Replace cylinder head or repair damaged sparkplug port?

Did a bunch of maintemance on my ‘82 XJ650 today and decided that I should have a look at the spark plugs before taking off on a ride. Turns out I should have left well enough alone. The previous owner crossthreaded the hell out of the spark plug on cylinder 1 and I am likely done for the season. I’ve got a bunch of aluminum shavings in the cylinder and there is no hope of saving what remains of the threads in the head.

I haven’t started looking into it yet, but does anybody have an opinion on what will be cheaper and quicker; replacing the head or installing a threaded insert?

While I’ve got the head off, anything else I should tear into?
Recommendations for parts to have on hand incase things don’t come apart nicely?

Would it be quicker/simpler to pull the engine and do everything on a bench? I don’t have a lift table.

I was planning on checking valve clearences over the winter and resealing/replacing gaskets on a few things that have slow weeps. Looks like I’ll be getting to that a little sooner. I was just hoping I’d get through the rest of the fall and still get to ride while I tear into my MkIV TDI to get that back on the road. I miss driving a car that gets better fuel mileage than a motorcycle.

 

blow or vacuum shavings and helicoil spark plug hole . put grease on tap and drill to pickup shavings as they are cut.

if cylinder is close to opening exhaust valve turn enough to blow shavings out the exhaust. add a small tube to end of vac hose to reach into cylinder to clean out

 

cylinder head can be removed when motor is in bike. if you remove it replace valve guide seals. look at cam chain guides

 

You can also use a tread chaser ,or a tap I bought one at autozone it is specially for repairing spark plug threads . Using this you do not have to pull head .

 

Insert.

Fun fact: aluminum shavings melt really easily in a cumbustion chamber. So don't sweat if you have a few chips in there after you vaccum it out.

 

Not enough threads for a chaser. That is probably part of what got it to the shape it is in currently. Most of the threads came out with the plug

Getting the chips out was my main concern. Fixing with the head on seems to be the standard way to repair the issue.

Looking into the Time-Sert kit. I'll have to call around to a couple of places tomorrow to see if I can get better pricing on the account from work. If not, there are a couple other threaded insert options to consider.

 

A helicoil repair kit , last one I bought was from NAPA was not real cheap as I recall was about 30$ but did the job .

 

Or— pull the engine. Have a friend get it onto the bench for you. NOW—- you can do all the work, and even more if you wish, in the warmth of your shop and when you’re done you can clean, degrease, repaint, and detail your engine before it goes back in!!

 

Or...pull the head, weld up the hole, drill and retap.

 

It's just gonna get dirty again...if used correcty.

 

But if it’s kept clean........

 

There is a good chance to cock this up if you do it in the frame - simply because if it's out of square the plug won't seal - there may be an insert that cuts the face as well- I don't know tbh.
Put the engine on the bench, and if you can get someone who's done a few of these to do it for you.

 

Yeah, my bike doesn't stay clean. With the roads I tend to find myself on, I would spend more time cleaning than riding. Looking to pick up a Himalayan, or maybe a Tenere 700 if I feel like spending the money, for next season so I don't have to turn around when I start bouncing off of rocks. An underslung exhaust and street tires don't belong that far back in the woods.
I may be doing some customizing over the winter that will keep this bike more on the paved roads and reserve the gravel back roads and logging roads for a more suitable adventure bike.

I'm waiting to hear back on pricing for a Time Sert kit. It recuts the spark plug sealing seat in addition to the recess for the insert seat. Time Sert is likely the most expensive option, but it does provide the most reliable repair and has the lowest risk for the threads being misaligned with the original threads. Hopefully the company discount applies.

I've had to do enough standard helicoil repairs and oversizing exhaust studs on the XJ to know how to do the process and what it feels like when things are going wrong. My main concern was doing the job with the head on the engine. I haven't had to repair sparkplug threads before (hell, I haven't had a vehicle with sparkplugs in a good 6+ years/240k+ miles). The plug port is very well exposed with little risk of interference from the frame or tank. After doing some reasearch combined with replies here, I am confident that I can manage this with the head on the engine. I have access to a borescope, or I may pick up an inexpensive one.

With the ridiculous project at work, I seem to be running out of patience in other aspects of my life. I overreacted a bit with my first post (done for the season). The process is simple and straight forward, depending on the willingness to spend the money on the correct tools. I've got the skills and experience necessary to do the job, it is a matter of finding the correct tools and process.

 

HAHAHAHAHA!

 

It's not ridden often enough?

As if I can talk, what with my 1 1/2 years of not riding prior to this summer.

 

I'm a machinist's kid. Many solutions to every problem, and many problems with every solution.

 

That’s a good saying, I like it.

I ended up grabbing a Time-Sert kit. It was a bit spendy, but it is an amazing tool. Quickest, most straight forward, and most worry free thread repair I have ever done. Just waiting for a new plug to arrive in the morning and then I’ll be ready to ride. I think I need to figure out a way to do a loaner tool program here so anybody else with the same issue can have it fixed quickly and cheaply. Although I hope nobody else has to deal with the damage I had to. The exhaust port for that cylinder has aluminum spatter on the walls. Those threads were damaged for a while.

Thanks to everyone that responded here. I was a bit hesitant to trust the recommendations of cutting threads with the head on at first, but after searching around for a bit (I would have been more hesitant to trust the search recommendations if I read those first) I realized it was the best way to go. I skipped greasing the threads of the cutter though. I think you would be more apt to get chips stuck in the cylinder if were to get recut and drop off covered in grease. I didn’t take the time to research cheap borescopes, but I am fairly confident that I got all of the chips and shavings out with compressed air and some tubing.