Engine won't start, runs only on choke and almost fully lean

[crassius]

I were looking for the gasket and I spotted a beam of light passing through the cylinder's corner XD
Yeah, as soon as I get to the store I'm going to use normal nuts, and for precaution, I will use the double nut method, so that the vibrations won't loose them up so easily!

vibration rarely loosens them - the studs stretch and get longer, the head gasket deforms and gets thinner, and the base gasket squishes down and gets thinner

 

[crassius]

sadly, google gives answers, but gives NO understanding

 

[gary55]

The constant re-torque problem is eliminated with large aftermarket heads. My guess why is that with the cooler running jug and head their is less variation in the thermal expansion of the dis similar materials, and with the greatly increased thickness of the head itself it is less prone to dis figuring and having the non touching corners constantly being pulled down under heat and returning when cooled down.

 

[Otto Neumann]

vibration rarely loosens them - the studs stretch and get longer, the head gasket deforms and gets thinner, and the base gasket squishes down and gets thinner

My engine has been sitting vertically for 24 hours, and I noticed which the really edge of the crankcase's gasket (exhaust side) were slightly wet, it could be due to the fact which I left the 5 screws of the crankcase loose and some mixture came out by capillarity, there weren't any signs of dripping on the table, today I'm going to fit this pepper grinder back on the bicycle and see if it runs

 

[Otto Neumann]

The constant re-torque problem is eliminated with large aftermarket heads. My guess why is that with the cooler running jug and head their is less variation in the thermal expansion of the dis similar materials, and with the greatly increased thickness of the head itself it is less prone to dis figuring and having the non touching corners constantly being pulled down under heat and returning when cooled down.

I got an update: I reinstalled the motor on the bike, and I applied a generous amount of grease around the suspicious crankcase gasket and it still won't start; I sit the plug on the cylinder's bolt and I cranked the motor with the spark plug's tool, and I have a spark, I can't tell if too weak or not, I've seen stronger sparks from an electric lighter.

I'll try to disassemble the crankcase as suggested, do you have any advice before opening the crankcase?

 

[crassius]

My engine has been sitting vertically for 24 hours, and I noticed which the really edge of the crankcase's gasket (exhaust side) were slightly wet, it could be due to the fact which I left the 5 screws of the crankcase loose and some mixture came out by capillarity, there weren't any signs of dripping on the table, today I'm going to fit this pepper grinder back on the bicycle and see if it runs

there are EIGHT screws holding cases together - three more are under the clutch

 

[Otto Neumann]

there are EIGHT screws holding cases together - three more are under the clutch

Yeah, I've seen it on a YouTube video which shows how to disassemble it, my only worry is the clutch spring, it will take a bit of time to get recompressed in place… I'll need to get a good gasket maker and apply the really necessary amount, if some spills inside the case when I'll be closing it back, it will make a mess in the carter

 

[crassius]

???????? - dunno what vid you're looking at, but taking off the clutch hub to get to those screws is simple

note, however that one of them has a washer on it becuase cases were cast a bit too deep for the length of standard screws

 

[Otto Neumann]

???????? - dunno what vid you're looking at, but taking off the clutch hub to get to those screws is simple

note, however that one of them has a washer on it becuase cases were cast a bit too deep for the length of standard screws

There's a YouTube animation that shows the complete disassembly of the engine, so that if I miss something, I can use it as a guide.

Yeah, I'll make sure to don't loose the washer, I always keep them inside the screws and the screws stored into a bowl or something like that, tiny details are quite capable of messing up far greater things

 

[crassius]

all 3 of those are same, but only one takes the washer - you should be able to see one hole a bit deeper than other two