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post #1 of 20 (permalink) Old 07-07-2007, 05:35 PM Thread Starter
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Angry Running lean and hot

I need some collective problem-solving. I was planning to take McKnight in for inspection today, but I don't like how the bike's running. First, it's running lean - I can get it to about 3800 rpm, but under load, it's not going above that. WOT leaves me right there, too. I've checked vent hoses, ducts, fuel lines - all look ok. So I'm thinking that I might have a problem with one (or both) of the needles/jets, but before I go yanking the carbs off again, anybody have thoughts? It runs pretty well at 1/4 throttle and speeds around 30mph. But that's all it's got. It'll never even get into town at that rate.

It's also running warm. I had some trouble with the fan (basically, it's broken), so I cannibalized the fan off of Orleans; and when I changed the fan, I drained the radiator and refilled with the bleeder valve open, so if there was an air bubble, there shouldn't be now. I also put in a little more oil because the oil level was below the sight glass line. But it's still running too warm. If I'm running lean, that can cause the bike to run hot, right, until basically it melts itself into one big hunk of unattractive and un-fixable aluminum?

What am I missing??

C
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post #2 of 20 (permalink) Old 07-07-2007, 09:47 PM
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Possible vacuum leak. Try spraying WD40 around the carbs and boots [email protected] a low idle. If you have a vacuum leak the idle should increase. Yes you are correct about running lean makes more heat.

Rckmtn
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post #3 of 20 (permalink) Old 07-07-2007, 10:14 PM Thread Starter
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Quote:
Originally Posted by rckmtn View Post
Possible vacuum leak. Try spraying WD40 around the carbs and boots [email protected] a low idle. If you have a vacuum leak the idle should increase. Yes you are correct about running lean makes more heat.
'Cause it's sucking up the WD40 and doing something untoward in there? I'll give it a few sploots and see what happens. If I don't have to pull the carbs, I'll be delighted...but one does what one must.

Another question: if I have a vacuum leak, would that cause my idle to just be "off"? At first I thought I had a stuck float bowl, 'cause the bike was idling high (hardly touched the throttle). But if I played with the idle adjust knob to reduce the rpms, the bike would die. I think it was a little better today (in terms of not staying at high idle), but I definitely am having trouble getting that to settle out.

Hey, Hyper! Idea for my new avatar - could really use a sledgehammer in there about now!

C
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post #4 of 20 (permalink) Old 07-08-2007, 10:43 PM
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Cindy I'm betting on a vacuum leak of some sort. The high idle is a pretty sure sign of that. You can also use B12 carb cleaner to shoot around the carbs and intakes, carb mounts and such to find vacuum leaks. What I've found with either WD40 or B12 is that the engine bogs down when you hit a leak. Your mileage may vary.

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post #5 of 20 (permalink) Old 07-09-2007, 06:52 AM Thread Starter
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Thanks, Fergy - turns out that as I was searching for a vacuum leak (spraying WD40 up around the carb boots on the air intake box), I noticed a lovely set of sparks coming off the rear ignition coil. "Hmmm," I said to myself. "I do believe those fireworks should not be there." Pulled the coil, and there were some crimps inthe wires - the coil was grounding itself against the exhaust chamber. Taped up all the visibly open points, reinstalled the coil, and took the bike back out last night - ran like a charm. Didn't heat up beyond the leftmost side of the symbol on the thermo gauge, punched it to 6K rpm in 4th gear, 65 mph, and not a problem. So I guess I was running on fewer than 4 cyls (I've been told that before, but, ya know...). I pm'd Dennis that the engine block itself felt really warm to me when I got back to the house (just a lot of heat coming up off the block), but a) it was 85 degrees and humid out at 8.15pm, b) I haven't ridden in the heat in awhile, and c) there was no indication otherwise that my bike was overheating. So I'm assuming it's fine.

Sooooo, we'll try this little trip for inspection again tonight...

C
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post #6 of 20 (permalink) Old 07-09-2007, 02:55 PM
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Fireworks you say? Wow! It's always nice to find the problem. Glad you didn't spray the sparks!

Fergy
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post #7 of 20 (permalink) Old 07-09-2007, 03:32 PM Thread Starter
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Quote:
Originally Posted by fergy View Post
Fireworks you say? Wow! It's always nice to find the problem. Glad you didn't spray the sparks!
Yeah...that'd be something that even safety goggles wouldn't protect against! Guess WD40 has a higher flash point than other combustible fluids 'cause I was mighty, mighty close...

C
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post #8 of 20 (permalink) Old 07-09-2007, 03:42 PM
 
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I think Crobins365 should forever be known as Sparky365
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post #9 of 20 (permalink) Old 07-09-2007, 07:02 PM
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Yo, Sparky, did ya pass ?

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post #10 of 20 (permalink) Old 07-09-2007, 07:49 PM
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Cindy -

I was going to suggest you check to make sure it's running on both cylinders as mine acted the same way when I forgot to connect the rear coil.

Let us know.

Carb cleaner is a great leak detector, rpm's go up if it ingests any.

Jon

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