Valve Stem Seals, or maybe throw in the towel

[Big T]

Rich,

Z1 Enterprises has all your spark plug caps

[Rich82GS750TZ]

Rphillips. I appreciate you taking the time to write. I really do. Please understand. I am not going to modify these 41 year old caps. I’m done playing with them. I’m moving on. If you’ve got links for what I need in NEW caps, I would sure appreciate it.

[rphillips]

Rich, don't get too excited with these caps. They're really simple, $80 for caps NO, though that Home seems odd. anything conductive, to replace those resistors will work, we think copper, but a screw with a small enough head to fit in there, cut a 10 penny nail or a piece of coat hanger to fit, I like to make just a little longer than the resistor to be sure both ends fits the inside connectors tight when the little brass thing is screwed back in. then you have non resistor caps. should have a complete full connection, no resistance, from the little pin that screws into the wire through the little brass part that connects to the plug. Heck just play with it, only takes a minute. Some will argue but I've ran them without the resistors forever never changed to resistor plugs and have never had any firing problems. I think the resistors are to restrict static on radios.... The compression test will tell a lot, the carbon on that piston looks normal, I can't see the oil you mentioned.

[Rich82GS750TZ]

Update:


Have disassemble, cleaned and reassembled all plug caps. 2,3, 4 read low to high 9K ohms. So they’re no better. # 1 cap I can’t get a reading at all no matter how many times I take it apart and put it back together. So I now have a new problem I didn’t have before my bigger problem of a mostly dead cylinder.
I will not be modifying these plug caps.
These caps are done.
Moving on.
I will be buying new caps.

Non- resistor caps and switching to resistor plugs seems like a good idea.
Known solutions, specific links for what I need would be appreciated. Parts that are known to work with the 16 valve 750 engine. I don’t know what to look for now.
Would like to put the coils and plugs to bed so I can get into rebuilding one of my other heads.

Endoscopic camera arrived today. So played with that a little. All pistons have quite a bit of carbon buildup on top. This is the offending cylinder # 4. You can see oil pooling in the indents.

[KiwiAlfa156]

Diaphragm is in perfect condition.

Turns out the diaphragm isn't my problem either as I swapped slides and the problem didn't shift. I'm beginning to think coil/ lead/ cap....

[LAB3]

Agree, there's little sense in running resistor caps when NGK resistor plugs are cheaper and easier to find than non-resistor NGK plugs. There are probably some other brands of non-resistor plug out there but at $4ea at the local automotive chain store I'll stick to NGK.

[rphillips]

Just swap 2 of the caps, put 4 on 3 and 3 on 4 and see if anything changes. I'm really interested in what caused this Groups cyl. to quit.... Also what ron said in post #50, remove the resistors, replace them with a piece of heavy copper, and reinstall. Now no resistor to be bad... I can't imagine why you would want one, but if you think you need a resistor, put in a NGK DR8EA, you'll still have a resistor just in the plug and not the plug cap.... $20 for a plug cap??? that's crazy.... Wish you were closer I've got 2 new XD05Fs new in box out in the garage.

[Nessism]

K&S sells spark plug caps for about 1/2 the cost of NOS NGK parts. I'm not sure how good they are, though. K&S turn signals are low quality on the electrical side, so it may be a risky...

Here is another source...

https://www.ebay.com/sch/i.html?_dkr=1&iconV2Request=true&_blrs=recall_filtering&_ssn=4into1motorcycleparts&store_cat=0&store_name=4into1motorcycleparts&_oac=1&_nkw=spark%20plug%20resistor%20covers

[Rich82GS750TZ]

Gonna do that right now, Ed.

[Nessism]

Ed, so should I get 4 of these: I can shop around, these are 19.95/each but they are actual NGK plug caps.

https://www.amazon.com/Spark-Resistor-Cover-Degree-XD05F/dp/B07GFQWQ4V/ref=sr_1_1?crid=2WNH88I1CY58A&keywords=ngk+xd05f&q id=1695222052&sr=8-1

Hey Rich,

Before spending that much, I'd open up your caps and try to clean them out. You don't have anything to loose! If that fails, buy new.

[Redman]

The VB and XB plug caps are for 14mm spark plugs like B8ES. The 16V GS engines, use the smaller 12mm thread plugs, D8EA, so the appropriate matching NGK caps are VD and XD

Ed, Thanks for correcting my ignorance from only having 650g 850g 1100g. I didn’t know the 16valve engines used different size plugs (needed more room for the valves hee hee)

Rich, Yah, what Ed said.
Yah can use four of the longer caps, just that will stick out further than need to (on 8 valve anyway), not a problem unless you are tall and your knee is right there.
also note what Ed said about spark plug size, that is what a compression tester will need to fit (most kits have multiple adapters).

has been a few years, but I recall the plug caps being 4 or 5 bucks each.

other thing to be aware of: some plugs have a thin threaded stud for the wire connector, some have the hour glass shaped more cylindrical connector, the plugs I am accustom to has the hour glass shaped cylindrical thing threaded onto the threaded stud and need to take that off so have the threaded stud….. to be compatable with the plug cap I am accustom to. But since the more knolodgable people haven’t mentioned it, I suppose isn’t a concern with what they have specified.

[Cipher]

Ed, so should I get 4 of these: I can shop around, these are 19.95/each but they are actual NGK plug caps.

https://www.amazon.com/Spark-Resistor-Cover-Degree-XD05F/dp/B07GFQWQ4V/ref=sr_1_1?crid=2WNH88I1CY58A&keywords=ngk+xd05f&q id=1695222052&sr=8-1

Crazy over price.
go to a local bike or speed shop.

[Rich82GS750TZ]

Ed, so should I get 4 of these: I can shop around, these are 19.95/each but they are actual NGK plug caps.

https://www.amazon.com/Spark-Resistor-Cover-Degree-XD05F/dp/B07GFQWQ4V/ref=sr_1_1?crid=2WNH88I1CY58A&keywords=ngk+xd05f&q id=1695222052&sr=8-1

[dorkburger]

Regarding the caps. A few years ago I was chasing a running issue and went thru what you're doing now with the caps / coils. I had to clean corrosion from three even though they were close to spec. The fourth was was bad even after cleaning. At the time they were still available new from the local Suzuki dealer but for more then the price you found for the NGKs. ($25 if I recall). The rubber seals at the bottom of the caps were in poor condition and allowing moisture into the cap. The seals are / were available separately.

[Nessism]

Look for XB05F and VB05F (2 each) . These NGK caps are used by lots of bikes, so maybe can find them at local multi brand dealer. Longer ones are for center cylinders.

The VB and XB plug caps are for 14mm spark plugs like B8ES. The 16V GS engines, use the smaller 12mm thread plugs, D8EA, so the appropriate matching NGK caps are VD and XD