3en2 Needle help.

[willandrip]

Excerpt from 3EN2 factory manual; I am unsure if the bottom section with 4 ~6 mm data even refers to carburation
( the rest of the carb info is all contained in the one "block" above it !!)

Oh the joys of import manuals

EDIT: After x reference (for Japanese description) using the SP 2TK manual;

The recommended fuel level is 24.8 mm

[willandrip]

Previously discussed fuel levels;
viewtopic.php?f=35&t=36106

[Flyingbroadyp]

Thanks for the quick responses, I didn't expect a reply this quick!
Could you you please confirm the needle clip position. Is that the 3rd position from the pointy end?

Regarding the fuel level line on the float bowl. Mine doesn't appear to have one?

I have not changed any seals in the carbs either?

[willandrip]

Needle clip is middle groove of 5 =3.
Are your carbs like the pic posted by Evilchicken0 in the link ;previously discussed fuel levels.?
Those are 3en2 carbs;the line can be clearly seen.

[Maelstrom]

Okay I don't want to sound like I am trying to flog you a carb kit, but http://litetek.co/Carb_Kit_Yamaha_3EN1.html
Take a look at that page and consider the number of seals and o-rings that are used in these carbs. Now you said that you have had the carbs stripped and 'rebuilt' 3 times and it still has the same seals and o-rings that it did 11 years ago? Maybe they are the original parts. They are a service item and they do not last 24 years, at least not OEM parts which are made from Nitrile. I would suggest that you rebuild the carbs with new seals and o-rings, check the diaphragms for holes, and set everything back to standard and take it from there.
cheers
Blair

[Flyingbroadyp]

My carbs look identical to the ones pictured, except for the line on the float bowl. I will get some pics so you guys can see them. It was mentioned earlier about my exhaust. It is a pretty free flowing one. MTC exhaust with quite a large exit? I'm going to take the carbs back to the settings you guys have suggested, see how she runs and will post a few pics.

[willandrip]

Is it not the problem that the revs wont drop below 2K ?

[Flyingbroadyp]

Hi Willandrip,

Yes when I rev it and close the throttle ( it snaps shut to the stop ) the revs are holding at between 2-3000 rpm. I have just put everything back to the suggested settings but unfortunately I haven't tried it. ( must dash to work) and so I will let you guys know next week when I'm off how the standard settings go.
Thanks so far for all your suggestions I really appreciate it!!

[willandrip]

I went out to the garage and inspected some scrap 3en2 carbs .
They to have no line on the bowls;
The figure must relate to float height.

Something is physically preventing the butterflies from closing fully.

The only other scenario is the that the carb to head rubbers have severe leaks but the revs wound hang before dropping to 2/3 k.

[Flyingbroadyp]

Ok guy's sorry for the delay,

So I put everything back to setting that were suggested (Standard settings) and it was still the same.

However I lowered the clip one more position and it made a difference. It only held the rev's for a little bit and dropped to idle. But because of the clip position it doesnt rev smoothly. and so have put bigger main jets in to compensate for the lean needle position. do you think it could be worn emulsion tubes and needles? it does appear to much fuel is leaking through the mains in the standard position and causing it hold revs? I havent riden the bike yet with the current settings, hope to do that later today.

My settings now are as follows;

Mixture screw - 2 1/2 turns
Float hights - 24mm
Needle clip pos - 2nd closest to flat end
Main jet (cyl 1 + 4) 97.5
main jet (cyl 2 + 3) 95