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bike carb manifold design


BlownCorona

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i presume a&e stands for rag and tape

 

also, keen to see steel manifold come together.

my biggest mistake was welding a balance tube in between runners and not allowing for movement. duh. pulled a decent bow in the flange and i had to mill it flat. would have taken a lot of filing

 

edit. su manifold that was. shame on me

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yeh pretty much. if you're not linking between runners by way of welding it should be sweat as

do you need to flare/taper the runners at all? just curious. i'd go for tapering tube over straight tube and tapered flangey holes.

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yeh you will always get some bend. but if you are careful and use a decent thickness flange, should be useable without out any planning/straightening.  when i used to make a few turbo manifolds, i used to bolt the flange to a big 150mm box section, then tack the flange to the box section between some of the bolts and anywhere, where it was likely to pull up. would always come out straight enough to use as is. 

 

bolting to the head usually works ok.  but do as you say. tack all the runners in place with some solid tacks. then weld part way around  then move onto the next runner, if you are using a tig  by the time you done a bit on all 4, should be good to go back to the first one and do more.  if your smashing it out with mig, might want to wait a bit.

 

edit: as above,  if you need to taper runners, do it over the whole manifold if you can. will work way better

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that's good info!

 

smashing it out on a dirty old mig welder, ill be patient.

 

and I don't need to flare/taper the pipes, the ports are about the same as my carbs (40mm). but I ports are squared, so ill need to form the ends into a squared end.

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  • 7 months later...

hey gang.

  so, piecing things together for a bike carb manifold myself now.

 carbs = cbr1000 keihin cvk36 or thereabouts

trawling the internet has given me more options than it has clarity on how to set up vac stuff with these.

i have no vac advance, just brake booster.

do i take vac from the carbs? or manifold?

do the vac lines from carbs go to booster etc, are they even vac lines? all  i really know for sure is theyre not the fuel lines haha.

 

 

leppa posted this

vacuumtank2.JPG

 

will a setup like this make sense for crabs, if similar connections are there to be used?

 

i are confuse.

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Yeah, that looks sweet. Unsure of your carbs, but all the weirdo hoses and fittings that come from it arent vacuum and are just free air things for over flows and breather things etc. Just taking the vac from the runners will suffice for braking. Might even be able to get away with only using the vac from 2 if its just for dirty braking?

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Currently I have only one runner tapped for brakes, it works, but not well cause I can feel the pulsing of that cylinder and that in turn pulses the boosters effect.

I have now tapped the opposite cylinders runner in hope that this will smooth the whole lot out, I'll know in a week or so when I actually plumb it up.

What size engine are the 36s going on? In my research 36 would be ideal for 1600-1800 but too small for 2000cc

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guess it's just there to keep engine running within spec across wider load range..?

goin on stock 4age. have drilled jets to 1.6mm, cleaned the ringpiece out of them and replaced seals. lucky i had another set of keihins to steal bowl screws etc from, these carbs must have sat with watery fuel for a while and steel parts were worse for wear

 

cool thanks dudes

sweet will make allowance for fittings in the runners, would like to connect all 4 , power of equality etc

chur ned. yeah breathers etc. plumb them in to the filter housing or straight to the great outdoors?

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