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Jetting on Keihin FCR 39 for GS1150

  • Thread starter Thread starter Flo
  • Start date Start date
F

Flo

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Hi,
I have a brand new set of Keihin FCR around which are setup for GSXR1100 oil cooled. They mechanically fit on the GSs too. Now my question:

Does anyone have the base jetting specs for FCR39s on a GS1150? Opposite to Mikuni I cannot find any Keihin data on the net which includes all jets, needles etc.

As Ape and Sudco do not offer FCRs for the GSs anymore I would like to change my GSXR-FCRs over to GS specs.

Any information appreciated
Flo
 
Flo, just so you know, if your 1150 is a STOCK bore & compression, those carbs are WAY too big! You would need at LEAST 1260 cc with some compression, ported, & cammed to need carbs that big. I know as I build these all the time. I have some 36 Mikunis if you would be interested in some sort of trade as I could use a set of 39s on a 1445 street motor I'm building. Ray.
 
I'm new to Suzuki's so maybe there's something that makes a difference, but in DOHC Honda land FCR39's work fine on an 1100. I'm running a set of FCR37's on the 900cc bike in my signature - no bogging, no missing, no running rich. Only mods are slightly hotter cams and the head/bore is stock.

Generally, you can go one or two sizes up over an equivalent CR because of the better off idle metering of the FCR's and the all important accelerator pump. Sudco in the US may not supply an 'out of the box' setup for FCR's on an early Suzuki, but Keihin Japan offer prejetted configurations on FCR37's, FCR39's and FCR41's for a GSX1100S.

I would ask Sudco for some recommendations and if you can't get any info. post back - at the very least I can see what the 1100 Honda guys are using and hopefully get you in the ballpark.
 
Hi to all,

thanks again for your replies!

The motor is a 1327ccm GS1150. It indeed has stock cams (street motor), but 12/1 compression, larger valves and professional porting what might be considered stage 2. I think it should be right for 39s. Otherwise I would run 38 Mikunis.

Also has custom fully programmable ignition... Any recomendations for a good map or curve? I can hook up a TPS with this ignition if I want...

APE and Sudco used to supply FCR39s for GS1100 until beginnning of this year. Someone needs to have the specs for them. I know this is only a baseline to start from for the dyno tuning, but I do not want to start totally off. I may just again ask APE's techline.

Regards
Florian
 
Last edited:
What ignition system is it? I think if you start off in the neighbor hood of 150-155 on the main jet you will be in the neighborhood. Why stock cams? Even a set of small G-4s would be a big gain on that motor. Ray.
 
The ignition is from a Czech company:

http://ignitech.cz/english/aindex.htm
Pretty interesting product. You need to do some of your own fab to place the rotor on your crank and the pickup in your case. But you have a lot more options than a Dyna and it is dirt cheap (round $150 to 160 with the current exchange rate). Also the company is somewhat of a one-man-show and I like to support stuff like that. You talk to him on the phone and via email directly. Which is also a downside as neither his German or English is really great...
If some one else wants one I can supply my drawings for the adapter parts I made.

For the cams:

I do not want to give up ANY lowend and drivability on that motor. I ride mostly on very tight mountain roads and on a local race track, where the longest straight is less than a 1/4ml.



I am considering adding other cams later on. But I would like them to be very mild. Open for any recomendations. Goal is to take part in the
"Classic Super Bike" championship next year.

I originally also wanted to put on 36 or 38mm flatslides. But now I have a set of brand new GSXR-FCRs around where the customer backed out so I am considering them...

Flo
 
Last edited:
Flo if you want bottom end I would go with the 36s & Cam Motion G4 cams. The bike will be an ANIMAL with this setup at 1327! Ray.
 
By the way this is what Keihin said:

"The baseline jet for the GS and GSXR Oil Cooled we used the same exact jetting spec- 160 Main, 200 Main Air, OC-EMP needle, 55 Pilot, and 100 Pilot Air Jet."

So if someone wants flatslides with roller bearings just get the FCR for the GSXR.

Greets
Flo
 
I'd recommend #135 mains to start from

as always start jetting with the PILOT circuit
move on to the needle
and last get to the mains
 
trippivot said:
I'd recommend #135 mains to start from

as always start jetting with the PILOT circuit
move on to the needle
and last get to the mains
Click to expand...
How do you get the needle correct with the wrong main?
I always start with the main, needle and then pilot.
 
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