'76 GT550: two sorts of news...

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nickst4
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Joined: Wed Feb 19, 2020 7:31 pm

'76 GT550: two sorts of news...

Post by nickst4 »

Lets start with the good stuff. Those nice people at the DVLA sent me a new logbook this week, saying my '76 550 is now reckoned to be Historic, and I need no longer waste petrol money on MOT or tax. Ta very much! :D

The other good news is the rebuilt motor is running beautifully. I'm staying around 4k revs, with brief forays to nearer 5K, obviously using the gearbox as necessary to keep the motor running free, and it is running very smoothly. Starting is now quite scary as the motor fires into action almost explosively. Before the rebuild, it was very reluctant, due to zero compression in crankcase or cylinders

The bad news is said gearbox is starting to whine rather unpleasantly in 5th, and 4th sounds quite positively nasty. This is at 130 miles since Pete Odell assembled the bottom end and gearbox. I've yet to check the oil in the box, but I probably put the specified amount of a semi-synth 10/50 Morris oil in there. I seem to remember some discussion about the box needing more than is stamped on it, and perhaps it needs a heavier grade in it too? I do hope the whole thing doesn't have to come apart again to sort it out!

Nick, in Norfolk
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malky
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Re: '76 GT550: two sorts of news...

Post by malky »

Its the 500 twin that has the oil capacity altered from 1200cc to 1400cc with the internal oil dam mod I wasn't aware of anything similar with the 550 though - I use ep80 or 90 GL4 grade oil in my t500 and it quietens the box down a lot
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canaletto5
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Re: '76 GT550: two sorts of news...

Post by canaletto5 »

nickst4 wrote: Thu Sep 17, 2020 8:36 pm Lets start with the good stuff. Those nice people at the DVLA sent me a new logbook this week, saying my '76 550 is now reckoned to be Historic, and I need no longer waste petrol money on MOT or tax. Ta very much! :D

The other good news is the rebuilt motor is running beautifully. I'm staying around 4k revs, with brief forays to nearer 5K, obviously using the gearbox as necessary to keep the motor running free, and it is running very smoothly. Starting is now quite scary as the motor fires into action almost explosively. Before the rebuild, it was very reluctant, due to zero compression in crankcase or cylinders

The bad news is said gearbox is starting to whine rather unpleasantly in 5th, and 4th sounds quite positively nasty. This is at 130 miles since Pete Odell assembled the bottom end and gearbox. I've yet to check the oil in the box, but I probably put the specified amount of a semi-synth 10/50 Morris oil in there. I seem to remember some discussion about the box needing more than is stamped on it, and perhaps it needs a heavier grade in it too? I do hope the whole thing doesn't have to come apart again to sort it out!

Nick, in Norfolk
If you are filling the gearbox after draining out old oil you need to put in the specified 1500cc. If you are filling it after an engine rebuild you need to put in around 1700cc. The very best thing to do is drain out the old oil and refill with 1500cc of fresh oil
nickst4
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Re: '76 GT550: two sorts of news...

Post by nickst4 »

malky wrote: Fri Sep 18, 2020 1:53 pm Its the 500 twin that has the oil capacity altered from 1200cc to 1400cc with the internal oil dam mod I wasn't aware of anything similar with the 550 though - I use ep80 or 90 GL4 grade oil in my t500 and it quietens the box down a lot
Hi Malky,

I wondered about putting ep80 in the box. I take it that this has no bad effect on the clutch or starter sprag, if the t500 has one? Maybe you can kick-start your t500, but I find the extra cylinder of the 550 means it's very difficult to get any meaningful movement on the kick-start. It's embarassing to be defeated by such tiddly cylinders!

Nick
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Chris57
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Re: '76 GT550: two sorts of news...

Post by Chris57 »

I always used GL4 grade transmission oil rather than a multi-grade engine oil in my Kettle. Don't use GL5 though, it's not nice to phosphorus bronze.
nickst4
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Re: '76 GT550: two sorts of news...

Post by nickst4 »

Well, an embarassing follow-up to my original post: I drained the oil today, and apart from some slight metallic colouration, the main thing is that very little more than 500mls came out! I find it hard to believe that I read the figures on the case as 500mls rather than 1500mls, since one has to be inches away to do the filling. The insides of the motor would have been completely dry, so a fair bit of oil would be taken up with coating everything, including the clutch and primary transmission of course. Whatever, I put 1500mls of mineral 20/50w back into it, and even then had to add some extra to get oil dribbling out of the level hole (this was with the bike on its centre-stand). I'll test-ride the bike tomorrow and am confident the gearbox will be very much quieter, and just hope I've not done any damage with my gentle running-in cruise of yesterday. Fingers crossed... :oops:

Nick
nickst4
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Re: '76 GT550: two sorts of news...

Post by nickst4 »

To hopefully wrap this up, I can report that putting the right amount of a heavier grade of oil in the gearbox has banished all gear noise, leaving just the familiar rev-related slight whine from the engine. What a relief! :roll:

I'm really enjoying riding the 550, and it's an excellent contrast with the sizeable vee-twin four-strokes I otherwise prefer. One major asset is the compliant suspension that minimises the shock from all the ripples in the roads around me. OK, so it gets a bit frisky over big bumps and would hardly be a bike to take on a track, but it holds its line well enough for the kind of riding I mostly do. I'm looking forward to getting it run in enough to have it make triple music at full revs! Fabulous! :D

Nick
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Alan H
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Re: '76 GT550: two sorts of news...

Post by Alan H »

Very under rated the air cooled triples. I love my 550s.
The Hippo is ok, but not as much fun.
Proof that four strokes are over complicated
nickst4
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Re: '76 GT550: two sorts of news...

Post by nickst4 »

Alan,

I've never ridden a kettle, assuming that's the same as a hippo? They certainly aren't as aesthetically-balanced and elegant as the air-cooled GTs, at least to my way of thinking...

Maybe one last item on the oil-in-the-gearbox theme is that my 550 appears to have a leaking final-drive sprocket seal, cos it makes a little puddle after a ride that a Triumph would be proud of! There's still no way that I lost a litre of oil that way though. I'm expecting it to be easy to replace that seal from the outside, given the setup is the same as any other bike?

Now to put more miles on it. Having dug out the owner's manual, I think I may have been pushing the revs a bit in the early stages, but I prefer to let the motor spin under light load rather than lug it and stay below 3.5K.

Nick
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Alan H
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Re: '76 GT550: two sorts of news...

Post by Alan H »

nickst4 wrote: Tue Sep 22, 2020 9:02 am Alan,

I've never ridden a kettle, assuming that's the same as a hippo? They certainly aren't as aesthetically-balanced and elegant as the air-cooled GTs, at least to my way of thinking...
Yup. Right on. Bear in mind I got my first 550 in 1972! Didn't like the early Hippos at all - then & now.
Maybe one last item on the oil-in-the-gearbox theme is that my 550 appears to have a leaking final-drive sprocket seal, cos it makes a little puddle after a ride that a Triumph would be proud of! There's still no way that I lost a litre of oil that way though. I'm expecting it to be easy to replace that seal from the outside, given the setup is the same as any other bike?
Yes, with a bit of faff, they are changeable. But make sure it isn't the gearchange switch first!
Now to put more miles on it. Having dug out the owner's manual, I think I may have been pushing the revs a bit in the early stages, but I prefer to let the motor spin under light load rather than lug it and stay below 3.5K.

Nick
Best way, air cooled 2 strokes like revs when running in.
Proof that four strokes are over complicated
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