Running lean, how bad is it?

[Burque73]

While I'm still waiting for my Morgan Carbtune to arrive, I pulled the tank and had a closer look at the carbs. It took about two turns to tighten the pilot screws to lightly seated. I warmed up the engine and got the most stable idle at 1.25 turns out. I also decreased the size of the vacuum hose to the petcock. The 1/4 inch was a little loose but the new 7/32 fit like a glove. Could this have been enough of a leak to cause the idle to raise when warmed up? Between the pilot adjust and the vacuum hose replacement the bike runs great with minimal idle variation. As soon as the carbtune and 5mm adapters arrive, I plan to sync and post an update.

[Steve]

Shiny surfaces warp the readings drastically. Broadly speaking, laser temperature measurement relies on the shifted reflection of the laser - but shiny surfaces bring it all kinds of out of wack (This is why plates used for calibration are matte black).

MOSTLY true, except for the fact that the laser is not the measuring device, it is only used for AIMING.

I have two thermometers. Both have lasers, but one of them I can turn off. When the laser is off, it still takes readings.

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[roeme]

Shiny surfaces warp the readings drastically. Broadly speaking, laser temperature measurement relies on the shifted reflection of the laser - but shiny surfaces bring it all kinds of out of wack (This is why plates used for calibration are matte black).

MOSTLY true, except for the fact that the laser is not the measuring device, it is only used for AIMING.

I have two thermometers. Both have lasers, but one of them I can turn off. When the laser is off, it still takes readings.

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Huh, the more you know. I always assumed that there were two lasers in play, one in the visible range for aiming, the other within the infrared range to take the aforementioned measurements.
Can't find any in-depth descriptions of the principle of the operation right now, from what I've garnered so far it would be sufficient to use a IR-sensitive diode and simply measure the object's radiation in the IR range. No need to measure shift.
Limitations re. angle/gloss still apply though.

[Burque73]

This is interesting, I apparently found the only I.R. thermometer that makes no mention of measuring shiny or reflective surfaces. Not doubting the previous comments on it as it makes sense. I picked this up at Lowes by the way.


Where do you guys get reliable readings? On the head, header collars (proper name?) Maybe the bolts? Also what's a good temperature range to be in?

[Steve]

Where do you guys get reliable readings? On the head, header collars (proper name?) Maybe the bolts? Also what's a good temperature range to be in?

I usually shoot about two inches from the collar on the pipe. Just before it goes into the bend.

The temp range depends on what has been happening recently. If you just fired it up, it's going to start at room temperature, of course, and get warmer quickly. Checking them as the warm up will give you an idea if they are all warming up evenly or if one (or more) are getting warmer (or staying cooler) than the others. Before moving the bike, it's common to see temps around 200 (F). Go around the block, it's going to get warmer, but I don't really remember just how much warmer. Regardless, you will be looking for consistency, rather than actual temps, most of the time.

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[1948man]

Did you ever try to just adjust the idle down after the bike is warm and then see if it will start suitably after it cools back down? Of course, the sync etc is all needed stuff.

[Burque73]

Did you ever try to just adjust the idle down after the bike is warm and then see if it will start suitably after it cools back down? Of course, the sync etc is all needed stuff.

Yeah, unfortunately it didnt help. It was too low to keep running afterwards. Carbtune came in the mail today, so im pretty excited to get to it. Probably not today though, we'll see.

[Burque73]

Thanks to many who chimed in on this. Also a big thanks to Steve for the answered emails and for sending me your valve spreadsheet. It's not just a place to organize data, but a very useful tool.

In a matter of about ten hours yesterday (off and on) I was able to get the bike running like a top. Now it runs very smooth and has stable RPM's at idle and while riding.

I intended to just use the carbtune to do the vacuum sync and ride but as suggested, I went ahead and checked all the valve clearances. The windjammer and bracket had to come off for that though. There were a couple valves on the tight side so I changed out two shims, switched two and got them all within the middle of the spec clearance range. None were more than one shim size out though. I also replaced the spark plugs and changed the engine oil and filter. Then after all that was done, I put the carbtune to work. I was struggling with the bracket that holds the throttle and choke cables on top of carb #3. It was blocking access to the sync screw. I had been trying to use the cable for the rpm adjustment and kicked myself when I finally realized I could use the knob under the carbs for that, and as Steve suggested just take that bracket off temporarily. The brass 5mm adapters that screw into the carb boots were a PITA! Here's what I ordered. Maybe some others are better to use than these. When they heated up the vacuum hoses kept popping off.


Now that it's running right I can ride down to see my boy at his college, NMSU, about 200 miles south of here which I'm hoping to do this week.