Hi all My new cb performance type 4 inlet manifolds are supplied with 2 x small hose barbs for a balance pipe, a large hose barb for the brake servo pipe and a blanking plug. The OEM brake servo pipe goes to both manifolds, so should I connect this OEM pipe to just one side (if so, which side?) & blank the other end off , or do I buy another large barb, do away with the blanking plug & connect the OEM brake servo pipe to both inlet manifolds? Also, shall I just use ptfe tape & threadlock to fix in the barbs? Thx.
Nice having them supplied that way and saves a bit of grief. Are they PDSIs ? I’d go for a single take off for servo and pipe directly from barb. Jury is out on balance pipes. I’d go flexibif I wee to do it! Not sure how different carbs react to it!
With the original cabs, the servo is Tee'd off the balance pipe - two birds with one stone. I'd connect the smaller barbs up to the original servo/balance pipe and get another blank. That's assuming they aren't tiny.
Which carbs. I had a pair with those manifolds some years back and the carbs were soles pdsi but venturis were a bit small. If I recall they were 24s rather than the standard 26s . I came by some dells a never fitted or ran them. I note they did have bigger vents available which I probably would have gone for.
It doesn't need to be all that big, I think the steel tube is about 8mm internal dia. Less pipes = neater? Using the steel one is tidy.
Just had a Google and they are 22s as standard at least on some kits supplied I’d check and fit the 28s if that’s the case
grub has threads about 34 ICT on a 1700 type 4, CB hex linkage and CB manifolds. I guess it’s all on the same engine.
The carbs are 34 ICTs. The kit comes with a length of rubber pipe for the smaller barbs as a balance pipe. The OEM metal servo pipe is tee'd off as Zed says and goes to each manifold. The larger barb on the new manifolds is the sane size as the rubber elbow on the end of the metal pipe. The question is do I blank off one end of this metal pipe and fit the other end to one manifold, or buy another barb and have the metal OEM servo pipe going to both manifolds?
Inner dia? if yes, use two of those then. Tres difficult to judge sizes on photos, but I have fed a servo off 2 x 8mm internal dia and it was dandy. I suspect even smaller might work.
Inner diameter of the rubber elbows of the OEM servo pipe is 12mm, and the OD of the larger Union supplied with the CB manifolds us 12mm, so they will push straight on. Would blanking off one end of this reduce the servo assistance of the brakes? If not, I may not be gaining anything by connecting both ends.. other than it may look neater? The other unions are 6mm ID, so I will connect the balance pipe to these, as per the original carbs.
Yes you will, it will become the balance pipe as well as the servo vacuum like it was when you had the original carbs. Then you don't need the other connections at all. That's then whole point of using the original steel balance pipe with it's servo take-off through the rear tin. Neat and tidy.
