Suzuki GT285

General discussion about Street two-stroke Suzuki motorcycles.

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dollydog
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Suzuki 2-Strokes: several gt250 ramairs

Re: Suzuki GT285

Post by dollydog »

hi alan, i'm sure i tried that at some time, but if i remember rightly the tops of the barrels hit the frame and i most definitely wouldn't get the [cutdown] ramair covers on :D
anyway, you had the last of my 550 bits, so i've got nowt left :D
think i'm going to plod on with the inline 500/4. i've got a press now, so when i've made a disassembly jig and reassembly jig, vee blocks, gauge etc, i can get cracking on the crank. up to now i've worked out i need 3 middle shafts. one stays as is, but the other 2 need shortening to use an oil thrower instead of the second seal. this is going to be a mega-project.
unless i do a len vale-onslow, at my age it should just about see me out :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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Alan H
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Re: Suzuki GT285

Post by Alan H »

And two oil pumps for CCI.
Or a single one from a 4 cylinder 2 stroke.............

Outboard motor perhaps?
Remember some are V and some are straight 4's so pump timing needs to match cylinder configuration.
Mercury or Force engines? Do these have a suitable pump?
Nothing straightforward in specials is there?
Think of how stupid the average person is, then realise that half of them are more stupid than that.
dollydog
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Suzuki 2-Strokes: several gt250 ramairs

Re: Suzuki GT285

Post by dollydog »

hi alan, the gt250 oilpumps are easy to get to bits and work on. the idea was to piggy back a pair of them, with a bit of machining, and use the tacho drive [modded to spade shape] off the bottom pump to drive the slot in the top one. that way easy to set up for all 4 cylinders and i can still use the tacho drive - off the top pump :D not looking forward to making up the 2 extra oil lines though, although i have modded some before with piece of thick wire pushed right in the pipe and heat gun to get the shape. but there's a loooooooooooong way to go before then :D
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
Craig380
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Re: Suzuki GT285

Post by Craig380 »

As you're rebuilding the crank anyway, could the mains be converted so they're lubed by the incoming mixture? Then you could just use 4 of the 6 oil lines from a stock 380 pump to feed oil into the inlets (like Yamaha RDs), and blank the spare two lines off.
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Alan H
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Re: Suzuki GT285

Post by Alan H »

Careful with that as the outlets from the pump are 3 higher flow and 3 lower flow, so you'd need four outputs similar, hence my comment about a straight 4 two stroke engine.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
dollydog
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Suzuki 2-Strokes: several gt250 ramairs

Re: Suzuki GT285

Post by dollydog »

craig380, that sounds complicated and modding a 380 pump to fit the 250 in the first place would take far too long - this way is easier. [for me] :D thanks for the input though! but basically all i'm doing is joining 2 gt250 engines together, side by side.
alan, i don't really get what you mean about a high and low. the height of the oilpump shouldn't make the blindest bit of difference. 50mm higher? they are pumps after all, and suck from one end and pump out the other. the banjo ends have non return valves in them, so as long as the 2 stroke tank never runs low it shouldn't be a problem. i think :D
if you were doing a mega stoppie down bruntingthorpe runway, with the oilpump a foot higher than it should be, it would still work as normal - with the engine running of course. if i set them up the same [as standard] on the marks with the dot on the carb slide in the right place they SHOULD be ok. can we come back to this in about a year or so when i get round to fitting it? :D at the moment the crank is my biggest concern - and the 100mm extension to the layshaft for the clutch :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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Alan H
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Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
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Re: Suzuki GT285

Post by Alan H »

Nonono! The pump pistons deliver different amounts at any rpm. Hence my description of high and low. Not pressures, oil flow.
The triples have 6 piston pumps which deliver differently as 3 pistons pump (bigger diameter and stroke) more oil than the 3 smaller ones.This is detailed on OJB but I can't find it on my phone as it's slow compared to my laptop.
IIRC the bigger flow goes to the bearings, the smaller flow goes to the pistons.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
dollydog
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Suzuki 2-Strokes: several gt250 ramairs

Re: Suzuki GT285

Post by dollydog »

so surely i shouldn't have a problem, if the bottom pump feeds barrels/bearings on 1 and 2, and the top pump feeds 3 and 4? 1 and 2 are getting what they always got and 3 and 4 ditto. no sris on these either, even though the crankcases have [blanked off] spigots for them :D and on the 250, there's a blanked off spigot between the bottom of the barrels, which i presume was going to feed the centre main bearing before they came up with the idea of feeding it with the gearbox? :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
Vintageman
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Re: Suzuki GT285

Post by Vintageman »

They are different in length and pin whole location if I recall. I could check if you really want to know, but I am sure they are too different.
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Alan H
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Re: Suzuki GT285

Post by Alan H »

Just make sure that any 'spare' pipes from the pump can feed oil somewhere or the pistons on those pipe feeds will just pressurise the old connections and blow oil all over the place. Not sure if you can remove the unwanted pistons so this doesn't happen, or if that will let oil run through and just leak anyway.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
dollydog
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Joined: Fri Aug 11, 2017 7:09 am
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Suzuki 2-Strokes: several gt250 ramairs

Re: Suzuki GT285

Post by dollydog »

i'm getting lost here alan - nowt new there - the gt250 oilpump is nothing like the 185/380/550/750 oilpump, it is a seperate entity, totally different. there are 3 banjo unions, one is inlet from the oil tank, one feeds [via a 'y' branch] the left main bearing and squirts up the barrel into the inlet manifold. the third feeds ditto on the right side. so piggybacked oilpumps will feed exactly what they did in the first place, there's no high/low flow/pressure or whatever. are we rate nah? :D
vintageman: i've got no intention of attempting to run 380/550 oilpump - far too complicated. i'll stick wth my original idea :D
as ever, input gratefully received even if i don't take the blindest bit of notice, it's still appreciated :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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Alan H
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Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
Location: The Republic of South Yorkshire

Re: Suzuki GT285

Post by Alan H »

What I was getting at is that there is two different outputs of volume from the pump depending on pump piston size. If you use them 'wrongly' the engine could be underoiled. Just for you to be aware. There's probably a graph of output from the pump somewhere. I've seen one for the triples ages ago.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
dollydog
Yeah Man, the Interstate
Posts: 630
Joined: Fri Aug 11, 2017 7:09 am
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Suzuki 2-Strokes: several gt250 ramairs

Re: Suzuki GT285

Post by dollydog »

hi alan, again, the gt250 oilpump pumps exactly the same out of all 4 outlets [banjo's]. so if i set it up as standard, with the dot on the carb slide in the centre of the hole and the pump arm on the mark on the oilpump body then it should be right - it normally is :D all i'm doing is doubling them up. they will both be going at the same speed, so output should be exactly the same :D at the moment i'm still working on the cranks, so that is in the far distant future :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
sportston
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Re: Suzuki GT285

Post by sportston »

Your project got me wondering....I wonder it if was possible to take 3 gt500 pots and put them on a GT380 or GT550 bottom end. I'd have an air-cooled 750 then!
I'm guessing it must be impractical to do so or someone else would have done it before. But I can dream.
dollydog
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Suzuki 2-Strokes: several gt250 ramairs

Re: Suzuki GT285

Post by dollydog »

you never know til you try - go for it :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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