carburetion Starter plunger/Choke assemby

[socks]

Choke Plunger, émbolo de arranque carburación, Plongteur dustarter, Starter-plungerkalben, gażników rozrusznik tłok, Karburátor starter dugattyú, καρμπυρατέρ μίζα έμβολο, carburetion voorgereg suier, and not least, 気化スタータープランジャー. My sincere apologies if I left your mother tongue from the above.

Re; the title, I am looking for all the correct measurements of the said plunger and the bore in which it slides, including the thread size/length.

I know this has been covered in part, in the past, yet I wish to expand this subject.

There are these products available; 1, 2KF1437101 (this may,or may not be a fit as it appears to be from another Yamaha XT?)
2,IJK1410A04 (replaced IJK1410A03)

The latter, (2) is standard OEM on the 3AJ.

Measurements on both would be great.
And with this information! I would like to get an engineer to make one (or more!) .

Hey, why not go out and measure the one on your XT we could see how many variations to which model of XT.

PS I can not get to my bike for a week of two, but will post dimensions etc asap

PPS, should we include the SRX 400 and 600 in this survey?


Thanks all

Socks

[GeoffD]

I can tell you the 3TB choke assembly fits straight onto the 3AJ... 2 of mine have them

[socks]

I can tell you the 3TB choke assembly fits straight onto the 3AJ... 2 of mine have them

Thanks Geoff, So that is also the same part number as is in the 2NF 1987 XTN ie; 2KF1437101

This makes this part approx £20.00 cheaper than the original, cable version.

Is it possible that you could measure up one of these and attain the thread size and depth?

Thanks socks

[ActionManMelb]

The screw thread is 10mm x 1.0mm
Some dimensions from right to left.
Needle end 1.80 mm x 8.0 mm
Plunger 7.98 mm x 18.5 mm
Shaft near plunger 4.07 mm x 22 mm
Shaft after screw nut 3.63 mm x 10.7 mm

[socks]

Thanks ActionmManMelb, that is what I'm looking for, detailed measurements and wow, photographs.

I see from the last photograph of the two items, on the shaft where the circlip sits, there is a further two stop ring groves (total = 3).

It looks as if the plunger could sit higher on the shaft.

What are your thoughts on why these are ?

Thanks
Socks

[ActionManMelb]

It is quite a complex part!
The plunger is spring loaded and the spring is deep inside the plunger. The amount of spring tension can be adjusted by moving the circlip to different positions.

The big question is why?

My thought is that the device needs to compensate when the choke is on and the bike is ridden at more than 1/4 throttle rather than just at idle.

The rush of air near the plunger would tend to push the plunger off the seat and make the mixture leaner. Without this device the bike may be way too rich when ridden cold.

Not shown in the photos is a rubber seal at the end of the plunger. As well there is an o'ring inside the nut that seals the shaft.

[xtzrick]

It is quite a complex part!
The plunger is spring loaded and the spring is deep inside the plunger. The amount of spring tension can be adjusted by moving the circlip to different positions.

The big question is why?

My thought is that the device needs to compensate when the choke is on and the bike is ridden at more than 1/4 throttle rather than just at idle.

The rush of air near the plunger would tend to push the plunger off the seat and make the mixture leaner. Without this device the bike may be way too rich when ridden cold.

Not shown in the photos is a rubber seal at the end of the plunger. As well there is an o'ring inside the nut that seals the shaft.

I think you adjust how much you can pull the plunger out by moving the circlip.
The spring holds the plunger against its' stop.

The end of the plunger is in a vacuum, that's what pulls the petrol up through the choke system.

IF I'm right:
The plungers in the photos show you can reduce the amount of full choke by moving the 'clip closer to the knob
So if your engine screams on full choke it might be possible to reduce the revs it goes to without needing to guess how much you pull your knob.

Rick

[xtrider]

I used these on 2 of mine , http://www.ebay.com/itm/Mikuni-Lever-Ch ... 9w&vxp=mtr They work on the older carbs anyways. No point sticking out in front but the oem(US?) ones didn't either .






.

[socks]

Thanks for the previous replies, I think, I'm getting the hang of how this damn thing works now. with the help of AMM and Rick,

XTRider, which model have you fitted, your attached advert ("Mikuni lever Choke kit TM38 Button VM29/47") to and have you got measurements pertaining to this item, must add this looks a good price.

socks

[xtrider]

The length of the plunger that goes down into the bore is shorter so doesn't seal at the bottom of the hole like it is supposed to . It does cover the fuel and air inlet hole in the off position so they do still work , probably not perfect. I've got 5k on one so far and all is going well. I wanted something to to get rid of that cable setup that simply sucked , but $45 for an oem 3tb option?? so I took a chance to see if they worked. I am running a little rich at idle, but it still needs to pull the choke out as it gets cold or it won't start so that's ok. I have a O2 wideband meter watching the mixture . It's actually one of my best/most reliable starting bikes in any weather , as long as the LiFE PO4 batt will turn it over .

I've only put them on my US model carbs used in later kicker bikes 43F ?

10mm threads , 8mm plunger dia. 31mm long (the debth the plunger tip is when fully screwed in the carb . The bore in carb is around 40mm deep.