carb adjustment, Gunson colortune, O2 Sensor

Engine troubles? Try here.
Post Reply
JimmyC
Posts: 217
Joined: Tue Feb 18, 2014 4:59 pm
Location: Lafayette, LA and Highlands, NC
Contact:

carb adjustment, Gunson colortune, O2 Sensor

Post by JimmyC »

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
Jim Chance
710M

All my post fully incorporate the Dunning-Kruger effect
User avatar
ako
Posts: 159
Joined: Sat Jan 17, 2015 11:41 am
Location: UAE

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by ako »

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.
og
Posts: 68
Joined: Tue Mar 18, 2008 7:32 pm
Location: San Jose, CA

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by og »

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

Best
OG
User avatar
audiocontr
United States of America
Posts: 1868
Joined: Fri May 01, 2009 1:30 pm
Location: Buffalo NY

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by audiocontr »

How'd you determine the proper color for a pinzgauer spark?
1973 712m
1968 Haflinger
1965 Pathfinder
1978 GMC Palm Beach (Hey, its got 6 wheels!!)
og
Posts: 68
Joined: Tue Mar 18, 2008 7:32 pm
Location: San Jose, CA

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by og »

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.
OG
User avatar
audiocontr
United States of America
Posts: 1868
Joined: Fri May 01, 2009 1:30 pm
Location: Buffalo NY

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by audiocontr »

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.
1973 712m
1968 Haflinger
1965 Pathfinder
1978 GMC Palm Beach (Hey, its got 6 wheels!!)
kdiqq
United States of America
Posts: 270
Joined: Tue May 26, 2015 3:30 pm
Location: Houston, TX

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by kdiqq »

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.

Sent from my Z30 using Tapatalk
1977 Austrian 710M
User avatar
Brickren
United States of America
Posts: 183
Joined: Wed Jan 02, 2008 1:39 pm
Location: NW Pa.
Contact:

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by Brickren »

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
1975 710M
2000 Ural Tourist
User avatar
Hotzenplotz
Austria
Posts: 371
Joined: Wed Jan 18, 2012 9:07 am
Location: Vienna, Austria

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by Hotzenplotz »

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.
Cheers
Albert
========================
My Pinz has NEVER been with any army
JimmyC
Posts: 217
Joined: Tue Feb 18, 2014 4:59 pm
Location: Lafayette, LA and Highlands, NC
Contact:

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by JimmyC »

I think it is 14 mm long. There is also a 14 mm short
Jim Chance
710M

All my post fully incorporate the Dunning-Kruger effect
User avatar
Hotzenplotz
Austria
Posts: 371
Joined: Wed Jan 18, 2012 9:07 am
Location: Vienna, Austria

Re: carb adjustment, Gunson colortune, O2 Sensor

Post by Hotzenplotz »

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 ...
Cheers
Albert
========================
My Pinz has NEVER been with any army
Post Reply