Tim Ramsay's 500 needs a new big end

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Tim Ramsay's 500 needs a new big end

Postby Stephen R » Sun Jun 09, 2019 7:52 pm

Can anyone give me some recommendations for a good builder who will refurbish the bottom end for me please? Its a 1959 18CS motor. The rod, wheels and casings appear undamaged, but the big end and the drive side mains are seized.

Steve

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Re: Tim Ramsay's 500 needs a new big end

Postby Pharisee » Mon Jun 10, 2019 8:18 pm

Stephen R wrote:Can anyone give me some recommendations for a good builder who will refurbish the bottom end for me please? Its a 1959 18CS motor. The rod, wheels and casings appear undamaged, but the big end and the drive side mains are seized.

Steve


Ken DeGroome is a very well respected engine builder. He advertises in Jampot magazine. He's located just outside Wisbech in north Cambridgeshire
email:- ken.degroome@btinternet.com

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Re: Tim Ramsay's 500 needs a new big end

Postby raffles » Tue Jun 11, 2019 7:09 pm

I would contact John Bolton see his add in the jampot under WORKSHOP 14
he is one of only a couple of people I would trust to work on my own bikes
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Re: Tim Ramsay's 500 needs a new big end

Postby choosey2 » Tue Jun 11, 2019 8:58 pm

I would certainly recommend Ian Farrington, he is in Sussex and advertises in the Jampot magazine, he rebuilt my G80 and did an excellent job,
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Re: Tim Ramsay's 500 needs a new big end

Postby Stephen R » Sat Jun 15, 2019 4:03 pm

Thank you all for your replies. I have spoken to two of the gentlemen who were both most helpful, but since neither have all the parts needed, I then spoke with Alpha Bearings, who do. Alpha are also keen to do the big end assembly work, so I have sent my seized flywheels to them.

This means putting the bottom end back together myself of course, so I checked out Club Spares today for the main bearings I shall need. Club Spares is selling the inner main 021872 in a C3 (increased clearance) but the outer 017191 appears to be standard. Why is that, is it because the inner runs hotter?

And another question, the 1959 parts list shows a single spacer 021859 between the bearings, but I found two spacers, of different diameters, when I stripped them. Again, does anybody know what is happening here?

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Re: Tim Ramsay's 500 needs a new big end

Postby LynP » Sat Jun 15, 2019 5:17 pm

My understand is that the C3 bearing has a little more clearance in the bearing to aid alignment. I would recommend using an old drive side shaft or close fitting bar through both when fitting them. I think one washer between was used when new. Hope this helps. LynP

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Re: Tim Ramsay's 500 needs a new big end

Postby SPRIDDLER » Sat Jun 15, 2019 5:28 pm

The inner main bearing is a looser fit enabling it to be positioned to avoid end loading.
One washer between the bearings is correct (provided that the crankcases are '55 or later).
Here are the changes made in 1955.......

1955 changes (640x89).jpg


The above extract from the Tech Articles on the club's website:

http://www.jampot.com/article_read.asp?id=28

You may find these two articles informative re bearings etc. and useful for inspection and the reassembly process.....
http://www.jampot.com/article_read.asp?id=159

http://www.jampot.com/article_read.asp?id=161

As an afterthought the reason for the big end and mains seizing needs to be determined as this (in my experience) is very unusual.
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Re: Tim Ramsay's 500 needs a new big end

Postby Stephen R » Mon Jun 17, 2019 6:32 pm

Thank you Lyn and Spriddler,

Yes the cause of failure is a mystery. It came just as we were riding into the reception area for the tunnel from the Calais side, having had a week's touring around the Flanders battlefields, V1/V2 sites and coastal defences during which time the motor gave no trouble at all apart from temperamental starting which may have had mostly to do with our lack of skill. It ws a "slow" seizure, with the motor running down rather than stopping with a jerk, so fortunately the conrod did not break. There was a couple of tablespoonsful of at least partly ferrous debris in the bottom of the crankcase, but if it is big end debris, I cant understand how that can have got out of the narrow side clearance of the rod between the flywheels.

Ken De Groome said oil starvation is a likely factor - he suggests ensuring the feed line has an i.d. of at least 3/8". I've checked and it has. Alternatively, he said, it might be the dreaded Anno Domini.

It is a fairly highly tuned '59 CS engine, with a lump of a piston and racy cams. One decision already made is to fit it with standard touring cams now; I'd like it to be a bit more tractable at slow engine speeds. Tim had prepared a replacement head for it already, with a 1-3/8" inlet tract like a Black Hole - I'm going to fit that, but with a tapered carb spacer to fit a smaller 30mm Concentric. Not sure about the piston: I do have a lower-domed one too but its +0.050" and I hate to have to bore out if I don't have to. The bore has some light scoring but very little wear, and only 0.004" diametral clearance at the base of the skirt, so I think I have room to hone out a thou or so and re-use the current piston. Maybe I'll fit a compresssion plate if I can find one from somewhere. Overall its going to be a much tamer beast than the Snorter which Tim built. Your comments invited on my ideas.

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Re: Tim Ramsay's 500 needs a new big end

Postby Stephen R » Thu Jul 11, 2019 1:38 am

Here is a post script. I am (at glacial pace) reassembling the motor. I put new drive side mains from the Club Scheme in with a new spacer, also from the Club. The two bearings are nicely concentric as evidenced by the even rotation when the drive side mainshaft is inserted through them, but they seem to be forced together (the inner races grip the spacer very tightly) and the action is not completely free. This makes me think I have pushed the inner bearing too hard into the housing. Is this possible and if so how do I pull it back just that small amount so that the spacer is freed?

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