imago

There's a bloke who knows the family that's going to ask, although the very early info will be all about the GT750 side of things. Apparently he only made 4 of these particular frames so it's a rare bird, but the thought of getting tangled up with Kettle rivet counters doesn't blow my frock up. So it'll be the GS/GSX evolution I'm focusing on.

I reckon half the time with modifications, lightening things, frame bracing etc the hard part is knowing when to stop. Without doing anything at all a bike's capabilities will far exceed most rider's. This question is/was part of weighing (excuse the pun!) up the benefits of building an 8v motor for the Dresda vs using the 16v I already have. It really is a no brainer in that a GS motor would cost a fortune to build properly for no advantage other than looking a bit more 'period'.

My thinking exactly. Any GS1000 engine now is going to need an extensive and expensive rebuild, so spending a small fortune on a 1085 seems like a daft thing to do when the more powerful air cooled engine is sitting there at zero cost beyond the carbs.

I know some rave about them, but those GT 750's were fucking horrible things IMHO. My brief experience back in the day was that they're heavy, thirsty, not very reliable and needed more maintenance than something from Italy. So I'm more than happy it got binned off in favour of an inline four.

Having been caught on the hop a bit with the appearance of another project it's taken a minute or two to (mostly) settle on a plan. Until I actually get it in the workshop there will be stuff that will be more mights & maybes than certain. So at the moment my thinking is this. The photo from the '90s shows it with the RG bodywork in black with orange stripes and lettering, and an orange frame similar to the Walter Wolf scheme. Looks pretty good in that so I think that's the way it'll go. Engine wise I'd like to use a GS1000 done to 1085 with a flowed head etc. but that'll be an expensive route to go down. However, if it'll fit in the frame I have that Roger Upperton ET engine with an 1170 big bore, flowed head with EF valves fitted just waiting for a home. That way the only cost (still a chunk) for a serious normally aspirated period engine would be a set of flat slides. I even have a solid Harris works exhaust to complete the look. That leaves the suspension, keep the existing wheels and have them coated at the same time as the frame and arm. Shocks are an easy bolt on, and see what's what with some RWU forks. I'm trying to avoid it becoming a money pit as I have the Throwback build for that.

Thanks to @Havoc's suggestion to join UK Specials on FaceAche I've not only got more info on the bike and its history, the previous owner's on there and has a photo of the bike at the Bol D'or in the 1990s showing the Q plate reg it had which is still on the DVLA system so I can apply for a logbook.

Yeah I saw that thread, shame nothing's happened with it since.

What's the cut off for knowing who's in and what they're bringing @Paulm? I know it's not for a good while, but there's a fair bit going on this end so I need an idea of when to aim for.

It starts when you find that limit point where you can get it up off the floor, or down off the bench, but going beyond that you know is going to end in disaster. This hydraulic table has been an invaluable piece of kit. Slide an engine off the rack, or lift it off the floor onto the table (6"). Then you can either work on the table, or let it down to the height of the bench, back of the van or whatever and slide it on.

I'm still pondering engine plans, but at this stage it's going to be normally aspirated and keep it as light as possible. Like the Harris these were frames designed for the race track so I need to keep with that I reckon.

You'll be the first person to see it. The bloke lives about 20 minutes North of Spilsby so after I've dropped the throwback off there I'm picking it up on the way to yours next Thursday.

Have you allowed for age and mileage in your calculations? I reckon the only person who'd be happy with my lifting either complete these days would be my chiropractor.

Anyone know what the weight difference is between the GS1000 engine and the GSX1100 engine?

The little I've found out so far about these is that there were 9 of these 'Solitaire' frames made by Dave Degens in the 1970s following his success both in racing and with building Triton frames. A couple were made for Yamaha, the rest being for CB900s and GS1000s. They were sold as kits with the option of you supply the donor and they'd build them like Harris etc. They were raced, but there's no info I can find so far on by who or where. If anyone has anymore info or can point me in the direction of somewhere I can find some then please do.

Get a shipping price and you can save me from myself.

You know when you say "No more projects" and the Gods of Hamamatsu piss themselves laughing? Well they're apparently in a particularly mischievous mood at the moment. Long story involving a dose of "I couldn't refuse the opportunity" means I will shortly be in possession of a Dresda frame with aluminium tank, braced arm and RGV bodywork which was built for a GS 1000 lump.

Given how far over square that is with the big block it'll scream its bollocks off. Sounds like the forged rods will be put to good use.

If you start cutting that frame about don't post any pictures of it on the internet. Chicken central would be surrounded by purists with pitch forks and torches.

I did chuckle, and I still do at how excited/hysterical whoever wrote the article were at the HP produced. Good for the day, but if that's what you got out of a litre plus engine after fitting a turbo now you'd be well upset. Which goes to the wider point of how much things have moved on. 100 hp more for a comparative spend on a turbo now, or use a GSXR/R1/Blade/Busa ... and have more than that without doing a thing. The impressive thing (to me at least) about bikes back then was the way they were built and the parts/materials that they used to achieve what they did.

I'm not saying they're bad, just that roller bearings are better in terms of longevity and reliability over greater mileage. I don't think anyone can argue against the longer life of a roller bearing, particularly with lower oil pressure. It's the same comparison as that between cast and forged pistons. There are plenty of cast piston turbo bikes running around, but they can't take as much boost and/or timing advance as forged, and they won't do the same mileage. You work with what's available, in the '80s that was plain bearing turbos and they worked. Now there's to option of roller bearing turbos which last way longer under the same conditions. So if you're building a turbo engine for prolonged road use, and in this case one with comparatively low oil pressure available, it'd be a poor decision to go with the lesser design.

Yeah, carbon seals and a plain bearing which wasn't so happy with low oil pressure which is why they didn't last very long on the road.

Agreed, it's why we're al here and it proves that power is of secondary consideration with what we like/build. If it was the first consideration we'd all be running 'busa engined monsters. But, it was nigh on impossible to build a 200 hp bike in the '80s beyond a proper drag bike that needed rebuilding every five minutes let alone buy one. Things have moved on, we've take some benefit from it but not tried to stay at the cutting edge. My throwback build for example is a draw through as per the '80s, but it will have a roller bearing turbo with carbon seals. Old build, new tech, better/faster/more powerful than back in the day but none the less far less than could be achieved with a modern bike.

That's my point really, look at what's available off the shelf now compared to back then. Blow through turbos which work, electronic control which is adjustable with a laptop, injection, carbs designed for the job, eve small changes in materials technology that mean the difference between pistons then and now are night and day. You can even walk into a dealership and ride out on a bike with 200+ hp, map it and have an instant 25-50% increase. It's a very different world and as always some for the better and some for the worse. As for me needing to ride a draw through, well yes, yes I do. Shouldn't be too long now hopefully and I've given my wife the log in details for here so that if I end up strewn across the countryside all the salvage and spares will go to good homes.

Yup, @Wee Man's bike has 100 hp more than what was as you say top drawer stuff back in the day.

I came across this article about Steve Burns' Spondon Turbo and thought it may be of interest. The astounding 169 hp made me chuckle, how things have moved on.