Keihin Carb set up?

J

JAD

New member
Hi all, this is my first post (after much reading!) ref jetting my new (to me) 2007 EC250.

The bike "peed" out fuel so I have removed the Keihin carb (screw top so I think it is an AS1) and meticulously cleaned everything and set the float height as per the instructions on here. Throttle cable is set correctly. Air filter is clean with fresh oil and mechanically the bike seems sound. The fuel no longer leaks and the bike starts well but has an unreliable and erratic idle which I am unable to stabilise using the techniques listed on here. The air screw (pilot?) is 1 turn out (360 degrees) and the idle screw is nearly all the way in. It will idle fast ish.. but dies after a short while. The plastic idle screw is super sensitive to even a tiny movement.


The current set up is 172, 35 with a N1EF needle in position 2 (*7 slide)

Having studied the jetting database it appears that in the UK (sea level up to 2000 ft) most people seem to fit 180, 45, and an LTR needle. I intend to do the same but I am struggling to find an "LTR" needle for sale.

Can anyone point me in the direction of a UK jet needle supplier please? (and what to ask for!)

Also, the jets appear to be available on amazon for very little money... are they likely to be low quality or does it matter? (I was thinking about buying a selection)

Thanks in advance and no doubt I will have many more questions as I attempt to get this bike sorted out!

Regards
John
 
this is where the LTR needles originated https://www.lt-racing.com/ but not sure if you will find one. best is to find a ktm N3eh (or similar N3** needle) or for a more trils like feel the suzuki NEDJ (or similar NE** needle) The N1 was probably put in the GG bikes by a disgruntled employee with shares in ktm
 
Do NOT buy jets off of Ebay. A lot are pure counterfeit, or even just cheap copies, but with their numbering system not meaning squat compared with real Keihin jets. Only buy genuine Keihin jets from a reputable shop like Jets-R-Us or the like.

If you have your idle speed screw turned almost all the way in then you are not idling on the idle circuit alone (main/needle is coming in to play which is not good). I would start with a pilot similar to what others have used for your elevation, adjust to see if it is correct for your setup (1 to 2 turns out on the air screw range, and get that sorted before even attempting messing with the needle or main jet. Everything starts with the pilot jet!
 
My 200 runs excellent and idles all day with a 42 pilot, 175 main and CEK needle at clip position #3. Air mixture screw 1-1.25 turns. It does have the RB divider plate and circuit mods, so this may affect the pilot selection. This setup has worked well for me from sea level to 2000 feet, rain or shine, without any adjustment.
 
The float jet valve wears and replacement will fix you peeing issue permanently. My mates bike (2010 300) lost its entire load in my van overnight. I cant tell you how painful that all was.
 
Yabadabadoo....!

Update... (2007 EC250)

Firstly thanks to all for the useful and relevant advice, it is much appreciated.

My new needle arrived today and I now have the following set up...

178/40 (nearest I could get locally) N3EH (clip in the middle) - note: NEDJ is on order as well. (thanks Gasser Nate)

Yabadabadoo... unbounded joy! How can this bike have been ridden since 2007 with the original needle in it? It is transformed...truly transformed beyond all belief! I am delighted and amazed.

Firstly...it now has a steady tickover (hurray!) with (I think...) 1.4 turns out and the idle screw is not "spring bound" anymore. It is screwed in most of the way so maybe I need to try the bigger idle jet when my new ones arrive?
The revs hang slightly but after a few seconds things slow down to "sewing machine" territory.

The engine sounds as sweet as a nut and revs cleanly..SO much better than before.

I had a quick ride down the farm track (the bike is not road legal yet) and it rips... this thing will catch pigeons!!!

Everything is relative and, to me, it is perfect but no doubt I will need to do some fine tuning. The bike is also quite mellow and manageable at small throttle openings and responds well to throttle input without any snatchiness or drama but when you open it up it hits warp speed as quick as you can open the throttle. Love it..

I also fitted a new throttle slide because the old one looked a bit worn and some new gaskets from a service kit I bought from Ebay.

I have a few more cosmetic jobs to do but I think this bike will be a bucketful of fun.

PS.. Whilst waiting for the needle to arrive I decided to try and cure the annoying rattles the bike has. I replaced the power valve bearings and inserted a shim to reduce end float... wow.. that annoying rattle on the over run has disappeared. It still had a metallic vibration noise which I eventually identified was due to the exhaust touching the engine. Two new rubber mounts and careful positioning has stopped that annoying rattle as well.

Overall, I am very, very pleased and wish to offer my thanks to all for the wealth of information and guidance available here...

Top forum!
 
Update.. EC 250, 2007 vintage. New setup is NEDJ - middle, 178/42, 1.5 turns out.

I am much happier with the bike after ditching the original needle.

My NEDJ arrived today so I thought I would give it a try. It is also a vast improvement from the dreadful original needle.
The NEDJ is more "mellow" at smaller throttle openings but also has a very healthy kick when you open it up (the previous new N3EH really ripped but was also perfectly manageable and smooth) The brass idle screw seems happy at 1.5 turns out which gives a slow but steady tickover. Pulls well and feels strong throughout the rev range. It need choke to start when cold and starts easily hot or cold. All good.

I am still struggling to get a "nice" tickover and after much fiddling I have a few observations.

1. The end of the plastic idle screw has a "blunt" and steep taper which means that the smallest of turns (I mean tiny!) has a significant effect on the throttle slide and can increase idle speed way too much. I had to be very careful to only turn it a tiny fraction. This would provide a nice fast idle but it was obvious that it was all controlled by the raising of the slide. The side effect was that the throttle would hang and take a while to settle down. As soon as I unscrewed the plastic screw the hanging ceased but obviously the idle also decreased. I suspect that a shallower taper on the end of the screw would help make adjustment more sensitive. I may see if I can buy a different/better screw.

2. The float height makes quite a difference to tick over - more than I thought it would. I had made an attempt to get it just right by measuring but I found that I had to use trial and error to get best results. I just bent the little tab a bit at a time and popped it back in...laborious.. but successful.

3. The N3EH was easier to get a nice idle than the NEDJ but both were successful.

4. The throttle cable was not as free as I would have liked so it was liberally lubricated and this helped ensure the needle/slide was fully seated when the throttle was closed.

5. Boy does this beast go through fuel! What range do people get from a tank?


Anyway, I am delighted with my new (to me) bike!

ps, I get some black dribbles on the end of the silencer... I think it needs a good run to clear the pipes out but does this tell me it is too rich? If so I guess the needle should be raised from the middle groove to the 2nd groove from the top?
 
Do not be to concerned about the leaky bum. A two stroke is not the most efficient beast on the planet and you will always have some unburnt oil/fuel. Jet for performance not spooge.
 
Thanks Gasser.
Am I correct in assuming that the tickover is totally reliant on the pilot jet /screw combination and that all the plastic idle screw does is lift the slide up a bit? My plastic idle screw has to be barely touching the slide to get a nice "sewing machine" (slow) idle and if I turn it in any further I get a hanging idle which drops down after a few seconds.

Essentially the plastic screw is redundant as far as idle is concerned.
 
quite a few posts on fuel consumption, depending on how you are riding you will get between 60-100km on a tank. I think i used to average at about 80km on a tank and that was pretty extreme riding, slow but lots of wheel spinning and revving over rocks etc

Think the main culprit seemed to be float height setting, there are a few threads on how to get this right. I believe this setting will also affect jetting
 
Cheers Matt.. thats only 50 miles so I have a problem... I need about 60 miles range for the routes I do so I will need to carry a couple of litres.. :(

I shall investigate float height further.
 
JAD said:
Cheers Matt.. thats only 50 miles so I have a problem... I need about 60 miles range for the routes I do so I will need to carry a couple of litres.. :(

I shall investigate float height further.
Click to expand...
think the tank is only 9 litres and i have always budgeted on 10km/l for 2-strokes.
You can get a bigger tank, but they aren't pretty

you can also try to find someone selling a smartcarb or lectron, they supposedly solve jetting issues and increase fuel range, not used one, but there have been a few floating around for sale recently. Probably at least double the price of a clarke tank
 
I get about 85-90miles on my oversized tank without even hitting reserve, running the keihin airstriker with Suzuki needle(forgot the part number) 178m, and 42 pilot and with my squish band dialed in from RK Tek. Get your head worked on, it majorly increases efficiency.
 
Just a quick note which may be helpful.. I was searching for a new air adjusting screw and discovered that it should have a washer and an O ring. Mine has neither (I looked down the hole) so this may be part of my idle problem.
b2a506c5f57439f21b0ee4f0b0943d6f.jpg


Sent from my LLD-L31 using Tapatalk
 
JAD, I went out and took a look at both my keihins and neither has an oring or washer on the idle screw. I have the original black plastic idle adjustment screws also.+1 with swazi Matt about the float height?these keihins are very picky when It comes to float height. Check your reeds also, it?s impossible to jet around worn reeds and if that?s all good check the needle seat, dirty air filter causes grit to wallow out the seat creating a rich mixture. Also did you replace your slide with a genuine keihin? Aftermarket jets/slides can be much different than oem specs.
 
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