1980 gs1100et starting/running issues

[Richieleo]

Hi guys, newbie to the fours but not to motorcycles at all! Infact I co-own a restoration shop here in Pennsylvania and we work in old bikes all the time but these 80’s bikes always rattle my brain. So we just completed a cosmetic build on this bike, new tail section, everything was stripped and painted, I fired it up for the first time yesterday and to my surprise it ran quite well, it was raining so No test ride, I came in today excited to take her for a rip and I noticed it breaking up when the mains opened (not surprised with pod filters and a 4:1 open exhaust) so i ran to the local motorcycle shop and picked up some new main jets (117.5) it had 115’s in it. Put them in, cleaned up the inside of the carbs, primed the bowls and boom fired up with the choke open but AS SOON as I gave it any kind of throttle it died. Turned the choke off same thing will idle fine but as soon as a touch the throttle (roll on gently) it dies. Now I’m scratching my head. I didn’t change the primaries why would it change idle/initial revs? I’m thinking maybe timing?

tl/dr bike will idle but dies with ANY throttle input

also if anyone has the procedure to set the timing and valve adjustments I’d greatly appreciate it!

 

[Rob S.]

Dynojet kits are usually required to get these running perfect. One was for my 11E.

 

[posplayr]

EDIT: Looks like DJ 132 and 138 so knock off 10 so 125 or 130 Mikuni
https://x.fortnine.ca/pdf/dynojet/3133.pdf


Iirc, dynojet mains are about 135 Mikuni for pod and 4:1. But again it will never run right without the correct needle and 47.5 pilot jets (+1 step)

 

[Richieleo]

EDIT: Looks like DJ 132 and 138 so knock off 10 so 125 or 130 Mikuni
https://x.fortnine.ca/pdf/dynojet/3133.pdf


Iirc, dynojet mains are about 135 Mikuni for pod and 4:1. But again it will never run right without the correct needle and 47.5 pilot jets (+1 step)

I have a 117.5 main and a 45 pilot. What?s the difference in the needle?

 

[posplayr]

I have a 117.5 main and a 45 pilot. What’s the difference in the needle?

The 4:1 has back pressure at 4-6 KRPM so the needle is thicker (i.e. less flow) in that region.

 

[Rob S.]

But aren't Dynojets shaped differently?

 

[posplayr]

But aren't Dynojets shaped differently?

"Thicker" means a different shape.

 

[Richieleo]

The 4:1 has back pressure at 4-6 KRPM so the needle is thicker (i.e. less flow) in that region.

but why did it run fine before I took the carbs off? Also still looking for timing procedures & valve adjustment specs

 

[posplayr]

but why did it run fine before I took the carbs off? Also still looking for timing procedures & valve adjustment specs

No idea what you might have done. Are you trying to run with open carbs(IE pods off)?
you need to cover the inlets to get some restriction.
You should get a FSM. Basscliff’s Site has one for download.

 

[Tom R]

but why did it run fine before I took the carbs off? Also still looking for timing procedures & valve adjustment specs

Assuming you have the stock CV carbs still, it goes against common knowledge around here that you can run stock jetting with pods and a pipe..... especially pods.
It ran well in that configuration before you restored it?

 

[posplayr]

Assuming you have the stock CV carbs still, it goes against common knowledge around here that you can run stock jetting with pods and a pipe..... especially pods.
It ran well in that configuration before you restored it?

Op thinks it is timing ; I’m starting to think tire pressure.

 

[Rob S.]

But aren't Dynojets shaped differently?

"Thicker" means a different shape.

I thought it was the taper of the tip.

 

[Rob S.]

Op thinks it is timing ; I?m starting to think tire pressure.

Broken mouse pad.

 

[posplayr]

I thought it was the taper of the tip.

the needle fits into an emulsion tube and it is primarily the clearance between top of needle and the ET that regulates fuel.
As the slide lifts the needle lifts and you are regulation nearer the middle. The tip has almost nothing to do because it never fully emerges from the ET.

 

[Tom R]

Unless you messed with something more under the timing cover, The only thing you should really have to do to the timing is make sure the mechanical advance is operating freely. I suppose you could throw a timing light on it to confirm it’s right. These are specs that are all available in the factory service manual... which you can find on basscliff’s website. Google it or I’m sure it’s in a sticky here.
Valve clearances and timing is covered in depth there too.

 

[posplayr]

Unless you messed with something more under the timing cover, The only thing you should really have to do to the timing is make sure the mechanical advance is operating freely. I suppose you could throw a timing light on it to confirm it’s right. These are specs that are all available in the factory service manual... which you can find on basscliff’s website. Google it or I’m sure it’s in a sticky here.
Valve clearances and timing is covered in depth there too.

I'm guessing he has the pods off which is why it will not rev.

 

[Richieleo]

Hey friends! Just posting a resolution, turns out I wasn?t getting fuel because the vacuum petcock was shot!

 

[Tom R]

Good to hear....unless your pods are more restrictive than everyone else’s, the jetting with your setup will be incredibly lean. Dynojet kits are popular, factory pro Jet kits less so, but it works just as well in my experience. When I bought my bike, it had the stock needle shimmed up (really the top spacer reduced in size), and 142.5 main jets, 47.5 pilots. It ran pretty good. It ran better with the factory pro needles though. That may not be what your bike wants exactly; but just to give you an idea what k&n pods and a v&h 4-1 setup might look like.