Greetings all,

I've restored a 1969 piston port DT-1B JDM motor and need some carb advice. The engine didn't come with a carb but I found a VM26 311 E2 from a later reed valve engine. I'm guessing that the jetting and settings might be slightly different for this later carb. Is there anyone running an early model engine that runs well that can guide me on how to set up my carb so I'm in the ball park? Mine is an MX machine that is set-up with autolube.

Appreciate the help and advice!

I should have mentioned my baseline setup. I have a 160 main jet, a 35 pilot jet, and the needle on the 3rd notch.

A service manual there should be, available for you! On this website!

www.yamaha-enduros.com/index.php/service...ctory-service-manual

Pay close attention to the air bleed.  I see it calls for a .5 air jet.  35 pilot, 150 main.  They also show the gyt vm30 in that manual, looks like a good one to have on hand!

Yep - I have the manual. Just wondering if there are tweaks and recommendations based on experience that deviate from the manual.

160 main is very lean 

180 full gasoline in the tank 

200 pre mix 32/1 in the tank

three notches down is fine

1.5 turns out is good

35 pilot should be okay 

air filter and exhaust questions unanswered 

asco

Will do. It's a standard enduro motor - not GYT-ed, so I stuck with the VM26.

I had the carb vapor blasted and worried about all those tiny air passage. I'll give them another look-see and make sure the air jet is the right size and is clean.

Any DT1 250 that rolls through the doors with a 160 main jet automatically get a new 170 installed regardless of circumstance. The newer prefix carburetor shouldn’t make a difference. I don’t vapor blast carburetors. It can change things that we don’t understand?

asco

The early dt1's specify a 5d1 jet needle on the 3rd clip, an o-2 needle jet, 2.5 slide cutaway.  And it shows a .5 air jet.  Having seen a dt3 carburetor I am sure the air jet was open on that one.  You'll want to check that, devil is in the details.  Sorry I just looked again at main jets, 160 after the first year.  This is just from the service manual, I'd run the 170 main as recommended.

I  vapor blast all my carburetors, and then use my ultrasonic cleaner with water and a drop of dawn, and then blow out all the passageways has always worked great for me plus I have a new looking carb

Love the sonic cleaners!  LA awesome cleaner as solution, brush and rinse with water afterwards, and blow dry with compressed air.