Left Handed Nut solution?

Hello everyone, I've really enjoyed reading everyone's contributions to making these motorized bikes...I recently made one and will be posting some pictures soon. Mine has been made entirely of angle iron... Anyway now i have a question.

My question is: how have you been attaching the drive spindles to the drive shaft of the engine??? Obviously welding would work but i dont have welding skills...

My 30CC Ryobi engine has a "left handed" threaded drive shaft tip. I took the clutch off and found that it had "3/8-20" stamped into it. I went to the hardware store and found a left handed nut which was also 3/8-20, however when i got home it would not fit, apparently the pitch must be different... I ended up grinding the clutch down to make a nut but i would like to be able to attach other drive spindles to the engine and this would require more nuts, or another way to attach them... What are your ideas? And has anyone been able to find left handed nuts which fit on outdoor power equipment???

Thanks for the quick reply Deacon... I was surprised that the hardware store had left handed nuts too, and they even had the size i was looking for...Only to find out it didn't fit anyway :-( I'm guessing the shaft is 3-4 inches but I'm not exactly sure...Here is a quick picture i took with my phone after i was done...Better quality pictures will come soon.

Thanks for the compliment Deacon. It does look like an erector set doesn't it?!?
I have not brought the clutch to the hardware store to check it. It's funny because i don't even have a real nut, it is just the actual clutch which i grinded down to a point in which it could fit inside the bike peg. The clutch had a threaded hole in it which attached to the drive shaft of the weed eater. The thing that really has been frustrating is that the clutch has the numbers "3/8-24" stamped right into it which is why I bought that sized nut at the hardware store. The nut almost fits on the drive shaft but it stops after about a 1/8 turn and i am pretty sure that if i continue it will strip the threads on the drive shaft... Maybe i'll go and get a 5/16-24 nut and give it a whirl, it wouldn't surprise me if that stamp on the clutch was wrong...

This months "Idiot Award" goes to...Drum roll please.... Me!!!!!!! Deacon, I read your above post while i was at work, and i sat there for a moment visualizing how i removed the clutch from the drive shaft, and I realized it was a standard 3/8-24 nut! I am such a moron! I spent two weeks looking for that left hand nut and even bought a whole box of them off the internet, and i was getting so frustrated that the left handed nuts i did find would not fit on the drive shaft! I don't know where i got the idea that it was left handed, i think i read it somewhere and just assumed it was not standard...
Anyway, i ran to the hardware store to pick up the 3/8-24 STANDARD nut and sure enough, it screwed right on the drive shaft. I could not believe the solution was so simple! So if anyone needs a 3/8-24 left handed nut, let me know, i've got about 20 of them!