What does it do???xt question

[Dave O]

On the side of the slide carb on my 3aj, theres a unit called a coasting enricher assembly. Can somebody please tell me what it does??????

Help anyone

[Bill Ryder]

Here in the states we call them a "anti backfire valve" . When you shut the throttle at speed it creates a high vacum and actuates this diaphram actuated valve. On most bikes it restricts the air bleed to the idle jet circuit which richens the mixture there by lessening backfires out the exhaust pipe. If you soak your carb in a tub of super cleaner and don't remove the rubber diaphram it will be eaten away putting the carb into a rich/plug fouling mode.

[Dave O]

Thanks Bill, I was wondering if this could this be a contributing factor to the problem with my bike. The bike seems to run fine through the gears, but if I'm doing about 70, at neutral throttle, the bike "skips" every now and again - I was thinking fuel starvation though.

I want to check my fuel level, and in the yamaha workshop manual, it says between 5-7mm. Wheres that measured from? Can anyone help on either of these points.

[aukeboss]

The 5 - 7 mm is, with horizontal carb (meaning, when carb is installed, you have to lift the frontwheel), the distance between fuel level inside float bowl and the edge of the connection surface of the bowl to the carb. And then, only when the engine has run a bit to stabilise the level. You can see the level inside the bowl by attaching a transparent hose to the drain of the bowl and opening the drain screw.

Bettter to measure in a different way: remove carb and bowl. Turn carb upside down. Measure between underside float and connecting surface to carb. To be 25 - 27 mm, or 26 - 28 mm depending on model. The XT is not very sensitive to this BTW.

Auke

[Martynbiker]

Originally Posted by aukeboss

Bettter to measure in a different way: remove carb and bowl. Turn carb upside down. Measure between underside float and connecting surface to carb. To be 25 - 27 mm, or 26 - 28 mm depending on model. The XT is not very sensitive to this BTW.

Auke

The Coasting enricher stops it cutting out when you 'throttle off' from 'giving it some Bigtime!'.......if that wasnt there...... the engine would die, and you would find yourself restarting every time you stop at the lights/ junctions/ etc.

FLOAT LEVELS yeah, XT aint too fussy on that!
I just "guestimated" mine at about23-24mm and it is OK. I didnt have internet connection on at the time and neither did I have the Manual handy,so i thought that looks about right, measured it, 23.5mm in actuality...... but it back together

She runs sweet as... so never bothered to readjust it....... if it aint broke n all that

The XT600 IS sensitive to Mixture & Idle settings though.

Martyn

[bruken]

Generally speaking a coasting enricher really comes into it's own when throttling off at speed and sustaining a fair amount of speed over a distance (long downhill etc) where the motor could otherwise lean out to the point of siezing.
Truth of the matter is this was added to the carb setup in on the XT550 K model for the first time. The prior XT550 J did not have a siezing issue tho, but one 'orribly bad backfire that would blow the back off the end can. There after great fun could be had terrorising motorists.......ahhh the good ol days :-)

[MarkLG]

Originally Posted by Dave O

On the side of the slide carb on my 3aj, theres a unit called a coasting enricher assembly. Can somebody please tell me what it does??????

Help anyone

These sort of add ons are pretty common - my DRZ400 had the same device attached to the side of it's FCR slide carb. It's not essential to the running of the bike, it's just to comply with noise/emmisions requirements.
Problem is they can and do malfunction, causing all manor of fueling problems. I've removed mine and blanked the air holes in the carb after it started sticking and the bike refused to idle properly.

[Dave O]

Martyn - you f**king legend. When I rebuilt the top end I used the old copper sealing washers. God knows why - I've got a set of new ones in a box! I guess I'll definitely be changing them now and taking the bike for a spin. Thanks again. I'll let you know what happens. Dave O

[Dave O]

The ongoing saga - Ok, so now i've fitted new exhaust gaskets and used a tiny bit of sealant. Put in a new coasting enricher assembly and fitted a new needle and seat (plus filter) above the floats. The carb rubbers are good and sealed. The rubbers from the air filter are nicely sealed. The fuel pump and tank (incuding taps) are clean.

I haven't yet changed the plug cap and lead. What else can this be, help, I'm tearing my hair out. By the way, no more backfiring, but still the same original prob!!!!!!!!

[Martynbiker]

Originally Posted by Dave O

The ongoing saga -

I haven't yet changed the plug cap and lead.


but still the same original prob!!!!!!!!

eliminate, eliminate, eliminate...... its not expensive Dave, worth a try..
at least for peace of mind, ( and if now't else gives you something to do eh?)

Martyn