Cross threaded spark plug in 50cc 4 wheeler

[Soundguy]

I agree with soundguy. Go to the next size plug. 10x1.0 is the smallest sparkplug threads. Go to a 12x1.25 and forget inserts and repair kits.

I've done that 'upsize' a few times with good results. Always works best the smaller the plug is.

I have some little farm golfcart thing that has small plugs like that. end is like the size of a big ballpoint pen. in my case there was plenty of room to go the next size up... good luck to the op.

 

[paulharvey]

I've done that 'upsize' a few times with good results. Always works best the smaller the plug is.

I have some little farm golfcart thing that has small plugs like that. end is like the size of a big ballpoint pen. in my case there was plenty of room to go the next size up... good luck to the op.

It's an aluminum head, but figured I'd try the cheapest way first, if for some reason the tap and insert doesn't work, I can over size to the next plug up. If that doesn't work, I probably will call it dead.

 

[Soundguy]

as long as you have metal in the port to upthread, then yeah, going to a larger size is possible. depending on how large you go up.. you could even upsize a couple times and install a repair bushing.. similer to an anti fouler, if they make one for your size engine.. then grind it onthe underside if needed, for clearance, stake it in and go.

 

[Jimmy Joe]

I would use the heli coil, it will be stronger than the original set up. Put the piston at top dead center pump grease in the hole before drilling. After drilling suck grease and filings out with shop vac.

 

[paulharvey]

The insert and tap finally got here from the slow boat from China, and guess what.... the OD of the inserts are 10mm, the ID is maybe 8mm, so this "10mm sparkplug rethreading tool" is completely useless. Now, I may have to so the 14mm thread and whole new plug,

 

[Soundguy]

weird. you'd think they would have advertised both diameters.

I think I'd take that hole to the next standard size and have good permanent threads in parent metal. ( if there is room to do this. )

 

[paulharvey]

weird. you'd think they would have advertised both diameters.

I think I'd take that hole to the next standard size and have good permanent threads in parent metal. ( if there is room to do this. )

Just picked up a M14x1.25 tap at Lowes, marked down to $8 from $16, and it comes with a M18x1.5 as well. I figured that was a sign. If for any reason that doesn't go well, I found a whole head for $27 on ebay, I just have to double check measurements to make sure it would fit. These Chinese parts don't seem to like to list model numbers and info very clearly

 

[paulharvey]

As an update, I got the M14 threads tapped, and it's actually a Qiye 110cc. Looks like the engine is some Chinese Honda copy.

The new, bigger plug isn't sealing up well, and I'm loosing compression around the base of the plug. I plan to barrow a Dremel this week end, and smooth the area so it can sit right. Even if that doesn't work, looks like a new cylinder head with valves is only around $60. I know I'm probably going to be into this way more then I wanted, but I figure it's a good project for me and son. I've got spark, but it didn't look super strong, so a new coil may be in order as well.

So, I had to admit it, cause I did a pretty dumb thing; I think the reason it died to begin with is.... drum roll, gas was turned off... so I never needed to pull the plug to begin with,

 

[Threepoint]

[snip]
I know I'm probably going to be into this way more then I wanted, but I figure it's a good project for me and son.
[snip]

That right there makes it all worthwhile, IMO! :thumbsup: Good luck.

 

[Soundguy]

is the face the plug gasket sets on true? it will need to be.