What am I to make of the dicoloration on my V&H heat shields?

[FrameMount1200]

Originally Posted by Tomcatt

Then pull the carb, take off the float bowl and see what size pilot jet is in there. If it's a 42 you've found the likely cause. Replace it with a 45 and set the idle mixture screw at 3 turns out.

I haven't taken the float bowl down yet, but I just checked the idle mixture screw and it was at 1.5 turns out. I'll turn it out further and see if things improve.

I did have a couple of pops back through the carb yesterday, but I don't honestly remember if the bike was fully warmed up when it happened. Could have just been cold, could be this setting, or could be a weak accelerator pump, although maybe not that because it doesn't show consistent signs of hesitating on acceleration.

I'm also getting a little deceleration popping which I understand is another sign of not getting enough fuel when the throttle has been cut.

I put new plugs in yesterday, so I'll be able to read those after a while.

Background to all this is the fact I'm still learning what the bike wants as it warms up. It's sill in the 30's and 40's here too.

.

[wedge]

Originally Posted by FrameMount1200

I haven't taken the float bowl down yet, but I just checked the idle mixture screw and it was at 1.5 turns out. I'll turn it out further and see if things improve.

I did have a couple of pops back through the carb yesterday, but I don't honestly remember if the bike was fully warmed up when it happened. Could have just been cold, could be this setting, or could be a weak accelerator pump, although maybe not that because it doesn't show consistent signs of hesitating on acceleration.

I'm also getting a little deceleration popping which I understand is another sign of not getting enough fuel when the throttle has been cut.

I put new plugs in yesterday, so I'll be able to read those after a while.

Background to all this is the fact I'm still learning what the bike wants as it warms up. It's sill in the 30's and 40's here too.

.

When you cut the throttle you cut the air, so it tends to run rich.

[FrameMount1200]

Originally Posted by wedge

When you cut the throttle you cut the air, so it tends to run rich.

According to these guys at DK Customs, deceleration popping is a symptom of too lean. But maybe they're only referring to FI engines.

https://youtu.be/iu8RVJdiEu4

[Ireeman]

Originally Posted by FrameMount1200

According to these guys at DK Customs, deceleration popping is a symptom of too lean. But maybe they're only referring to FI engines.

https://youtu.be/iu8RVJdiEu4

There is no such thing as fuel injected gasoline motors. It's fake news.

[Ludwig von Buzzthoven]

Originally Posted by madnss

That brand of exhaust is known for that for bt evo and Xl’s. Every chrome exhaust I’ve ever used turned gold, blue and purple. And the internet riders swore up and down it was lean haha ��

As others stated you can always check your carb pilot and main. Maybe pop the timing cover off too and peak around

I have owned four Harleys total and three of them (a ‘15 Forty-Eight, a ‘17 Softail Slim, and a ‘21 Forty-Eight) had V&H Straight Shots on them for a long period of time. None of them - either the slip ons or the heat shields - ever turned blue.

[John Harper]

Originally Posted by wedge

When you cut the throttle you cut the air, so it tends to run rich.

Interesting. I recall the throttle positioners on VW carbs to slow the throttle plate closing on deceleration. Perhaps to avoid rich mix and smog on decel. Seems the opposite on bikes perhaps, maybe more varied rpms? Maybe fast lean out causes more bad smog?

But those were butterlly carbs, most of ours are CV.
John

[wedge]

Originally Posted by John Harper

Interesting. I recall the throttle positioners on VW carbs to slow the throttle plate closing on deceleration. Perhaps to avoid rich mix and smog on decel. Seems the opposite on bikes perhaps, maybe more varied rpms? Maybe fast lean out causes more bad smog?

But those were butterlly carbs, most of ours are CV.
John

I think John, that the CV having a throttle plate as well most likely shares some symptoms.

The proof though is that the roll off test for checking jetting on the top end follows that logic perfectly. When you roll off and the bike likes it and tries to accelerate a bit, then you have been running too lean and that slight enrichening gives it a lift, but; if the bike falls flat on it's face, that shows that the bike was too rich on the top end and going richer choked it out. Naturally, if there is no reaction other than to coast, then the bike is about dead nuts on the top end. That works with Mikuni's too, so the slide alone doesn't seem to alter the physics much if at all.

The other thing that I should mention, is that I have always looked at the popping issue as supporting evidence that going rich quickly like that can cause popping too. I have always thought it sounds a bit different, like deeper in tone? Lean popping has a real snap to it like gun shots. We call it "shooting ducks" in circle track.

[John Harper]

Originally Posted by wedge

The other thing that I should mention, is that I have always looked at the popping issue as supporting evidence that going rich quickly like that can cause popping too. I have always thought it sounds a bit different, like deeper in tone? Lean popping has a real snap to it like gun shots. We call it "shooting ducks" in circle track.

Interesting, perhaps more of a "rumble" noise on decel instead of sharp popping due to lean conditions.

I tuned my main jet the way you described, slightly backing off throttle on freeway to see if it accelerated or had smooth transition to decelerate.

John