RS34 jetting suggestions, 1992 GSX1100G

[1100G]

I got tired of dealing with my leaky BST36 CV carbs. so I found a set of new RS34s at a good price and bought them. The catalog lists the jetting as being 115 mains, but when I took off the bottom plugs I saw every one was jetted @ 125 (they came with 110, 115, and 120 jets also). I didn't take the float bowls off yet but did verify the needles were all in the -3 position. I found a chart here that lists a bunch of jetting suggestions:

http://www.braigasen.com/Mikuni_jetting_chart_four_stroke.htm

The closest RS34 application is for the GSX600 or GS750, and it lists stock 115 jets. There is a listing for the GSX1100 with RS36 and it lists 120 MJ and all of the other stuff is the same as the RS34.

The bike has no engine mods, the OEM exhaust, and I'm running pod filters.

Any advice on where to start?

[Gixer1460]

125 not likely to be a million miles out and it'll give you a baseline. The 34's will give good depression over the jet so requiring a size or two smaller than if using 36 / 38's for example. I started with 125's in 36's fitted to a 1360 EFE engine!

[MeanBean49]

Best answer is get it on a dyno. Its not really worth the wasted time and effort trying to do it your self or even trying to get it somthing like prior to dyno, takes very little time in comparisson on a dyno to get a good setup even if starting from it running like a sack of shit.

Reccomendations for other bikes are largely pointless and irrelevant, as is advice based on different sized carbs and what jets have been used in them.

Not sure exactly what is being reffered to above with "good depression" carbs work on a pressure differential where the pressure in the float bowl is higher than through the carb body which causes fuel to be effectively blown/sucked (whichever way you want to look at it) into the airflow. The main jet is there to control the ratio of fuel added is correct at max demand, the needle helps modulate the fuel for lower throttle openings and constant throttle.

 

[1100G]

Thanks for the input. I am waiting on some other  parts, so maybe I'll begin with the 120 jets.

A dyno while a great idea simply is not feasible for a number of reasons such as geographic and economic.

[MeanBean49]

9 hours ago, 1100G said:

Thanks for the input. I am waiting on some other  parts, so maybe I'll begin with the 120 jets.

A dyno while a great idea simply is not feasible for a number of reasons such as geographic and economic.

Ahh, so it will be hours of the test ride and plug chop cycle then.

Might be worth looking at a Gunson Colourtune kit

[Reinhoud]

You need the size your bike runs properly on, don't look at someone elses bike, you can use it as a base, but not for fine tuning, if you don't have an A/F gauge yourself, put it on a Dyno, this will take the guess work out.

Too lean or too rich can somewhat give the same symptomes..

[Dezza]

Is this an 1100G shaft drive we are talking about here? If so, such a machine is probably going to be best suited to the original CV carbs. Maybe it will be better to spend cash and time finding out what is wrong with the BST 36s rather than changing to RSs, and it will probably be cheaper too.

My guess is there is a dearth of jetting information for RSs for your bike as to put it mildly, it's probably not that common that anyone would want to fit RSs to an 1100G shafty .

[Reinhoud]

32 minutes ago, Dezza said:

Is this an 1100G shaft drive we are talking about here? If so, such a machine is probably going to be best suited to the original CV carbs. Maybe it will be better to spend cash and time finding out what is wrong with the BST 36s rather than changing to RSs, and it will probably be cheaper too.

My guess is there is a dearth of jetting information for RSs for your bike as to put it mildly, it's probably not that common that anyone would want to fit RSs to an 1100G shafty .

If that was the case this forum didn't exist

[Dezza]

46 minutes ago, Reinhoud said:

If that was the case this forum didn't exist

???? What proportion of all bikes on OSS are 1100 shafties? My guess is very low as the machine doesn't even register as a donor bike, except, ironically, for the BST 36 mm carbs which may be useful on common OSS bikes

 

I do think a heavily modified 1100g shafty could be mega-cool though (didn't Havoc begin to build one on here a while back???), in a similar manner as Wraith's powerscreen.

Edited February 25, 2021 by Dezza

[Reinhoud]

21 minutes ago, Dezza said:

???? What proportion of all bikes on OSS are 1100 shafties? My guess is very low as the machine doesn't even register as a donor bike, except, ironically, for the BST 36 mm carbs which may be useful on common OSS bikes

 

I do think a heavily modified 1100g shafty could be mega-cool though (didn't Havoc begin to build one on here a while back???), in a similar manner as Wraith's powerscreen.

I mean, I think a lot of people on this forum spend way more money on their old skool suzuki as what it's worth.

[Tinsnips]

6Sigma does jet kits based on engine, carb, intake type, exhaust model, and altitude. You could inquire with them what they would suggest. I bought one of their kits for my 40mm BSTs and it was an easy swap.  They include the base settings and specific instructions.  

[MeanBean49]

7 minutes ago, Tinsnips said:

6Sigma does jet kits based on engine, carb, intake type, exhaust model, and altitude. You could inquire with them what they would suggest. I bought one of their kits for my 40mm BSTs and it was an easy swap.  They include the base settings and specific instructions.  

Pretty much all jet kits are model speciffic and come with base settings. 

They also all advise setting up on a dyno to get them right.

Also pretty unlikely anyone will do a jet kit for aftermarket flatslide carbs.

Its all just guesswork without a dyno or some way to monitor afr, or at worst plug colour

[1100G]

Looks like the closest dyno is about 2.5 hours away and $95/hour. I just sunk over $700 on carbs and filters and other odds & ends to mount them. Aside from the fact I have no way to get the bike there w/o riding it (catch-22), I can't spend hundreds more right now.

Mikuni has basic tuning instructions with them that seem pretty decent.

The old BST36 carbs were gone through  after the side tube on one was leaking. I used some JB Weld to patch it. I also had replaced the plastic slide housings, emulsion tubes, and needles last year. Reset the float levels. Worked great for a few months and then the coils went out. Replaced those, and then #2 carb started leaking. At that point, I was done with patching up these nearly 30 year old carbs. I didn't want to waste money on used carbs. The only new option for a bank of 4 were the RS flatslides.

I'm not looking for maximum performance, just a reliable daily rider. At some point if I keep the bike I'll likely convert it to Microsquirt.

 

[Reinhoud]

https://www.Eblag.com/itm/AEM-30-4110-WIDEBAND-O2-UEGO-CONTROLLER-AIR-FUEL-RATIO-GAUGE-KIT-BOSCH-4-9-LSU/360538007974?epid=1130294172&hash=item53f1bd69a6:g:uocAAOSwdxJaqZCs

[1100G]

I have the AEM on an LS V8 swap that is underway, and this one on another bike, seems like a good product & price point:

Spartan Lambda 2

Either one could be reused if I go EFI. Seems like curved mild steel bungs are now hard to come by- all of the ones I saw were stainless.

[Gixer1460]

That lambda seems remarkably cheap $125 with a sensor and seems quite similar to an Innovate LC-1 / 2? Stainless bungs are used as less likely to rust into the sensor but can be welded into MS pipe - just need the right filler wire.

[Duckndive]

Use stainless filler rod to weld the S/S bung into mild steel pipe...

I have the innovate kit but the sensor soon dies if you use leaded fuel 

[Reinhoud]

Get a drillbit and a tap and make them yourself

[Gixer1460]

1 hour ago, Duckndive said:

Use stainless filler rod to weld the S/S bung into mild steel pipe...

I have the innovate kit but the sensor soon dies if you use leaded fuel 

They all have a pretty much + / - life with leaded ! Best do the set up as good as you can then remove. I guess unleaded does have its advantages LOL!