NC50 stocko shocko install wont fire

Hoping someone can give me some pointers:

Installed a the 60.2cc big bore kit on my NC 50 and now it wont start.

I have spark, have compression, have fuel

stock exhaust, stock reeds, stock head

VM18 carb, with the MLM intake elbow.

I've gone through it like 10 times with no luck.

Re: NC50 stocko shocko install wont fire

Did you touch your timing at all? Your jetting's probably off, what is it?

Re: NC50 stocko shocko install wont fire

Timing was good before the kit so I didn’t mess with it.

I think I’m running a 78 main jet, I think I have a bigger one on hand I can try.

Re: NC50 stocko shocko install wont fire

Jack Rutherford /

That vm18 comes with a 30 idle jet which is way too big. You need a 17.5~ or so.

Re: NC50 stocko shocko install wont fire

Ok, ordering up some new jets...

timing seems perfect. Points start to open just as the F hits the mark and are fully open at T.

Re: NC50 stocko shocko install wont fire

Jack Rutherford /

And also put back in the stock vm18 70 main jet. Get it started with smaller idle jet and 70 main and adjust your idle screw to 1 1/2 out. then adjust your main up or down from there once you get it started and idling right.

Re: NC50 stocko shocko install wont fire

did it run before? maybe reclean points and a new plug.

Re: NC50 stocko shocko install wont fire

Ran great before. I’ve got great spark at the plug.

Re: NC50 stocko shocko install wont fire

is the plug wet w fuel? or black/oily from too much fuel? or dry

Re: NC50 stocko shocko install wont fire

You installed the piston up side down

Re: NC50 stocko shocko install wont fire

Jack Rutherford /

I was considering the upside down piston possibility.

Re: NC50 stocko shocko install wont fire

IIRC some of these Hondas use extended electrode plugs and when you swap out from stock cylinder and piston the longer electrode can make contact with the piston and mess up spark gap and ground it out. Just something to check

Re: NC50 stocko shocko install wont fire

Re: NC50 stocko shocko install wont fire

Piston is installed with the EX down toward the exhaust port. Decomp passage on the jug was filled with JB weld.

Plug is wet when I pull it. Fuel is getting into the cylinder. I would think I would hear a knock or ping if the piston was hitting the plug. The gap on the plug is still fine.

Re: NC50 stocko shocko install wont fire

a flooded engine wont start as well, ru even getting a pop? if flooded turn off petcock, wide open throttle and pull.

What ive seen is the crank seal just popping off which isnt good but happens, dont ask why. im suspecting the one seal under your variator, hard to see and pull unless u have the puller. If theres any wetness in the area its your problem, theres also one under stator plate take a peek.

Re: NC50 stocko shocko install wont fire

no pop at all, I will check it out some more

Re: NC50 stocko shocko install wont fire

Here are shots of the head, stator side crank seal, and piston... still no idea why I can’t get it to fire.

86D327DC-9CE6-4D11-9949-07A889CDF86A.jpeg
EC9689C3-D1CB-4E07-BC5F-6EE0C49591A2.jpeg
30B14A4A-7036-44BA-ABE2-A086894D0E64.jpeg

Re: NC50 stocko shocko install wont fire

hmm looks too clean, is that cylinder scored, i see vertical streaks.

Re: NC50 stocko shocko install wont fire

It’s all brand new, has t fired yet. No scoring on the jug or piston that’s actually fuel in the cylinder

Re: NC50 stocko shocko install wont fire

Inside the case

D508CAD1-B2EA-43DD-91F9-57336F919759.jpeg

Re: NC50 stocko shocko install wont fire

hmm, theres is one more crankshaft seal under your variator. is that side spotless as well?

Re: NC50 stocko shocko install wont fire

Jack Rutherford /

It would be under the clutch on an nc50. I’ve had one or two clutch side seals go bad.

Re: NC50 stocko shocko install wont fire

Here is the clutch side seal...looks pretty dang gorgeous to me! The fluid inside the transmission housing was pristine as well, didn’t look contaminated with any leakage through the seal.

44597B05-F452-49F3-A089-ADED7AE09EC8.jpeg

Re: NC50 stocko shocko install wont fire

^actually, shiny n wet looking are good for pictures but for crankshaft seals are ugly. believe me the seal no good, you'll see when u pull it out. take a close look at the sealing surface on your crank to ensure its smooth, maybe hit it with some 600 grit.

spoiler: what youll find is the seal lip on the inside is partially damaged, ripped slightly or completely with spring floating around. change it out and change the other side for good measure.

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