Jetting issues

[TheChairman]

I'm having issues with jetting.

I ordered and installed the jet kit from CSC.

Naturally there are no instructions.

The bike runs excessively rich at idle. So insanely rich it loads up, fouls plugs, and stalls. Obviously, the air screw is sealed by law. It needs to be adjusted but nobody seems to know how to unseal it. I need to know if it's a cap that can be punched and pried out, if the screw is installed and the head mushroomed so it can't be adjusted, or if it's a soldered plug.

Jap bikes are usually soldered in place. This doesn't look like a lead slug in there. Either the factory screw is out about 5 turns, or this jet they sent me is many sizes too big. I attached a photo of the plug. That streak of brown tells me it's probably looking good on the needle and main, it's the idle that is way over fuelling.

[JerryHawk250]

You can drill the plug out. The pilot jet they sent you may be to big.

[franque]

In my experience, Japanese bikes do not have the plug soldered in place, they're usually swaged in place.

The trick is to drill a hole in the plug, and then run a wood screw in it. You can then either pull the wood screw out with some pliers, taking the plug with it, or if the hole is bigger, but not too big, you can run the screw down until the threads force it out.

You could also just bore it out, but where's the fun in that? Also, the plug doesn't go too deep, so take it slowly.

[TheChairman]

Ok. Got the screw changed. The kit did *NOT* come with a washer or spring, so I reused the originals.

It still runs insanely rich at idle, even with the screw seated completely.

This is after starting it and allowing it to just sit at idle with the engine warm.

I'm convinced they sent the wrong kit, and incomplete kit, or the pilot jet they sent is about 10 sizes too big.

[Megadan]

Put the original pilot jet back in and see if it stops. If it does, then yeah, somethings funky with the one you were sent. If not, either the float needle isn't seating or the float level is too high.

[TheChairman]

I did once before and it did correct it, but before I replaced the adjustment screw. It went back to being very lean with the factory jet. Now with the new jet and the replaced screw it stays too rich.

I suppose now I can try and enrichen the factory jet with the screw and see what happens. It's just aggravating because I have to break the bike down every time a jet gets changed.

[TheChairman]

Ok. Went back to the factory "40" jet. Screw to industry standard 2 1/2 turns out. Let idle at temp for 7 minutes. Beautiful, if just a touch too rich for easy starts.

I believe the CSC jet kit is set up to be used with the charcoal canister which represents a significant vacuum leak. Mine vanished while I was rejetting. Weird.

Anyhow. I'm pleased with this outcome. I'll see what the middle and top look like with some mixed riding.

[TheChairman]

Mixed riding. Went from a 102 to a 110 main. Stock 40 pilot. 2 and 1/2 turns. Raised the needle (lowered clip) one position past neutral. No charcoal canister (plugged vents)

39 feet above sea level. 85 degrees outside.

[Megadan]

Have a 112 or 115 main? That should richen up the top and mid throttle ranges both. A tad bit lean at the moment.

The idle mixture is a tad lean, but not the worst ever. Looks to me like you need a 42 or not screwy 45 pilot and it would be just about right. That one they sent you must have been mislabled or drilled way too big from the factory.

[TheChairman]

I do have a 115 main. I considered putting that in and moving the needle to neutral.

[franque]

You might want to get a new socket, too.