GT550 crank seals

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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: GT550 crank seals

Post by Alan H »

Where did you put the oil? A two stroke only has oil in the gearbox/clutch and the engine is supplied from the two stroke oil tank via a pump. A 550 gearbox takes 1500cc - it says that on the cases. Oil needs to be 20w50 or similar, definitely NOT synthetic or the clutch will slip.
Seam between the crankcase? They are split horizontally, about half way up, so if they are leaking you have a big problem. Have another look.
I suggest that you get some books on two strokes and 550s in particular, and start reading! In the meantime, do a search on here or HERE for GT550s and see what you get.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
garyscc
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Suzuki 2-Strokes: GT250, GT350, TC90, TC125

Re: GT550 crank seals

Post by garyscc »

Thx, im trying to find info. There is a black knob that rotates like in the last picture. I imagine a few quarts of oil should be in there? But how do you know if its full? Do u just look down hole? Could I jb weld the area at the seam where it leaks?
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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: GT550 crank seals

Post by Alan H »

No the black knob on top is the filler.
The gearbox takes 1500cc (look above the kickstart shaft!) and there should be a gasket between the cases and outer casing. The casing faces must BE clean of all crap/debris/whatever, I guess that's where the leak is coming from?
There is a difference between the oil levels in the clutch and gearbox due to an internal weir, so drain all the oil out, and refill with 1500cc. Make sure you get the drain plug (the vertical one) not the selector studs (angled ones). there is a level plug for the clutch case - if you press the brake lever down, it's behind it and should be a 6mm thread hex head bolt with a cross head in it.
If you want a copy of an EARLY manual (for J,K models - but lots still relevant to later ones), PM me your email addy and I'll send it FOC. If anyone else wants one, same goes. I copied the original manual that I bought in 1972 when I got my first 550!!

Don't JB anything without trying to do it right first. These aren't Harleys.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
Big John
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Suzuki 2-Strokes: 1972 GT550

Re: GT550 crank seals

Post by Big John »

i'm new to the forum...and Suzuki two strokes and just purchased a 1972 GT550. I think the front brake is absolutely gorgeous! And it seems to stop the bike very well (just around the block). A couple of questions. I have a Clymer's manual but it doesn't have a lot of information about the crankcase. I don't think there is any oil in it and the starter grinds when I use it...the starter does work. I'm going to drain the oil and but some oil back in it and hope that will take care of that terrible grinding noise. I would love to get a better manual for the bike. Is there a way you can email me one. And I can't figure out how to PM you. Any help would be appreciated. Thanks!
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jabcb
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Re: GT550 crank seals

Post by jabcb »

Alan has the GT550 shop manual posted here: https://www.oldjapanesebikes.com/mraxl_ ... /index.php
He has the service bulletins posted here: https://www.oldjapanesebikes.com/mraxl_ ... ins/page-2

Suzuki had some problems with starter clutch in the early GT550s . Service Bulletin GT-26 covers the upgraded version.
New upgraded parts are no longer available, but used upgraded parts show up on eBay from time to time.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
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GTandcbr
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Re: GT550 crank seals

Post by GTandcbr »

Like most forums you cant PM until you have posted a few times.
98 carb Blackbird and GT550j
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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: GT550 crank seals

Post by Alan H »

Favourite cause of a grinding noise when using the electric start with the early clutch, is that the plate behind the clutch holding the rollers is loose. This needs sorting asap or it could damage the clutch centre. It should hopefully just be a matter of tightening 3 countersunk screws when the clutch centre is removed. Of course it isn't quite that easy but is fairly straightforward.
BTW, I'm currently in Barbados on hols, so anyone needing a copybof the service manual won't get it for another week until I get home.
Please don' t show me any sympathy as I'm struggling through ok..........
Think of how stupid the average person is, then realise that half of them are more stupid than that.
Paul Phillips
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Suzuki 2-Strokes: GT 550, Gt 500, A 100, T 10

Re: GT550 crank seals

Post by Paul Phillips »

Toystoretom wrote:Hi Guys and Girls!

I just bought a 1974 GT550 that won't start. Long story short, I've gone through the carbs, have fresh gas, petcock works, good spark timed right, good compression, new battery and so on. If I'm lucky when I spray a bunch of carb cleaner in the carb throats it might hit on one cylinder. I pulled the exhaust and fabbed up a steel plate with a gasket to seal it off. I made a fitting that will go into the carb boots. Hooked up a pressure gauge and tried to pump each cylinder up to 6 psi. The center and right sides won't hold squat, in fact on the right cylinder I can hear it hiss out behind the points plate. The left cylinder will hold a little pressure for about 15 seconds. The crank seals have to be shot.

So I have started to yank the engine to split the cases to get the crank out. Where is a good place to get replacement seals that aren't 30 years old and already petrified? Also, who do you guys use to rebuild the crank and install the seals? I haven't seen the crank yet but this is a 5000 mile bike that is in very nice shape (except for the crank seals) so I'll bet the crank is in pretty good shape so it shouldn't need much.

I have a nice shop press and bunches of things like bearing splitters and all kinds of plates and adaptors. Is a GT550 crank something that I could press apart? I was thinking of buying a junk one off of Flea Bay and practice on that. Or should I leave it to the pros.

I live in Kansas City so maybe you guys know someone local to me. You would think a machine shop the does dirt bike cranks or 4 wheeler cranks could do this.

Thanks!

Tomo
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Alan H
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Re: GT550 crank seals

Post by Alan H »

? :roll:
Think of how stupid the average person is, then realise that half of them are more stupid than that.
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