Sunday, August 30, 2009

by 'manual' I mean 'by hand'

This space has been moto specific for so long. Bikes will always be a big part of the equation, It's also about doing other things, like chopping out dovetails, or the experimenting with my own bicycle shifting mechanism.

Anyway, I've got like 30 little wooden boxes to make for this upcoming wedding party. Hope I make it all in time. Just spent the weekend organizing my tools, honing the irons, building some jigs, making a proper shooting board...Macbeth Hardwoods is 5 minutes away and the logo on their staff shirt says it all: "Wood Is Wonderful"

Still chasing that oil leak in John Henry's cylinder head, tho. Don't think I wont be getting into that until the week after October 3, but for now, wish me bueno suerte!

Monday, August 17, 2009

ride report

OK, a handful of scrambles up into the hills and around briones reservoir, and I've accumulated a little data. Butt dyno says it's pretty good. Got a bit of an oil leak around the cylinder head, left side. Now a little oil leak aint the end of the world and there are more than a few XL600's out there with the affliction...I prefer to think of an oil leak as affirmation of oil actually getting to that part of the insides, myself...would be awful lot worse if it weren't. Still, how much is too much? I notice little spatters of oil on my left boot after a ride, so it's obviously producing more than just a little bit. I'm guessing that black stuff is road soot as opposed to some sort of precipitate from the oil, which itself looked pretty clean to me:

Here's a closeup of my plug. I did a Wide Open Throttle run in an industrial area right near home, probably not long enough to truly test that fuel circuit but still here's what the plug looks like

And finally, that rubber interface between the carbs and the intake manifuld does get pretty hot, not sure how I feel about the fuel line draping across like that. There's a mechanic's joke from the North Woods about assessing something ambiguous yet critical like this, you're supposed to shrug and then say: "It's probably OK". But you're laughing because you know that's the same thing muttered by regretful space shuttle engineers, aircraft ground crew men, and any number of botched shade tree mechanics out there.


Here's a picture of the cylinder when I was doing the engine rebuild. I don't see how oil could be weeping out the left side of where the head makes contact...most likely oil coming from somewhere else...but where...

Thursday, August 6, 2009

finishing up seatpan

...hahah so funny to use the word 'finishing' when discussing this project which will never be done...

Well after a short trip to a land of tasty treats: , I've been back at it in earnest with what time there is left in a day.

Just had to reposition some mounting warts for the turn indicators, rewire the lighting and get the mounting hardware glued up

I had a Lucas style tail light from the J&P catalog kicking around and decided to go with it since it throws a more emphatic signal than the LED array that I had previously. Plus the clearance makes it okay now for a bigger light...heck There might even be enough room for some TRUCK BALLS on that thing:

The finish is rougher than a pimply teenager's face when you get up close thanks to my hamfisted technique but it's at least road worthy enough to vroom around in the local hills...soI think that's what I'm gonna do. Bye for now!

Wednesday, August 5, 2009

jetting reference

Just placing this thread submission here for now, a succinct rundown on how to tune a carb; probably my next exercise once back on the road...


Tuning a carb is far more than just changing out a jet. Your first step is to ensure the engine runs well at full bore - that's when the jet is in full flow. You do this by putting in a new set of plugs and run the bike up to full throttle (on the road). Cut the ignition and check the burn color on the plugs - if they are a nice light brown and your bike is running good at full throttle then the jet size is correct. Your next step is to determine how the bike runs at 1/4, 1/2 and 3/4 throttle. These settings are adjusted by moving the jet needle up or down depending on the reaction of the engine. When the needle is moved down, it leans the bike out - when moved up it will richen up the mixture. This tuning step is used to adjust the mid-range of the carb. In most cases there is a little give and take when adjusting the mid-range.

Finally - there is the idle adjustment setting. This is done be adjusting the idle air screw. Typical setting is 1 and 1/8th turn out from the air screwed all the way in. On some bikes there is an additional idle screw that is used to set the carb idle. In a multi carb setup (2~6), carb sync gauges should be used to sync the carbs to each other. Again the air screw and/or the cable is adjusted so each carb provides the proper amount of gas for all throttle settings.

Bikes that stumble a little during fast throttle cracking is usually cased by the mid-range not set up correctly. Engines popping is usually a combination of valve, ignition and carb adjustment settings. Valve timing is easy - just set them up as called for by the manual. Ignition timing again is an easy setup. Carb tuning is done in the order of full jet operation, mid-range and finally idle settings.

Strictly referring to a chart to pick a jet size will only get you into a ball park. You still must do a plug reading to determine if you have selected the proper size jet. Things like state of your engine (beat or new), density altitude, what kind of pipe and air filter you use will determine your jet size selection. Charts are useful to getting your close - you still must tune for good performance.

From your description - it difficult to tell you if you have the proper jetting. Try checking the plug burn at full throttle and move on to mid-range adjustment. Your valve and ignition timing should be checked and adjusted before you start messing with the carbs. Remember to ONLY change one item at a time and check for improvement.

Take your time, follow your manual and you should have good results.