5R modification

[Stelios_Rjk]

Hello guys,

I hope my post find you well.

I posted a 5R recently to New Zealand so I had the chance to take the spanners out. There is one more 5R from the past that belongs to an old lady.
If it is still available and I manage to get it, I was wondering. Could I replace the main bearings of the crank case with bushes? We have the tolerances of the bushes from the earlier models. Possibly I can find a workshop that can perform the reaming in a vertical way in regards to the motion of the piston.

The question is, would that work?

Also, for the issue with the big end pin, is it possible to add material by welding on the crankshaft, so removing the pin and putting back a new in, could happen in a safe way?

[Horsley-Anarak]

Hi Stelios hope you are well, speak to Charles he must be the global expert on 5Rs

[Stelios_Rjk]

Thank you, I will try.

[Oyster 49]

I suspect it could be modified back to a bush crank, but the crank is designed to run inside a roller bearing, not directly in bushes like a kingfisher. So you would have to fit a kingfisher crank designed for bushes too.

Re the crank pin, its designed to be pressed out, but apparently there is very little metal around the crankpin holes in the crankshaft halves.

Some great background info here, explaining all the issues that are very expensive to fix:
http://www.saving-old-seagulls.co.uk/i_ ... ll/5_r.htm

I'd imagine custom made bushes and a kingfisher crank could be a solution, Charles is the guy to talk to in detail about this though. A lot of work putting a 5R right for sure. I've always kept away from them!

[Stelios_Rjk]

Thank you Adrian, today so far I was welding together a metal frame that will form the flooring for a shed in the garden. No time or money at the time to spend on a messy 5R.. I will read the thread you sent as I would like to know details.

[Oyster 49]

Sounds like you are busy, are you back in Athens?

[Stelios_Rjk]

Yes with the covid situation we work locally.. thanks God!

[Paskoya]

Hi Stelios,

Another potential to resurrect a 5R with a dead crankshaft is to fit it with a standard Kingfisher/Osprey crank and 35mm OD - 5/8" ID roller bearings.

My current race motor is a Kingfisher/5R hybrid - I'm using a 5R crankcase, 35mm - 5/8" bearings and a remanufactured roller bearing crank that has the main journals ground to 0.6235" - the same as a Kingfisher/Osprey/Century crank (5/8" minus 0.0015" for oil clearance). With high temperature sleeve retainer compound holding the crank in the bearings (and taking up the 0.0015" gap), the motor has been running without any problems. I raced around Bermuda last year with it without issue.

I think a similar approach using a standard Kingfisher crank would be by far the simplest (and probably least expensive!) way to get that 5R running again.

[Charles uk]

Just a quick question, how do you remove the crank from your hybrid?

[Paskoya]

Just a quick question, how do you remove the crank from your hybrid?

Gentle heating with an electric hot air gun seems to do the trick, the cases then separate without too much force, and the crank can be pulled out of the bearings by hand. I've not had to use a crank puller/extractor.

[Charles uk]

I built a Curlew with a 5R crankcase & a welded on tiller arm stud using a needle Kingfisher crank & 6202 5/8" bearings, I used Loctite bearing retainer to stop the crank rotating in the inner bearing sleeves & destroying itself, I had hell of a job pushing the sides apart, I even had to put spacers between the crank webs to stop stretching the big end eyes.

Waste of time really, as the Curlew put all the Centurys to shame (with 33% more power straight out of the box) so it was sort of excluded from most racing rules.

[Stelios_Rjk]

Hi Stelios,

Another potential to resurrect a 5R with a dead crankshaft is to fit it with a standard Kingfisher/Osprey crank and 35mm OD - 5/8" ID roller bearings.

My current race motor is a Kingfisher/5R hybrid - I'm using a 5R crankcase, 35mm - 5/8" bearings and a remanufactured roller bearing crank that has the main journals ground to 0.6235" - the same as a Kingfisher/Osprey/Century crank (5/8" minus 0.0015" for oil clearance). With high temperature sleeve retainer compound holding the crank in the bearings (and taking up the 0.0015" gap), the motor has been running without any problems. I raced around Bermuda last year with it without issue.

I think a similar approach using a standard Kingfisher crank would be by far the simplest (and probably least expensive!) way to get that 5R running again.

Thank you! I will keep it in mind just in case.