First run out on newly restored Bantam . . .Didn't End Well

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zitman
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Location: Midlands

First run out on newly restored Bantam . . .Didn't End Well

Unread post by zitman » Sun Aug 15, 2010 9:22 pm

Well the Bantam is finished.

It started looking like this:
Image

And ended looking like this:
Image

A few starting problems, especially when hot but did about 30 miles today. Unfortunately on the way home it started to lose power and then about 100 yards later a bit of a clunk and it stopped. Got it home and lifted the lid and found this:
Image

Circlip failure! So new piston and rebore then. And am thinking about a Rex Caunt ignition. Funds permitting!

Z


The Mighty Gusset

Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by The Mighty Gusset » Sun Aug 15, 2010 9:25 pm

Oooooooh !
Nasty.

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Greenbat
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Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by Greenbat » Sun Aug 15, 2010 9:31 pm

Ouch!

Quick suggestion: Bin that horrid 3 ring piston and put a D14 (domed 2 ring) one plus suitable head (Or ask T&G if he'll skim your squish band, I suspect it can be done).
Failing that, I have two used pistons-a +30 D7 and a +40 D14. Might need new rings-maybe totally useless, but if you want to try them they're doing nowt here.

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zitman
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Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by zitman » Sun Aug 15, 2010 9:36 pm

Greeno,

Thanks for the offer but it was on +20 and its left quite a deep gauge in the bore (the newly rebored bore :( ) so its gonna need to go out to +60. Will have a good old think about the D14 piston and head though.

Ta

Z

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Hooli
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Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by Hooli » Mon Aug 16, 2010 3:53 pm

oops.
Classics ain't built in Metric

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jezbikes1
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Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by jezbikes1 » Wed Sep 01, 2010 3:40 pm

Eeek! That's a shame, but glad it's fixable. Nice work on the bike though, it looks great.
Jez

Clueless mechanical muppet... but trying to improve.

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lazybandittattoo
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Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by lazybandittattoo » Sat Dec 24, 2011 12:35 pm

I had a piston seize on my D7. Something like that though the damage was not so severe.

I decided to go for a bigger re-bore. Rex Caunt Racing can supply an over-sized piston and there are also some Yamaha and Suzuki pistons that are suitable. I opted for the smallest of his big-bore piston kits. 64mm diameter turns your bantam into a 187cc.

The re-bore was sorted by a mate of mine, Roger, in Huddersfield. I can provide his number if you need work doing and can't find anyone locally - he doesn't charge the earth and is a first class engineer. His BMW specialist motorcycle engineering shop is located near the Galpharm Stadium.

Rex also supplies pistons in 64.5mm and 65mm plus I know some trials bantam riders in the past have used various Yamaha and Suzuki pistons. I don't think even with the larger re-bores that you are reducing the opp];, ortunity for future re-bores due to damage to the cylinder bore. There are plenty of options and the Bantam has a good strong cylinder with plenty of metal to machine away as required.

Make sure you use a good new base gasket when you put it all back together. It really makes a difference - particularly when starting. I tried to skimp (I was fed up of buying gasket kits to just use one or two gaskets and have loads of the others leftover) by making a few out of corn-flake box (didn't have any gasket paper thin enough at the time) but I was surprised how much different that half a mm makes.

Tony

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FastFrank
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Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by FastFrank » Sat Dec 24, 2011 3:59 pm

Hahaha! Roger the sidecar, next door to Tony Archer the seat upholstery wizzard! Know them well
If iver tha does owt for nowt alus duit for thissen!

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Hooli
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Re: First run out on newly restored Bantam . . .Didn't End Well

Unread post by Hooli » Sat Dec 24, 2011 5:14 pm

FastFrank wrote:Tony Archer the seat upholstery wizzard!


:lol: :lol: :lol: Is that the blind arse wipe who can't fit seat covers straight or get the creases out of them after cutting the foam totally wrong to make the seat ultra uncomfortable & designed to cripple you?

I'd rather shove pins in my eyes than pay for his 'services'.
Classics ain't built in Metric

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