Scooterotica

Hiya

I think I'm after some divine insperation. Fitted a brand new Malossi 166 to a px125 lump with a scorpion exhaust and a 17mm cut crank. The kit was from Readspeed and the head has been machined by Jerome.

It fired straight after fitting the engine and ran sweet for a minute or so. I turned it off and went to the pub. Now I can't get the bloody thing to fire up.

The one thing I did do was that I left the fuel tap turned on overnight. But other than I can't think what I may have done to change the setup. Now I'm pulling my hair out.

What I've done so far:
I've tried different jet settings and there's definately fuel getting through. I've drained the fuel and tried fresh stuff. I checked electrics and they seem fine. I've tried a number of plugs and swapped out the CDI. However, compression seems to have got progressively worse, to the point now that there is hardly any there. I dropped the new oil and it doesn't seem to be contaminated with fuel. I took the head off and the piston is the right way round. So I'm at a bit of a loss.

My next course is to drop the engine and strip the kit to see what I can see. After that I'm wondering whether the fuel has contaminated the oil seals and compression is being lost through the crank. So that will be the final act, but I'm wondering whether there might be another reason for the problem. Could it be the head and Jerome's fettling? He's probably done one or two of these though!!

Any ideas?

Whip the head off and check the bore , losing compression is not a good sign. Even if seal has gone there will be plenty of compression. My quick guess is poss a circlip has came out , but you'll be better double checking everything. Good luck and stay out the pub till you suss it!!

Check the woodruf key on crank/stator not sheared

Woodruff key good - forgot to mention I also tried changing timing........no difference.

Not clutch binding on , making you think compression down?

As Bazman said above....sounds like one or both of your circlips has come off the piston /crank, happened to one of our club on the way down to Scarborough at the weekend and the exact same symptoms.........hope it's not that though mate

Did you check the bore when you had the head off?

What's the outcome of that then? - damage to the rings and, God forbid, the barrel?

Suppose that would account for the loss of compression then.

Afraid so mate, possible damage to rings, piston and bore (my mates was) and you need to find out where the circlips end up - you don't want them damaging anything else later.

If its not the circlips. Have you checked for spark. Take plug out, reconnected to lead, rest plug on casing holding the lead not the cap and depress the kickstart. You should see your plug spark. If it does, squirt about 10ml of neat fuel down barrel, hand tighten plug and then give it a kick. You may need to try this a couple of times and have your choke out. This will help draw fuel into the carb float and start your engine. I always use this method after a rebuild and sometimes squirt neat fuel directly into carb.

Yes mate......tried all that. There seems to be plenty of fuel getting through. Too much it seems to me. I've even tried heating up the plug.

I'm almost getting to the point where I'm going to torch the cockin thing!