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I was fiddling with my carbs and found it surprisingly difficult to set the idle mixture by ear. I think what was giving me trouble was that there were 4 idle mixture screws rather than what I am used to where there was one screw for everything. This means that adjusting the screw only gives 1/4th of the effect that I am used to.

Three of the mixture screws gave a notable effect but it did not seem like a "sharp" response. By this I mean that I could not tell within a small part of a turn where the lean drop-off occurred. One screw seemed to give little effect, though I am fairly sure the cylinder is working, at least off idle. I need to look into it further.

I have access to a fuel/air meter (works off of a wide-band O2 sensor) but it looks at the exhaust gas from all cylinders combined. I think I could be rich on one and lean on another and they would cancel. I am thinking about adding bungs to the header pipes so I can look at the mixture on each cylinders individually. I am wondering if anybody has tried this.

I also saw something called a "Gunson colortune", it is a special type of spark plug with a glass window. According to the manufacturer's info you can tell the mixture strength by the color and see misfires as well. Has anybody tried one?

http://www.gunson.co.uk/item.aspx?code=G4074

Although not exactly the answer you are looking for, an infra-red thermometer 'gun' can be pointed at each of the exhaust manifolds to check if you are getting the same temperature (and hence burn) in each cylinder.

Colortune is exactly what you need. I have used it on my pinz and it works as advertised.

Best

How'd you determine the proper color for a pinzgauer spark?

By the color. It is in instructions which came with colortune. It was some time ago, so I'll need to read instructions again, but you notice when color just starts changing from blue to red (or vice-versa, sorry I forgot), that is the optimal mixture.

Is there any reason the pinz combustion would want to be on the rich side? I mean, i see the concept behind the colortune - I wonder if the blue combustion is the right color for a pinz? I'd love to see what the color is after the carbs have been set by Jim or the likes and compare.

Everything I've had that's air cooled has ran rich. The Pinz has great cooling but if there is ever a situation where it starts to get hot, fuel is the only thing cooling it and a carb doesn't compensate for temperature. On all my bikes I just ran it on the rich side. When it got hot outside, I never cooked and I wasn't hunting max power, so I was happy with the extra protection.

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I ordered a color tune kit. Anyone know what size adapter I will need? They are all in mm. EBay number 251430839110. How about for a Ural? I would also like to try my mercury sticks. Are there ports that would work best? Could I hook up all 4 sticks at once? Thanks, Brian

Hi

After checking the video at https://www.youtube.com/watch?v=osUUjJz5OCQ I am confident the kit will fit on the Pinzgauer.

There is only a single spark plug replacement ( as far as I can tell), but 14mm IS the thread diameter of Pinz plugs.
On a multicylinder engine you will have to adjust once per carburator; so a Pinzgauer will require 4 passes , as it has two dual carbs.
A 4 cylinder Volkswagen beetle will be done in a single pass.

Ural is also metric, you should be good to go, too.

I think it is 14 mm long. There is also a 14 mm short

There is even an " unboxing" video for Colortune on youtube.
https://www.youtube.com/watch?v=tPfelrWMfD8

Here you can see the whole content of the package you buy ...