sea level setting?

panterra_rider · 07-21-2006, 08:20 PM

This probably could have gone under the "sputtering" thread below but I just thought I'd mention that a lot of these bikes are probably set for sea level or close to it. Where I am it's 1900 feet above sea level meaning our bikes probably needed a richer mixture...that's where the needle/clip trick comes in. I've actually set the needle on ours at it's highest setting and they run pretty good...they're a little rich BUT if I change the air filter box to a POD filter then we're probably set.

Correct me if I'm wrong but I just remember something about this when I set some Suzuki ATV carbs. Plus I didn't see it mentioned elsewhere...

Thanks,
R.

frostbite · 07-21-2006, 08:49 PM

I was always under the impression that you typically don't need to adjust jetting unless your elevation is above 6000 feet. I'm at about 60 feet so its never been a question for me.

Do we have any Colorado riders who can confirm?

panterra_rider · 07-22-2006, 12:57 PM

Correcting myself...did some thinking. Higher altitudes = less dense air = less oxygen for fire. This means that you actually have to lean a carb out at higher altitudes (usually smaller main jet...and you're right, only at pretty high altitudes).

What I did on my bike made it run richer...so basically, for whatever reason, it seems manufacturers just set it too lean out of the box.

I'm going to continue to run on the rich side...especially for break-in. Runs slightly cooler plus it will probably be the correct setting for the fall when the weather gets colder around here.

Cheers,
R.

tzrider · 08-07-2006, 01:35 PM

6K feet is about right. By "highest needle setting", do you mean the needle position or the clip position? If you raise the needle, it will come on the main jet quicker (richer at mid throttle). If you lower the needle (raise the clip) you make it come on the main later (leaner mid throttle). The needle really doesn't affect much, just the transition from needle jet to main jet. Changing the pilot and main jet sizes is the biggest change, but most of the Chinese stuff uses Walboro carbs and I haven't been able to find a source of jets. I haven't really tried, though, other than to call Diamo about it and they didn't have any.

Redneck carb tuning (works, but is sort of redneck) is to drill out the jets and use various gauge wires stuck into the jet and bent over the ends so it won't come out to adjust orifice size. First time I saw this, I nearly passed out from laughter, but I'm told it's kinda routine out on the west coast with the flat trackers. Guess they're too broke to buy jets or something.

panterra_rider · 08-09-2006, 12:57 AM

Actually the needle has been raised (clip moved down). I was under the impression that changing the needle position can affect mixture across a large part of the rev range. All I know is the spark plug is a nice brown colour (it was quite light prior) and the bike doesn't burp and fart through the carb like it did when it was first out of the box. I'd say the carb is set pretty well then out of the factory with regards to main jet, etc.

Thanks,
Rian

tzrider · 08-09-2006, 06:55 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.

07-21-2006, 08:20 PM	#1
panterra_rider Join Date: Jun 2006 Location: Saskatchewan, Canada! Posts: 85	sea level setting? This probably could have gone under the "sputtering" thread below but I just thought I'd mention that a lot of these bikes are probably set for sea level or close to it. Where I am it's 1900 feet above sea level meaning our bikes probably needed a richer mixture...that's where the needle/clip trick comes in. I've actually set the needle on ours at it's highest setting and they run pretty good...they're a little rich BUT if I change the air filter box to a POD filter then we're probably set. Correct me if I'm wrong but I just remember something about this when I set some Suzuki ATV carbs. Plus I didn't see it mentioned elsewhere... Thanks, R. __________________ 2 Hensim-built 150cc dirtbikes (Panterra branded) Kazuma 110cc Lacoste quad
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07-21-2006, 08:49 PM	#2
frostbite Join Date: May 2006 Location: Fredericton, NB, Canada Posts: 1,744	I was always under the impression that you typically don't need to adjust jetting unless your elevation is above 6000 feet. I'm at about 60 feet so its never been a question for me. Do we have any Colorado riders who can confirm? __________________ Frostbite "The beatings will continue until moral improves"
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07-22-2006, 12:57 PM	#3
panterra_rider Join Date: Jun 2006 Location: Saskatchewan, Canada! Posts: 85	Correcting myself...did some thinking. Higher altitudes = less dense air = less oxygen for fire. This means that you actually have to lean a carb out at higher altitudes (usually smaller main jet...and you're right, only at pretty high altitudes). What I did on my bike made it run richer...so basically, for whatever reason, it seems manufacturers just set it too lean out of the box. I'm going to continue to run on the rich side...especially for break-in. Runs slightly cooler plus it will probably be the correct setting for the fall when the weather gets colder around here. Cheers, R. __________________ 2 Hensim-built 150cc dirtbikes (Panterra branded) Kazuma 110cc Lacoste quad
	0

08-09-2006, 12:57 AM	#5
panterra_rider Join Date: Jun 2006 Location: Saskatchewan, Canada! Posts: 85	Actually the needle has been raised (clip moved down). I was under the impression that changing the needle position can affect mixture across a large part of the rev range. All I know is the spark plug is a nice brown colour (it was quite light prior) and the bike doesn't burp and fart through the carb like it did when it was first out of the box. I'd say the carb is set pretty well then out of the factory with regards to main jet, etc. Thanks, Rian __________________ 2 Hensim-built 150cc dirtbikes (Panterra branded) Kazuma 110cc Lacoste quad
	0

08-07-2006, 01:35 PM	#4
tzrider Join Date: Jul 2006 Location: Texas by gawd! Posts: 407	6K feet is about right. By "highest needle setting", do you mean the needle position or the clip position? If you raise the needle, it will come on the main jet quicker (richer at mid throttle). If you lower the needle (raise the clip) you make it come on the main later (leaner mid throttle). The needle really doesn't affect much, just the transition from needle jet to main jet. Changing the pilot and main jet sizes is the biggest change, but most of the Chinese stuff uses Walboro carbs and I haven't been able to find a source of jets. I haven't really tried, though, other than to call Diamo about it and they didn't have any. Redneck carb tuning (works, but is sort of redneck) is to drill out the jets and use various gauge wires stuck into the jet and bent over the ends so it won't come out to adjust orifice size. First time I saw this, I nearly passed out from laughter, but I'm told it's kinda routine out on the west coast with the flat trackers. Guess they're too broke to buy jets or something.
	0

08-09-2006, 06:55 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.
	0