79 850G, sounds like popcorn

[AF_Bill]

So I had an issue with the coils after a lil degreasing. New coils are on and running smoother untill i roll the throttle. Little better responce but still not what she used to be. She sounds like popcorn when I rev and roll down the road. I'm gonna replace the inline fuel filter I installed and might pull the carbs and clean them. Any other suggestions????

[Stahlgrau333]

Running lean, maybe? Might try coming a 1/2 turn or so out on the mixture, see if that helps.

[AF_Bill]

All cards? And turn the fuel screws on the bottem of the carbs?

[Steve]

I'm gonna replace the inline fuel filter I installed and might pull the carbs and clean them. Any other suggestions????

Yes.

While you have the fuel filter off, just leave it off.

You can also check your ignition timing and the advancer mechanism to make sure they are both correct.

.

[AF_Bill]

Thought it was a good idea to have an extra filter on?

[Steve]

That would depend greatly on whether you have a proper filter.

Too many times, one will simply go to Auto Zone and grab a filter, then put it in the bike's fuel line. The problems is that most of the filters you find at Auto Zone are designed to go in pressurized fuel systems, so a little bit of restriction is OK. The only "pressure" in our systems is the result of a few inches drop, due to gravity. Not much we can do to enhance that "pressure" unless we raise the tank.

Another problem is the sizing. Fuel filters will likely come in American (Inch) sizing. Our stock fuel lines are 7 mm, which is between 1/4" and 5/16". If you get a 5/16" filter, you will stretch out the fuel line. If you get a 1/4" filter, you will have to use a clamp, not to mention that the smaller diameter just might not flow enough fuel.

Also keep in mind that there is already a filter inside your tank, around the petcock inlet. I don't remember if your VM carbs have filters on the inlet valves, but the CV carbs do, so adding yet another filter in-line is usually unnecessary.

If you really insist on running another filter, go to the lawn mower department and get one for a lawn tractor. Most of them also have gravity-fed fuel systems, but you still have to figure out the sizing.

.

[AF_Bill]

Thats the kind of filter I have right now (small lawn mower filter). And no my carbs don't have filters on the inlet valves.

[TheCafeKid]

79 runs a P&C ignition system. Did you take that into account when purchasing your coils? Or was it replaced with an electronic system like a dyna S?

With a P&C system, dyna green coils aren't plug and play IIRC, they'd require an in-line resistor...

[AF_Bill]

TCK, the coils I used are OE coils. Not the green ones. They were tested before I bought them and they are good.

Lil update, just took her for a ride. Here's what shes doin:
Jerks in 1st gear, starts popping at 3500 rpm, and in 2nd gear, at 5k rpm, I'm slowly creeping up to 40 mph. The fuel filter didn't change anything.

I'm at a loss.

[sachsaca]

I have the VM carbs and my petcock has a very fine mesh screen filter on it that does an excellent job. They're right, ditch the filter the mesh one in the tank is finer than what you can buy to go inline.

[tas850g]

What are your air screws and fuel screws adjusted at? If all is stock it should run better than that when air screws are 2 1/2 turns out and fuel screws are 3/4 turns out. If we are still considering the carb settings.

May need to check the timing too.

[BassCliff]

Hi Bill,

Did you install the coils from an '82 650 on your '79 850? Mr. TheCafeKid may be on to something since the '82 has electronic ignition and the '79 uses points and condensers. I didn't consider this earlier. Sorry.


Thank you for your indulgence,

BassCliff

[AF_Bill]

Yes Cliff you are correct. Do I need to install a resistor or what?

[BassCliff]

Hi,

If the new coils have less resistance than the old ones, then a ballast resistor may be necessary to keep the current down at the points (less resistance = more current). Unfortunately, I know very little about this workaround. We'd best wait for someone else to weigh in. Sorry for the inconvenience.


Thank you for your indulgence,

BassCliff

[AF_Bill]

It's no inconvenience. You were a great help. Since I'm at my part time job now, I had to stop workin on Bags. Tomorrow, I'm gonna head down to my parts guy so he can give a listen and help me out. Tecnically I can ride her but it's gonna take a little longer to get there.