RS36 conversion from BS34's

:huh: ...bike has the stock: vacuum activated petcock, single cable throttle, and stock air box. My preference is to use them all, but can I with RS model carburetors?
Would the conversion be worth the investment?

Not if the bike is bone stock.

baldy110 wrote: Not if the bike is bone stock.

Sort-of...
Here is what has been done to the bike: It has a ZN/GPZ 85 (stock) Bathtub head and 85 GPZ cams. The header is a V&H 13009-J Street model, with the Street baffle (Competition baffle in a box). The stock ignition was replaced with a Dynatek 2000, with MINI-coils, solid core wires and non-suppression caps (currently). The electrical has been upgraded with an SH775BA regulator w/wiring kit.
That's all :whistle:

Dave,
I am doing the opposite. Going from RS36'S to BS34'S. Granted, I have put Dyna jet kits in them. If you can hold off I will share how the change is. Like I said in the PM, I am running 1075 w/10.25:1 Wiseco kit, Andrews 1X cams, ported head and a C5 optical(tri-fire) ignition system. I had to order new fuel tubes last night so it should be running by Monday if all goes well.
The RS36'S are simply TOO big for your application. Secondly, RS carbs are race carbs not street carbs and will always have a flat spot somewhere. Just my 2 cents.

I am running the RS36 carbs on my ELR clone. It's an 82 GPz1100 engine with an 1175 Wiseco kit, 10.5 -1 compression, .385 lift Web cams, ported head, 4 into 1 Kerker KR pipe with the large 2.5" comp baffle, green Dyan coils and the Dyna S ignition. The RS36's are almost to big for my engine, I say almost but I plan on doing more work on it. The carbs are jetted pretty good, it idles smooth, (they do rattle a bit) pulls very hard and have no hickups or flat spots anywhere. I did at first right off idle but after much frustration that turned out to be the mechanical advance mechanism which I solved by buying a brand new one. It also get 35 mpg at 80 mph.
I say if you are planning to go bigger in displacement, compression, bigger cams, head work, ect. then go ahead and get the 36's but if not then go with the RS34's.

baldy110 wrote: I am running the RS36 carbs on my ELR clone. It's an 82 GPz1100 engine with an 1175 Wiseco kit, 10.5 -1 compression, .385 lift Web cams, ported head, 4 into 1 Kerker KR pipe with the large 2.5" comp baffle, green Dyan coils and the Dyna S ignition. The RS36's are almost to big for my engine, I say almost but I plan on doing more work on it. The carbs are jetted pretty good, it idles smooth, (they do rattle a bit) pulls very hard and have no hickups or flat spots anywhere. I did at first right off idle but after much frustration that turned out to be the mechanical advance mechanism which I solved by buying a brand new one. It also get 35 mpg at 80 mph.
I say if you are planning to go bigger in displacement, compression, bigger cams, head work, ect. then go ahead and get the 36's but if not then go with the RS34's.

Is that a tear running down the fairing of that beautiful 650 in the back ground. :laugh: ....... Guess I can see why it doesn't get rode much anymore when you have this to choose from.

OK, considering I get a set of RS34's instead... :whistle:

...what changes will be necessary to install and make a set of (good as new) RS34 flat slide carburetors work exceedingly-better than the BS34's that have been on the the bike forever?

Thats way too much carb,I know of an extremely healthy 1385 kz sleeper running the streets of omaha that runs a set of 36s.

daveo wrote: OK, considering I get a set of RS34's instead... :whistle:

...what changes will be necessary to install and make a set of (good as new) RS34 flat slide carburetors work exceedingly-better than the BS34's that have been on the the bike forever?

a little port work,a set of cams,the right valve springs,a good header.

then you you need enough jets(mains and pilots) to get the carbs dialed in( few sets above and below whatevers in it) .

some 34's could be dialed in on a 900 also,with the mods i listed to take advantage of the bigger size.

but they are gonna take some fiddling and most folks wont spend the time or money on the jets and spark plugs to get them dialed in right.
so they won't be happy and they will tell everyone they put big carbs on and they just can't get it to run right.

carbs mix fuel and air proportionately to the amount of air the throat can pass.
so if you get the air fuel mixture correct too small a carb or too big a carb can be tuned to work .
too small a carb is going to limit the maximum power you can make.
too big a carb is going to be hard to get dialed in to pull clean from the closed to open throttle,but will scream on top.
considering the intake size of 36mm and then restriction of the port and seat,valve stem guide boss area i would guess somewhere between 28 and 32 mm to be an ideal size.
but i'm a fan of a bit of over carburation and squeezing all the compression you can out of it to help the bottom end.
if you don't mind spending some time and money on dyno sessions you can get em dialed in,or countless plug chops on a road by your house.
thats my.02,

fwiw

leon

but they are gonna take some fiddling and most folks wont spend the time or money on the jets and spark plugs to get them dialed in right. so they won't be happy and they will tell everyone they put big carbs on and they just can't get it to run right.

+1 The lazy dog bark. :lol:
Steve

Is there a vacuum hookup for the petcock, and are these carbs tune-able with a vacuum sync tool like the Morgan Carb Tune? Are the main jets accessible without having to remove the float bowls, and the floats best-adjusted by using the clear-tube method? Can each float bowl be drained independently?
:ohmy: So-many questions...
As I understand, the throttle control would have to be changed to the push-pull type, which creates other adaptation challenges. And then, as with the BS34's, I'd like to retain the air box. :huh:
I'm not adverse to trying things that supposedly don't work, because sometimes they do. :S

Yes, you can attach the petcock vacuum lead to any of the vacuum ports in front of the carbs, each carb has one for synching, yes, they can be synched like the BS34. Yes, mains can be changed via the large nut on the bottom of the carbs. Yes, using the clear tube method is the best way to set float levels. Mine were way off and I bought them new, so always check. Yes, each bowl can be drained via the large nut on the bottom of each bowl. I tried to run a single cable for throttle used the stock setup the BS34's had. It did not work for me, in normal riding it worked fine but if I got on it really hard and accelerated to redline then shifted the slides would stay open causing me to shift under load, very bad unless I was drag racing. It is a very scary feeling to get on the gas to pass a car and not have the engine RPMs drop.
Some people I have talked to have used the single throttle cable just fine but those motors were pretty much stock. I believe my engine produces such a high vacuum that when throttled up the slides are forced to the front of the carb and hang up. That is probably why Mikuni recommends the dual cable setup
My solution was to use the right switch gear/throttle setup from a 1982 Honda CB900F, they have the pull/push cables and the switch gear looks almost like the Kawasaki ones. That solved my run-on problems.
As far as retaining your stock airbox you're going to have to get pretty creative to get it to work.