Increase in jet size on Mains ?

[JTGS850GL]

An 82 1000SZ is a 16-valve engine while 1980 1000E or S are 8-valve engines, There is a significant difference between 16 and 8-valve engines.

Yep, sorry for not thinking this one out. Doing too many things at one time and my brain wasn't fully involved. Thanks for catching my screwup. With that said, a 1981 1000G is an 8 valve engine and, factory stock, came with 115 mains and 40 pilots. Now using 120 mains, 40 pilots and needles with 3 washers. Only change is 4-1 exhaust and K/N filter in stock airbox. Don't think that there's much difference between a 1000 shaft drive v/s chain drive of the same year.

[mike10]

Ok, I have recleaned my carbs. No dip this time. I dipped them about 3 weeks ago 4 hours in the Berrymans. and installed 112.5 main jets. Original issue, stumble into mid range A little boggy full throttle. a little back firing/ popping on hard decelleration. All because I put the Delkevic 4 into 1 exhaust on a compleatly stock GS1000E 1980 CV BS34SS carbs 107.5 mains. 3 washers on top of the clip on the non adjustable needles. replacing the plactic spacer. All O rings are new. Before I put them back on do I need to change pilot jets too. the pilots are 40s, thanks

[mike10]

Ok, I have recleaned my carbs. No dip this time. I dipped them about 3 weeks ago 4 hours in the Berrymans. and installed 112.5 main jets. Original issue, stumble into mid range A little boggy full throttle. a little back firing/ popping on hard decelleration. All because I put the Delkevic 4 into 1 exhaust on a compleatly stock GS1000E 1980 CV BS34SS carbs 107.5 mains. 3 washers on top of the clip on the non adjustable needles. replacing the plactic spacer. All O rings are new. Before I put them back on do I need to change pilot jets too. the pilots are 40s, thanks

Ansewer to my own question. 40 pilots will be fine because I have the stock airbox on.

[tkent02]

Even with pods the stock pilot jets usually work fine.

[rudeman]

By placing the washers on top of the clip you are not changing the needle height. You want them to extend into the fuel feed tube less than they are at stock setting. In other words the distance from the bottom of the slide to the lower end (tip) of the needle needs to be shorter. I ran 42.5 pilots and a stock air box. It ran significantly better than with the 40 pilots. Have you tried 42.5 pilots yet?

If that pipe is worth its salt you will need to compensate for increased airflow.

I ran 120 main jets and it ran perfectly. Like I mentioned earlier in this post, with those main jets and 42.5 pilots and RAISED needles the my 1000ST had great snap off idle; no bog when rolling open the throttle; and pulled hard all the way through redline.

1980 GS1000 has 107.5 main and 40 pilots.

[rudeman]

Maybe it's just me but, judging by the throttle plates, it sure looks like your carburetor balance might be way off.

[mike10]

[mike10]

Maybe it's just me but, judging by the throttle plates, it sure looks like your carburetor balance might be way off.

I had not done the bench sync yet

[mike10]

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.

[hjfisk]

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

[duaneage]

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.

[rudeman]

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.

[duaneage]

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

[mike10]

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.

Yes new exhaust gaskets were installed with the pipes. Thanks

[mike10]

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.