Hey 04,

These bikes are jetted very lean from the factory (when they used to make them). When I first got mine I also ran it half choked for a while because it seemed to like that more than the stock set up. You may foul a plug running it on half choke though.

From what I gather folks around here either mod the stock carb or go with an aftermarket. I run a VM36 mikuni and it's felt like night and day from the stock set up, never looked back.

Safe travels

Philly.  You should try something between 185-200 main jet in that VM36 carb from Murray's Carbs.  Murray installs a 165 main jet and swears it's right, but Lancer builds and recommends something between 185-200 main jet for his VM36 carb builds.  I never ran "Woody" with the Murray VM36 with 165 main.  I went straight for the 200 main jet and Woody could rip!  With that 200 main jet, the midrange tuned in the best in the 2nd groove from the top (leaner side of the middle groove).  Your exhaust is similar to what Woody had.  Give a 185-200 a try - I bet you'll like it.  But get that clutch fixed first!

I don't know if its lean or rich on the 1st notch. It actually felt lean and I hit reserve @ 115 miles. It ran perfect, just felt like the throttle was hanging just a tad coming to a stop.  I'm not sure but that works out to be over 55mpg. One thing for sure I'll be using that feature on some of these deery roads in the evening. I ordered some floorboards should be here tomorrow, see how they work out https://www.amazon.com/dp/B08CGQHYXQ?ref=ppx_yo2ov_dt_b_product_details&th=1 gonna put them in the front.

Surviving Philly wrote on 05/07/24 at 19:29:55:
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I disagree with the "very lean" and the "half-choke" comments.  Maybe "slightly lean" for some locations and the "`half-choke" is there for a reason.
If you DON"T need to half-choke during warmup, your bike is likely jetted too rich.      

There is a bit of misunderstanding and misinformation on these topics.

Sorry, this is confusiing between your comments and OhioMoto’s comment.

If you can start up and ride away without using any choke, I’d consider this normal when the outdoor temperature is above 65°.  

To OhioMoto’s comment, 1/2 choke or full choke should only be needed for warmup when the outdoor temp is lower.  If you have a really small (undersized lean) pilot jet, you probably do need the choke all the time.  But I think it’s incorrect to say the pilot jet is too big if you don’t need the choke.  Perhaps this is a colder climate issue (like OH and PA), but my bike would laugh at me for using the choke in TX most of the year.  I need the choke in January for a couple minutes when I want to ride in 55° weather.

That said, it’s not a bad practice to use the choke for 2-3 minutes with every cold start.  You want/need the higher idle RPMs to ensure oil flow to the top of the motor.  Letting the bike stumble at low rpm while trying to idle on the side stand doesn’t create sufficient oil pressure to the top of the motor.  Admittedly, even today’s modern computerized fuel injected vehicles will usually cold start up at a higher warmup enriched fuel mixture rpm even in the hot summer.  So, I guess I can agree you can always use the choke at initial cold start.

The choke is designed to be a “cold start” warmup aid.  It’s not designed to be a “dial a jet” mechanism to create proper air/fuel mixture when the bike is up to operating temperature.  The choke has a “run position” (off).  When the carb is jetted and tuned correctly, the choke should be in the RUN position while riding.  

If you think you are also running lean with the choke 1/2 open, I think you are mistaken.  If anything, it would create an overly rich condition once the bike is up to operating temperature.  I think you are mistaking a rich bog for a lean bog when you say the rpm’s hang (I’d need to experience this first hand to better understand this description).  That said, it is highly unlikely you are running lean with the choke on.  It’s contradictory to what the choke is designed to do (enrich the fuel mixture when it’s cold and the bike needs extra fuel to warmup and get going).

Afterfire (backfire thru the exhaust) is caused by unburnt fuel entering the exhaust header.  It mostly only happens on deceleration.  It’s counterintuitive that the “white spacer mod” that enriches the low midrange fuel mixture alleviates afterfire on deceleration.  That brings us to the  “transient enrichment valve” (TEV).  The TEV is designed to address afterfire.  In a perfect world, it would always do its job, but it’s not 100%.  Tinkering with the TEV spring (spring length, spring weight) has also been tried with mixed success to alleviate afterfire by some forum members.  More on that in the tech section - but at minimum, clean your TEV (you don’t have to remove the carb to do it, but it’s probably better if you do).

Your afterfire is being alleviated because you’ve enriched the fuel circuit (low midrange circuit under high vacuum specifically under deceleration) by using 1/2 choke.

It’s contradictory that you think you are running lean using partial choke while simultaneously curing afterfire that’s created by a low midrange lean condition under deceleration (low carb vacuum).

Don't confuse climate with operating temperature.  If engines maintained abient temperatures during their operation the combustion engines wouldn't need chokes and enricheners. EFI systems account for operating temperature.  Carburetors expect the user to account for it.  It's a thing.

I am a carb expert and have worked on-rebuilt-modded 100's over the past 50 years or so. Your carb on your bike has no choke. What it has is a variable manual enrichment circuit. Thats why on the 1st notch the bike runs perfectly. A choke is a device that chokes off the opening allowing atmospheric pressure to push more fuel out the jets.

Something to think on, engine vacuum DOES NOT pull the fuel out of the carb into the cylinder! Engine vacuum creates a low pressure area and atmospheric pressure acting on the the fuel in the bowl forces it through the jets and into the engine.  Do a little test, block off the bowl vents to amost and watch the engine stop running.