277 Rebuilt, Misfiring when hot.

[CannonFace]

Hey Guys,

My bike runs amazing when it is cold, like perma-grin amazing....then it gets hot and turns into perma-frown. (that's within 10 mins of riding)

When it is hot, it can barely climb a hill (I have to ride out the clutch which I hate doing) it misfires every stroke...both cylinders on and off.

I just recently rebuilt it with a 277 crank, all stock internals inlcuding the charging system.

Charging checked: good
Gaps Checked: good
Plugs Checked: Burning that perfect brown.
Timing checked: freaking dead on
CV38 Carbs: Freshly rebuilt and cleaned (UNI Pod filters)
Valves Clearance: Just re-did it....again and it's good

I did have the green coil packs on there, but I sat for at least 10-15 minutes trying to get the bike to light with those, wouldn't run under 2500. I switched to the Dual Output Coil (the one you get from Pete's Kit: Ignition Coil (#17-6822) and the bike fired right up without protest....I can't figure out what's going on.

 

[ippytattoo]

Are you saying that you are running a dual output coil with a rephrased engine? If that's the case then you should only be running on 1 cylinder. What about intake, exhaust, carbs, float height and jetting. Give us a little bit of details on these as they can affect the way the bike runs.

 

[CannonFace]

Yes I am running a dual output coil with a rephased motor, I read up on it a while ago and from what I gathered Pete said it shouldn't be an issue...which it isn't because the bike runs perfect, idles and everything until it warms up and is under load.

Stock everything (intake/exhaust/carbs) other than the pods I mentioned earlier. The bike ran perfectly before the rephase...not one issue. the only thing that has changed is the crank and cam...it's a stock bike.

 

[rebel542]

WOW ???

 

[rebel542]

I'm not sure what to ask next?

 

[CannonFace]

Problem solved....and the culprit was!
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Grounding bike runs fine now.

 

[pamcopete]

CannonFace,

Well, I'm glad you got it going, but I don't recall ever recommending a dual output coil for a 277 rephase. How do you have the coil wired?

 

[joebgd]

What is the dif of dual out put coil and a standard coil? What is on stock tci 1980. Would i get benefit of changing it.

Posted via Mobile

 

[CannonFace]

Pete:
thanks for responding, I have both signal wires (green) running to one terminal on the coil. There was a thread on here where I guy asked if he could use a dual tower Harley coil with it and you said it should be okay...unless that coil has 2 inputs for triggering haha....but it works, I don't have any issues...unless there should be issues then I might switch back to the greenies

Joe:
a "normal" coil generally has 1 spark plug lead coming out (so on our bike's case you would need 2 "single" output coils) for tci though I believe they use a dual output which is a single coil with 2 leads coming out.

as for upgrading, I have no clue...I'll leave that to Pete haha.

 

[CannonFace]

Put the green coils back on, bike runs just fine (even got a little more juice out of it)

 

[pamcopete]

CannonFace,

Well, that is very interesting. I did not think that you could use a dual output coil on a 277 because of the valve overlap between the two cylinders, but perhaps you have found a new way to fire the 277 rephase.

 

[CannonFace]

Pete,

That was my thought as well, but since it's not really tested fully...I'd say you could use it in a pinch. Cruised at freeway speeds just fine, the only time I noticed any type of backfire/misfire from that setup was on deceleration.

The green packs haven't popped while on or off the throttle.

 

[CannonFace]

Here's a pic of the coil, I have a dual female plug to accept both inputs from your ignition.