Lightweight gearbox problem

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clanger9
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Re: Lightweight gearbox problem

Post by clanger9 »

I don't have a head steady. 250s are quite short stroke - do they need one?
1989 Moto Morini Dart 350
1993 Ducati 750SS
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Ozmadman
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Re: Lightweight gearbox problem

Post by Ozmadman »

clanger9 wrote:I don't have a head steady. 250s are quite short stroke - do they need one?
Do you have a hole in the top tube to take the bracket bolt? 350 has a bracket but not sure about a 250
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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clanger9
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Re: Lightweight gearbox problem

Post by clanger9 »

There's a horizontal hole. It's well aft of the head, so I figured this was for a fuel tank mount (?)
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1989 Moto Morini Dart 350
1993 Ducati 750SS
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Ozmadman
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Re: Lightweight gearbox problem

Post by Ozmadman »

Yep, that's it but whether it is used or not is another question, here is a pic of my 350 one
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Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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clanger9
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Re: Lightweight gearbox problem

Post by clanger9 »

Thanks, Paul! Now I know what the hole is for. ;)
1989 Moto Morini Dart 350
1993 Ducati 750SS
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Ozmadman
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Re: Lightweight gearbox problem

Post by Ozmadman »

Well, opened packet from Andrews today and the bushes are perfect!! They must be the Norton type as they have a small recess in the flange for a retaining pin but that is no issue for us. I would get onto them and order some whilst they still have some left. Not sure why Andrews sent the club the others though in the past
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
Steve S
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Joined: Fri Sep 30, 2016 12:03 pm
Location: Hertfordshire United Kingdom

Re: Lightweight gearbox problem

Post by Steve S »

Thanks for the head steady picture, that's what I need but where from? Kempton I guess.

Thanks also for the layshaft bush confirmation, now ordered 2 from Andrew Engineering where Malcolm told me he had bought out some London stock which is genuine original stuff so not manufactured by him then.

Also ordered 20 tooth sprocket from Andrews and new plunger and spring from Russell Motors.

Tried to get the plunger nut off yesterday so soaked it overnight and warmed up the housing today in the oven whilst the cook was out. Couldn't budge it one bit even with a spark plug socket that seems to be a perfect fit. Any suggestions or can I re-assemble with it in place?

Oil seal on the main gear came out without too much protest, seems to have been put in with some blue adhesive - loctite perhaps?

Getting nearer to re-assembly now...

Steve S.
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Ozmadman
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Re: Lightweight gearbox problem

Post by Ozmadman »

Looks like it is all coming together now. That blue stuff sounds like blue hylomar. As for that plunger nut I am not too sure but I suppose you could but it will put quite a bit of tension on the selector gate so may make the cases difficult to put together. When I rebuild a box this is the last thing I put in. I lay the box on its side put in the plunger then the spring and finally the nut. Then check all gears select ok.
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
Steve S
Posts: 123
Joined: Fri Sep 30, 2016 12:03 pm
Location: Hertfordshire United Kingdom

Re: Lightweight gearbox problem

Post by Steve S »

Thanks Paul, sounds as though it will be a lot easier if I can get the plunger bolt out.

Soaked it in WD40 again last night but totally resistant this morning. How warm can I heat the housing to assist?

Steve S.
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Ozmadman
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Re: Lightweight gearbox problem

Post by Ozmadman »

Hi reckon you can heat it up quite a bit. I heated up my crankcase to fit the bearings and my cylinder head to fit the valve guides and that was pretty hot,
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed
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