Black fouled plugs, good compression, hard starting the longer it sits

[pbdavey]

I tried to put as much concise info in the title. I have a 79 550 that needs a plug chaser on #3 apparently (and maybe a shop vac - what happens if I got any slivers in the combustion chamber?).

That aside, all 4 plugs are fairly black, replaced earlier this year. It does seem to be harder to start as it sits longer (> week), but maybe I'm imagining. I'm in the middle of compression tests which I think will all be okay. The ones I've done are already have okay compression but black plugs still. I haven't finished because of the #3 plug threads. Now there's some oil out on the outside of the head, so I'm starting to wonder if I just need to do my valves and replace my valve gasket...does this sound like a rational solution at this point?

[BassCliff]

Hi Mr. pbdavey,

When I used a thread chaser on my #2 cylinder plug hole, I put axle grease on the end. Then I took it slowly, a couple of turns at a time, removing the chaser, cleaning the end, re-applying the grease, then continuing. The aluminum shavings should stick to the grease as you clean the threads.

If you do happen to drop a shaving or two into the cylinder, it's not critical. They should burn and be exhausted.

When was the last time you checked the valve clearances? This should be done every 4000 miles. Are the plugs fouled with fuel or oil?


Thank you for your indulgence,

BassCliff

[pbdavey]

Last valve clearance is unknown. I'm not sure how to tell oil or gas...it's a dry black, not a wet black...here's some photos...the second is no flash so it doesn't wash out how black it is.

[don_gibb6512]

Dry, black fouling is usually from an overly rich fuel mixture. Check the air box and cleaner to be sure you're getting good air flow. A thorough carb clean is almost always necessary on these old bikes. If you don't know what the valve clearances are, you need to find out and yes, you'll need to change the valve cover gasket. Might be a good time to get your head around the fact that there is no quick and simple fix to making these old bikes right. Takes time, A LOT of patience and good, old fashioned hard work.

Good luck.

[pbdavey]

I was hoping to make it through the season without riping everything apart...oh well!

* Clean air filter
* Clearances
* Rebuild carbs

This will cost a pretty penny

Thanks guys!

[flyingace]

Probably not it, but are those plugs the recommended heat range for your bike?

[Matchless]

* Clean air filter
* Clearances
* Rebuild carbs

This will cost a pretty penny

Only really if you pay someone else to do it!

[don_gibb6512]

If you do the carb clean, be sure to pick up the O-rings you need:

http://www.cycleorings.com/

[tkent02]

I was hoping to make it through the season without riping everything apart...oh well!

* Clean air filter
* Clearances
* Rebuild carbs

This will cost a pretty penny

Thanks guys!

Maybe a valve cover gasket and a bucket of dip, $30 or so total?

[pbdavey]

Shims at $7 a piece. Manometer (whether homemade or prefabbed). Maybe intake boots for $25 ea. and their o-rings cuz I can't get them from the nice guy at cycleorings. See, money can pile up on this .

I believe the plugs are the correct NGK plugs .

[Matchless]

Shims at $7 a piece. Manometer (whether homemade or prefabbed). Maybe intake boots for $25 ea. and their o-rings cuz I can't get them from the nice guy at cycleorings. See, money can pile up on this .

I believe the plugs are the correct NGK plugs .

Buy your o-rings from an engineering supply if Mr Barr does not supply those and use the swap club to swap out shims. The intake boots if required unfortunately will cost you about $25 each, unless they are reusable and not stiff and broken.
Good luck.