Kymco 250cc - Can't Start it

[garibaldi]

Hi,

I just installed the MRP 300cc upgrade kit on a 250cc Kymco motor. Now I can't get it to start. I put my hand over the carb intake while cranking, and it has lots of suction, and lots of fuel. Brand new spark plug, and it's sparking. Battery is fully charged. It just doesn't seem to want to fire. Just cranks and cranks. It's not even trying to start. Any suggestions?

[Shaka]

Did you change the carb or at least the jet?  Seems to me that you would need more fuel.  I had the same problem when I did my 70cc upgrade.  I'm still trying to it fully tuned.  All of my issues have been with getting the carb adjusted properly.  I just can't seem to get enough fuel to it!

[garibaldi]

The carb thing crossed my mind. But I figured the stock jetting would at least let it start, especially with the bystarter adding extra fuel when cold, etc... I even tried spraying carb cleaner in while cranking. That didn't even make it try to fire (except that it caught on fire on the outside...    that was fun.)

I'll start looking for a scooter shop local, and get underway with the jetting thing. It's something to try. But even with lower fuel access, shouldn't it at least kick over and attempt to start? I covered the carb inlet with my hand while cranking, and it about sucked my fingers in, and my hand came back soaked with gasoline, so I know it's getting fuel and spark (the fire mentioned above...).

I keep thinking maybe there is a "safety switch" that I'm missing or got unplugged? I have it on the center stand, with the side stand folded up. The kill switch on handlebar is set to run. I'm holding in the left brake lever, the key is on... It ran before i took it apart.

Oh, and can someone answer this: How often does the spark plug fire on this motor? Is it every stroke, or does the electronics somehow keep track of which cycle it's on? how does that work without a mechanical distributor cap like on a multi-cylinder engine? (I'm new to this small engine thing).

[zombie]

It may sound too obvious, but try putting the air box back on. Lot's of these scoot's are soo senstive to mixture ratios that they will stall if the box is off. There is a Pulsar coil Mounted to your engine case that delivers a signal to your cdi box when it needs to fire. The flywheel has a small tab that energizes the coil on each revolution.

[Shaka]

Pull the spark after cranking it and see if it is soaked in fuel.  It may just be dumping too much for it to fire.  This will give you some indication of which direction you need to go with getting the carb close enough to start.  It's probably either way too rich or way too lean.  Set both the idle and the mix screw on the carb at about 1.5 turns out from all the way in.  This is usually a good starting point to tune from.

[OldGuy]

First thing that comes to mind for me is did you get the cam timed right?

[garibaldi]

First thing that comes to mind for me is did you get the cam timed right?

That's the first thing that came to mind for me too. I have pulled it apart at least 6 times now to check and test and readust it! Tedious. That's why I asked about the spark thing. I thought maybe I had it off 180 degrees. But if it fires every crank revolution, then that's not an issue, but I flipped it 180 anyway, just to see. I've even tried rotating the cam one tooth both ways.

The manual isn't real clear, so I'm working off the assumption that the little cap with the big screwdriver slot on the RH Crankcase is the view hole where the "T" mark is supposed to align. If that's not accurate, then cam timing is my problem. When I took it apart originally, those 2 punch holes on the cam weren't perfectly aligned with the head, so I'm not sure what was/is going on.

The weather finally cleared up, so I'll give the carb an adjust today, to see if that helps. That's probably what I should have done first. Don't know how the previous owner had it set.

Thanks for the input guys!

[garibaldi]

There is 2 vacuum hoses on the intake manifold between carb and cylinder. I pulled one off while cranking the engine. There is a VERY strong stream of air blowing OUT of this "vacuum" hole... Why would the intake side be pressurized like this? Is it valve timing? If so, can someone possibly give me some input on how to set the valve/cam timing correctly? I have it exactly as the service manual says (I think). The big hole on cam is up, the two little holes level with the head surface, the "T" mark lined up in the little viewing hole.

At this rate, I'm going to do the entire break-in process with the scooter's starter motor...

Stupid question, but when looking at RH crankcase side, the motor IS supposed to crank in the clockwise direction, right? 

[garibaldi]

I finally gave up and took it to a shop. They said their leak-down test shows 95% leakage in the head. It's only getting 30psi compression or something. They will charge another 1.5 hours to tear it down and diagnose... then more for fixing the problem, parts, and reassembly. Don't really want to pay the insane shop rates for this so I'm heading out to pick it up and do it myself. Anybody have a link where I can get new valves? Funny that's the only part I didn't tear down. (I had to move, so scooter has been on hold for a month.)

At this rate, it looks like if I want to ride it at least once this year, its going to be on ice in freezing temps while its snowing.... 

[zombie]

If it is still the stock head, Stadium Yamaha has the best OEM price, You can also try Kymco Parts On Line! I think these shops should start giving a kick back!

[garibaldi]

Thanks for the quick reply. I went and got my scooter back from the shop. I don't know why I was thinking they wanted $72/hr (which is painfully high). But when I got the invoice for $90/hr, I was pissed. Good thing it was only 1 hour for the diagnostics! So, with tax I'm $102.51 poorer.    That was an expensive leak-down test.

So, now I have the head off, and I'm looking at it. And I'm seeing lots of light around the intake valve... that would explain why it was pumping air back into the intlet side. And why it only had 25psi compression. How did I miss this?    $102 stupid moment. Starting problem solved, I hope.

Can someone help me decipher the part number for the valve seal? It shows part 2 numbers: 12209-GDB4-68A and 12209-GDB4-68B, with both saying 2 Required. Does the A/B differentiate between intake/exhaust? Or is the A/B signifying some other special engine variation that I should know about? Or do I actually need 2 of each for each valve?

[zombie]

What year, make, model do you have?

[garibaldi]

Its a 2006 (Mfg Nov 2005) Daelim S2-250. The head says "Kymco KHE7 1" in between the valves, and "KHE7" on the face of both valves, if that matters.

[zombie]

From what I can see it is 2 seals per stem A being intake   B exhaust. Tear yours down to verify it. The stems are different diameters so that explains the a/b #'s. as for 2 seals per stem I don't see why not!

[garibaldi]

After disassembly , there is a single seal on each valve, and they appear to be identical. So I ordered new seals and valves from a local shop. Whatever he gave me matches exactly what was there.

So, here's the weirdest thing. I just put it all back together. Set the cam timing exact by the book. Visual check shows both lobes pointing down, piston at TDC, rocker arms have clearance. I set the clearance to .003" (book says .1 mm, google says that equals .003"). Super carefully put it all together, triple checking everything. Hand crank to make sure it spins freely. Compression feels MUCH better now.

Ok. so I hit the starter, and I got the most horrible CLACKing sound!! I'm certain it's smashing into one of the valves. So I take the valve cover off, and back out the valve clearance adjusters all the way out to see if that helps. Same exact nasty sound. I don't feel anything when I hand crank it though. So, before tearing it down, I pulled out the intake rocker arm shaft and rocker arm completely. No intake valve now. No sound.

Next, I put the intake rocker arm back in, and pulled out the spark plug. No sound! What? If the piston is hitting the valve, what does it matter if there is a spark plug or not?  Is the valve hitting the spark plug? I put the plug back in only 3 turns, just enough to hold it in, but not enough for it to be sticking into the combustion chamber. CLACK CLACK. WTF?? (the spark plug is not plugged in at this point, so it's not ignition firing.)

It's a very solid metal-to-metal impact sound. But it doesn't happen if either the spark plug or the intake valve is removed. And there aren't any signs of impact on the spark plug either. And it is the exact spark plug specified in the book. NGK DPR 7EA-9.

I'm stumped. Guess I have to strip it down again, and have a look inside. grrr....