550 Maxim head removal, exhaust work, and into the carbs

Well I've definitely got my winter work cut out for me...

I got set to winterize my bike, and part of doing so was to replace the plugs (bike hit 10k and no idea when PO had replaced them).

All went well until cylinder 2 plug got stuck (while hand tightening) about half-way in. Backed it out, cleaned the threads in the head with alcohol and tried again. No dice, so I used a back-tap plug threader with some grease.
Nifty little tool seemed to work slick as could be, but as I drew it up, I found a finger-tip full of metallic bits - presumably thread hunks from the head.

That being said, confirm my suspicion that I need to replace the engine head? Or at the very least remove and do some serious rethread work?

On the laundry list of chores, the bike has hideous hollow pipes on it (on stock collector box), but I found an ebay steal of the stock maxim pipes that I would like to put on. I would assume that the carbs would have been rejetted by PO to accomplish the somewhat smooth performance with hollow pipes.

This means if I want the stock pipes I should rejet to stock, right? How can I tell if the jets have been swapped?

And assuming I have to remove the head, what other work should I do while I'm in there? And in what order should I perform these repairs?

I know 550's are less common, so I'll post pics along the way.

 

You don't necessarily need to replace the head. Since it's an "inner" plug, it might be easier if you have the head off to get the plug hole "helicoiled" but repairing a stripped spark plug hole is a common repair. How "torn up" is the hole; is it now hopelessly stripped, or did you just bugger a few threads?

While the head is off, it would be a good idea to lap the valves and replace the valve stem seals.

My '81 550 came with an open 4-1, never rejetted for it; don't assume your PO knew he had to or did it.

You can tell by reading the numbers on the jets and comparing them to what the stock jets are for your bike. Len has that info buried somewhere in his stuff, or it's in your book (if you have a factory book.)

 

I think about the top 1/4th of the threads are buggered. After reading a bit about helicoil repairs, I think this might be a good candidate.

That being said, I am a bit more encouraged that I didn't royally screw myself over, but this winterization definitely just got harder haha.

 

There are some alternatives to Heli-Coil.

Time-Sert Kits is one.

This is also an alternative.
I used this Kit to "Re-thread" the No.-1 Hole on my 900.
The Head does not need to be removed if you GREASE the Tap to collect the Swarf.
Cut the New Threads 1/2 way.
Reverse and remove the Tap.
Clean, dry and re-grease it for cutting the rest of the hole.

Seat the New Threaded Insert with THREAD LOCKER.
Let it Cure.
Apply AntiSeize to the Spark Plug.

http://www.amazon.com/gp/product/B0025P ... B0025NDK7U

 

Ya, if the PO didn't re-jet when he put the after maket pipes on then chances are you won't have to do anything with the carbs because they will still be set up for the stock pipes.
I would put the pipes on and try it first.

 

Rick, thanks for the info.

As I mentioned, the tap I used took a bunch of metallic bits out of the thread in the head. Because I have a 550, I know the plugs are 12mm, not 14mm, but do any of you know what incline they are - m12x1.25...m12x1.5..?

Perhaps the tap I used was off on the threading, and totally chewed the head.

 

According to NGK, the thread pitch for the 12mm plugs is 1.25.

 

Thanks, Fitz. Interesting... That is the same specs of the back-tap I used, so that is not the source of my problem. Onward and upward as they say..

 

Only you can see for sure, but if the top quarter of the thread was removed by the thread chaser (cross threading ?) and the rest is okay and is used by the spark plug thread, then according to my university engineering instructors, you only ever actually use two-three threads for strength, the rest do nothing until the bolt is stretched/other threads are stripping. If you're thinking about redoing the thread anyway, I'd just put in a spark plug and see if you can tighten it as usual.

If you can't, then a helicoil is the least invasive option and requires the least removal of aluminium. Time-serts are lovely pieces of engineering, but when I last used them (fifteen years ago ?) they needed you to drill out a lot of metal, and then you'd have to be sure that you have a good seal around the insert.

If I seriously wanted to go to the extent of removing the head, I suspect I would either have it ally welded and retapped, or change the cylinder head. then again, I have two-three cylinder heads lying around.

See if you can't just tighten the spark plug first, though - even if it strips it will make a helicoil no more difficult.

The kits aren't expensive either:
http://www.ebay.co.uk/itm/14mm-HELICOIL ... 45ff707885

 

AutoZone offers "Fix-a-thread" Kits for 14 X 1.25 Spark Plug Thread Repair with I have found to be a life-saver.

The uncomplicated D-I-Y Kit is very easy to use.
The TOOL is a Combination Thread Chaser and Tap and Shouldered SLEEVE Installation Tool.

Grease the Tool and the flutes gather the Aluminum Swarf keeping it out of the Cylinder.
Cut half the job.
Remove, clean and re-grease Tool for the second half.

The Tool cuts a slightly over=sized set of Threads that accommodate a 14X1.25 Shouldered Sleeve.
You treat the sleeve with Lock-tite and Insert and stake it in place.

http://www.autozone.com/autozone/access ... ier=141511

 

The first thing to do is pull the tank, and get some SERIOUS LIGHT on what you're doing. Use your shop vac (or substitute) to get the plug gallery clean. Use rags, brake cleaner and carefully clean up the mess and see exactly what's going on. This is an inner plug hole; you need to be able to see what you're doing. I suspect your problem was caused in part by not being able to.

 

Thanks all for the wonderful advice. Just finished finals week in school, so I'll be taking some time and christmas money tofixing this as best I can.

I like the auto-zone kit idea - nice and inexpensive, local, and the guys there typically have some great advice in my experience.

I'll get some pics, or at very least a better description, once I get the tank off and take a much closer look.

 

In the interest of preparing for the worst, I hit flea-bay quick for this find.

Or this one too

Looks like a wonderful deal to me - those intake books leaving the carbs are pricey in my experience.

What do you guys think - should I get this as a spare head/extra rubber bits?

 

Don't use the Lock-Tite that comes with the AutoZone Kit.
When I did, ... even though I treated the Plug Threads with AntiSeize Compound ... the Sleeve backed-out on the Plug and I had to re-seat it.

Use Locktite RED 271.

Clean the Receiving Threads and rinse with Isopropyl Alcohol.
Snip the Cotton off a Q-Tip and put a drop of Thread-locker on the end of the stick.
Treat the Receiving Threads.
Treat the Sleeve's OUTSIDE Threads with Thread Locker, too.

Lightly Oil the Threads of a New Plug.
WRAP the Plugs Threads with two revolutions of TIGHTLY wrapped Teflon Thread Tape.
Smear AntiSeize on the Teflon Tape.

SEAT the Sleeve using the New Plug as the Tool.
Once the Sleeve is Torqued-in TIGHT, ... Let the Thread LOCKER cure.

After the SLEEVE is Permanently Installed; remove the Plug.
Retrieve the Teflon Strip.
Apply AntiSeize to the Plug Threads

-fini-

 

Thanks for the detailed instructions - I'm going to have a go at it.

Would you recommend doing that torquing with an old plug instead of potentially damaging a new one, or is that not likely?

 

The New Plug will have nice, clean threads that will mate with the Sleeve without having any issue that might "Snag" the Sleeve or cross-thread with it.

It screws right-down through the Sleeve and makes the Install nice and smooth and clean.
Leave the Sleeve behind when you remove it; because the Threads intertwine so well.

The idea is to get that sleeve seated just like it needs to be when a Plug's installed.

 

i see that you are going to try other means first, but i just wanted to vouck for the time-serts - holy wowsers, the first time i actially saw one being used, it blew my mind how well it worked!!

Good luck! if you run out of options, the timesert will solve it!! much better than a helicoil, as they have a tendancy to come out sometimes.

http://www.timesert.com/

 

Re: the heads you found on eBay: The one with the cams is a much better deal; however--

you did notice that BOTH of them have broken-off exhaust mounting studs, I hope.