Anyone running different carbs.

[Little Pink Steve]

Just wondering if anyone here is running carbs off different bikes.  I'm not talking about dropping a grand on a set of flat slides.  CV36BS are a decent carb but are getting a bit long in the tooth are there more modern alternatives that have any advantages? 

Also anyone in the U.K. with a broken CV36BS going for beer money.  I want something I can cut up.

[JPaganel]

Well, I did just see a post on FB from a guy who runs fuel injection...



Beyond that, I really don't think carbs significantly advanced from the time of the BS series. There is only so much advancement you can put into a mechanical sprayer.

[Pat Conlon]

Have a read: http://www.fjmods.co.uk/Carburation.htm
The carb spacing for the FJ is 77 - 85 - 77
Currently 3 options that I'm aware of
1) Mikuni RS flatslides
2) Mikuni TMR roller flatslides
3) Keihin  FCR roller flatslides
All 3 of the above carbs have accelerator pumps and offer *immediate throttle response*  unlike our CV carbs that have a slight delay while you wait for the vacuum to raise the slide and needle. They are offered in larger sizes (38/40mm) that will flow more air than our 36mm carbs. These carbs, along with the correct cams can give you 20-30+ more rwhp and....did I mention *immediate throttle response*.....I was startled when I rode a FJ with flatslides.

I know both Franks use the Keihin FCR's on their 1350's, (Brutus and Wizard)
The flatslides are racing carbs, the drawback is they do not compensate for air density (altitude) like our CV carbs.
Although Frank has reported that his Wizard has no trouble at sea level and at altitude.

Cheers

[T Legg]

Coincidentally I just got back from a ride with Ian between Washoe valley and Reno on my fj1100 with rs-38 flatslides . I've almost got the jetting perfect now. Ian took off on his zzr1200 that would eat my lunch in the past on a section of road with an uphill grade at 5300 ft altitude and this time it was hanging pretty well with his . It hit 150 mph indicated and it still had power to accelerate. The midrange is also excellent and when I finish getting the jetting right I think my idle to eigth throttle will be strong. My flatslides were well worth a thousand bucks to me.

[Bozo]

Coincidentally I just got back from a ride with Ian between Washoe valley and Reno on my fj1100 with rs-38 flatslides . I've almost got the jetting perfect now. Ian took off on his zzr1200 that would eat my lunch in the past on a section of road with an uphill grade at 5300 ft altitude and this time it was hanging pretty well with his . It hit 150 mph indicated and it still had power to accelerate. The midrange is also excellent and when I finish getting the jetting right I think my idle to eigth throttle will be strong. My flatslides were well worth a thousand bucks to me.

Just curious, do you find the stronger return springs hard to hold for longer distances. What mods have you done to the engine as I would've thought the carby's alone wouldn't be enough to keep with a ZZR

[T Legg]

The throttle springs are stiff but they don't bother me on long trips. I do use a cramp buster to relax my grip .the motion pro throttle assembly requires a lot of rotation to reach full throttle . My bike was set up in the late eighty's by the original owner.it had rs- 36 carbs four in to one exhaust and pod filters . The suspension was also set up by Lindemann enterprises with a Penske shock and the antidive units removed. I've not had the heads removed I assume it's stock inside. I can see that someone match ported the heads to the intakes but I can't see any other porting from the outside. The cam shafts have slotted gears but I don't know if they are stock or not,they look the same as the cams on my other two fj's. With the  rs - 36 carbs on it the highest speed I had hit was 146 mph at 4900 ft elevation on level ground and it was almost out of poop by then although I did have saddlebags on at the time. My son's zzr would pull away from it pretty well on long straight aways. With rs-38  carbs on yesterday's run at 5300 ft elevation going up a decent incline it hit 150 mph and was still accelerating. My son on his zzr ahead of me hit 162 mph and was only easing away from me.all these speeds were speedometer readings the actual speeds could be ten to fifteen percent off.In twisty road riding I don't feel any disadvantage to the zzr. My FJ 1100 with the flatslides is much faster than my fj1100 or my fj1200 that both have stock carbs four into one exhaust and pod filters.

[Little Pink Steve]

Well, I did just see a post on FB from a guy who runs fuel injection...

Do you have a link?

[JPaganel]

Well, I did just see a post on FB from a guy who runs fuel injection...

Do you have a link?

https://www.facebook.com/groups/1440193869604433/permalink/2370634806560330/

[Bozo]

The throttle springs are stiff but they don't bother me on long trips. I do use a cramp buster to relax my grip .the motion pro throttle assembly requires a lot of rotation to reach full throttle . My bike was set up in the late eighty's by the original owner.it had rs- 36 carbs four in to one exhaust and pod filters . The suspension was also set up by Lindemann enterprises with a Penske shock and the antidive units removed. I've not had the heads removed I assume it's stock inside. I can see that someone match ported the heads to the intakes but I can't see any other porting from the outside. The cam shafts have slotted gears but I don't know if they are stock or not,they look the same as the cams on my other two fj's. With the  rs - 36 carbs on it the highest speed I had hit was 146 mph at 4900 ft elevation on level ground and it was almost out of poop by then although I did have saddlebags on at the time. My son's zzr would pull away from it pretty well on long straight aways. With rs-38  carbs on yesterday's run at 5300 ft elevation going up a decent incline it hit 150 mph and was still accelerating. My son on his zzr ahead of me hit 162 mph and was only easing away from me.all these speeds were speedometer readings the actual speeds could be ten to fifteen percent off.In twisty road riding I don't feel any disadvantage to the zzr. My FJ 1100 with the flatslides is much faster than my fj1100 or my fj1200 that both have stock carbs four into one exhaust and pod filters.

Thankyou sounds like a neat FJ you have there

[Little Pink Steve]

Thanks for the replies guys.

I'll rephrase the question.  Are there any OEM carbs from other bikes that would work well on an FJ1200?  Happy to re-engineer them to fit, only mods to the bike are 4-1 pipe and some head work (possibly filters or airbox mods).  I don't fancy dropping £3k into it.

[FJ1200W]

Well, I did just see a post on FB from a guy who runs fuel injection...

Do you have a link?

https://www.facebook.com/groups/1440193869604433/permalink/2370634806560330/

Seems like a decent deal for someone

[Pat Conlon]

^^ Wrong spacing, you want 77-85-77

[FJ1200W]

^^ Wrong spacing, you want 77-85-77

I wonder how he had them mounted on his FJ dwarf car? Interesting!

Good catch

https://www.facebook.com/groups/1343924852335564/

I believe the spacing can be changed on the brackets.

"Check your carb spacing as per the picture and if not 77-93-77 as supplied here but only requiring a 77-85-77 spacing adjustment this can be either done by yourself or we can do it by selecting the re-spacing labour option for $88 in the RS carbs accessories page"

https://www.mikunioz.com/shop/rs40-d1-k-mikuni-rs-40mm-carb-kit/?v=7516fd43adaa

*** Update ***
The spacing is correct, the seller used generic information for his listing. Here is a picture of them next to a set of stock FJ carbs.

[Pat Conlon]

Good to go! 

[FJ_Hooligan]

The carbs from a 1st generation FZ1 have spacing that's identical to the FJ.

The FZ1 carbs are very similar to the FJ carbs.  Both are Mikuni, the FZ carb is a modern version of the FJ.

Not sure on the performance difference.  Ivan makes a carb kit for the FZ that really improves throttle response.