Help with Carbs for a 3aj

[ferzz]

My German 3AJ also got an altitude compensator. I know more 3AJs in Germany got this.



Connect it to 17 on the left side of the primary carburetor:


And to 5 on the right side of the primary carburetor:


Pictures © www.XT600.de

[000nicec]

Thanks a mill.
Hopefully that will help my Babee start easier.
I have no pipe on the number 5 and have blanked off number 17.

She used to start like a dream. Could stand for 2 weeks walk up to her pull the choke and within a crank or 2 she fired.
Now it takes a full battery charge to get her to start.

She eventually starts and dies starts and dies starts and dies.
Choke doesn't even seem to make a difference.

Well its trial and error........Especially when you not a boffin on these things.
But live and learn.

[Mezo]

Well its trial and error........Especially when you not a boffin on these things.
But live and learn.

Im no boffin either, i just stripped mine down & rebuilt it, to be honest i hate bloody carbs (so temperamental)

Just keep plugging away (no pun intended) and you will become said boffin.

Mezo.

[keny72]

If I may come on to this topic. I have 2 3AJ:s, both 89-90 models and both imported from Germany. The one I first did buy has the altitude compensator, the second did not. As I had the carburetors apart today, yes both as I try to build a runner of 2 bikes, seem the first Tenere has the right carburetor as jets compare to the spec I found on that xt600.de site, but the second tenere has carburetor whit out the tube for the altitude compensator and jets like a 1988 3AJ aside main jet that was a 155 even should be a 165. I did put in the 160 from the other carbs. I got it running and feels like it runs rich. I have not check the needle posissions. Before the engine was like your, starts but dies. Only fault I found in the carbs was the small filter under the float needle was blocked by dirt, mainly paint flakes! Have to see if I check the needle clip positions or change all jets as needels to the 1990 spec as in the first teneres carb but use second teneres carb body. But first other things to do.....vibration issues....

[Juan Pablo]

Hello, I am planning to trip to Bolivia this summer and run in the Argentinian and Bolivian "Altiplano", were altitude goes from 1500 to 3800 meters over the sea level.
I did a similar trip last year and my bike (Yamaha 1jv) run so bad over 2000 mts that I had to run most of the time at no more than 60km/h and no more than 1/4 throttle to avoid engine start to fail...
I should do something with my carbs, change jets perhaps, for 2000 metes altitude, but after seen this post I wonder if this altitude compensator could be adapted to my carbs. I see in mines that where this devise is connected, there are small bronze plugs. What I don't know is if I remove them, will I find the ducts completely machined or if they will be plugged.
Where these connection goes when they get into the carbs? what they do? they decrease the pressure in the float bowl making vacuum (this will affect both carbs) or they send more air to the air bleeder?
Is the altitude compensator devise easy to find? anyone one have one? what the cost? thank in advance for your comments. Regards

[Jenik]

Hello, I am planning to trip to Bolivia this summer and run in the Argentinian and Bolivian "Altiplano", were altitude goes from 1500 to 3800 meters over the sea level.
I did a similar trip last year and my bike (Yamaha 1jv) run so bad over 2000 mts that I had to run most of the time at no more than 60km/h and no more than 1/4 throttle to avoid engine start to fail...
I should do something with my carbs, change jets perhaps, for 2000 metes altitude, but after seen this post I wonder if this altitude compensator could be adapted to my carbs. I see in mines that where this devise is connected, there are small bronze plugs. What I don't know is if I remove them, will I find the ducts completely machined or if they will be plugged.
Where these connection goes when they get into the carbs? what they do? they decrease the pressure in the float bowl making vacuum (this will affect both carbs) or they send more air to the air bleeder?
Is the altitude compensator devise easy to find? anyone one have one? what the cost? thank in advance for your comments. Regards

You need compensator and carburetor too, because regular 3AJ carb hasnt got the additional tubes for compensator. You should get 3DS carb or mode your current. Having 3DS and 3AJ carburators in my garage.

[jibber]

https://www.ebay.co.uk/itm/Yamaha-XT-60 ... Sw1BFaRhUV

[Juan Pablo]

Jenik, Jibber thanks for your soon answers, in the carbs that has the connections for compensation, where do the pipes go? Can you sea from some where in the carb or tha go to internal chanels? How the system works? It reduces the pressure in the float bowl? Regards

[Jenik]

@google translator https://www.xt600.de/xt_stammbaum/model ... _88-91.htm

As the air gets thinner and thinner as the altitude increases, logically, the mixture becomes increasingly richer because the fuel content remains constant. To counter this, additional air ducts for the idle (17) and the partial load system (5) were installed in the primary carburettor of the Ténéré's 3AJ from '89 -91. If the air pressure decreases with increasing altitude, the barometer (air corrector) releases the air channels, the mixture becomes leaner. In the can I examined, the canals were opened at an air pressure of about 900 mbar, which corresponds to a height of about 1000 m above sea level.

[Juan Pablo]

Thank Jenik! So both, 17 and 5 are air inlet...?