Hello,

I tried a search but it was uneventful. You have been very helpful in the past so perhaps you can help me again. I have a '90 CBR 1000 and am lookin at a set of carbs to have around for a spare. Theses are reportedly off an 87. On the left side they have the same nomenclature as mine (V something or other, then Keihin, etc). However, they do not have a vac nipple for the petcock, nor the intermediate fittings between the carbs near the top of each carb (IIRC, these ports have two hose npples which connect to the crankcase ventillation atop the valve cover). Oh, the fuel line runsdown the driver (left) side of the frame-rail on this set of carbs, whereas mine runs down the right-side frame rail.

Anyone familiar with these carbs or know if they'd work ok?

Thanks!

 

Hey:

87-89 have electric fuel pumps and are not controlled by vacuum like the newer CBRFs.
Thats why they do not have the same vacuum points, you may want to find a 90 or newer set,
or get a 87-89 electric fuel pump and wire it up like an 87-89 CBRF.

Good luck
Dub

 

Hello Dub,
Thank you for the quick reply! Your thoughts sound very logical. Because I enjoy torturing myself I picked the carbs up anyhow (I've had a hard time finding any for a decent price, period). I've added a small 4-6 PSI electronic fuel-pump to other projects before so that's not a biggie. I just need to figure out a way to have the petcock flow without restriction (probably sourcing a petcock from an 87-89 tank is a way to go, though I'd prefer to cheap shadetree a solution if I can).

Or maybe I can find some sort of vac source for the petcock. I had tried using one of the synchronizer ports but it wasn't quite sufficient. However, that could have been due to my hose having seen better days and being stretched to the max to reach (I'll try again with a fresh, longer hose).
What is the purpose of those vacuum ports on top of the ('90+) carbs? Is it purely a means to close the crankcase ventillation system, or do those ports have another purpose? Honestly, IIRC I have run without them connected before (there was a time where I ran a breather on the crankcase port and plugged those two ports on the carbs).

I very much welcome any thoughts you might have. I've never had more than the cheapo repair manualas a resource, and it can leave a lot to be desired, especially when it comes to the cleanest way to modify something.
Thank you again Dub!