g5 con rod

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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g5 con rod

Postby Cookie666 » Tue Dec 05, 2017 6:20 pm

Hi

Can anyone help please ?

I'm after the bush/ liner that fits on the bigger end of the con rod.
I have a new small end bush, but I am not sure about the opposite end ?
Hope someone can understand my very little knowledge lol. Would this be called a big end bush?

Regards

Matt

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Re: g5 con rod

Postby clanger9 » Tue Dec 05, 2017 8:51 pm

You'll probably need more than just the big end bush: the bush isn't available as a separate part, as normally the whole big end (including shaft and rollers) would be replaced together.
It needs a skilled mechanic to press the thin bush into the big end without damage. It's probably easier/cheaper to get an exchange con-rod complete with big-end bearing. Here is a picture of an exchange 250CSR con rod. You need the 350 part (p/n 044023)
IMG_1839.jpg

Try calling Les at Russell Motors or Alpha Bearings. You'll also need to get a machine shop to align and assemble the crankshaft.
Sorting out the big-end is an expensive business, I'm afraid...
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1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: g5 con rod

Postby Cookie666 » Tue Dec 05, 2017 9:20 pm

the problem is the the big end bearing is all band new but the bush hasn't been replaced this is where my dilemma is, that why I was asking just for the bush ?

Thanks

Again

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Re: g5 con rod

Postby clanger9 » Tue Dec 05, 2017 9:27 pm

That's strange. Did the new big end not come with a new outer track?
I'd give Alpha Bearings a ring: they should be able to press a new track in for you. I believe it's a tricky job.
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: g5 con rod

Postby Cookie666 » Tue Dec 05, 2017 10:12 pm

I've not long had this bike, rode it then decided to strip it & rebuild it & things that other people have done are beginning to unfold like, wiring ect

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Re: g5 con rod

Postby SPRIDDLER » Tue Dec 05, 2017 10:37 pm

Do you actually need to replace the big end?
As said, it's a skilled job replacing the big end assembly (probably one the most demanding/critical jobs on our old engines) as you need some pretty hefty tools and it is also essential to correctly realign the flywheels afterwards. You should also have the big end eye checked for ovality after removing the liner (outer race) of the bearing in the conrod.
You must also have the old crank pin checked as well as you only mentioned the 'bearing' which I take to be just the rollers and their cage.
Do you have a workshop manual and/or the various technical articles on engine rebuilding?
What if the Hokey-Cokey is what it's all about?

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Re: g5 con rod

Postby Cookie666 » Wed Dec 06, 2017 7:50 am

Hi

I dont need to replace the big end as its new, just they just havent replaced everything that should have been done,Yer have workshop manuals & someone with work shop with the tools.

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Re: g5 con rod

Postby SPRIDDLER » Wed Dec 06, 2017 8:28 am

O.K. but I'm not sure how it is that you have been riding the bike with a new big end and now discover that you need to replace the big end liner in the conrod.
Never mind, I'm old and easily confused, so as Clanger advised, Russells or Alpha may be able to help with a liner.
What if the Hokey-Cokey is what it's all about?

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