Motorcycle Repair: 1984 honda magna v45 vf750c, honda magna v45, 1984 honda magna

Question
Hi so i have this 1984 honda magna v45 vf750c motorcycle. this bike has been aggrevating me lol. I bought remanufactured carbs for it that were suppose to be good to go. So i bolted them up and my bike was bogging out and dying and wouldnt rev past 5 and also had no power really. I checked everything else out changed the fuel and air filter too. decided to take the carbs off flipped them over and took the float bowls off. So inside one carb the float bowl was at the right setting, 2 of the other ones collapsed to the metal. and the 4th one has spring but 4 mils farther in than the right one. So i think this might be my problem right? I also noticed two carbs have #135 main jets and the other two have #128 jets, do you know which jets if any are the right ones and also are they also all suppose to be the same? would this affect the performance as well. the other smaller jets are all #40's.

Answer
Hi Reid,

The floats will definitely have a big effect
if not leak proof and adjusted correctly.

Tip the carbs over until the float tang
is just touching the top of the float needle.
It should measure 7.0 millimeters from
the float bottom to the carb body.
Do not compress the needle spring if it has one.
Just make sure the needle is closed but the
spring is not compressed and check the measurement.

The float needle valves in these carbs have some small
filters that can cause problems eventually.
You can remove them and run an external filter
which has more fuel flow.

The stock jets are #112 in the front and #110 in the rear carbs.
The 1983 models did use #128 in all carbs.
#40 are the stock pilot jets.

The main jets will affect the 3/4 to full throttle running
for the most part. If your plugs run dark or black colored
then the mains are too big. You will have to run it
to find out. Possibly the carbs were modified for open pipes
or something, I don't know.

Pilot screws are set at 2.5 turns out initially.

The rear carb main jets are smaller because the rear cylinders
get warm less dense air as it passes over from the
front cylinders.

The warm air has less oxygen in it
so the rear cylinder needs a little less fuel
to attain the proper fuel mixtures.

The front carbs get cooler air so they use larger mains
to mix the fuel/air at the proper ratio for denser air.

If you get the floats set it should run okay.
If you have high speed problems then check
the plug colors. Black means the mains are too big.
If the plugs run brown or tan then it is okay.
Check them after a run at the throttle opening
you want to check.

To get these bikes running smoothly it may
require some carb sticks to synchonize the carbs
to each other.
This makes sure they all run evenly according
to the vacuum they pull.

Check that your floats can actually float
and then set them up carefully.
Check that the float needles are also sealing
when you lift the floats.

Multiple carbs can be a pain but should be okay
if you can get them clean and adjusted.

Good luck!
Wayne S.
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