Monday, June 8, 2009

second start

Restarted the bike again yesterday and managed to verify while running that oil was indeed flowing (gushing) out the head feed line so that was a good sign that the life juice is getting where it ought to.

Still, the thing felt a LOT hotter than what I recall my 650L got in the minute or two that it was idling on it's own in that time. and then as I was backing it out of the garage to go do some DOT approved test runs up and down the street, engine died and would not come back to life.

First thought was: carbs might have a booger in the idle circuit. Since the thing wasn't going to be doing anything for an hour anyway I decided to yank the carb assy (Forgot how much fun that was!) and just give everything a once over since it had been sitting for so long...all those seals hate drying out with no gasoline running through. This time was much easier because I replaced every OEM phillips screw with an equivalent stainless allen head in the rebuild. This turned a screwdriver and four-letter-word shouting afternoon into a non-event: an old lady's fart out on a windy Manhattan street would have proved a greater interruption.

Everything looked okay inside the carbs, altho I did see a little residue in the pilot jet -- likely because I made the mistake of running dirty gasoline from the original bike thru the carb when I started it back in '07...dumb. Still not something I'd expect to cause the bike to die like this.

Somewhere after I was too committed to yanking the carbs, I recalled that the valve clearance could definitely be an issue from the forums and most recently here. Then Joel, the XL600 Whisperer, chimes in here from my previous post

That's right, you'd better start it!

You adjusted the valves I'm sure. You may want to do it again. Also make sure the manual decompresor (on the right exh. valve) is adjusted right and not decompressing even a little.

Try turning the idle screw up. Way up. You can always turn it back down.

Still only runs on choke? Now look for leaks on the intake manifold. Unlit propane torch, WD40, starting fluid, you know, to see if the idle perks up any.

The reason it may not have restarted is that if you don't get it all the way warmed up to about 150 or so degrees, it is somewhere between wanting choke and not wanting it, so it is hard to start. This is made worse if the idle is set way too low. Then you try to correct that with opening the throttle, and without the right feel for doing so, it can kick back on you if you open the throttle too much. Sometimes in this confused choke/no choke situation the best thing to do, with the idle adjusted crrectly to start with, is to just turn the choke off and kick it about six times. Around the sixth kick, you may be able to apply the slightest throttle to coax it, and it should sputter right to life.

Good work, FINALLY you start it. Took you long enough, you Really Finnicky Vulnerable Creep.

Will check those valves tonight, Joel, PROMISE! Not so sure about hte Creep part...but claims of my vulnerability are nothing new :)

Meanwhile, SIDEBURN Magazine left a nice oomph in my direction today. Funny because I just sealed an envelope for their latest issue yesterday. If you haven't checked it out, a very lovely print magazine, so always an honor to get on their radar.

Check 'em out, I personally can't wait to read about D. Mann and that builder in So. Cal, Mule:


  1. Adam, I'm trying to recall if you changed the big ends on your rebuild. I'm thinking that you didn't. So then the only bearings that might be new are on the wrist pin/piston. The only really new wear parts are the rings getting set into the cyl walls. This always makes a lot of heat and usually you can run the engine at some higher rpm to help them along. The friction is good for eventually making a good seal. There HAS to be oil in the process, of course and you have identified that is being circulated okay. Running it rich will help keep it cool. The plug looks like it might even be a bit lean. You gotta make sure the manual valve lifter has plenty of play so that the valve can close all they way - a good point. Although that is probably not what lets it die after a few minutes. Can you keep it running with the throttle open?- not razzing the throttle just some smoothe fluctuations in rpm? It seems like it just needs some more running and some fuel flow adjustments.

  2. Good points all around, Dad - I'll try not to worry about the heat part too much then. The choke on our bikes is not really a choke per se but another fuel richener circuit emitting right into the primary carb's output tract. So perhaps it's just thirsty right now.

    The Supertrapp is set up with all the discs right now so very open. Might need to step up on the Main jet but I don't think too open an exhaust matters as much on the idle? For street use I'll have to reduce the number of discs; just a little too noisy.

    Also, there's a teeny weeny fuel-air mixture screw that also makes an important difference in all this. I think I've got it set correctly...but will take some fiddling.

  3. Righteous, Flying Venerable Commando!

  4. ah, I see now that I
    Vicissitudes of