New pipes and carb rebuild, running lean on rear cylinders

[dodgediesel59]

So this bike has been through a frame up rebuild. I redid trans but did not touch top end or timing. I went through the carbs and rebuilt them and also installed new diaphrams for all the slides. Just put new marks exhaust on tonight and fired it up and went to sync carbs and thats when problems started. The bike started to backfire terribly at anything below 1500 rpms. I shut down and checked all plugs and front 2 are black and rear 2 are completely white. Any ideas what would be causing two rear cylinders to be running so lean? Also shimmed needs .035 and set mixture screws to 3 1/2 turns.

 

[Redbone]

One thing to check is make sure the forward 2 spark plugs are run from the opposite side coil, in other words the fronts coils to front spark plugs cross.
I hope that makes sense and helps!

 

[dodgediesel59]

Ok i did a COP conversion when i had this apart. Anyone know the wire color and corresponding cylinder?

 

[npthayer]

Not sure of the wire colors I just followed the wire when I was replacing them, but as Brian said the front coils get criss crossed; the front left side coil runs the front right side cylinder, and the front right side coil runs the front left side cylinder. The rear is pretty straight forward; left side coil runs rear left side cylinder and the right side coil runs the rear right side cylinder. Check out NaughtyG's write up on the COP converison, he explains it in there. Its a sticky in the user mods section.

Good luck.

 

[dodgediesel59]

Redbone if you lived closer i would buy you a beer!!! Flipped the two wires around and it runs absolutely perfect. Thanks guys!

 

[Redbone]

That's cool, glad that's all it was. I did the same thing too when I did my COPs conversion.

 

[dodgediesel59]

I will have to get some videos up of the exhaust when i get it out of the shop. It sounds amazing!!!

 

[SpecOps13]

Yes, Videos... More Input.....:biglaugh:

 

[allisontech]

I love this site! "RedBone just saved days of aggravation,and headbanging!"
:bang head::bang head::bang head:
This site rocks! :worthy:

Bill

 

[06VMAXIMUS]

I love this site! "RedBone just saved days of aggravation,and headbanging!"
:bang head::bang head::bang head:
This site rocks! :worthy:

Bill

Plus he's got the HOT avatars. This site has good advice with a show. unk:

 

[dodgediesel59]

So I just took the bike out today for 15 miles or so and it is overheating now. The little valve is in the right position by the thermostat. Just wondering what the heck is going on? Maybe bad thermostat?

 

[gamorg02]

could be a clogged radiator?

 

[dodgediesel59]

Not going to rule anything out, but let me say that before i disassembled bike last fall everything was working fine. I just checked the valve again and that was fine. Took the thermostat out and reassembled and it was very weird. The Gauge slowly rose a touch then it started bouncing all over the place until it finally stabilized right at the first red mark. When i shut it off i let the fan run then started a few sec and repeated a few times to circulate and cool it a bit. But when i had it off you could hear alot of gurgling in the lines above the heads and such. Is it possible its just trapped air? If so how the heck do i get it out? When i filled i had bike running and filled till it wouldn't take any more.
Thanks guys!

 

[[email protected]]

Running it with the coolant cap off bleeds out the air.
cap ok?

 

[dodgediesel59]

as far as i can tell the cap looks ok and seems to be working. I slowly backed cap off and there was a ton of pressure behind it.

 

[Redbone]

I had to run it for a while before all the air came out of it. That process took a while b/c I had to shut off and let it cool before continuing a couple times.
Good luck with getting her burped.

 

[dodgediesel59]

Well turns out some idiot stuffed a little rag in the water pump port when he painted it ......:bang head: So now we are in great shape, put about 40 miles on it today and its performing absolutely amazing. I cant believe the power gains just from putting the marks pipe on. I can pull the front wheel off the ground in first as high as i have the sand to take it!!! Now to get some miles on! Thanks for all the help guys, hopefully i dont have anymore problems for awhlie.