RM250 new problem

[vlxk]

Hi everyone, my RM250C2 is close to completion. I had the cylinder bored 1/2mm and everything is back together except fenders and fork boots.

I got ready to start it yesterday, went back over everything to make sure all the nuts/bolts were tight, oiled the airfilter and got it wedged down in there! Poured a little fuel in (using Motul 710 @ 20:1). Gave her a couple of good kicks and she barked for just a second, then nothing. I kicked and kicked with not even a hint of starting.

Changed to clear fuel line to make sure fuel was flowing, good to go. Removed carb to make sure fuel was getting into the bowl because the clear hose shows fuel going into the carb and filling the fuel line maybe a couple of inches above the inlet and stopping. I thought the fuel would completely fill the fuel line? still no starty.

Pulled the plug, grounded and kicked it, good spark, I can hear it click and see the spark across the electrode. No starty.

Pulled the carb and removed the bowl carefully to not spill any fuel, bowl is full. Kick it multiple times, nothing.

Pull plug, can smell fuel on the plug, test again for spark. Test old plug for spark, same as new one. I can see the spark when cycling through with the kickstarter.

Removed stator cover, the timing mark is centered under the top screw, although the bottom screw is slightly off center.

I am this close () to trying starting fluid to see if it will fire with that.

I have spark, it seems I have fuel, and I have compression, what can the problem be?? The bike ran when I bought it several months ago. It ran even though the crank drive gear nut had backed out to where it just barely touched the inside of the case. The left side crank seal was in crooked, and the float was way off and the pilot jet had been changed to a #25 from #45-#50 as the OE specs say. Now I take the good time and trouble, not to mention expense, to make things right and this is what I get!!!

Anyway, any ideas as to what might be holding things up?

Thanks

[Tomas]

is you rotor siting where it should. it could shear the woodruff key of and that causing your timing being out. hapens to my dads lawnmover all the time. 

[vlxk]

I had not thought of that. I'll check it out and report back.

Thanks.

[bigk]

You don't have a bung in the exhaust do you? Seen it plenty of times, guys forget to take it out, bikes won't start, then by the time they realize the bikes are flooded to the point of having to be turned upside down to drain the crankcase. Just a thought.
K

[William Doe]

You don't have a bung in the exhaust do you? Seen it plenty of times, guys forget to take it, bikes won't start, then by the time they realize the bikes are flooded to the point of having to be turned upside down to drain the crankcase. Just a thought.
K

Yep that's a Classic  guilty as charged 

[motormouse]

Did you remove rag from intake before fitting filter?  A mate carted his bike 100 km to a bike shop to find that one. A bit embarrassed!

[pokey]

and the plug was wet when you removed it? if so its flooded
if it was dry you have a carby/fuel tap issue

[Lozza]

aerostart/start ya bastard problem solved.

[Curtis]

Choke working properly? Mixture screw set currently?

[vlxk]

You guys are great! I travel during the week so I won't be able to do anything with it until Friday night or Saturday.

I don't have a bung plug so that isn't the problem, although I can picture all the hoops one would jump through before realizing the exhaust is stopped up!

I set up the carb per the OE specs, 300 main, 45 pilot, mixture screw 1.5 turns out, float at 13 whatever mm. What about the fuel not completely filling the fuel line between the tank and carb?

Plug was slightly wet, I could smell fuel on it.

There are three marks on the face of the rotor, are those some sort of timing reference?

[tony27]

Pretty sure that the fuel line not being completely full is normal, I run an inline filter on most of my bikes with black lines & the filters always have a certain amount of air in them

[vlxk]

****Update****

Checked the key under the rotor, all is good there. In a weak moment went down to the local Auto Parts store and bought a can of "Start ya Bastard!" and gave it a try. Believe it or not, it made no difference. Wouldn't even try to fire.

My front yard has a bit of slope so I pushed the old gal (motorcycle, not wife) down the yard and clicked it into 2nd gear...nothing...tried it again and it tried to start. Third time it fired and ran although poorly! Lots of smoke and no rev. I had to really be gentle with the throttle to keep it running.

Since it is a fresh bore and new Wiseco piston I didn't let it run long. A couple hours later I tried it again. I had to push it again but it started much easier that time. Still considerable smoke and spooge was dripping from the muffler/pipe joint. I assume it is/was extremely flooded. I dribbled a bit of 2T oil on the bigend and crank bearings on rebuild.

Third time an hour or so later, it tried to start by kicking but I pushed it to get it going. Here's where the next questions come in. It's running poorly, lots of smoke not as much spooge this time. Just to see what would happen I turned the fuel valve off. After a minute or so the old gal (motorcycle not wife) cleared up and had good rev! I tried it a couple more times with the same result. With the fuel valve open it runs like crap, as it runs out of fuel with the valve closed it cleans up and runs very good. I did a little dance with the valve and kept it going for several minutes.

My first thought is the float level is too high. I was very meticulous with the carb. The float is set at 13.9mm as the manual says. I restored the carb to new specs, 300 main, 45 pilot, (had a 25 in it) , needle clip in middle slot, mix screw is at 1.5 turns out. New oiled air filter. Premium 91 octane no meth fuel with Motul 710 @ 20:1.

Changed the float level to 12mm and it didn't make any difference. With the fuel valve open it runs poorly, close the valve and as it runs out of fuel it runs much better. I did notice air bubbles coming up the fuel line with the fuel valve closed,

What should I look at now? The way the carb was set up when I got it has me wondering. Very low float level, 25 pilot, I don't remember where the needle clip was. Very worn piston/rings. Those settings would make it very lean wouldn't it? I'm about 1000ft above sea level here.

Sorry for the long post

[Davey Crocket]

Sounds like the needle and seat are not closing off, there are a few different types off needle/seats for Mikuni's, I alway's put a brand new carby on every resto......30 plus year old carb's are fraught with problems, cheapest part you will buy to make your bike run properly.....under $200 with the correct/extra jets/needles bla bla. Ring T D Hatrick in Townsville tomorrow.

[Lozza]

As above needle and seat.

[ITDOG]

Try roll starting it .....with a bit of speed