V-Twin Forum banner

1 - 4 of 4 Posts

·
Known Associate
Joined
·
175 Posts
Discussion Starter #1
HDMD88;

I have an unusual situation with my 1200 (883 conversion) and hope you can help me.

A little background on the motor:
1990 883-1200 conversion with 10/1 comp. and Total Seal "gapless" rings, Thunderheader w/your recommended 'adjustments',
re-jetted CV (45/190 w/DynoJet kit and Yost Power Tube),
Crane Single Fire Ignition and coils.,
Andrews V6 cams (.500 lift / 302 duration),
Crane aluminum adj. pushrods,
SE spark plugs and Accel wires.

It runs very strong, but what puzzles me, is that when I fire it up cold, you can hear very distinct cylinder pulsing from the exhaust, much like a bike with straight pipes (no crossover).

However, after it warms up the idles becomes very smooth, like it has a stock cam! It doesn't seem to affect the power at all, just idles smooth. Any idea what's happening? Thanks for your help.

If anyone else has any ideas, I'd like to hear 'em, too.
 

·
Registered
Joined
·
9 Posts
???????????? maybe

It sounds like it could be a combination of things starting with the fact that during start up you are using the enrichener?? With a high lift / duration cam, it's even richer during warm up. That would give the pulsing (too rich), somewhat like a high lift/duration cam in a car (I know, a car will "LOPE" at start up and after with a cam but we are talking H-D here).The cam must be reasonably moderate in this application which is good, because the engine idles smooth after it's warmed up. The other Mods you have done better compensate for the slight extra richness from the cam when warm and no enrichener.
This is a guess on my part but I know that my Dad showed me how to make a car with a stock cam sound like it had a big one by screwing up the mixture too rich and uping the idle speed. Too much gas runs rough. therefore pulses.
Just a thought, Hope it Helps.
In any case, shouldn't hurt anything the way it is running.
 

·
Banned
Joined
·
5,114 Posts
Mad Dog said:
HDMD88;

I have an unusual situation with my 1200 (883 conversion) and hope you can help me.

A little background on the motor:
1990 883-1200 conversion with 10/1 comp. and Total Seal "gapless" rings, Thunderheader w/your recommended 'adjustments',
re-jetted CV (45/190 w/DynoJet kit and Yost Power Tube),
Crane Single Fire Ignition and coils.,
Andrews V6 cams (.500 lift / 302 duration),
Crane aluminum adj. pushrods,
SE spark plugs and Accel wires.

It runs very strong, but what puzzles me, is that when I fire it up cold, you can hear very distinct cylinder pulsing from the exhaust, much like a bike with straight pipes (no crossover).

However, after it warms up the idles becomes very smooth, like it has a stock cam! It doesn't seem to affect the power at all, just idles smooth. Any idea what's happening? Thanks for your help.

If anyone else has any ideas, I'd like to hear 'em, too.
I did answer your PM...didn't you get it?? Let me know because I see more than one problem you have with your set up, for an example you can not run a DynoJet needle with a Yost Power Tube.
Total seal rings cause a problem unless you have a vacuum pump on the crank case, the 883 ignition needs to be replaced with a 1200 ignition when the conversion was done...the spark curve is different.
 

·
Known Associate
Joined
·
175 Posts
Discussion Starter #4
Stargateops, thanks for your input.

HDMD88: I did get your PM back, this was posted at the same time. Sorry for the confusion and once again, thanks.

Wes.
 
1 - 4 of 4 Posts
Top