Carburettor Carb Cleaning 101

Carb Cleaning 101
By M. Shively

The elements of internal combustion engines are: correct fuel/air ratio, spark at right time, adequate cylinder compression.

There are many passageways and openings to check and clean. All are important in function and when obstructed or not working properly, have subtle to radical effects on engine performance. Vacuum leaks and carburetor synchronization also effect performance and should be inspected and adjusted following the below procedures.

Carb Cleaning 101

Understanding Fork Springs by Larry

My brother’s VFR8 had appalling dive. It would dive so much it would bottom the fork very early and lock the front tyre. I don’t recall how much I reduced the air gap but it transformed the bike. From memory probably the worst dive I’ve experienced was on the FJ11 and 12.

Did you measure the air gap before emptying the oil out? Compare it to spec to ensure you have what you’re supposed to and then reduce it (put more oil in) by about 20-25% and try that.
Are you able to measure the current spring rate? Simplest way is to:

1. stand the fork on a bathroom scale with a tape measure alongside.
2. Zero the scale then push down and read off the scale as a mate reads off every 10mm of compression.
3. Then graph it – and average the kg/mm if it’s a linear spring.

If you can measure the height of the spring when the fork is extended (probably by adding and subtracting the fork cap height) then you can compress the spring fully and see how far you can go before it becomes coil-bound. If it’s more than the travel you have in the fork then you could cut a spacer (25mm conduit) to fill the difference but don’t go so far as to actually allow the spring to bind in use.

How to check motorcycle drive chain stretch

How to check motorcycle drive chain stretch, with video demonstration.

1. At the middle/end of the rear sprocket grab a chain link.
2. Try to pull the chain off of the sprocket to the rear of the bike.
3. Any slack movement distance of the chain link up the sprocket tooth is the stretch of the chain.
   New chain and sprockets should have negligible slack at this point.
   Old chain will move up the sprocket tooth.
   Drive problems can occur when the chain rollers can slip up off of the sprocket teeth, skipping sprocket teeth instead of turning the wheel.

Introduction to Carburettor Tuning

Three adjustments in fuel metering, pilot jet and screw, needle, and main jet. All three have an effect at all engine speeds/throttle settings. Adjustments to the pilot jet and screw have the most effect at low throttle settings. Needle adjustments have the most effect at mid throttle settings. Main jet adjustments have the most affect at high throttle settings. however, the main jet does affect part-throttle operation, but not much. The pilot jet and screw do affect operation at high throttle, but not much.