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This R50/5 has throttle slide carburetors (not constant velocity). I can't use my home made hydrometer on them because they don't have the ports for the hoses. So I am going to use the method whereby you remove each plug wire and adjust to keep the idle the same on each side. The info I'm reading says: "Put adaptor (antistatic cartridge Beru EP 1) into spark plug cap. This prevents the spark plug cap from being damaged while it is removed from the spark plug and is placed on the cylinder while the engine is running."

Are they telling me to short out that plug wire that is removed. Are they saying the resister in the cap can be damaged? Is the Beru EP1 the same as a spoke to short the cap out? I assume yes is the answer but it won't hurt to ask.

Are we to assume you are not running any kind of electronic ignition on your bike?

This is one of those hot topics like oil and tires. So, beware!! Basically, once you get past the /2 machines, pulling a spark plug cap on a running machine can (although not always) lead to some kind of damage to the electrical system. [The /2 systems had a safety gap setup on the coils which provided a path to ground for the spark in these situations.] It has to do with the spark energy not finding a path to ground. In some situations this can cause damage to the coils, either cause them to fail or weaken them or shorten their life. In the later bikes with electronic ignition ('81-on), the Hall effect sensor in the system can be affected and/or damaged.

What you want is to give the spark an alternate path to ground. This is done by putting an extension on the end of the spark plug which fits inside the cap. I have put together a small piece of threaded rod (maybe 3 inches long) of the right diameter to fit inside the screw-on tips for the spark plugs...you know those things that you unscrew and throw away? Using a set up like this, a portion of the threaded rod will be exposed. By taking a long plastic handled screwdriver, you can temporarily touch the exposed rod to one engine fin, causoing the spark to run to ground rather than go through the plug. For the time you have the screwdriver touching the rod, the other cylinder will be running and you can go about your synching process. By alternating each side and making adjustments, you can find settings where each cylinder operates at peak performance and/or operates such that it matches the other cylinder.

Snowbum has an article on this...if you're interested in reading it.

Kurt in S.A.

We tried that method (and many others) and it is fraught with ways to be tripped up. Those carbs are super easy to adjust by ear, even easier than the vacuum carbs on the R75/5.

1. You must have good advance springs so that the rpm has no tendency to "hunt" due to it starting to advance.
2. The carbs already need to be quite close in adjustment to operate at that low rpm.
3. You must have the idle jets clean, or it won't respond correctly to idle speed adjustments.

Don't even think of using that method for adjusting the cables. You must be well above the full advance rpm while on one cylinder. You must be fast to avoid over heating. Best to use a large fan on the cylinders for cooling. You have to be quite coordinated to short one side out at a time and then the other side. All the while adjusting the throttle cables.

Hello Duane. You say those carbs are super easy to adjust by ear. I knew someone would say that and that's why I included the picture of my exhaust. Is it still possible with my exhaust?

And yes Tim, the ignition is stock.

I just never heard of a "Beru EP1 tool"!

you can pull the muffler off to do it

Oops, didn't notice the two into one exhaust. That is just one of many reasons one shouldn't use 2 into 1. The other is the loss of power. Of course the R50/5 is so snappy that one can afford to give away a few hp:-)

I can still tune them by ear, but it requires a lot more experience. Since these days I only tune a couple per year, I am not sharp/fast at it.

Duane Ausherman wrote:
I can still tune them by ear, but it requires a lot more experience. Since these days I only tune a couple per year, I am not sharp/fast at it.

Duane is our R50/5. Not allways that quick, but once you get him going he ticks along pretty well.