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plus 30 piston rings
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larryc
burnley lancashire
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December 11, 2019 - 2:48 pm
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Hi, started on engine rebuild and I need a set of D1 +30 piston rings, all I can find is +20 +40 and +60 It would be a shame to bore out to +40 the cylinder is smooth with no wear lip the piston is good and marked +30 on the top, the top ring had a crack so they need replacing. does anyone know where they can be bought, I have put searches on the web and looked on fleabay but no joy.

regards Larry

Riding a D1 springer with a D3 engine, 2 x more D1's being built from bits one will be a GPO lookalike the other I am just collecting bits for at the moment

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cocorico
Central France
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December 11, 2019 - 3:03 pm
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Thinking back over many similar requests, I think they may be virtually 'unobtainium'. It might be better to contact ** Please log in to view ** recommended.

I have had no dealings with either, myself, just passing on the info.

Good luck!

1956 D3 running, lights to sort. 7 other bikes in the Barn. 1950 D1 engine being rebuilt (slowly).

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Unitminor
Norfolk
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December 11, 2019 - 3:20 pm
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Back in the 80s I had D1 with +030 bore I was unable to buy a piston even then . I ended up going to +040 if I remember correctly because there was not much to bore out the machine shop said they would have to hone it out .

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Scribbler1953
BH31 7BS
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December 11, 2019 - 3:34 pm
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Hi, I recently bought a set of plus 30 rings from Cox and Turner in Yeovil, see coxandturner.co.uk/piston-rings

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larryc
burnley lancashire
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December 11, 2019 - 8:07 pm
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Scribbler1953 said
Hi, I recently bought a set of plus 30 rings from Cox and Turner in Yeovil, see coxandturner.co.uk/piston-rings  

Thanks, I have looked at the web site, I will give them a call and see if they have any, otherwise a +40 skim and new piston will be the alternative

Thanks or all the suggestions

Larry

Riding a D1 springer with a D3 engine, 2 x more D1's being built from bits one will be a GPO lookalike the other I am just collecting bits for at the moment

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wildun
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December 11, 2019 - 10:41 pm
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An alternative solution is available but in no way technically correct and I cannot believe that I am suggesting it, but it is a method that has been used many times in the past. I bet some of the older, more experienced engine builders on here have done it at some point.

You could get a set of +0.040" rings and adjust the gaps to suit your cylinder bore. Even if your bore is still at the machined size when it was rebored you are only talking about 0.010" difference. You would have to put each of the new rings into your bore, just below the wear mark/discoloured area to check what gap they have, if any, and then carefully file/grind the ends of the ring until you achieve the specified gap. Being a two stroke it becomes more complicated in that you also have to do the step that fits to the piston peg.

As I say, not at all technically correct, but done correctly it will work. Your choice though entirely whether you follow this method. I have to admit to using this method once, many years ago on a four stroke single cylinder race engine. With no correct size parts available I would have missed the next weekend's events so it got me out of trouble and my engine ran fine.

Your choice.

1951 Bantam D1 125, 1954 Bantam Enduro 125, 1970 Bantam B175, all Bantams on the road and ridden regularly, 1995 Yamaha Diversion 900 and 2016 Honda Integra 750 scooter. Horses for courses, all very different to each other, but a bike for every occasion.

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larryc
burnley lancashire
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December 12, 2019 - 3:23 pm
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Scribbler1953 said
Hi, I recently bought a set of plus 30 rings from Cox and Turner in Yeovil, see coxandturner.co.uk/piston-rings  

Thanks Scribler1953 your recommendation paid off, I rang coxandturner.co.uk and they had a set of +30 in stock, a bit expensive £30  inc vat post etc but a lot cheaper than a re-bore new piston and rings, they are the correct ones with the peg locator at the ring gap

Thanks Larry

Riding a D1 springer with a D3 engine, 2 x more D1's being built from bits one will be a GPO lookalike the other I am just collecting bits for at the moment

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larryc
burnley lancashire
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December 12, 2019 - 3:26 pm
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wildun said
An alternative solution is available but in no way technically correct and I cannot believe that I am suggesting it, but it is a method that has been used many times in the past. I bet some of the older, more experienced engine builders on here have done it at some point.

You could get a set of +0.040" rings and adjust the gaps to suit your cylinder bore. Even if your bore is still at the machined size when it was rebored you are only talking about 0.010" difference. You would have to put each of the new rings into your bore, just below the wear mark/discoloured area to check what gap they have, if any, and then carefully file/grind the ends of the ring until you achieve the specified gap. Being a two stroke it becomes more complicated in that you also have to do the step that fits to the piston peg.

As I say, not at all technically correct, but done correctly it will work. Your choice though entirely whether you follow this method. I have to admit to using this method once, many years ago on a four stroke single cylinder race engine. With no correct size parts available I would have missed the next weekend's events so it got me out of trouble and my engine ran fine.

Your choice.  

Thanks wildun, good idea the step for the locating pegs would have to be carefully ground, I would have tried that but managed to locate a set from cox and turner, 

regards Larry

Riding a D1 springer with a D3 engine, 2 x more D1's being built from bits one will be a GPO lookalike the other I am just collecting bits for at the moment

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wildun
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December 12, 2019 - 11:34 pm
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Great news, Larry. You have solved your problem through the power of this forum.

There are no new problems with Bantams, any problem a current owner may have with their Bantam has been suffered by someone else at some time, You just have to find that person to give you the answer. This forum is as good as anywhere to do that, with very little duff info or red herrings.

Thanks to Scribbler1953, who has been able to successfully point you to a supplier, your problem is solved. The established Bantam specialists look after us very well but they cannot cover all parts at all times. Although I firmly believe in supporting these specialists, sometimes we have to look elsewhere.

Good luck with your rebuild, I am almost at the end of my second D1 engine build (different bike), and it is still a learning curve.

Onwards and upwards.

1951 Bantam D1 125, 1954 Bantam Enduro 125, 1970 Bantam B175, all Bantams on the road and ridden regularly, 1995 Yamaha Diversion 900 and 2016 Honda Integra 750 scooter. Horses for courses, all very different to each other, but a bike for every occasion.

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larryc
burnley lancashire
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December 13, 2019 - 1:24 pm
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wildun said
Great news, Larry. You have solved your problem through the power of this forum.

There are no new problems with Bantams, any problem a current owner may have with their Bantam has been suffered by someone else at some time, You just have to find that person to give you the answer. This forum is as good as anywhere to do that, with very little duff info or red herrings.

Thanks to Scribbler1953, who has been able to successfully point you to a supplier, your problem is solved. The established Bantam specialists look after us very well but they cannot cover all parts at all times. Although I firmly believe in supporting these specialists, sometimes we have to look elsewhere.

Good luck with your rebuild, I am almost at the end of my second D1 engine build (different bike), and it is still a learning curve.

Onwards and upwards.  

Thanks, the forum is going to be a real help for me, I do have an engineering background but experience of others is vital, just to mention the piston rings have arrived the day after ordering....great service! P.S. I have just joined as a member today

Larry

Riding a D1 springer with a D3 engine, 2 x more D1's being built from bits one will be a GPO lookalike the other I am just collecting bits for at the moment

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