Carb needle clip settings

edman2478411 · #1 04-18-2009, 12:36 AM

Greetings! Ok so for a while I've been looking for a definite thread for the carb needle adjustment clip. Seems this is a really big part of the engine performance but I can't seem to find absolute information on it.

Here's my issue. I live in the coastal bend in Texas near the beach. I have my needle clips at factory default which on my new engines is the middle out of 5 and on my commuter is 2nd from top not sure though. None of my bikes can run with the choke on which makes me think, even though I'm at sea level, the mixture is too rich....

Is it really that important if the engine does not idle on choke? I thought that maybe if I was able to run it on choke the performance would increase slightly when the choke is off.

I have a mountain bike (commuter) with an 80cc engine and a 34T sprocket that hits around 35 tops. Is that normal 34T speeds?

My main point is about the carb needle adjustments. Other than making the mixture rich or lean what effects do these settings have on performance?

--Thanks guys been waiting forever to join the forum but I've had computer problems.--

dishpointing · #2 04-18-2009, 08:50 AM

Hi, first on the needle there 5 slots on it for the needle. Position 1 being the top and 5 the bottom of the needle. Position 1 being the less fuel and 5 the most fuel, with that info we can dial the mixture. Forget the choke once it is started I can't run with it, only open position here around 90F weather.
Get some tools for removing the spark plug and some rags will be removing it when it is hot. Make a good run at full throtle and stop the engine pull aside and remove the spark plug color of the electrode ceramic the white part. Black to much fuel, Tan getting good, White need more fuel.
Mine's runs on needle 2 position on 87 octane fuel with an oil-fuel ratio of 3oz per gallon of AMSOIL DOMINATOR, no problems.
Hope this help you.

edman2478411 · #3 04-18-2009, 01:36 PM

good idea dishpointing, I'm going to go out and do that on my bikes right now. I'll be back to report my findings!

edman2478411 · #4 04-18-2009, 02:43 PM

Alright, I tried out on my cruisers and both the mountain bikes and it seems that one notch up on all of them makes them bog at higher speeds. I'm guessing it's because the mixture needs more gas. Although the plug was pretty clean after running like that, the bogging just doesn't cut it. Went back down another spot and they ran fine although the plug got pretty dirty. So i guess I'm stuck with dirty plugs huh?

dishpointing · #5 04-20-2009, 10:16 PM

Hi again color of spark plug will be the tuning factor you should get a tan like a light brown, not black go for that it is the normal color, stay away from white that is to lean and could damage motor.
Want to know what is dirty plug for you post a pic of it. Also open fuel bowl and check for derbis and blow main jet, is a good idea to have a fuel filter installed on fuel line.
Maximum performance will be from correct mixture, a expansion chamber and a good air filter.

Shadeslay · #6 04-28-2009, 01:52 AM

A snippet from a post I read. Spark plus color should be the major factor for determining where the clip goes. Also you can adjust your lean/rich by your mix, which will allow you to dial in performance. The needle controls 1/4-3/4 throttle, jet is 1/2-wot, if you have an air mix screw it affects closed - 1/4.

Mark the throttle grip at 1/4 and 3/4 openings. Ride the bike between these two marks. If the bike bogs for a second before responding to throttle, lower the clip (raising the needle) a notch at a time until the engine picks up smoothly. If the bike sputters or sounds rough when giving it throttle, raise the clip (lowering the needle) until it runs cleanly. There isn't really any way to test the needle other than by feel, but it's usually quite obvious when it's right or wrong.

Full post on carb tuning.

Spankeys Jetting Guide - Info 2 Stroke riders must have - Kawasaki Motorcycle Forums

mechanickid · #7 05-05-2009, 02:31 PM

a few people on here (including me) have had great performance from tapering the needle itself. making a gradual transition, grind or file it lightly so that it reaches full thickness 1/3 of the way to the top, it doesn't need to be smaller at the tip, only in between the tip and 1/3 of the way up. sand smooth to finish.

Cabinfever1977 · #8 05-05-2009, 06:22 PM

its not a good idea to remove the plug when its hot,you might remove the threads too.

edman2478411 · #9 05-09-2009, 03:55 PM

New update!

So I noticed my mountain bike lost some a few weeks ago power so I checked all your standard problems
-spark
-leak
-gas ratio
-clogged muffler

I moved the clip up to the highest on a 4 notch clip
(was at 2nd)
(it has heated up down here in Texas past few days)

And wow!

No bogging anymore just flat out power!
I still have power on the mid 30's it's insane!

**Bikeguy Joe** · #10 05-09-2009, 09:18 PM

Ambient temps will make a difference in tuning, as will humidity.

I will also second the advice to NEVER remove a plug hot, you may remove the threads with it.