850, What Exhaust is this? jetting for it

[Kingsoup]

Hello friends! 

I've been working on restoring this 1981 GS850GL I bought 6 months ago (after being inspired by a 79 GS1000 a friend  fixed up recently) did new\used stator, carb clean, fixed wiring, etc etc lots of small things, still has a bunch to go (forks, more brake rebuild, turn it into an E from a L) sat for 14 years++ in garages before I got it. (likely from stator failure) 775 Regulator on the list for the future.

Does anyone have an idea what this exhaust type is? it got the flat black spraypaint which I haven't removed yet, it seems to combine 1+4 and 2+3, there is no crossover underneath, with dual pipes.

 

It runs pretty well at wide open (decently quick, different character to the 1000 motor) but it pops on decel, and mid throttle is pretty janky.  I have full factory airbox with a new filter, I believe it has the stock 115 mains, I read that the pilot circuit shares fuel on the CV's from the main, and that going to a 120main and removing airbox lid (vance and hines instructions) should be enough to resolve the lean condition.

 

Thanks for the help! (I just got an old E style seat, feels like it has triple the padding of the cruiser seat thing currently on it, waahoo!)

 

 

[wraith]

Hello and welcome to OSS.

Don't know what the exhaust is but sounds like it's running lean, so going up to a 120 main will be a good starting point. 

[Kingsoup]

Its certainly lean! with the GS firing order of 1-2-4-3 this header would seem to seperate each exhaust pulse from running into each other, and at the exit as well with a single outlet for each of the combined 2 cylinders.  It sounds decent, luckily not too loud or I would have to fix or remove it (hate loud exhaust).  I've researched a bunch and can't seem to figure out who makes it.

[Gixer1460]

9 hours ago, Kingsoup said:

 with the GS firing order of 1-2-4-3 this header would seem to seperate each exhaust pulse from running into each other, and at the exit as well with a single outlet for each of the combined 2 cylinders. 

Is It? I mean firing order? Normal order is 1-3-4-2 and will have same characteristics as you describe?

[Kingsoup]

I checked the factory Manual, its 1-2-4-3 , thats got to be why this dual exhaust header thing is the way it is.

Nobody on the facebook group could figure out what it is either, maybe after I scrape the paint off I"ll find a manufacture logo!