Ignition timing

[scoot71]

I bought this bike 2 yrs ago, it does 2 things, cold start it only runs on 2 cylinders until it warms up for a minute, I can live with that issue, I did go thru the carbs and sync'd them, it does run nicer warm since then, my real concern is under light load, such as going thru town, it stumbles around in "coast" throttle, when engine has low/ no load on it, back in my younger days when we used to probably overadvance a car engine, they would act the same way. I looked thru the service manual and didn't see a procedure, I also haven't taken side covers off to ck anything out yet. Any information would be appreciated

[Tonyvdb]

when was the last time you checked the spark plugs?
There are a couple issues I can think of: 1) junk in the spark plug wells or 2) either your plugs are bad or the wire caps may not be connecting properly.

[Highway Rider]

What year is the bike
May even be a bad coil

[scoot71]

new plugs this spring, I am a auto tech by profession, been wrenching for 30 yrs now, now I will admit I am not an expert at cycle drivability, but experience has me believing it is something with timing, I can pull hose off left carb, the one that goes to igniter modual, and make this stumble/ surging issue go away, It could be a weak coil, but its funny it would be as coils tend to fail under higher engine loads.

[Highway Rider]

Have you checked the pipes and found the cold ones and if they are in pairs like 1-4 and 2-3 then that would tell me it was a coil. These are kinda cold blooded on start up first time for the day. But after that it should pop right off. Usually no chock after that, depending on out side temp like. Say like 40 degrees and sets for a few hours, then it may need to be chocked. Mine will run on 2 cylinders at first but after 5-10 seconds it starts to fire on all 4.

[scoot71]

sorry its an 01 with 25k miles

[Mr Jensee]

Scoot you can download a service manual for the 1200 from the link in my signature if that will help.

[scoot71]

I scrolled thru ignition part of manual earlier today and I don't know if I missed it so I looked again and I cant seem to find adjustment or timing mark reference

[scoot71]

Highway Rider, I did ck the pipe temps last year, and there was 2 cold ones, I cant remember which ones, and ya, after you run it, the rest of the day is usually ok like you said, it don't miss a beat once it warms up a little bit

[Tonyvdb]

I had issues with mine after changing the plugs to Iridium and on one of them I had cracked the ceramic end of the plug and then found that had probably damaged the wire cap (The resister had gone bad). Another problem is that the wire gets really brittle right where it screws into the cap so that can be a weak point.

[triton28]

The usual problem with ignition coils is that after they warm up, the windings develop an open circuit due to thermal expansion and they will not spark. They are fine when cold and often I have had to wait by the side of the road for the coil/s to cool down enough to go for another time period until they got hot again and stopped firing. So I don't think you have a coil problem.
Engines with multi carburetors are notorious for rough running upon cold startup, but as has been said, they smooth out with warming up. Even so, every idle jet/passage, needle jet, intake passage, back surface of the valves, and piston crowns carbon buildup are different from each other, so some difference in fuel charge flow characteristics will always exist. It usually is worse when the engine is cold.
Surging is another matter altogether though and generally is caused by a lean mixture condition due to blocked jets/passages or incorrect float levels. If the surging is not at idle but rather just above idle, there is an article in the Voyager XII portion of the Tech Center, located on the AVA Home page under the heading "Engine" which covers how to enrich the off idle fuel charge. This may help.
Dave

[scoot71]

Maybe I am not describing the problem properly, maybe described as a bucking, to the point where the slop in driveline clunks, like if you got on and off the gas repeatedly, I mean minimally, its a bit more than subtle, but not to the point where it jerks the bike, all you have to do it just give it a very small amount of throttle and it goes away, I tried putting the choke on and it still does it, perhaps fluttering is a better word, it never bogs out at all, that's why I think its timing, like I said I can bleed off a little bit of vacuum from the hose on left carb and it goes away.

[triton28]

There is a " T " and an " F " line on the exciter coil timing rotor, driven by the crankshaft, which lines up with a line on an aluminium boss on the crankcase, located directly below the top exciter mounting screw, behind the RH chrome cover on the crankshaft end.
See Engine Top End, page 4-11 of the Service Manual. This is a cam chain timing illustration but it illustrates the lower end rotor mark #6, and the crankcase boss mark #5.
The " T " is of course top dead center and the " F " mark is the firing line @ 10 degrees BTDC for #1 and 4 cylinders at idle.
You mention over advancing of the timing and this was a problem with the # 21119-1179 IC Igniters of the 1986 and 1987 models so a revamped igniter having the part # 21119-1248 was introduced in 1988 and subsequent model years. Check yours for the correct #.
Some machinery just doesn't like to run at idle with a load imposed. I like 900 rpm for mine and, as opposed to chain driven M/Cs, drive shafts are touchy being so direct in their connection to the wheel/transmission.
I hope this may help,
Dave

[scoot71]

Thanks Dave, I would have figured the service manual would have a better description, this bike will flutter, if that's a correct term, at any rpm below say 2500, at speeds of 40mph and below, I suspect its due to more wind resistance and you always have load on engine at those speeds and above. I will ck the ignitor number, I think I did ck that when I found out about the old number breaking the starter chain. I just want to rule out timing before going any further, I assume its 10 degrees with the vacuum hose disconnected???? Like an old distributor ignition?

[triton28]

I can't say as to with or without the vacuum hose connected due to the fact I haven't had a situation where I wanted/needed to check the timing yet.
Although I would try it both ways just to see if there was any difference. I would think there should not be any difference at 800 +- rpm, but I could be wrong. Above 800 rpm the " F " line should in theory should start to rotate counterclockwise as the timing of the spark advances due to the increase in vacuum to the IC igniter from the carb.
Others may have a more definitive suggestion I hope.
Dave

[Orangejbird]

Did you ever resolve the issue?
My Dad's '86 is doing the same thing.

[823JIM]

Did you ever resolve the issue?
My Dad's '86 is doing the same thing.

I had the same problem with my '02 when I first bought it. I put two new coils, new wires and caps on it,(already had done new plugs) did not want to just pick away at the problem and keep revisiting it. Never had anymore problems, started great on all 4 cylinders every time. May have just been wires and caps but as said wanted to fix with one try, and not keep having to tear it apart.