Jet size in relation to elevation

[mogollonmonster]

Ok I stepped up the jet size I'm now one size up from where I started, which is .0292. Starting with the needle at the leanest setting (highest groove) and worked up from there. At the richest setting, it was gutless, wouldn't idle, just blah. One setting up the needle (leaner), it idled, but still running rough, four stroking. Should I go a size larger on the jet and look for a sweet spot on the needle? I'm assuming that's how yall do it?

All carb issues aside, I did what I could to tighten down the manifold bolts, as replacing them and checking for casting slag was how I discovered my leaky gaskets. My gasket sealer was trash so tighten down was all I could do. Could the leaking gaskets be the real cause of my problems?

Lets say my carb is tuned perfectly, could the gaskets be causing the issues? Perhaps a leaking intake throwing off air-fuel, while the exhaust is causing a possible loss of compression?

 

[2door]

An air (vacuum) leak downstream of the carburetor can most certainly change your air/fuel mix. A leak allows an excess of air to enter the equation after it has been mixed in the carburetor. It leans out the mix. A leak from a bad gasket can also change as the engine temperature changes. It might be worse when the engine is cold or as the engine heats. Either way, you need to assure that there are no leaks in the intake circuit. That means where the carb attaches to the manifold as well as the manifold to the cylinder.

Intake gaskets are easy and simple to make. Auto parts stores can provide good quality gasket material. A pair of scissors and an Exacto knife are the only tools you'll need although a gasket punch can be a nice addition to your tool collection.

An exhaust manifold gasket leak won't effect the running near as much as a bad intake gasket. It needs to be replaced, but it isn't as critical for a good running engine.

Tom

 

[mogollonmonster]

Thanks tom, that's what I was afraid of with my intake gasket I'll have to either ride or hitchhike to town tomorrow and pick up some Permatex. The gasket is intact, I think a little sealer to take up the differences between the mating surfaces is in order. Should I mill the intake,? It looked like it was that side of the gasket that was leaking. do you think its safe to keep riding? I don't want to harm anything any worse than the last 300 miles has... It seems to be running fine temperature wise and from my fuel ratio, and the exhaust it's getting plenty of lube.

You folks have been beyond helpful. Thank You.

 

[2door]

If your intake manifold is steel there's a good chance it is warped. The heat from the welding process does that. It might need to be milled, or sanded flat to get a good gasket sealing surface.

Here's a hint. Clean the flange then 'paint' it with a magic marker or machinist dye then run it over a sheet of sandpaper laying on a known flat surface such as glass. You'll quickly see any high or low spots.
The mating gasket area on the cylinder is usually in pretty good shape but you might want to check it the same way for any irregularities.

The same for the exhaust flange. They're usually warped too.

Tom

 

[mogollonmonster]

Thanks Tom, that seems to be my new "catch-phrase", hehe. I weld some myself and am aware of steel's tendancy to curl towards heat.
Sandpaper and glass are old friend's, and what I meant by "mill". My esteemed Grandfather once did it to the heads and jugs of his 1945, 74" Indian Chief, on her glass topped dining table... In his words; "It went over like a lead balloon." Although, he always claimed the biggest trouble was special ordering the sandpaper.

Thanks to the "progress of modern society", I've got plenty of sandpaper. Maybe someday the wife will let me buy a mill...and a lathe, I have other hobbies that could benefit from a lathe, they go 'bang' too. However, as you've pointed out before, she knows me. Perhaps I'll just have to content myself with her unequivocal beauty, my finely accurate rifles, and my China Doll. Alas, what is a young lad to do?

 

[ckangaroo70]

Just recently swapped out my stock NT jet for a 65 Jet. I am at around 500' ASL and the bike is really running smooth. However with cooler temps coming I suspect that I may have to richen back up some.?