^^^^^By looking at the vacuum secondaries, it appears the vacuum line is directly connected from the diaphragm to the secondary throat, my opinion it shouldn't be a problem if you fit to an earlier rolla, simply because there is no other way it is connected. I'd just block off any unnecessary lines on the carby with vacuum block off's.

 

Oh and haven't forgotten about the jet sizes,

 

cheers!

okey doke,

 

finally sussed out the jet sizes in the 5k stock carby,

 

Primary was 106

secondary was 157

 

cheers!

Wow. That primary is really quite small.

Yeah I was quite surprised myself, minor things are different in uncommon ways with the carby, if your ever up this way, pop in and have a look if ya want,

 

cheers!

There are many variations of the 3k carby venturi size.

19,21mm were common Pri sizes

24,25mm were common Sec sizes

All were mech secondary’s with a air valve in the sec venturi.

The 3kb had different sizes again sorry I cannot recall the sizes.

Interesting early 3k carbys all have 21mm pri and 24 mm sec and have smaller 6mm throttle shafts and later ones run 8mm shaft.

Dyno shows no difference between the 24mm sec and the 25mm sec.

So I've got my twin Aisans running well but cannot get new air filters that fit!

 

Any solutions other than changing the housing (not changing it!) or getting custom filters made??

I cut the bases out of a couple of single carb air cleaners and welded those into ( onto) a pair of chrome air cleaners meant for stromberg carbies.

I have the genuine oval twin filter housing... not changing that, just can't find filters (2 x round or 1 x oval) to fit in it :(

When I had the original air cleaner, I used to get the oval element from toyota. This was 20 odd year ago though. Sorta making me feel old :(

Thanks Coln. I couldn't find the oval filter but I did find the part number for the original round filters! Even found a pair up for auction on Ebay.

My bad, had the twin round ones too. Used to get those from Toyota

 

Pretty sure UNI FILTER will make any size you want if it is not in there std range , but for a price of course. They may have something in there catalogue that may fit from there bike , quad or rally filter range . .

K&N have a handy little find section on their website you just enter the size you need and presto it finds what you need

Thanks Andy, I tried that already and they don't make these (except custom).

 

From what I found only Toyota make this size and they are not stocked anywhere any more.

Part number is 17801-24020, a few people had stock for sale on Ebay and you can order them in from Japan :)

How did you end up going with the twin carb jetting? I have a worked 5K just about finished and will be fitting twin Asian carbs I think they are off a 3KB from what I can see everything is the same size on both. Any advice for set up?