Vacuum Ports.

10569 Views 26 Replies 8 Participants Last post by Aduro, Nov 5, 2012

Aduro

Discussion Starter · Jun 29, 2010

My current project may have hit a wall already.

I made the assumption that being a four cylinder, four carb engine the carbs would have four vacuum ports, at this point i can only see two (mind you it was dark and i havnt taken the carbs right off yet)
Aiming this at Stud or the more experienced boys, how many vacuum ports are on the MC22?
If there are only two does that mean a manometer cannot be used? only a synchrometer?

1 - 20 of 27 Posts

G

· #2 · Jun 29, 2010

It does have 4 vacuum port outlets, but some cbr's have only one fitted and the rest are plugged with a small 8mm bolt.

It's a case of removing the 8mm bolt and fitting a vacuum pipe.

Aduro

Discussion Starter · #3 · Jun 29, 2010

Thanks Stud, will def take a closer look tomorrow.
Attempting to Maguyver up a manometer, quite sure someone on here has done it before, if they'd like to chime in thatd be great.

Aduro

Discussion Starter · #4 · Jun 30, 2010

Still struggling to work out where these ports are, (pretty sure this pic is to big but not sure how to resize?)
The trumpets have been removed and this is the view form top. The two tubes circled in green are what i thought were the ports, just trying to work out where i would connect this manometer up to once its made.
The screw circled in red is one of the three used to balance the carbs correct?

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p4ndor4

· #5 · Nov 1, 2012

@ Aduro, where do I source the "vacuum tubes"?

Aduro

Discussion Starter · #6 · Nov 1, 2012

As in the carby balancing tubes? Or as in those green things I circled so many many moons ago when I was a newb?

K916

· #7 · Nov 1, 2012

Lol

Its the first time Im seeing this thread

The ports are below the carbs on the cylinders

p4ndor4

· #8 · Nov 1, 2012

I saw a brass tubes connected to the carb vacuum ports.
There are pictures courtesy of 'didjabringabeer'.
http://cbr250.com/forum/thread-2450-page-3.html?highlight=carbs

Anyhow, my plan is to balance my bike carb with home-made carb balance.
I'm basing mine on this:
http://forums.sohc4.net/index.php?topic=58677.0

Thanks Aduro.

motthomas

· #9 · Nov 1, 2012

Yup. Yer looking in the wrong place. As K916 said the ports are on the intake stubs on the cylinder head.

#1 is viewed through the hole in the frame at the side and shouls have a brass nipple and tube connected going to the fuel petcock.

#4 is in the same position at the other side and should be blocked off with an alloy cross-head screw.

#2 & #3 face straight back and can be seen and accessed from behind the carbs & airbox. They should have brass nipples in them too and blanked off with rubber sleeves. You will probably need a long nose pliers to reach in and pull off the blanking caps and to slip on the vacuum hoses for balancing. Unless you have tiny hands.

Middle two here. Well... follow the tubes and get the general idea!

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p4ndor4

· #10 · Nov 1, 2012

motthomas said:
Yup. Yer looking in the wrong place. As K916 said the ports are on the intake stubs on the cylinder head.

#1 is viewed through the hole in the frame at the side and shouls have a brass nipple and tube connected going to the fuel petcock.

#4 is in the same position at the other side and should be blocked off with an alloy cross-head screw.

#2 & #3 face straight back and can be seen and accessed from behind the carbs & airbox. They should have brass nipples in them too and blanked off with rubber sleeves. You will probably need a long nose pliers to reach in and pull off the blanking caps and to slip on the vacuum hoses for balancing. Unless you have tiny hands.

Middle two here. Well... follow the tubes and get the general idea!

I am assuming that I can attach my 'flexi-tube' of my carb-balancer directly into the ports. Am I right? Or do I need a brass tube to connect my hoses? (those that are supplied in the proper carb balancer kit)

motthomas

· #11 · Nov 1, 2012

On #1, 2 & 3 yes. On #4 you should have got brass nipples with the carb balancer that you can screw into the port instead of the screw.

p4ndor4

· #12 · Nov 1, 2012

Thanks mottomas. Would anybody in Sydney know where to source the adapter?

Lane

· #13 · Nov 2, 2012

Any good fluid transfer company will have them, Pirtek, Kwikfit etc.

A good auto store might have some but chances are they'll be plastic.

jlyall

· #14 · Nov 2, 2012

^^Try a wreckers for one of the same of any of the other vacuum ports on a CBR250

findapart

p4ndor4

· #15 · Nov 2, 2012

Would a 3/16 Inch diameter barbed hose do?

aj26

· #16 · Nov 2, 2012

FYI - Just incase someone wanted these in the future.
As for the hose you could rip the vacuum one from the tank to match at the shops get one to replace the existing hose too

I would replace the rubber caps and circlips on 2 & 3 inlets, pretty cheap to buy but hassle to get if you break it on the day when balancing

M5 Washer (Washer 5mm) 90452-323-000
http://www.cmsnl.com/honda-cbr250rrl-mc22-japan_model14665/washer-5mm_90452323000/

Inlet Port Vacuum (JOINT BOOST) 16214-MB0-000
http://www.cmsnl.com/honda-cbr250rrl-mc22-japan_model14665/joint-boost_16214mb0000/

Rubber Cap (CAP,BOOST) 16215-MV4-000
http://www.cmsnl.com/honda-cbr250rrl-mc22-japan_model14665/cap-boost_16215mv4000/

Cap Circlip (Clip B7,tube) 95002-020-70
http://www.cmsnl.com/honda-cbr250rrl-mc22-japan_model14665/clip-b7-tube_9500202070/

4th Cylinder Bolt Plug (BOLT5X8) 92301-050-080A
http://www.cmsnl.com/honda-cbr250rrl-mc22-japan_model14665/bolt-recessed-5x8_92301050080a/

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G

· #17 · Nov 2, 2012

:lol:

motthomas

· #18 · Nov 2, 2012

Actually +1 on replacing the rubber caps. If they havent been off in a while they can be brittle and break when pulling off. The circlips should be fine though.

Rob

· #19 · Nov 2, 2012

just buy them from honda only cost like 2 bucks

aj26

· #20 · Nov 2, 2012

roobars said:
:lol:

:bootyshake:

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