Thanks, but no. I'm an old guy and I like the quieter sound of the stock muffler. I'm waiting patiently for the day someone produces an electric bike with a style and price I like. Met a dirt biker on Green Mountain with an electric dirt bike he bought at Cliff's Cycle Center, and I was impressed with the speed and agility he was able to achieve. As dino oil will run out, it's the way to go.

That's already figured out, if the yabos pushing electric would just frigging admit it
got a cordless drill? that's your answer, replaceable batteries
go to the 'recharge station' trade your low battery for a freshly charged one, done and done
but the idiots that be can't seem to grasp the concept

that just leaves...infrastructure dun dun DUUUUN!

Oh yes
As a former pro wrench I makes my blood boil when I hear tales of incompetent / sleazy mechanics costing customers money unnecessarily
Though I do tend to look at it carefully before I decide it was a bad job, it's amazing what gets blamed on mechanics sometimes
"he put a fuel pump in and then the brake master cylinder went bad, I think he rigged it to go out"
"That's not actually possible"
lol

having an accurate charge gauge on the car would help mitigate this somewhat, a bad battery would I think sow less than a full charge

For what it's worth, I'm at sea level near Boston and my 2009 S40 popped very frequently on decel. I checked for exhaust leaks, cleaned the carb, used a richer jet, and tinkered endlessly with the idle mix screw, and none of these things eliminated the decel pops. However, clipping 1/2 round off the spring in the TEV (Transient Enrichment Valve) on the right side of the carb has virtually eliminated them, with a negligible effect on gas mileage. Instead of one or more pops almost every time I decelerated from more than 40mph, I get one or two mild pops, at most, on a three-hour ride.

I'd try everything else recommended here before tinkering with the TEV spring, but it worked for me.

David OF MA

Were you able to work on the TEV without removing the Carburetor?

Kenny G

David,

Thank You. I was able to get the screws out and one at a time and replaced them with Socket Head Cap Screws.

Tomorrow I will pull it apart and work on the spring.

Kenny G

Today I pulled apart the Transient Enrichment Valve and cleaned everything and blew out the tiny hole with carb cleaner and compressed air.

Since I had an Ace #90 Spring I replaced the Mikuni Spring with the Ace instead of cutting down the factory spring. The Ace spring is about a third shorter in length than the factory spring

Results:

I had to increase the idle speed quite a bit, perhaps a turn on the idle speed screw, maybe more then a turn.

I had absolutely no popping on deceleration. None what so ever.

Slight popping when changing gears going up through the gears. No popping when going down through the gears.

There was a very slight hesitation when the engine returns to idle, the idle speed dips just a trifle. I increased the idle speed to about 1350 RPM on my Ryca Tachometer and that appears to have smoothed out the transition from cruising speed to idle speed.

I went for a 47 mile ride on rural roads with a lot of shifting and braking and accelerating. The results appear to be an improvement.

When I arrived home I turned down the idle speed to as low it would go before stalling. I then re-adjusted the idle speed screw. This adjustment is not as sensitive as it was before the spring change. But turned it in until the idle started to stumble and then turned it out until it almost choked. I then moved the screw half way between the stumble and choking conditions. After the next test ride I may be able to slow down the idle a bit.

I am going to leave well enough alone for a tank or two of fuel.

What is needed here is a Progressively Wound Spring. I am going to search the new Ace Hardware Store that just opened for a variety of progressive wound springs.

Update:

Went for a 20 mile ride this evening and was able to slow the idle down to about 1275 RPM. The adjustment that I made to the idle air screw earlier today corrected the idle dipping down in speed and hesitation when coming into a stop.

I think this is as good as it is going to get.

Kenny G

I filled the gas tank this evening and checked my gas mileage.

The last few tanks I averaged 47 miles per gallon.

The tank today I only got 44 miles per gallon. I guess I am going to run a couple more tanks through to see what kind of mileage I get before I change anything else.

If mileage doesn't return to 47 mpg I will then look around for a couple of  different Progressive Wound Springs at Ace Hardware.

I suspect that I am using more fuel during deceleration because the Transient Enrichment Valve is activating more quickly with the #90 Spring, thus using more gas. I can live with this level of MPG rather then listening to the after firing if I have to, but I want to get the maximum MPG possible.

Kenny G