Stripped spark threads

So I purchased an 81 xj550, and the spark plug hole thread on one of the cylinders is stripped. I got the plug out but can’t get a new one in. The D8EA is a 12mm and .75 deep but I can’t seem to find any thread tool that will help me. Does anybody have any idea on how to fix this? Need help

 

Will this work ? https://www.amazon.com/gp/aw/d/B07594P3Z6/ref=sspa_mw_detail_0?ie=UTF8&psc=1

 

you need a thread reformer tool not a tap
https://www.amazon.com/SING-LTD-Hel...816&sr=8-1&keywords=spark+plug+helicoil+12+mm

or you can do a helicoil
https://www.amazon.com/OEMTOOLS-256...49404709&sr=1-14&keywords=spark+plug+helicoil

 

you may want to go to auto parts store to get one so you can make sure it will fit inside the fins

a machine shop could fix it for you

 

Autozone , sells a nice thread chaser , think I paid 12$ very handy tool . Unless threads are completely gone I would try this first.

 

Don’t forget to put heavy grease on any tap/thread chaser you use to catch shavings from going in cylinder.

 

NO...NO...NO...
You do NOT want to use any standard tap or thread-chaser for stripped spark plug threads.
You DO want a "BACK-TAP"... (link)

This is a thread repair tool that can be inserted into the cylinder, expanded, and then the treads are straightened when you back the tap OUT.
You do need to use heavy grease to catch any burrs.... that result from straightening the threads.

 

Those do have a reputation for occasionally breaking and requiring head removal to remove the broken peices.
Due care with any tool (this one, or a traditional thread reforming/chasing tool) prevents those sorts of problems though.

 

If you don't have enough "meat" left to chase and rethread the damaged plug hole you can use one of the following.
It provides steel threads and is made specifically for spark plug applications. They are locked in mechanically but red Loctite can also be used for insurance measures.
Do a search and you'll find numerous videos that walk you through the process.
Good luck and let us know how everything works out.

I used one of these on my dirt bike when it blew the plug out while doing hill climbs. I can vouch that these work great and the operation, in my case, did not require removing the head.

 

Have used those save a thread inserts to repair many ford Triton engines that have expelled a spark plug with very good success.

 

Okay so I fixed the threads, thanks guys. Now the next problem is the bikes fuel system, for some reason it’s being starved so I don’t know if it is the vacuum line or what but I pulled off the petcock and it didn’t have any lines to it like it should. The PO installed a inline filter as well. This is how it came off the bike

 

Is that how these bikes petcocks look?

 

The fuel flows freely in the prime position, but as soon as I connect the fuel line the prime position no longer flows as it should

 

do you have the "tank filter" for that petcock?
that part is what sets fuel levels and determines when you need to turn to reserve from Fuel (on)

is there a second nipple on that petcock or just 1?

if it is a vacuum petcock there should be a hose running from one of the carb manifold ports. there are 4 3 with caps and 1 for hose.

 

some of them. that face plate looks like the one on my 550 seca. 550 maxim has a different look. I do not think the petcocks are year specific. just what they had at the time

 

Yeah it has 2 nipples. One is the fuel line and the other is the vacuum line. There is no in tank filter either which is confusing to me. Would that be a reason the bike is starved ?

 

not having the tank filter would let the larger crud through into the petcock .
with out it in place you will have no reserve feature but will operate in both fuel or reserve

remount it on tank do you have a vacuum bleeder ? connect it to the nipple pump and see if gas flows
or put the vacuum hose on it and suck on the end you should be able to activate the diaphragm in the petcock and see gas flow in the run position

you could just need a new vacuum hose 4 mm I would search out a complete petcock and replace the one you have just because the tank filter is missing.

 

So I tried everything you just said and the fuel flows nicely on prime when I remove the inline filter however when I place that same filter back onto the tank side hose, the flow stops which is weird since it is not clogged. Is there a possibility of air from the engine and Carb side stopping the fuel from flowing? Also could the lack of airflow be due to the picture below?

 

Sounds like the fuel bowls are either stuck in the closed "up" position or something is blocking the fuel from going into the carbs. The bowls could be full of fuel already and that is why you don't "see" any flow in the filter. The gas could be so clean you don't see if flowing too.

Do the carbs have fuel in them? There are drain screws in the bottom outside of carb bowl. If you loosen that, fuel should start to flow our of the drain for each of the carb bowls.

 

I just checked the bowls and they do have fuel in them, so is there any explanation besides the vacuum line that the bike is not getting fuel?