sea level setting?

tzrider · 08-09-2006, 05:55 PM

Once the needle is withdrawn from inside the needle jet, the carb is on the main. This is around half or a little over throttle. The needle jet controls carburetion from off the pilot to on the main. The movement of the needle up and down controls jetting in that range, about 1/8 to 1/4 throttle up to about half throttle. If the bike has a lean spot on throttle application, it can help eliminate that, but at high speed it has absolutely no effect. You're on the main at that point. The main jet is the most important because it is at high speed where bad things can happen if it's too lean and it can burble and foul plugs if it's too fat.

As my bikes have come set up, they've all been on the lean side. Opening up the exhaust or especially going to a much less restrictive intake filter system will further lean the motor, not something I wanna do, personally. Don't really want a burned exhaust valve if I can help it. I mean, it's a 200. If I want a 400 I'll buy one. I have an SV650 that'll run 135 mph if I want to speed.

Now, concerning engine mods...........

I've built several XR100 race engines. I have 2500 bucks in two engines, mostly head work. One has 33 percent more valve area, overbored to displace 124cc, uses titanium valves that are reangled. The machine work is art. Jay Wright of http://www.barebones.net built it. We blew a rod bearing in a 12 hour race couple of years ago and I need to pull the crank out of it and send it to Jay. It uses a one off Carillo rod. This motor makes about 15 horsepower at the rear wheel, probably five more than our 200s make. I have outmotored KX60s with it. I run a 26mm round slide Mikuni on that bike with a K&N filter pod.

My flat tracker is a Frank Nye 150cc Stroker ( http://www.xr100.com ). I run a 24mm Keihin flat slide CR on that bike, no idle circuit at all. Both motors have full race Megacycle cams. The Nye motor's headwork isn't near as elaborate as Jay's and doesn't flow as well. All this is important in a race engine. It's more than just a big carb, it's flow from intake of the carb through the engine and out the pipe. One of Jay's 145cc strokers can run with any 80cc two stroke, makes nearly 20 rear wheel horsepower. I'm thinking about getting Jay to build me a 145. :twisted:

All that is a little off this thread topic, but someone was talking about a "race engine" on ebay. I had to chuckle.

08-09-2006, 05:55 PM	#6
tzrider Join Date: Jul 2006 Location: Texas by gawd! Posts: 407	Once the needle is withdrawn from inside the needle jet, the carb is on the main. This is around half or a little over throttle. The needle jet controls carburetion from off the pilot to on the main. The movement of the needle up and down controls jetting in that range, about 1/8 to 1/4 throttle up to about half throttle. If the bike has a lean spot on throttle application, it can help eliminate that, but at high speed it has absolutely no effect. You're on the main at that point. The main jet is the most important because it is at high speed where bad things can happen if it's too lean and it can burble and foul plugs if it's too fat. As my bikes have come set up, they've all been on the lean side. Opening up the exhaust or especially going to a much less restrictive intake filter system will further lean the motor, not something I wanna do, personally. Don't really want a burned exhaust valve if I can help it. I mean, it's a 200. If I want a 400 I'll buy one. I have an SV650 that'll run 135 mph if I want to speed. Now, concerning engine mods........... I've built several XR100 race engines. I have 2500 bucks in two engines, mostly head work. One has 33 percent more valve area, overbored to displace 124cc, uses titanium valves that are reangled. The machine work is art. Jay Wright of http://www.barebones.net built it. We blew a rod bearing in a 12 hour race couple of years ago and I need to pull the crank out of it and send it to Jay. It uses a one off Carillo rod. This motor makes about 15 horsepower at the rear wheel, probably five more than our 200s make. I have outmotored KX60s with it. I run a 26mm round slide Mikuni on that bike with a K&N filter pod. My flat tracker is a Frank Nye 150cc Stroker ( http://www.xr100.com ). I run a 24mm Keihin flat slide CR on that bike, no idle circuit at all. Both motors have full race Megacycle cams. The Nye motor's headwork isn't near as elaborate as Jay's and doesn't flow as well. All this is important in a race engine. It's more than just a big carb, it's flow from intake of the carb through the engine and out the pipe. One of Jay's 145cc strokers can run with any 80cc two stroke, makes nearly 20 rear wheel horsepower. I'm thinking about getting Jay to build me a 145. :twisted: All that is a little off this thread topic, but someone was talking about a "race engine" on ebay. I had to chuckle.
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