted new valves and sorted the valve timing out. I know about the half teeth advance or retard and tried both. Didn't have much time to work on it again till now. Fitted the motor in the frame, then it turned out this guy swapped intake manifolds as well and only way it will fit is with the carb in front right behind the mudguard leaving no space for any kind of filter. Unable to find one that fits, i made a manifold up myself, same lenght, bend and id as the one that came off, bottom flange just turned so carb can fit in the frame. Now here's the problem: no matter what you try it simply will not start unless you take the airfilter off and choke it with your hand. I checked for air leaks, nothing. Starter plunger channels is open, in fact i rebuilt the whole carb making sure there is no blockages. I've tried the needle in every position, its currently in the bottom clip so needle is at its highest, i went from a 95 main to a 102. Pilot jets i have is not marked but i tried 2 different sizes. Tried the fuel screw at the bottom making it as rich as possible, its about 5 turns out now, started at half turn. Still the same problem. If its hot it will start, but if its cold you have to choke it by hand, with the carb set as rich as i possibly can at the moment it only takes one kick to choke it by hand second kick it starts. Once it starts it runs fine i splutter here and there depending on what needle,jet,fuel screw settings i'm on. Regardless of the settings the revs is sluggish when valve timing is half a teeth retarded. Half a teeth advanced is very responsive but blows flames out the exhaust. Regardless of valve timing again the revs drop very slowly, and its not the slide thats sticky. After running it for a while and killing it with the throttle open, the spark plug stays between grayish and biscuit color, never black. Also a puff of white smoke now and then but very little. Which tells me its lean, i.e sucking air on the intake system but i checked it with wd40 several times and no change in the revs. What did i miss? Valve clearances is set at 3 and 4 tho. New ngk spark plug new airfilter, fuel is fresh and clean. Exhaust not blocked. Any body got any ideas? I'm thinkin that maybe the id of the manifold is too small. Btw its a 25mm mikuni. The id of the manifold is on 26 now. The inlet port is 28. Surely 2mm cant cause this problem? Any ideas or advice will be appreciated. Thanx

 

[sean01]

crap that was hard to read mate... try spacing it out a bit hey lol..

anyways, you either have a massive air leak or your carb belongs in the bin..

post a pic or 2 up of this manifold you made and how its all setup on the bike..

 

[diff333]

Sorry Sean, i'm posting from my cellphone, forgot about the spacing issue lol. I'm gonna try upload pics now hope it works. Anyways i believe i might have found the problem, turns out the piston valve has almost a millimeter clearance! I could kick myself for not noticing it sooner. Piston not worn so must be the carb body itself. Trying to locate another carb now will keep you posted. Thanx