Ever seen one of these things run lean?

[thebook92]

I don't have problems with leaks on the NT carbs once they are firmly seated on the intake, but some say they do.You can see some small cuts in the carb inlet beneath the clamp. You should be able to see the intake slide past the end of those cuts to make sure it is seating all the way on. Some get a small Oring and put it in the inlet of the carb for a better seal. I believe it would be a 19mm OD Oring. Others wrap a little electrical tape on the intake.
The only way the plug could be closing is if the piston is slightly kissing it. Not good. Don't know why your clearance is so low there, cause this shouldn't be happening with a normal reach plug. If your using a plug with a longer reach than stock or you have removed material from the jug or head that could explain it, but it's still rare and needs to be fixed. Have you done a squish gap check?

O-ring might not be a bad idea, I'll give that a shot. Spark plug issue is an easy enough fix: the NGK is longer than the original one by a thread or so (pic attached). Swapped it back in and all was good.

 

[gary55]

O-ring might not be a bad idea, I'll give that a shot. Spark plug issue is an easy enough fix: the NGK is longer than the original one by a thread or so (pic attached). Swapped it back in and all was good.

I figured you probably went to a longer reach than stock. It just kinda throws me that the ngk was to long. This usually isn't the case with the H plugs. I guess if you wanted to stick with the NGK you could try finding a B6LS. They are 1/16" shorter or a B6SS is a full 1/8" shorter.

 

[thebook92]

Tried an O-ring. Helped a little, but still died when I checked it. Wrapped the whole joint in tape just to see, still died. Just for giggles, checked the gasket between the two case halves (directly underneath the intake/carb joint), and it died. I think what's been happening is that the runoff from me spraying the intake is getting into the crankcase via that failed gasket, and I haven't noticed because I've been focusing on the carb.

Now for the $64,000 question: Is it worth trying to split the cases to fix this gasket, or should I just toss another motor at it and call it a day?

And the $32,000 question: if I DO split the cases, what kind of "while I'm in there" jobs should I take care of?

 

[gary55]

That's a loaded question. How bad do you want to know. If all you want is to get something running then a new engine might sooth the itch. It may vary well have a glitch of it's own that will head you toward the same question. Find it or replace it. I'm in the mindset of trying to figure it out so it don't fool me again. You have 2 air leaks as described so fix them acordingly .

 

[Frogslayer]

Cheap and not that hard to split these cases. I just used silicone for a case gasket. If you're not good at working with possibly stubborn fasteners than a new engine would be faster with less sweat dripped.

 

[extremeodd]

I'd suggest splitting it and replacing the gasket. It's less than $10 and only takes a couple of hours if you have no clue what your doing.

While your in there, I'd match the cylnder transfers to the case. If you look at the base gasket once it's taken apart you should see where they don't line up. By grinding the case to match you allow the air/fuel mixture to flow more freely through the transfers and free up some power. That and take the time to clean out any casting defects from your intake, exhaust and transfers. No need to reshape or make anything larger, just grind the case to match the jug transfers and clean up anything that could be obstructing airflow (casting flaws, gaskets that arent port matched, etc).