5R

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Chicken
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5R

Post by Chicken »

Why is stripping a 5R before running so important? Ive got one sitting on my bench feels fine how bad can it go? Do I have to pull it to pieces?

Chicken
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Charles uk
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Re: 5R

Post by Charles uk »

That's going to involve me in a heap of typing Camden, & I'll have to find out where I've saved the pictures so you might have to wait a bit for the full answer, sorry.
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Stelios_Rjk
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Re: 5R

Post by Stelios_Rjk »

I have found really useful this article Charles has written http://www.saving-old-seagulls.co.uk/i_ ... ll/5_r.htm
But I am also looking forward to see the response to your question :)




Cheers,
the neighbor of a 5R owner :lol:
I love the 10600/145 turns!!!
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Charles uk
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Re: 5R

Post by Charles uk »

The 5R was one of the very last motors that ‘Chillington’ developed in 1992 & 93.It had a slightly thicker crankshaft (17mm), with three deep groove ball bearings, one at the bottom and two at the top. A needle roller big end was also fitted.The sealing of the crank was made with two 17mm x 35mm oilseals.

The block was a modified QB and the top part of the crankcase was altered to take the roller bearings and seal.The bottom half had only the tiller arm stub removed and a drilled hole for the fuel pump.A modified Wipac Mk IV ign was fitted.

The block had the exhaust flange removed, and the unit sat on a Yamaha leg with an FNR gearbox. There was an adapter plate made from a machined block of cast aluminum, & fitted with a Yamaha twist grip tiller arm. The adapter plate had the engine number stamped into it.

The leg had an FNR gearbox with a ratio of 2.03:1.

Engine Numbers were apparently prefixed ‘SK’. The ‘L’ was used for long shaft versions, and the ‘R’ in the model ID related to the ‘Remote Tank’ option, which was fitted to many soon after production started.



This article by Charles was added to the Forum in 2008, following a 5R being offered on that auction site... it was felt it might be an idea to print it again here, good idea too, so here it is!

Now I feel I should give a little history on this motor series.

In the early 90’s British Seagull were in competition with mainly Japanese manufactures who were turning out 5hp outboards, that were running on a 50 or a 100 : 1 oil mix, at this time the best British Seagull could run on was 25 : 1 in the QB series, after fitting the needle roller crankshaft in the Kingfisher they upped the fuel ratio to 50 : 1 to try & keep up.

Only to discover that many of these motors were not lasting the first year before suffering lube problems on the main bearings, often requiring a new crankcase, a very expensive warranty claim for what was now a small English manufacturer.

So they decided to follow the Japanese example, & move to a fully bearing crankshaft this coincided with the FNR gear box availability problem, so they looked at buying complete legs first from Selva & then from Yamaha, the decision was taken to follow the Yamaha route & a leg from the 4B single cylinder 4hp outboard was chosen, probably on the grounds of cost, as the Selva would appear more useful for British Seagull traditional user base, with it’s lower gear ratio, larger prop & it’s through the prop exhaust, giving a quieter engine more suitable to the larger hull.

To attach the Yamaha leg to the Kingfisher power head an adapter plate was designed, a complicated heavy aluminium casting that solved the problem of delivering the exhaust gases to where the leg needed them & the cooling water to the cylinder & the coolant return to cool the exhaust tract in the leg, only to discover that the British Seagull tiller arm fouled the adapter plate, so provision for the Yamaha tiller arm/throttle was made in the adapter plate.

To permit the Kingfisher cylinder fit, without it being too high, it was found necessary to remove the exhaust stub from the base of the cylinder.

Up to this point Kingfisher crankshafts had always run in phosphor bronze bearings reamed to 0.625” ID but the crankshaft was ground to 0.6235” to give sufficient oil clearance.

Ball races with this ID, were & are not available (though they are available 0.625" x 35mm x 12mm, still too big for an interferance fit on the 0.6235" main bearing journal) & would have had to be custom made, a very expensive answer to this problem, so the crankshaft was redesigned with 17mm main bearing journals to suit a standard 6003 deep groove ball race, it was then found that while the lower crankcase half, had sufficient meat to permit the boring of a 35mm hole for the bearings, the top half would not, so a new meatier casting was designed to cover this.

This all fitted together real nice but there was no provision for fitting a fuel pump & the Yamaha tiller arm fouled the British Seagull tiller arm stub, this was just cut off, & the fuel problem answered by fitting a plastic tank.

At this time the largest prop available from Yamaha for this lower unit was a 7 ½” by 8” pitch which on a small hull allowed the power head to rev at over 6000 revs, a bit too much for a motor that was designed to run to 5000 revs maximum, so to prevent this British Seagull had the props pitched up locally, to circa 10”.

At some point a vacuum operated fuel pump was cobbled onto the crankcase to permit the use of an external fuel tank, creating the 5R, a British Seagull 5 with a remote fuel tank.

Now the problems with 20 year old Seagulls 5 & 5Rs.

First the crankshaft, to utilise a steel conrod with needle roller big end bearings it was necessary to use a 3 piece crankshaft with a removable big end pin made from a better grade of steel than the rest of the crank to cope with the loads from the needle rollers, these bearing wear & as any scooter owner knows it a simple job for your local scooter shop, they just separate the crank halves & replace the conrod bearings & big end pin.

Not so with the British Seagull 5, due to the design of the crankshaft with very little support around the pin the hole tends to get slightly larger each time a pin is pressed in place, & as con rods & pins have not been available for about 15 years, when your big end gets tired all you can change is the caged needle rollers, which means your using a worn pin & conrod, so this set of needles won’t last too long. The next problem is that the interference fit of the pin in the crank web holes is not as tight as it should be often permitting movement during use, causing tight spots & very rapid main bearing failure, hence the spots of weld often found on these pins,& the next time the pin has to come out, the weld usually damages the hole even more.

A proper repair on these crankshafts requires a new custom made pin made slightly larger where it goes into the crank webs to give the correct interference fit, the crank web holes to be ground round once again as with an uneven amount of steel around them, the holes tends to stretch triangular, & a new steel conrod & new needle rollers to suit.

The only way I found to get con rods was to order 25 to be made for me & Ross Leger in New Zealand, an expensive & serious undertaking.

The next problem with these cranks is it’s location, it’s in close proximity to the returning, leg cooling water. Where the lower half of the crankshaft connects to the Yamaha drive shaft there is an oil seal to prevent crankcase compression loss, below this the end of the lower main bearing journal runs dry, that is until it come in contact with water, often salty, causing surprise, surprise, rust adjacent to the oil seal, which tends to start to fail soon after, a which point when you’ve used your motor & it’s cooling down, water tends to be sucked onto the lower main bearing causing corrosion on the balls, now as it has some corrosion on it, it will start to run much rougher & hotter, on these crankshafts they seem to run hot enough that the portion next to the crankshaft expands to permit the crank to spin in the now tight main bearing, wrecking the crank journal.

See picture below, it will clearly been seen that the area of corrosion is enough to rapidly degrade the bottom nitrile oil seal, causing the loss of some crankcase compression & the possible ingress of water on the piston upstroke, on the picture below it will be seen that the bottom main bearing carried on working perhaps because it was lubricated by water, but the top 2 main bearings must have suffered lube problems, possibly due to lower crankcase compression but certainly enough to cause the 2 top main bearings to tighten & spin on the crank, as seen from the witness marks.

Many British Seagull 5’s died down this route in fact of the 5 that I've owned, all have had this problem to some extent.

The second picture is just to illustrate what British Seagull did to solve their loose pin problem.

To repair/rebuild any of the Kingfisher/Seagull 5 cranks expect to spend more than £250, that's if you can find someone who has the expertise, rather than claims to have it, many crank top ends require the flywheel nut thread to be straightened so that it's perfectly true when placed on centres for machining, & a majority of 5 cranks require the fitting of a shrunk on hardened stainless steel sleeve to reserface the area where the lower oil seal runs


When the bearings got this hot the outer diameter often stretched the crankcase enough that the next set of bearings would rotate in the crankcase necessitating a new crankcase.

If you leave a 5 standing for more than 6 months without a full bearing change before use or at least a full strip down inspection, your could be looking at a very expensive problem.

British Seagull themselves drilled & tapped 3 holes in the steel centre of the flywheel on the later 5,s so that the flywheel could be removed with a special puller tool to prevent the hammer removal method stressing the big end pin retaining holes, bending the top thread & causing the early demise of your engine.

The next problem that seems to plague the 5 series outboards is corrosion.

The Yamaha leg that seem to last very well when used by them, but did not seem to like, the very mixed metal environment of the British Seagull & suffer very badly, so much so that the three of 5’s I’m restoring have needed new legs, perhaps British Seagull should have used sacrificial anodes.

The adapter plate seems to love dissolving in water, I think it must be made of a very cheap casting alloy, so much so that often the water feed to the cylinder runs into the exhaust & seems to be almost impossible to weld up, even when the white powder has been sand blasted away. So new adapter plates & all the machining that needs.

The water cooled Kingfisher head that was used on this series seems to have a life expectancy of 5 to 8 years before needing renewal, while the cylinders last much better, expect to have to have the top face where the head sits, resurfaced, when your cleaning out the water jacket & renewing the head.

So if your bidding on a motor with a view to using it, DO NOT START IT UNTIL IT’S HAD A COMPLETE STRIP DOWN, you can total the crank in 10 seconds !Nothing else will fit.

And if your adapter plate is in a useable condition be prepared to buy yourself a good phosphor bronze Kingfisher for £350 to £450, spend £50 on the machining & build yourself a British Seagull 5 that you can use year in year out.

Thanks for reminding about that Stelious you saved me loads of typing!
Attachments
2008_0422NZ5R0014.JPG
2008_0422NZ5R0016.JPG
2008_0422NZ5R0013.JPG
Make it idiot proof and someone will make a better idiot.
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Stelios_Rjk
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Re: 5R

Post by Stelios_Rjk »

The spots of weld are pretty obvious on this crankshaft.
Would you be able to repair it or you have to use another one?
I love the 10600/145 turns!!!
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Charles uk
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Re: 5R

Post by Charles uk »

This one was repairable as it wasn't too bad.

First I had to make a copper electrode 10" thou smaller than the pin diameter so that the middle of the weld could be spark eroded away so that the big end pin could be pressed out from both sides without stressing the crank webs around the pin.
Press out the pin.
Then straighten out the flywheel thread so that the centre was central to the main bearing journals & the centre on the inner face of the crank web.
Measure the main bearing journals to ensure there was a good enough interference fit for the 6003 main bearings, the bottom end was OK but on the top end it was close but not close enough, so spacers were turned to move both top main bearings sidways so that both bearings were located on a better area of the journal where I felt there was more chance of a good fit stopping them slipping.
On the bottom end of the crank I then reduced the diameter of the corroded section enough to permit the fitting of a heat shrunk stainless sleeve.
Then shipped everything off to the crank rebuilders where they had to straighten the thread a little more (centre not true enough), they then ground the stainless sleeve to a suitable diameter & finish for the oilseal, then they lightly ground the edges of the witness marks on the top end journals so the new bearings would locate properly, the bigend pin holes were then reground round & oversize so that the new bespoke big end pin would have the correct interference fit.

The crank then pressed together by them, with a new steel conrod & bearing kit that I supplied. using a fixture I made & then they gave the crankshaft a final true.

The 2 top main bearings were then Loctited into position to prevent any spinning, the bottom had a very good interference fit & didn't need it.

With the level of expenditure that all this requires can you now understand why we say "DO NOT START IT UNTIL IT’S HAD A COMPLETE STRIP DOWN".

Over the last 10 years I only managed to find 1 company Worldwide, that would offer a guarantee of their workmanship & materials, that I've only had to call on once when a big end pin broke at 6500 revs due to a flaw in the material (fully rebuilt No Charge).

Many of these problems were caused by Seagull's lack of experience with 3 piece crankshafts as they only made circa 100 5R ones & 1000 QUB.
I've no doubt that, had they'd carried on producing them, their production modification regime would have cured these problems as soon as they knew about them & we'd have ended up with crankshafts as long living as their forged parents.

So my verdict is "Wether your Kingfisher or Seagull 5 has run recently or been standing for 15 years please check before pulling that rope"! As it's almost cheaper to buy a 4-stroke Honda than a new crankshaft!

Chicken when you get the crank out of yours, could you post some pics of the bearing conditions.
Make it idiot proof and someone will make a better idiot.
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Charles uk
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Re: 5R

Post by Charles uk »

There is a loud sound of silence from your end of the World Chicken, I understand this is not a 10 minute job.

The easiest way of getting an indicator, would be to.

Remove powerhead by undoing the 7 M6 cap heads or bolts at the very top of the leg, & lift off the powerhead, pray that the gasket is only stuck on the leg side so it doesn't get destroyed (£14 here), remove the 2 fuel pipes if it's the "R" version & the throttle cable, & undo the 4 cap heads holding the powerhead to the adapter plate & separate, careful with the exhaust gasket as no longer available & you'll need the old one as a template, all that you need to do now is pull out the lower crankcase nitrile oil seal (17 x 35 x 7) with a small screwdriver, don't worry about wrecking the seal as they cost less than £2.00 & you should be able to see the bottom main bearing, any sign of any discolouration & it's a full strip down.

Most of the 5's I've stripped have been fitted with single lipped seals, meaning the wet part of the journal is right against the seal holding the crankcase compression, so I always replace them with the double lipped seals with grease between the lips.
Make it idiot proof and someone will make a better idiot.
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Chicken
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Re: 5R

Post by Chicken »

Yes it is definitely not a 10 minute job, Nothing like the low maintenance classics, these require bit more TLC, From the outside they can be quite deceiving its not until you get them open does one see the many things that could have gone wrong if it was jut started and run.

Once the Powerhead was off and the cylinder block was taken off the crankcase the damage done on the bearings was visible, Carefully turning the crank by had let one feel the grit and wearing in the bearings, that was not evident when the powerhead was together.
Corrosion on the bearings
Corrosion on the bearings
Once the crankcase was carefully pressed apart with a spacer placed between the crank webs to stop it from bending and ruining the crank, It was easy to see the rust and crap that had assembled in the bearing, It wasn't until the bearings were taken off the crank that the great amount of wear there was out the door they went to be replaced with some nice smooth clean bearings.
Crud on the big end
Crud on the big end
Also apon taking the powerhead to pieces I could also see how much crap was in the big end bearing from sitting around, Luckly after cleaning it up there is no damage to the rollers and is moving very smoothly. It is very easy to see how one could total the motor if run with out checking the inside.
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Stelios_Rjk
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Re: 5R

Post by Stelios_Rjk »

Great post, I love such details.
Well I can't stop ideas coming out from my head. Could the con rod be replaced by an newly manufactured in which the big end bearing will be formed by phosphor bronze? A construction similar to the aluminum con rods we see on most of the Seagulls. It would certainly save much of a trouble but would that withstand the forces applied?
A question for the specialists I suppose.

Good luck to all 5R owners!
I love the 10600/145 turns!!!
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Oyster 49
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Re: 5R

Post by Oyster 49 »

I sense the 5R is too complicated! Too many roller bearings and seals to go wrong. Perhaps a 170 with an upgraded con-rod would be a better basis for a race engine?
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Re: 5R

Post by Michael »

Nothing complicated about a 5R, poorly designed and made, yes.
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Robin Anderson
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Re: 5R

Post by Robin Anderson »

A fascinating post - thanks Charles for all the work. I never had a 5 but I did have QB Kingfisher. Potentially a great engine, it just did not have enough testing and development invested in it. It has long gone but the old Century 100 that I had at the same time is still a keeper.

Robin
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Paris H
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Re: 5R

Post by Paris H »

Here is the Team NZ 5R that Mr Chicken has just bought back from the dead and re-built for me. The work list was long and every fix revealed another problem! But now she's a runner so full credit to you Cam.

Thanks for your hard work.
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Robin Anderson
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Re: 5R

Post by Robin Anderson »

That's looks to be a superb 5R and what a great aviary.....
Robin
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Stelios_Rjk
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Re: 5R

Post by Stelios_Rjk »

Could you re-post the pictures please?
I love the 10600/145 turns!!!
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