GS850 need help with jetting

[86turbodsl]

put the 120 mains, 42.5 pilots in and took it for a ride this morning. the plug chop after it was warmed up didnt show it as rich and its still popping and backfiring. is there something else i should be looking at? ignition? its still got points but everything is new. i know i have fuel down to the carbs. petcock is good. i'm at a loss. i thought if anything it would be rich by now...

any ideas?

[7981GS]

You have new manifold O-rings installed?
I might have missed that part in this thread.

Daniel

[86turbodsl]

Yes, new o rings, new boots, new airbox boots, sealed airbox.

[TheCafeKid]

You change out your exhaust gaskets? And the gaskets on the crossover joints will leak and suck air. Cold air introduced into the exhaust will make it poppity pop. What size pilot air jet are in those carbs?

[86turbodsl]

Gaskets at the heads are new, with new allen bolts holding the headers on. Which crossover gaskets? Between the two left and two right pipes? I don't have a 80- exhaust, it's PRE-80 without the center crossover. Pilot AIR jets are 180's. Pilot FUEL jets are 42.5's.

[86turbodsl]

On a hunch, I just went and did some digging on the ignition. I found weird readings on the coil secondaries, and decided to pull the plug caps. They are the original 79's, and they measure resistances as follows:

9.5kohm
28 MEGOHM
9.4kohm
9.9kohm

The coils both tested at 12.5kohms on secondary. I'll measure voltages on primary next.
But this has got me thinking, with the bad plug cap, is it possible my backfiring / popping issues are just ignition related, and my messing with the jetting is sort of invisible with that problem?

Been thinking of upgrading to a dyna S to head off problems with points too. My little wick thats supposed to hold oil won't stay in contact with the eccentric.

thoughts?

[86turbodsl]

Got the new plug caps today. Put them on, and it's still backfiring and popping. It seems to do it more as it warms up. Not as much cold.

I also found a couple of small exhaust leaks mid-pipe on both sides too. Roughly under the footpegs on each side. there's some sort of joint there, or something. I need to look at it closer.
they aren't BIG leaks, but I can feel them with my hand.

[Big T]

Air leaks in the exhaust can cause popping, especially on decel

A Dyna S is always a good thing

[86turbodsl]

Ok, I got a good look at them. Head under the pipe. They're pinholes. Anyone have any luck welding them shut?

Edit: Ok, I guess there is supposed to be a hole for drainage here, are they supposed to leak exhaust?

[Big T]

Ok, I got a good look at them. Head under the pipe. They're pinholes. Anyone have any luck welding them shut?

Edit: Ok, I guess there is supposed to be a hole for drainage here, are they supposed to leak exhaust?

Not exhaust, water from the outer pipe only

[keman]

Too bad you are not closer to Seatle, I have a set of stock 80 pipes available...

[86turbodsl]

Looked at them again last night. The right one has about a 2-3mm hole, and definitely leaks exhaust not water. The left one has a steel strap welded over it like a reciever for a tab or something and underneath it, you can see about a 1/2" hole. It leaks exhaust too. I guess this means I'll never get rid of the popping with this exhaust? Might be time for a 4-1...

[86turbodsl]

Update for anyone viewing this one later on:

The popping is gone now when I swapped to a Dyna S ignition. No amount of point fiddling seemed to work. The dyna fixed it. Smooth and crisp no popping.

[OldVet66]

The Dyna-S works even better with the Dyna green coils and wires.

[BassCliff]

Hi,

This is a good thread and an excellent example of how engine systems can be inter-related. I'm glad you stuck with it and were thorough in your troubleshooting and maintenance. Jolly good show! Have you done a plug chop since the new ignition? What jetting did you end up with? Thanks for sharing.

Thank you for your indulgence,

BassCliff