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Mark Creek
(@mark-creek)
Posts: 22
Eminent Member
Topic starter
 

I’m hoping to get some help. I have a 1975 R90/6 that I just added the wedgtail ignition too. Now it stumbles and sputters around town. Idles great and runs great at full throttle. I’ve cleaned the jets and fuel lines from tank as it acted like a blockage. Timing set for new ignition. Valve lash checked. Both diaphragms appear to be fine and without holes or tears. New ethanol free fuel as well. 

Would a binding carb slide cause these symptoms? I noticed as I replaced a needle it had play in it side to side but it wasn’t “flopy” the way I usually see them? 

any ideas where I should look?

 

 

 
Posted : 11/20/2022 09:44
Scot Marburger
(@8166)
Posts: 438
Member Registered
 

You mention replacing a carb needle. Many problems are caused by "the last thing you did". Did you use the correct needle(hard to tell by looking at them) and install it in the right groove? The Bing book I have here says it should be a 247 installed on the 2nd groove from the top.

Is it possible that the slide is installed backwards, front-to-back?

 

Or maybe one of the cables isn't seated properly (check both ends, and at the splitter if there is one).

 

 
Posted : 11/20/2022 11:21
Richard Whatley
(@wobbly)
Posts: 2286
Member
 

I don't know anything about the Wedgetail, but maybe I can help you work through the issue to find your own solution. In order these suggestions are...

• First and foremost.... did the bike display any of these characteristics BEFORE the ignition was added ? IOW, how did it behave the week before ? If the answer is "it ran great", then it's highly unlikely that the bike developed carb issues overnight. 

• The FIRST RULE of adding a new ignition is to ALWAYS get the bike running perfectly on the stock ignition. THEN add the new ignition. If you are doing the dual chore of bringing the bike out of storage AND adding a new ignition, then I highly advise you to completely remove the new ignition, and do all the carb sorting in the BEFORE, or OEM state.

• Unlike points, there is no way on God's green earth that the timing of an electronic ignition (EI) can be statically set. Read the instructions again. The initial setting is simply to get the ignition close enough for the bike to be cranked so that an ignition strobe timing lamp can then be used to finalize the ignition timing settings. This "finalization" MUST be done at high RPM (4500 RPM plus) using the flywheel's Full Advance (usually an "F") timing mark. Ignition timing is absolutely not set at idle !

• This last one is based upon common electrical misconceptions and myths. Your new EI does not operate on 12VDC, any more than your home computer runs on 120VAC. What !? No, sir. The voltages inside the box are proabably more like 3VDC. And the voltages for the Hall Effect devices are proabably more like 1.5V !! Ohm's Law thus tells us connection quality is more important than ever !! 

The addition of EI means that you've got to stop thinking of your ignition in terms of "record player" (popular in 1975), because it's been catapulted right past cassette player, past CD player, past digital micro cassette, all the way to MP4 player in a single, quantum jump. That means the installer's way of thinking about the electrical requirements of the unit also needs to take a quantum leap !

Believe me, the days of twisting wires together and covering them with electrical tape are as GONE as the vinyl record player. So are the days of "grounding" items to rusty motorcycle frames and expecting them to work perfectly. Why? Because in the digital world, the micro-computers inside the box are testing the power circuits maybe 2-3 million times per second ! And if it perceives a tiny weakness (either a break, or a lower voltage due to higher resistance in a shoddy connection), the ignition will misfire. No once, but several hundred times. And then what we hear is several misfires in succession, which most people interpret as bad fuel or carb settings. And that's because they haven't mentally transitioned from "record player" to "MP4".

The quality of the wiring done during this installation MUST be perfect. Perfect solder joints. Perfect heat shrink. Perfect copper connections all the way back to the battery. And the battery had better be perfect itself because the new digital circuits are looking for (say for instance) 12.300VDC and 12.299V just won't 'cut the mustard' any longer. 

The follow-on then is if you work in military electronics or aerospace electronics field, and your installation wiring is Excellent, then start checking your analog charging system. This because any event that brings the system voltage below that newly imposed digital threshold is going to have a negative effect on ignition quality. 

Hope this helps.

[color=blue]Don't hide 'em, Ride 'em !!
#15150[/color]

 
Posted : 11/20/2022 12:14
Mark Creek
(@mark-creek)
Posts: 22
Eminent Member
Topic starter
 

Thanks for your reply Richard. I like the music analogy, helps understand the perspective.

I’m not sure it did this before the EI change. What I mean is that it sat 3 months sorting out EI installation issues and I don’t remember but I don’t think it was an issue. My main issue and reason for switch was the difficulty in getter idle down to 1,000rpm’s which many in this sight thought might be related to my advance unit. Unfortunately, I think I changed several things at once attempting to solve idle issue before it ran. 

actually, unless I miss understood the instructions, the timing is not to be checked at speed at install? I would think a timing issue would show itself with starting and wide open throttle issue which it doesn’t. 

I can revert back to points to try it (points where damaged removing it) but I thought I’d throw my question out here first.

 

thanks!

 
Posted : 11/20/2022 13:56
David Elkow
(@4949)
Posts: 195
Estimable Member
 

With the engine warmed up, connect a timing light and observe the timing marks. At idle, it should be on or near the S mark, and be a nice, clear, steady image. Now, what happens when you increase the RPM slowly?  I had a similar ignition that developed a problem with the module.  It would idle fine, however, when I tried increasing the RPM, the timing marks would begin dancing around erratically, instead advancing smoothly. Once up to 3500-4000 rpm (full advance), the image would become steady again, on the F mark. The problem was with the digital advance, which is built into the module. 

Watching with the timing light, the timing marks should be nice and clear, and NOT JITTERY. As you slowly increase the rpm, the marks should just nicely roll down and out of the window. As 3500 rpm approaches, the F mark should nicely roll into view. 

 
Posted : 11/20/2022 18:01
Richard Whatley
(@wobbly)
Posts: 2286
Member
 

Posted by: @mark-creek

Thanks for your reply Richard. I like the music analogy, helps understand the perspective.

I don't know how I thought of that. Sometimes I surprise even myself !

Posted by: @mark-creek

I’m not sure it did this before the EI change. What I mean is that it sat 3 months sorting out EI installation issues and I don’t remember but I don’t think it was an issue.

With any 3 month wait, fuel quality becomes your most likely culprit. Remove the float bowls and the tank and put ALL that fuel into your car. Modern cars have the ability to change the timing and mixture on-the-fly so you can burn that with no problems, but your 1975 Airhead MUST have fresh fuel. November's regular is 200% better than July's premium

Posted by: @mark-creek

Actually, unless I miss understood the instructions, the timing is not to be checked at speed at install? I would think a timing issue would show itself with starting and wide open throttle issue which it doesn’t.

• When the unit is physically installed, obviously the engine is static (not running). The instructions probably tell you that with some flywheel feature visible in the timing window, that the new Wedgetail "points plate" should be in an exact position. << That is "static timing". And it's ONLY good enough to start the engine.

• This static setting MUST be followed by dynamic timing using an ignition strobe lamp. And that procedure MUST be carried out at Full Ignition Advance. And because your new ignition realizes that the 2022 fuel is excrement compared to 1975 fuels, the advance curve it uses is MUCH longer, so Full Ignition Advance is not reached until 4500 to 5000 RPM, versus 2200 RPM for 1975 fuel. 

Posted by: @mark-creek

I can revert back to points to try it (points where damaged removing it) but I thought I’d throw my question out here first.

You may need to. The object of ANY repair exercise is to reduce the problem back to 1 single variable. It might take you a year to work out a multi-fault problem. Sometimes your second variable can be easily eliminated by attacking the "most wanted list"... fuel, spark plug wires, spark plug caps, spark plugs, dead battery, corroded battery terminals, etc. 

Ultimately, you'll be very happy you installed this... (if it doesn't kill you getting there !! 🤣  ) Just keep the phonograph vs. MP4 analogy in mind because this is NOT anything like the conversion from standard to radial tires, or wet-cell to AGM battery. 

👍

 

[color=blue]Don't hide 'em, Ride 'em !!
#15150[/color]

 
Posted : 11/21/2022 08:06
Mark Creek
(@mark-creek)
Posts: 22
Eminent Member
Topic starter
 

Well, all resolved. It wasn’t the wedgetail, it continues to work perfectly. It was a midrange jet issue. The problem was (other than the fact that I’m a green airhead mechanic) is that the bike ran well before I did the wedgetail. But what i failed to notice was that its now cold. I went from 2.66 mid range needle to 2.68 and it solved the problem. I had no idea such a small change could make such a difference. I thought the cv carbs were more forgiving as I’v gone the other direction with less noticeable changes. I live at 7,000 feet, it was 50 degrees outside and that seemed to make the difference. I run 2.66 in summer and they work well. Thanks for all of your input and thanks to Tom Cutter for his help and patience. I love my wegetail!!!

 
Posted : 12/04/2022 17:20

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