Throttle Return Spring Details

You might consider this item: Randakk’s GL1000 Carb Rebuild Video

Recently, a GL1000 owner was in my shop with an odd complaint. He reported that very heavy pressure was required at the throttle twistgrip to increase or maintain engine speed. Suspecting that the throttle cables were worn or damaged, the owner had just replaced both throttle cables, but this offered no improvement.

My test ride verified that indeed there was something amiss. This bike ran great, but after just a few miles the effort required at the throttle made my right forearm ache!

Close inspection back at the shop revealed the source of this unusual problem. A previous mechanic has installed the throttle return spring incorrectly!

It turns out that creative mechanics can find many ways to install the main throttle return spring on a GL1000. But, there is only one “correct” way – plus one acceptable variation. Other configurations are incorrect and dangerous!

Correctly installed, the “hook” on the throttle spring engages the throttle bellcrank at approx. 1 o’clock (viewed from rear) and the “loop” engages the spring retainer at approx. 10:00 o’clock. These clock reference points assume the bellcrank is resting in the curb idle position and the spring is fully secured by the retainer.

Obviously, the spring retainer has to arrive at the desired position under tension which is wound in by rotating the retainer in clockwise fashion (viewed from rear) before the retainer is secured to the pivot post by the retainer bolt.

The photo below shows the correct, installed placement of the throttle return spring:

Correct Throttle Spring Placement

Below is a photo of the incorrect throttle spring fitment which I mentioned above. Notice that in this case, the “hook ” and “loop” orientation is reversed plus the connection to the bellcrank has been made at a protruding lug which was not designed for that purpose! 

Incorrect Throttle Spring Placement

This setup has several problems:

• Too much tension. A very tiring “death grip” at the throttle is required to maintain cruise speed!
• Excess tension will prematurely wear inner throttle cable sheaths
• Potential for dangerous binding of throttle.

If you inspect your throttle return spring and determine that it has been incorrectly installed, you can usually remedy this without removing the carbs from the bike. Small hands, small tools and patience help but it can be done! More on throttle springs and bellcranks… Here are the two versions of bellcranks fitted to various models of GL1000s…”early” vs. “late” model. Notice that the “early model bellcrank has additional “slots.” There is a useful hole in the bellcrank at approximately 8 o’clock.

“Early” Bellcrank

“Late” Bellcrank

If you have the early version, you can try an alternative spring mounting as shown below: 

Alternative “Light Action” Spring Placement on “Early” Bellcrank

Note that the spring retainer has been rotated counterclockwise 180 degrees to about 5 o’clock and the “hook” has move counterclockwise to different position on the bellcrank at about 8 o’clock. The result of this changed orientation is a significant reduction in throttle spring close pressure compared to the normal setup.

This will yield a very light return pressure which you may find more comfortable for long cruising. The return to idle will be lazier than the normal setup (even with perfect throttle cables), so the margin of safety for proper throttle return is greatly reduced! Implement this throttle spring fitment at your own risk!