1981 GS1000E Chasing a Nightmare Tuning Gremlin...

[Phaedrus]

so you tried a set of carbs with st.3 jet kits?

"So the question then becomes, what could cause an excess of air at mid-high rpms, and only mid-high rpms. She pulls up to 6k fine, and pulls past 7.5k through redline fine. It's just this little range that isn't breathing right. "

the above statement just about exactly describes a set of carbs with big mains and factory shaped needles.
without a jet kit the middle suffers but runs wide open fine.

Nope. Didn't think to try the kit. I'll shop around for one and let that be the final shot. Thanks for the reminder...

[Phaedrus]

After far more hours than I'd like to admit, the ratbeast is finally cruising along with smooth throttle response throughout the power band.

It turns out the gremlin was hidden somewhere in my failed attempts at tuning the carbs. Today, it was time to rebuild the cam chain tensioner on my GS1100E due to a leak, so while the carbs were off I popped them on the GS1000 (as per blowerbike's advice). She opened right up. Even idles better... Carbs are in desperate need of a proper sync and could probably do with dropping the jet needle a notch, but otherwise she rides smooth as butter. Total blast.

Next step will be to gut one of the GS1100 carbs and see what jets and needles it's running so I can clone it.

Very happy to have this beast back on the road... Thanks for all of the tips and advice. Aways appreciated.

[blowerbike]

be aware....
8 valve BS 34's and 16 valve BS 34's are not the same animal.
look at the throat's from the front.
8 valve has 2 holes and 16 valve has 4 holes.
glad you found it to be carb problems 100% so you can quit pulling your hair out.

[Phaedrus]

be aware....
8 valve BS 34's and 16 valve BS 34's are not the same animal.
look at the throat's from the front.
8 valve has 2 holes and 16 valve has 4 holes.
glad you found it to be carb problems 100% so you can quit pulling your hair out.

Good to know. Thanks for the heads up.

Amen. Was ready to chuck the thing... Though, the hair's been gone longer than this bike has been in my life...

[JTGS850GL]

be aware....
8 valve BS 34's and 16 valve BS 34's are not the same animal.
look at the throat's from the front.
8 valve has 2 holes and 16 valve has 4 holes.
glad you found it to be carb problems 100% so you can quit pulling your hair out.

Can you explain exactly what makes the BS34SS carbs off of an 8 valve engine so different then the ones that came on a 16 valve engine? So much deferent that you would call them a deferent animal? It seems that the 2 extra holes on the 4 hole carbs are blocked and look like they would have been used as mounting points in a different application but were never drilled and tapped on the GS. I understand that the jetting would have been different, but other then jetting, what else is different?

Not trying to be difficult, or thread jack but definitely would like clarification on this since I have several sets in storage of both kinds.

[blowerbike]

2 different jet kit's needed..it's more than just main jet sizes as the needles are different in length and shape also.
i have never cut each carb in half and examined them so i can't give a technical description of any differences..only visual(2 hole/4hole.
if the OP tried swapping jets and such we would be right back where we started.
my suggestion kept the OP from dissembling his engine for no reason.
in my 25 years of working on these shlt boxes i always had a spare set of jet kitted carbs or access to a set to swap on a bike that had confusing issues.
it appears my suggestion to the OP saved him some(a lot) of grief.
the end....

[JTGS850GL]

OK so, as I stated, jetting is different between 2V and 4V engines. I assumed that included the needle jet and needles as well. Aren't the main bodies interchangeable? Like I said, it seems the two extra ports on the air cleaner side are dead ended and don't contribute. Just for clarification sake, assuming that the carbs were going onto the same engine, are you saying that you would need two different jetting kits based on 2-hole v/s 4-hole carbs? I was not aware of this.

[Phaedrus]

OK so, as I stated, jetting is different between 2V and 4V engines. I assumed that included the needle jet and needles as well. Aren't the main bodies interchangeable? Like I said, it seems the two extra ports on the air cleaner side are dead ended and don't contribute. Just for clarification sake, assuming that the carbs were going onto the same engine, are you saying that you would need two different jetting kits based on 2-hole v/s 4-hole carbs? I was not aware of this.

To expand on this confusion a little bit: there are two separate jet kits that dynojet makes, one for the 8 valve and one for the 16 valve '80 GS1000. I assumed that my engine is 8 valve, I'll need the 8 valve jet kit. Are you saying that the jet kit is carb-specific and that if I'm running 16-valve carbs I need a 16-valve kit, no matter how many valves the bike has? (Makes perfect sense to me... Just hadn't put it together)

[blowerbike]

here is what we have...think about it.
WHY would suzuki make 2 different BS 34's in the same year(s)?
they have done this sense 1980 through around 1984...WHY?
if they was the same or interchangeable then how much money could suzuki have saved making only one casting?
instead of asking me question i can't answer just ask yourself WHY?
these was never a 16 valve 1000/1100 with 2 hole BS 34's.
there was never 1000/1100 8 valve with BS 34's with 4 holes.
WHY?
because they are not interchangeable and have different internal passages and or sizing.
WHY?

[blowerbike]

To expand on this confusion a little bit: there are two separate jet kits that dynojet makes, one for the 8 valve and one for the 16 valve '80 GS1000. I assumed that my engine is 8 valve, I'll need the 8 valve jet kit. Are you saying that the jet kit is carb-specific and that if I'm running 16-valve carbs I need a 16-valve kit, no matter how many valves the bike has? (Makes perfect sense to me... Just hadn't put it together)

YES and
YES
but........
you always have to be sure your carbs are correct for your year/make/model.
the above is crucial when ordering a jet kit because you can not return them after they are opened.
added!!!!!!

YES the jet kit is bought per carburetor size/style.(this is determined by the year/make/model) as long as you are 100% sure your carbs are correct for your bike.
if you have a known set of 80-83 1100E carbs but was going to install them on a 1978 GS1000.
you WOULD purchase a st.3 kit for a 80-83 GS1100E.

ok i hate typing and thinking and typing...you get idea

[JTGS850GL]

here is what we have...think about it.
WHY would suzuki make 2 different BS 34's in the same year(s)?
they have done this sense 1980 through around 1984...WHY?
if they was the same or interchangeable then how much money could suzuki have saved making only one casting?
instead of asking me question i can't answer just ask yourself WHY?
these was never a 16 valve 1000/1100 with 2 hole BS 34's.
there was never 1000/1100 8 valve with BS 34's with 4 holes.
WHY?
because they are not interchangeable and have different internal passages and or sizing.
WHY?

So, another words you don't know why they're different. I can accept that. I was just curious as to interchangeability since my current GS1000 has a 4 hole carb with stock jetting and seems to run just fine. I just assumed it was a running change since I've seen too many 82+ GS1100Gs (8V engines) with 4 hole carbs to account for PO changes but who knows what can happen over a 30+ year period.

Example:

http://www.ebay.com/itm/SUZUKI-GS1100G-GS1100GL-CARB-SET-CARBURETORS-OEM-UNMOLESTED-ORIGINAL-CONDITION-/161368155707?pt=Motorcycles_Parts_Accessories&hash=item25924aa63b&vxp=mtr

On a side note, just for clarification: Suzuki never made a carburetor for the GS, Mikuni did and there never was a 16V GS1000.

[blowerbike]

So, another words you don't know why they're different. I can accept that. I was just curious as to interchangeability since my current GS1000 has a 4 hole carb with stock jetting and seems to run just fine. I just assumed it was a running change since I've seen too many 82+ GS1100Gs (8V engines) with 4 hole carbs to account for PO changes but who knows what can happen over a 30+ year period.

Example:

http://www.ebay.com/itm/SUZUKI-GS1100G-GS1100GL-CARB-SET-CARBURETORS-OEM-UNMOLESTED-ORIGINAL-CONDITION-/161368155707?pt=Motorcycles_Parts_Accessories&hash=item25924aa63b&vxp=mtr

On a side note, just for clarification: Suzuki never made a carburetor for the GS, Mikuni did and there never was a 16V GS1000.

yes i know mikuni made the carbs for them and yes there is a 16 valve 1000cc...it's called a 1982 katana.

[blowerbike]

this is why i help less and less....i hate to type and even more i hate to argue.
your right...i'm wrong.
take over captain..........

[JTGS850GL]

Corrected... Forgot about the two year run of the Katana in order to meet racing rules.

[JTGS850GL]

this is why i help less and less....i hate to type and even more i hate to argue.
your right...i'm wrong.
take over captain..........

This is not an argument. Please don't make it into one. I was simply asking for clarification on a blanket statement that was made by you, and you didn't have the details I was looking for to clear things up. Since this is a technical forum, and you have some technical knowledge, I was hoping for a more detailed explanation other they a simple "WHY?". WHY are you being so touchy.