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Increase in jet size on Mains ?

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Bench sync

Bench sync

I did the Bench sync using the sliver of light method shining from the back. The carbs are back on the bike, started in an instant. I have the idle set at 1500 where i will do the Vacum sync. So far smooth idle no hanging RPM. rev's nice. I plan to let it cool and restart it just to make sure I can repeat the first result. I showed my carb pictures to show how clean they got just dipped in Berrymans a few hours. Air screws out 2 and 1/2 turns. 112.5 mains. 4 into 1 exhaust. I will soon see how it likes it. Oh yea, Spark Plug check before new jets showing lean condition.
 
Stock jetting calls for 115 mains so you may need to jump to 117.5 or 120 On my 80 I am running 120 mains , with stock exhaust and air box but it does have a K&N filter, and PO drilled the exhaust out. It is smooth through out the entire rpm range
 
I did the enrichment thing on my bikes because I had a pipe and everyone recommends massive increases in the Jets. After wasting a lot of time and gas I ended up at stock settings. Plugs read proper and no running issues.
If you're having drivability issues enriching will only cover up a lean condition caused by leaks or other problem.
You need to test and diagnose not just take someone's word for what to do.
I'll sit back now and wait to be flamed.

BTW did you use new exhaust gaskets when you changed the pipe? Leaks at the head cause problems by letting air enter the stream.
 
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Just to set the record straight. Assuming that we're talking about a US model GS1000T, here is a scan from the GS1000T Factory service manual supplement.



A bike with a header that actually increases airflow will need to be rejetted to compensate. Sure it will run without rejetting, but it will run lean. In extreme cases it may damage the engine. Not all systems are created equal.
 
Believe it or not some pipes flow no better than stock. Testing and plug reading is the only way to know for sure on an engine with no other issues.
Compression needs to be in spec for example as it determines much in the way it runs. Altitude matters if you are above 3000 feet, more for some combination s.
The fuel today is probably not the same as 35 years ago and it varies by area thanks to the EPA
 
duaneage said:
I did the enrichment thing on my bikes because I had a pipe and everyone recommends massive increases in the Jets. After wasting a lot of time and gas I ended up at stock settings. Plugs read proper and no running issues.
If you're having drivability issues enriching will only cover up a lean condition caused by leaks or other problem.
You need to test and diagnose not just take someone's word for what to do.
I'll sit back now and wait to be flamed.

BTW did you use new exhaust gaskets when you changed the pipe? Leaks at the head cause problems by letting air enter the stream.
Click to expand...
Yes new exhaust gaskets were installed with the pipes. Thanks
 
As far as I know the bike is a US bike. As far as the letter after the GS1000 I have never been sure. The parts seem to match best with the E models when I'm buying them. The bike was a basket case. I got the engine, frame, back wheel from a (1970s bike the spokes) Carbs and brakes, a few other things for 100 bucks on craigs list. Compleatly disassembled in boxes. Between 1980 and 1982 it looks like they used different main jet sizes on 1000's and 1100's. But mine, I replaced are 107.5 mains, pilots 40's I checked them all. 112.5 mains are in there now. Off work tonight so I will be playing with it. My bike ran fine before the exhaust change, even with some maintenence issues due to my lazyness.
 
GS1000T - 1980 Spoke wheeled basic model
GS1000ET - 1980 Alloy wheels (17" rear), triple disc brakes, stepped seat
GS1000ST - 1980 Sport Model fairing alloy wheels (18" rear) rearset pegs, diamond stitched seat cover
GS1000LT - 1980 "L" model (cruiser style)
GS1000GT - Shaft drive model

C = 1978
N = 1979
T = 1980

Download a copy of the factory manual and the 1980 model year supplement.

http://zeus.mtsac.edu/~cliff/storage/gs/GS1000_C-E-S-L_Manual.pdf

http://zeus.mtsac.edu/~cliff/storage/gs/GS1000_1980_Supplement.pdf
 
rudeman said:
GS1000T - 1980 Spoke wheeled basic model
GS1000ET - 1980 Alloy wheels (17" rear), triple disc brakes, stepped seat
GS1000ST - 1980 Sport Model fairing alloy wheels (18" rear) rearset pegs, diamond stitched seat cover
GS1000LT - 1980 "L" model (cruiser style)
GS1000GT - Shaft drive model

C = 1978
N = 1979
T = 1980

Download a copy of the factory manual and the 1980 model year supplement.

http://zeus.mtsac.edu/~cliff/storage/gs/GS1000_C-E-S-L_Manual.pdf

http://zeus.mtsac.edu/~cliff/storage/gs/GS1000_1980_Supplement.pdf
Click to expand...
Thank you I will check it out
 
Carb sync

Carb sync

Thats as close as I can get so far. With a 4 into 1 levels should be all even. # 4 a tad lower but, Good enough?
 
For what it's worth my 1000 g ended up with 112.5 mains and 42.5 pilots which is a little lean . The mains were 115 out of the factory. I've got a Vance and Hines 12500 pipe with no other mods. Compression is 140 lb across the board.
I have a tiny stumble at 2800 rpm which some custom needles might fix but I'm ok with it. 97% of the time it's great and I get 36mpg all day long in mixed traffic and Highway driving.
Searching for perfect tune gets exhausting after a while. I was tired of dirty oil and plugs, 30 mpg, black smoke and pulling carbs.
A magazine in the 80s tested a 1100 with 8 different pipes and all except the super trap flowed less than stock. Keep in mind all the variables tend to cancel each other out eventually if you don't have any boot leaks, airboxe issues, proper timing, good fuel Flow through the petcock, clean plugs, good spark plug wires, etc.
 
Just took a ride. Stumbles from standing start. Taking off through about 3000 RPM first 1/4 of throttle then good after that.
 
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