Keihin Carb set up?

[JAD]

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?

[Gasser Nate]

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.

[JAD]

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.

[swazi_matt]

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

[JAD]

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.

[swazi_matt]

Originally Posted by JAD

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.

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

[cbutler]

I get 75 miles on my stock tank on both my 250 and 200 no problem

[BrandonEc300]

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.

[JAD]

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.

Sent from my LLD-L31 using Tapatalk

[BrandonEc300]

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.