Motorcycle Repair: trouble getting into 1st gear, drum groove, motorcycle transmission

Question
Dear Mark:

I have some trouble shifting into first gear on my 1986 Radian 600.  The bike has about 30k miles on it  and it appears to have been ridden a little rough.  The trouble starts when I stop and I want to shift into first.  In addition, sometimes the gear will slip out of 2nd into neutral if I give it a lot of gas/torque.

Two questions:
Mechanically - what could be the issue
Second, is this something I could fix myself or is it something for my mechanic.

All the best,

MW

Answer
Hi Mario,

I suspect 1st and 2nd gears are worn and need attention. The dogs and cogs are likely rounded causing the gears to slip apart under load.

The task of a complete engine tear down may not suit the novice mechanic. I recommend obtaining a copy of the service repair manual and reviewing the procedure of rebuilding the transmission. Then decide if you can perform the work.

Respectfully,
Mark Shively




Gear Shifting Faulty:

Doesn't go into gear;

shift pedal doesn't return
Clutch not disengaging
Shift fork bent or seized
Gear stuck on the shaft
Gear position lever binding
Shift return spring weak or broken
Shift return spring pin loose
Shift mechanism arm spring broken
Shift mechanism arm broken
Shift pawl broken

Jumps out of gear:

Shift fork worn
Gear groove worn
Gear dogs and/or dog holes worn
Shift drum groove worn
Gear positioning lever spring weak or broken
Shift fork pin worn
Drive shaft, output shaft, and/or gear splines worn

Overshifts:

Gear positioning lever spring weak or broken
Shift mechanism arm spring broken





Motorcycle Transmission Information
By Mark Shively

Slipping out of Gear:

Trying to mate slower spinning sliding gears with very high spinning fixed gears is hard on the transmission. If the transmission is slipping out of 1st or 2nd gears, the dogs and cogs are rounded (worn) and must be replaced.

Race Shifting:

If it won't shift from 1st into 2nd at or near redline, try pre-loading the shift lever with your toe (raise the lever) and when you want to shift, quickly twist the throttle closed and then full-throttle again. Don't use the clutch. The transmission will shift into the next gear. This is a racing technique known as "pre-loading" the shifter. It should shift as quickly as you can turn the throttle. It's not the best thing for the clutch and transmission, but racing MC's get complete rebuilds frequently and parts inspected and replaced.

Inside the Engine:

When you step on the shift lever, the shift linkage turns the shift drum slightly and causes shifting forks to move. Shifting forks mate with shift drum via dowels and grooves. The shift forks move sliding gears to engage the gear's dogs with its mating gear's cogs.

When a gear is “forced” to engage another gear, as if trying to shift from Neutral to the next gear, expensive damages may result.   This causes premature transmission and clutch parts wear and failure.

Hauling in Neutral:

Tie-down straps secure our motorcycles and ATV's well when used properly during transportation. We tend to use a variety of materials and things to secure motorcycles and ATV's when transporting.

When the motorcycle/ATV is not properly secured, it may move during transport. If the transmission is placed in gear, shift forks flex under the load and weight of the motorcycle as it moves. Same goes with the clutch and drive chain. These parts are easily damaged. Place the transmission into Neutral and properly secure motorcycle with quality tie-down straps.