I had pulled the spark plugs when I first picked up the Ural and they looked brand new so I couldn't really assess whether it was running too lean. Now that I have put on about 2k km, I pulled the plugs again and the center electrode was still a bright white. This indicates that it is running lean. Mickey, the Anchorage Ural dealer, recommends changing both the idle and main jets to larger ones as he feels that they run too lean due to emission requirements which cause the engines to run hotter. i.e. Running richer may help the engine to last longer.
The Keihin carbs have this handy drain on the bowls but use phillips screws to hold the bowls on. Most of the screws came out without issue but one needed vice grips to break it free. I don't think the bowls have ever been taken off. That's probably a good thing. In the picture below, the main jet is on the left, the pilot jet is in the hole just below and to the right and I believe the on on the right is for the enrichener.
After the bowls were off, the pilot and main jets were removed. The original pilot jet was #40 and the original main jet was #122. The recommended pilot jet is #45 and the recommended main jet is #130. I went ahead and put these in. The previous owner has been running this setup for several years and suggested that I also follow Mickey's recommendation. The bowl screws were replaced with SS allen head screws to simplify removal of the bowls in the future. Buttoned everything up, put the petcock on the prime position to allow the bowls to refill. Hit the starter and it started right up. Since it's still raining, I didn't take the rig for a test drive but it should be running a little bit cooler. It no longer "pops" when first started so this is a good start. I gotta admit that the "popping" was annoying. Hopefully the mileage won't be impacted too much.
I checked the idle mixture adjustment just to see what it was set to and it was 1½ turns from a soft seat. This, I believe, is the default setting.
Richard, you must have one of the most well maintained machines on the road. I have come to believe that you truly enjoy taking your bikes apart and putting them back together, a useful talent and fortunate hobby.
ReplyDeleteI gotta admit that I like messing around with things. And that goes far beyond motorcycles.I think it came from "I wonder how it works?". That's why I like bikes that I can actually dink around with. The Airhead and the Ural both fit that definition well.
DeleteYep, 1.5 turns CCW from soft seat is the good start point for the idle air mixture screw. Was it the same on both sides? The replacing of the stock screws with allen headed screws is standard procedure, the stock ones tended to strip in the old models. I still prefer the float bowls that come with the BING carbs on the Airhead Beemers. I think you'll be happy with the larger jets.
ReplyDeleteYes, it was the same on both sides. This afternoon after running a bunch of errands in town, I turned them both in ¾ of a turn to smooth out the idle when warm.
DeleteI also prefer the Bing carbs, The drain is nice to have but it would drain right onto the exhaust system. Not good. Hopefully I won't have the water issue that I had with the Airhead.
Hopefully you'll find the new state of tune a better one, sure sounds like it's the right thing to do. I'm hoping to re-jet a couple of them this winter since they're on the lean side as well.
ReplyDeleteAnything that improves reliability is a good thing in my book. I don't know whether or not it's my imagination but the engine seems to run quieter overall.
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