G: Gearbox (Twin) G92 spring etc.

[druridge]

Bit of a disaster kicking over the Rapide a week ago, when a lump of engine got spat out!
This turned out to be the bottom front corner of the gearbox outer casing G1, included on the road were the plunger, spring, and housing (G97, G92, G98).
Once all dismantled and me calmed down; the spring was measured at 1.3" long. I am presuming this was coilbound by the arrival of the kickstart quadrant; and the spring (now operating as a drift) just burst out the casing.
At last weekends Lakes Camping, almost everyone I spoke to had experienced the same problem at some time.
KTB has a paragraph all about this problem, much of which seems to come down to tired / squashed up springs. Also mentioned is a 'new' spring length of 1.75".
The casing is away being alloy welded, and there does appear to be room on the inside to beef things up a bit.
The 2 new springs arrived today from the Spares Co. both are 1.5" in length.
I'm wondering if this spring (G92) is really up to the job? I understand the length of the spring need not be the only factor in keeping the kickstart quadrant from loading up the spring until it is coilbound; has anyone come across a spring better able to cope?
I'll attach a photo if I can....

 

[druridge]

Photos attached

 

[Robert Watson]

I would be interested to see a picture of where the kick start lever was located before you broke the casting. I have come across some bikes where it is rotated so far "up" that it bottoms out whilst you are in full swing. I tend to locate mine further "down" so that when arriving the the final destination the energy is mostly expired!

 

[ClassicBiker]

I had mine break out a few years back as well. Combination of a couple of things. Spring not up to the job and coil bound and the had become jammed in the guide. I wonder sometimes if the plunger might not have become hydraulically locked somehow as well. I had a local welder, weld it up for me and bought all new bits from the club to replace the originals just to be safe. I considered drilling a small hole at the end of the guide to be on the safe side.
Steven

 

[druridge]

I would be interested to see a picture of where the kick start lever was located before you broke the casting. I have come across some bikes where it is rotated so far "up" that it bottoms out whilst you are in full swing. I tend to locate mine further "down" so that when arriving the the final destination the energy is mostly expired!

I would imagine that could be a factor. I'm quite new to the bike so will be more careful to position the kickstart correctly when it goes back together. I will also measure up the plunger and the depth of the hole it goes into, then we have the potential travel from 'full out' to 'full in'. Interesting to compare that to the difference between max and min spring length.

 

[b'knighted]

The people I have known to have this problem generally start the engine by leaping on the kickstart while the bike is on its stand. If it is on its original rear stand the suspension will take some of the shock when full travel is reached. On a centre stand the cover has to take all of the shock.
If the bike is started with its tyres on the ground and the rider astride the engine is rotated by the leg muscles not by the full weight of the rider assisted by gravity and the swing is terminated by the riders foot reaching full downward travel. On some bikes the kickstart lever is down to the ground by this point.

 

[BigEd]

Photos attached

Your gear cover looks to have been modified to fit an electric start. Assuming that you have an electric start then once you have had your cover repaired you could do what I have done which is to remove the kickstart lever.

 

[druridge]

The people I have known to have this problem generally start the engine by leaping on the kickstart while the bike is on its stand. If it is on its original rear stand the suspension will take some of the shock when full travel is reached. On a centre stand the cover has to take all of the shock.
If the bike is started with its tyres on the ground and the rider astride the engine is rotated by the leg muscles not by the full weight of the rider assisted by gravity and the swing is terminated by the riders foot reaching full downward travel. On some bikes the kickstart lever is down to the ground by this point.

I have to admit to generally starting the bike on the Hills centre stand; where a mate mentioned I was starting the bike 'lustily'(!)
Bike is fitted with a Grosset starter, maybe I had better start using it a bit more.
On a related matter, I forgot about not rolling the bike back in gear once and locked up the starter. I've been since told that if the bike is then rocked forward (still in gear), it is freed off. Is this correct?

 

[vibrac]

Starting it on the stand will do it
At the Sardinia rally last week Dick Whealdon was about to borrow a shadow for the ride outs and said that the owner had started it on the stand and that it was not a good idea
The very next day the owner did it again and the casting broke....

 

[Marcus Bowden]

If you don't want it to happen again buy a series "B"KS cover as you will never see one of these having had a repair job on it. As for being in gear the bike will not revers due to the high gearing to the motor but I finf this useful at hill starts as F brake & throttle together is relying on adjustment of brake cables and thickness of gloves. Certainly don't engage KS and press the start button.
bananaman.