Gilera b300 gearbox problem

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Todd
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Gilera b300 gearbox problem

Post by Todd » Tue Apr 14, 2020 8:38 pm

Gilera b300 gearbox problem, does this gear need replacing? It has obvious wear but is it causing problem? And I replaced broken spring in selector it’s a generic spring I cut to length
I have had gearbox apart 2 times and still have problems with jumping out of gear and false neutrals 2nd gear is worst
Any help Appreciated
I have plenty more photos
Cheers
Todd
New Zealand
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Joachim
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Re: Gilera b300 gearbox problem

Post by Joachim » Tue Apr 14, 2020 8:50 pm

hi

i have moved your article from earlier today into the Vintage range.
Here around classic is meaning Saturno, Nordie .... the BI-4 engines
Yes it's confusing ;)
Better we leave both of the articles

ciao Joachim
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lambs
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Re: Gilera b300 gearbox problem

Post by lambs » Sat Apr 18, 2020 11:18 am

The 'dogs' (4 round pins) on that gear are very badly worn and that would certainly explain the jumping out of gear problem. You should also check the mating gear 'slots' since they are also likely to be worn....hopefully not as badly. Replacement is the usual way to go, but might not be so simple with these older bikes. Maybe send an email to Bob Wright in the first instance, he might have stock. A secondhand gear will be a bit of a lottery.

It might also be possible to repair the gear by welding and then machining the dogs back to their original shape, but that has to be done by a specialist and finding the right person can be difficult. Also won't be cheap.

The false neutral problem could be related.....wear in the shift linkage/detent system could be the problem. Suggest a close examination of all components for condition (wear, etc) is required.

Todd
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Re: Gilera b300 gearbox problem

Post by Todd » Sun Apr 19, 2020 9:37 am

Thanks for feedback, i will try to get replacement or repair gear, does anyone do exchange/ reconditioned selector drum ? Drum looks ok but the pawls and springs and the selector plate probably need repair/ replacement
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Todd
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Re: Gilera b300 gearbox problem

Post by Todd » Sun Apr 19, 2020 9:42 am

More pics
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lambs
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Re: Gilera b300 gearbox problem

Post by lambs » Sun Apr 19, 2020 11:24 am

I don't know of anyone that reconditions selector drums (there's probably someone out there....), but that selector drum groove doesn't look too bad, although I think I can see some wear and burrs. A clean-up with a Dremel linishing drum/grinding wheel should be enough. The mating pins need to be in good condition as well. There's some B300 repair manuals on rpw:

http://www.rpw.it/Documentazione.htm

Scroll to the Gilera section. I had quick look and there's some info in the "B300 - Istruzioni per le riparazioni" manual that shows wear limits for the shift pins and linkages, see attachment. It's in Italian, of course, but decipherable. Good Luck
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Todd
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Re: Gilera b300 gearbox problem

Post by Todd » Wed Apr 22, 2020 9:28 pm

Great thanks for info very helpful, I think you are right I need to work my way thro components and measure and repair as needed, I have found someone local who can repair dogs on gears .
I have added couple more pics
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Todd
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Re: Gilera b300 gearbox problem

Post by Todd » Wed Apr 22, 2020 9:34 pm

Oops more with better resolution
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