INDEX PLUNGER SPRING

My bike is jumping from first gear to neutral and someone suggested to replace the Index plunger spring.
Is the Index plunger housing the bolt underneath the gearbox? Can you just remove the housing and replace the spring without dropping the oil?
Sorry for my ignorance but if this is easy I will try this first.

Stuffa said:

Is the Index plunger housing the bolt underneath the gearbox?

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Yes

Stuffa said:

Can you just remove the housing and replace the spring without dropping the oil?

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No

Could do with a bit of background
Has it just started doing it?
Has there been any work done on it lately ?
Is it actually jumping out of gear or not going into gear properly?
Cheers

It’s been doing it since I’ve owned it. The gearbox has been reconditioned recently. When it gets above about 3000 RPM it will go back to neutral and occasionally will go back into first. It doesn’t jump out every time.
It is fitted with CNW Rearsets so the gears are reversed.
The bloke who did the work said he would send me a new index plunger spring to see if that was the problem as he may not have replaced.
The gearbox changes smoothly and it selects neutral easily, all the other gears are fine.

Reconditioned means as new (a bold word unless it is all but a new unit) unlike rebuilt.
If reconditioned it has been checked for everything including shift fork indexing to dog clearance in gear.

Check the quadrant in the knuckle window in first gear to eliminate any form of casting contact and that the detent plunger is seated .
Draining the oil will be the easy bit if it is a mechanical problem.

The aftermarket shift linkage would be the first thing verified being an add on and external..

Stuffa said:

It’s been doing it since I’ve owned it. The gearbox has been reconditioned recently. When it gets above about 3000 RPM it will go back to neutral and occasionally will go back into first. It doesn’t jump out every time.
It is fitted with CNW Rearsets so the gears are reversed.
The bloke who did the work said he would send me a new index plunger spring to see if that was the problem as he may not have replaced.
The gearbox changes smoothly and it selects neutral easily, all the other gears are fine.

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You might want to sit on the running bike with it in second and the clutch pulled and look down at the gear shift while reving the engine to the rpm where it happens - does the lever jump up and down?

Could easily be the rearsets, but if not, could be the spring, could be the plunger, could be the plunger sticking in the housing, and it could be the housing not screwed all the way in. It normally has a very firm hold on things. You will lose part of the oil taking it out but I would do that and inspect that the plunger moves freely in the housing, that the plunger is still pointed, and that the spring is strong. Don't mess with the gearshift with the plunger out.

My pre unit Bonneville, i'd paid someone to check over the gearbox , when it was out, when I first had it .

It'd ' lost its edge ' just , when I sold it . Tho Id recently dropped THE INDEX PLUNGER SPRING .

Prevoius , at times , it'd throw itself out of second , on occasion . At FULL WELLIE .
Sounded like the big ends'd go through the head , when it did . Tho one got adept at anticipateing & cutting the throttle .
ANYWAY ,
when eventually I puklled it out , I thought ' Thats a bit soft ' and gave it a quick stretch . To About Six inches .
I thought this a excessive length , manadged to get it back to about 2 1/2 in. & put it back in .

Gearshift then was more friction & not as light. But you couldnt get it to jump out of gear .
There used to be a ' put a ball bearing under it ' dodge .

One must watch it dosnt bottom out / get coilbound then .
SO , basically its a non critical part , maybe . If its strong enough long enough & free enough ! . asin anythingll do , if it works .
Plunger .
( Its one of the 5.000.000 pieces you inspect for burrs & galling , along with the cam track ( and everthing else ) if its in front off you .
so the pointy wedge should be clean & straight . A light stoning if irregularities present themselves should ensure positive action . )

If the springs sprung you might consider ALL springs in it , as a set . Then your ahead off yourself next time your in it .

Thanks for posing this question, Stuffa.

Mine never jumped out of gear, but it sometimes would not go into 3rd up shifting without a lot of tap dancing. The piston was apparently not going into the cam divet quick enough so it would back up into second when I let off the shift lever. So I took the plunger housing out this morning and took a look at the plunger piston. Looked dirty and had a couple of long fine scraps up the side. Spring looked fine to me. When I change gear lube, I don't pull out the plunger housing and clean everything up. Never occurred to me. I will pull it and clean it out from now on. Anywho, I polished the plunger piston and the inside of the plunger housing and put it back together. No more missing 3rd gear.