Fri, 03/12/2010 - 04:00
Hi folks. I need some guidance on setting up the carburetor on my R62. I have just completed an overhaul of the motor. The motor starts easily,but, the gas mixture is very rich,resulting in lots of black smoke and very black plugs. The jets have no markings,so, I cannot identify their size. The carb float also needs to be set correctly. Any guidance would be appreciated.
- 586 reads
Sat, 03/13/2010 - 07:35
#2
R62 carb settings.
Hi Darryl. I am pretty certain that the air valve is full open. Like you, I only close it for starting. The manual gives guidance on setting the slow running which is ok on my machine. There is an adjustment screw on the carb, close to the manifold. I presume that it is an air adjustment. I set it to the fastest running position, and then backed it off a little.
I will be in Spain for the next week. When I get back I will take another look at the problem. In the meantime, I would welcome any firther advice.
Sun, 03/14/2010 - 12:14
#3
Tim, I am green with envy. I
Tim, I am green with envy. I was fortunate enough to spend 4 weeks riding around Spain in 2002, and I want to go back. What a beautiful country with wonderful people.
The screw you're talking about is the idle air screw, and it sounds like you're adjusting it correctly. But there's a throttle stop screw, which controls the idle mixture. It's located on the right side of the carb. There's a lock nut on top and an odd looking screw head underneath. As this screw is turned clockwise, it raises the throttle slide stop position.
If you haven't noticed it before, the idle "circuit" on these carbs is pretty strange. The idle jet projects up into the carb throat. When the throttle slide is less than about half open, it covers the idle jet and so it doesn't participate in the carburetion. (Above about half way, the small contribution it makes is not noticeable.)
When the throttle slide is all the way down, there's a horizontal hole that runs through the throttle slide, and lines up with the tip of the idle jet. At this point, the idle jet contributes its fuel to the carburetion and allows the motor to run.
The throttle stop screw seems to do two things: it adjusts the alignment of the hole with the idle jet, and it also controls how much air goes under the throttle slide, and therefore, how much the main jet contributes to the idle.
To set up the carb, you should first get the engine thoroughly warm. Then loosen the adjusters for both air and throttle cables so that there's some play at the levers.
Now, adjust the stop screw for the slowest consistent running position, and then adjust the idle air screw to fine tune it. It may take a couple iterations to zero in on the best running condition.
Once you have the idle set up, adjust both cable adjusters so that the cables have a very slight amount of free play, 1-2mm. You need the full swing of the levers to open and close the slides, so they do need to be adjusted properly.
If you can achieve this and your bike is still running very rich, your main jet is probably suspect. The owners manual says that the jets are supposed to be stamped with their size, but it doesn't say what that size is.
My motor also runs somewhat rich. In my case, the air and throttle cables appear to be the wrong lengths, and so are at the ends of their adjustment ranges on top of the carb; the throttle is slightly short and the air is slightly long. I haven't fixed this because, at least on my bike, the cables appear to be permanently attached to each slide. I believe that the throttle slide is being held slight up off the stop screw and that the air slide cannot be pulled completely out of the carb throat. In both cases, I think the distances involved are very small, maybe 1~2mm. (For example, the throttle stop screw does nothing on my bike until it is most of the way in.)
Mon, 03/15/2010 - 07:07
#4
R62 carb settings.
Hi Darryl. Greetings from Spain. I agree with your comments regarding Spain. It has everything for the motorcyclist, great weather,great roads with no traffic and great scenery. The food and people are an added bonus.
Thank you for your posting on the carb settings. It is most helpful. Do you have any guidance on the float setting? At present, I have set it so that the fuel level is just below the tip of the main jet.
Dreher in Germany has a selection of main jets. I will buy a few different sizes and experiment with them, to get the mixture right.
Mon, 03/15/2010 - 07:51
#5
I hope you'll report back
I hope you'll report back your experiences. There's so little information about these early bikes available, every tidbit helps!
When you're getting black smoke, do you have the air lever open all the way? It acts as a choke and richens the mixture. On my R52, I find that I only use the air lever when starting, and to get a really slow idle.
Do you have the R52/R62 Owners Manual? It has a detailed description for setting up the carb.
VBMWMO Webmaster,--Darryl Richman
Rider #52 in the 2012 Cannonball--follow my blog!
http://darryl.crafty-fox.com