Plain weird behavior

[chuck hahn]

Get the BS carb oring kit here and the new intake manifold orings on page 3 i think it is. remove the intake manifolds and measure the ID of the groove the oring sits in to know the size to order.

1 kit does all 4 carbs.

http://www.cycleorings.com/

[wymple]

Sounds about as likely to be an intermittent spark as much as intermittent carburetion. Leave the carbs alone until you are 100% sure of your electrics. Crank it up under darkness and stare at things awhile. You can usually see tracing around bad wiring.

[glib]

The intake manifold is cast into the head on this model so no need for the o rings there. I used that o ring kit on the carbs when I opened them up but I do wish I would have at least checked the needle jet. I'll check the electrics and do a quality job on the carbs (I have the original jets from the PO but a couple of them got roughed up a bit on removal) over the next week and hopefully I'll get to the bottom of this. Thanks for the input.

[GregT]

I will go through the carbs again before tearing the motor apart but regarding the plug wires--which would be a maintenance item on most vehicles--they are part of the coils and can't be replaced without replacing the coils, correct?

Correct - but if you can see a spark jumping to earth off the HT lead insulation, there's nothing stopping you slipping some plastic tubing over the leads...
If you have access to a multi meter, check the resistance of the plug caps. It's not unknown for one or more caps to have the internal resistor fail.

Check the floats when you strip the carbs too - if one has been spread a little it may be fouling the carb body which would give symptoms of intermittent starvation such as you describe.

[Brendan W]

Got the bike to idle and the exhaust temps after about two minutes were #1 115, #2 245, #3 280, #4 380.

Gonna dip the carbs.

Swap the ht leads on each coil over to their respective partner plugs and see if that temperature profile remains.
Probably nothing but I reckon there is only a 1 in 24 chance that four different temperatures arrange themselves in order of increasing temperature. Was it on the sidestand?

These are degrees F or C ?

[glib]

IMG_0613.jpgGotta say--it pays to follow instructions. A terrible picture I know but you should be able to see light coming through four little holes in this needle jet--but you can't because they are plugged. The guy who "rebuilt them" skipped this step. So no, you can't tell for sure unless you do it yourself and yes, I'm ready to hear a stream of I-told-you-so's. Odd thing is the #1 cylinder would not fire unless choked--but it's needle jet was the cleanest of the four.

As far as the plug wires, I think I'll just go ahead and order replacements. They are too cheap to ignore.

[Brendan W]

[ATTACH=CONFIG]35629[/ATTACH]Gotta say--it pays to follow instructions. A terrible picture I know but you should be able to see light coming through four little holes in this needle jet--but you can't because they are plugged. The guy who "rebuilt them" skipped this step. So no, you can't tell for sure unless you do it yourself and yes, I'm ready to hear a stream of I-told-you-so's. Odd thing is the #1 cylinder would not fire unless choked--but it's needle jet was the cleanest of the four.

As far as the plug wires, I think I'll just go ahead and order replacements. They are too cheap to ignore.

That's almost as bad a picture as mine. As far as told-you-so's go well, that's a 'cast the first stone' type of thing
When the carbs are back on I like to open the drains and run fuel through on prime with the odd tap of a rubber mallet. It seems to be a law of nature that no matter how well you clean things there is always something still in there on the first run through.
I would hold on the ht leads unless you have hard evidence that they are at fault. It's not a trivial job to replace them and you could up end up becoming an expert on something you wish you hadn't. I would wipe them clean, apply WD-40 and take it from there. I can't see them getting better of their own accord to let the bike run unless there was a significant difference in weather i.e. misfiring in the rain.

[glib]

OK, did the carburetors very thoroughly AND put the original jets back in. I did leave in the float valve from the previous rebuild because the old needles were clearly worn. Freshly rebuilt and painted .jpgHere is a picture of the carbs after paint and pretty enough to be on the kitchen counter--at least IMO. I started the bike and rode it around the neighborhood. Very smooth. Main concern at the moment is that the exhaust temperatures vary widely at idle--from 200 degrees to over 500. I guess the adjustment screws may make a difference but I'm not really clear on dialing them in. Initially I thought they were adjusted with the vacuum gauges but then I saw where they are adjusted based on the engines reaction to "flipping" the throttle and all four should be the same.

[huntb]

Describe "very thoroughly". Did you take them all apart and dip them in carb dip?

[glib]

Thoroughly in this case means I followed the instructions for dis-assembly, dip (jets and bodies), and reassembly checking the tiny passages for flow. They are truly clean.

[Brendan W]

OK, did the carburetors very thoroughly AND put the original jets back in. I did leave in the float valve from the previous rebuild because the old needles were clearly worn. [ATTACH=CONFIG]35669[/ATTACH]Here is a picture of the carbs after paint and pretty enough to be on the kitchen counter--at least IMO. I started the bike and rode it around the neighborhood. Very smooth. Main concern at the moment is that the exhaust temperatures vary widely at idle--from 200 degrees to over 500. I guess the adjustment screws may make a difference but I'm not really clear on dialing them in. Initially I thought they were adjusted with the vacuum gauges but then I saw where they are adjusted based on the engines reaction to "flipping" the throttle and all four should be the same.

Now might be a good time to swap the ht leads around and see if the temperatures follow them

[glib]

Maybe I don't understand the suggestion. If swapping the "ht leads" requires removing them from the coils, wouldn't it be just as easy to replace them with new? I believe the four are only $20.

[Brendan W]

Maybe I don't understand the suggestion. If swapping the "ht leads" requires removing them from the coils, wouldn't it be just as easy to replace them with new? I believe the four are only $20.

Each coil drives a pair of plugs. I think the left coil does 1&4 and the right one 2&3 If you swap over the leads without removing them from the coils it would show up any defects in the leads themselves or the plug caps.

[glib]

So they fire at the same time and can be interchanged?

[Brendan W]

That's the idea. If the temps don't change it eliminates the leads and plug caps from the equation. It doesn't eliminate the coils but you have your min and max temps on 1&4 which is one coil. It's an easy way to try and make the defect move, a lot easier than tearing into carbs.