cylinders 2 & 4 running lean

[starrider1946]

I have a problem with cylinders 2 & 4 running lean. The plugs in 1 & 3 look good to me but 2 & 4 don't have much color to them. I have a stock 1600cc Type 1 in my Roadhawk Trike. It has dual 34 ict Webers on it with stock jetting. Has a aftermarket svda distributor with vacuum advance. Has headers with glass pack type mufflers. Timed at 32 degress full advance at 7.5 degrees at idle with vacuum plugged. I am running bosch plugs.
When I am going down the road in what I would call cruise mode it sounds fine. It does sound like it spits and sputter if I am not giving it a little gas. If it was just on one side I might suspect a vacuum leak or something but since it's on 1 & 3 I don't know. Any suggestions. Oh, I just checked the valve setting and it is ok.

[MdKnightMan]

Ok a couple of things come to mind.

Are you running an 009?

Your fire my not be equal.

Check your plug wires for corrosion, check your distributor for scoring or burn areas and check your rotor for pitting.

Some aftermarket caps are not equal distance all around.

[peteg59]

/\...What he says, it sounds electrical. If it was a fuel issue it would likely not be in only 1 cylinder/side. Same for vacuum leak unless an intake gasket is toast on each head.
I've read timing should be @ 30, but 32 isn't too far off.
Best of luck on straightening it out.

[starrider1946]

No I am running a sdva distributor with vacuum advance. I put new wires on it today. I have a new rotor and cap I'll try. Hadn't thought about that. I'll post tomorrow. Thanks for the suggestions.

Ok a couple of things come to mind.

Are you running an 009?

Your fire my not be equal.

Check your plug wires for corrosion, check your distributor for scoring or burn areas and check your rotor for pitting.

Some aftermarket caps are not equal distance all around.

[DeathBySnuSnu]

Dual single barrel set ups tend to only idle on 1 cylinder on each side.
It is worse with a cam that has more overlap than stock.
Unless you do a lot of low rpm near idle speed running it probably would not make much diff in spark plug color.

[starrider1946]

Wonder how I would know if I have a problem. When I ride I wouldn't say I do a lot of low speed idling. It probably has been running like this for a while. It was running so bad with the carbs that were on it that when I switched to the 34's and it ran so much better I didn't really pay that much attention to the lean part. I put new plugs in i yesterday and like I said 2 & 4 were a whole lot whiter than 1 & 3 which I figure they should all be about the same but I am not sure with this air cooled motor. Thanks for the sugggestions.

Dual single barrel set ups tend to only idle on 1 cylinder on each side.
It is worse with a cam that has more overlap than stock.
Unless you do a lot of low rpm near idle speed running it probably would not make much diff in spark plug color.

[Loner]

Try richening each carb by about 1/4th turn (counterclockwise) at each mixture screw. Any type of popping or unusual noises coming from the exhaust when the motor is just off-throttle often is mixture related.

[starrider1946]

I now have the right carb mixture at 2 1/2 and the left just shy of 2 1/2. I went on a little ride and check the plugs an it seems like 2 & 4 have a little more color. It idled good and has good throttle response. I am not sure where my throttle stop screws but I don' t want to fool with them. The carbs are in sync. I have read where they should be around 1 1/2. I did check the idle jet and it is a .060. Thanks for the suggestions.

[stinger608]

Any update on this Star rider?

Is it still running good man?

[starrider1946]

Yes it is definitely running better a little richer. Thanks

Any update on this Star rider?

Is it still running good man?