VF750C Magna




My Tips&Tricks

Headlight adjustment and Carburettor synchronisation

Headlight adjustment:
Put yourself on the bike and position it upright (riding position) in front of a wall. Have another person measure the distance from the center of the headlamp to the floor/road.

Measure off 7,6m (25') from the front of the lamp and draw a horizontal line (same height as the center of the lamp ) on the wall.

Turn your lights on and put theme on high beam. While your weight still on the bike, adjust the light vertical so the light is even above and below the horizontal line you drew on the wall. Then adjust the light horizontal so you have an equal amount of light to the left and right of the center point.

This puts your high and low beam "almost perfect".

Carb sync.:

You need phillips screwdriver, 4 vacuum gauges, or a Cartune II, and an "L" bend tool with either an 8mm socket or
a flathead screwdriver on the end. I used the following:

"L" bend tool with an 8mm socket
Carbtune II

Cylinders are numbered as follows:

left side: 1 rear, 2 front
right side: 3 rear, 4 front

The vacuum ports are the philips screws visible in the upper corners of each carb. Remove the philips screws and washer from each carb (1, 2 and 3) and screw in the brass connector tubes. Just hand tighten the connector tubes.
Plug the vacuum gauges into the vacuum ports on these three. Carb 4 has a vacuum hose. Start the bike and let it idle for a few minutes to build up pressure. Take a pair of sissor clamps and clamp off the hose BEFORE detaching it from the plug. Then slip on gauge #4 hose. DO NOT TURN OFF THE BIKE!.

Adjust the calibration screws "on the gauges" until each is steady or barely moving.

Cylinder #1 is the base cylinder. You will adjust the other 3 so their vacuum matches whatever is on #1. Sync the carbs in this order, 2 to 1, 3 to 1 and 4 to 1. Repeat as necessary, as the next carb may throw off the previous..
Up under the carbs you will see 1 sync screw on the back row and 2 screws on the front row. You can see which screw adjusts which carb by turning the screw while the engine is running and watch which vacuum gauge changes its reading. Use your "L" bend screwdriver to adjust the screws until all the vacuum gauges read the same.

Once the above is accomplished, you are done! Turn the bike off, disconnect the gauges, put the Phillips screws back in and re-attach the vacuum hose. No need to do anything more as below...

******* To get the carbs super-accurate *******
Next, put the bike on a stand so it's vertical, rest the carb sync gauges on the seat (with all their hoses attached to the cylinder ports), put the bike in neutral, fire it up and let it warm up fully. Adjust the dampers on the vacuum gauges so the needles stop jumping around and are just barely wiggling. Just looking at the gauges you'll see how "close" your carbs are. To get the carbs super-accurate well beyond the specification, repeat the procedure described above at an idle of 2500-3000rpm.

(Thanks to MrsWilli for writing it down)

Check out my Modification page for more tips!


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