1972 Suzuki GT 550

montessa172

Been Around the Block
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Picked up a 72 ( stripped chassis with ownership) and 77 GT 550's.. Both are complete and both are seized, the 72 was run by a PO with a fresh set of pistons installed backwards *sigh* and supposedly the rings caught the ports, pictures of that disaster to follow once I get the head and barrels off. The 77 sat outside for "only five" years and is seized from sitting - I hope. I also have a race chassis from a mid 70's t500 that will be donating its front suspension, wheels (alloy) and brakes.. First on the to do list is assessment of engine damage and the search for pistons and rings.. Any suggestions or recommendations on vendors is appreciated, this isn't my first smoker but its my first rebuild of one...
 
Should be cool, I love the two strokes.
Are you going to keep that ram-air thing on the heads? That was one of the things that put me off on these back in the day, now it's cool cuz it's period retro.
Cheers, 50gary
 
Have you checked with Suzuki for oversize pistons? Of all the Jap manufacturers, I think Suzuki is the best at having OEM parts still available for old bikes stowed away in a warehouse somewhere.
 
I know my t500 will work with 2 gt750 pistons so there i would not be suprised if some dirt bike 185 ish or a os for a t350 piston wouldnt be the same. Good deal man there is not enuff gts on the board
 
Good point, Brad. There was a lot of interchangeability like that with Suzuki parts. I think the TS250 pistons worked in the T500 and GT750. All three of those engines had the same bore and stroke, just different number of cylinders.
 
Thanks for the piston input guys, appreciate it.. Got some part numbers for GT 550 pistons and TS 185 pistons today, going to the dealership in the next little bit to scope it out. In the mean time I've started stripping the wheels off of my T 500 race chassis.. So some pics of that and of the front end that i'm using.. Rear hub is actually pretty neat, allows the rim and tire and brake assembly to be removed without touching the chain / chain tension..
 

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and @ 50Gary, the ram air cover shall stay... I've read that there was an actual benefit to it - in regards to head temperatures..
 
You sure thats a 72, should have a 4LS hub on the front wheel? the hub alone would pay a huge chunk of your build. cant wait to see your build. Thx Dick
 
It should have the drum brake that everyone wants, but I'm pretty sure the PO scooped it and swapped a later wheel, easy come easy go I guess...
 
Should have known better... The 72, that's stripped down, came with owner ship and I was told when I looked at is the reason it wasn't running was backwards piston syndrome and rings hit exhaust port ok ... 100% accurate..

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The engine had the barrels and head back on and bolted down " to keep stuff out of the bottom end" when I went to grab the kicker and turn it over the PO said don't do that the con rods will hit the ports... Made sense.... Or the fuckin bottom end is seized solid... I hate people.. Diggin deeper now...

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All right, bottom end isn't seized, the stator is interfering with the rotor? Maybe the wrong stator for the year, I know Suzuki used two different ones i'll deal with that later.... So on to the good news, picked up a 32mm socket to pull the clutch, verified that the machine shop that I use occasionaly is still in business and stopped by my friendly local Suzuki dealer... For once I got a parts person who's eyes didn't glaze over immediately upon hearing Ninteen Seventy..... Super helpful lady and an awesome instant gratification visit... Stock bore pistons, rings, base gaskets, wrist pin bearings all ordered... Head gaskets didn't come up though, so she's doing some more looking for find those for me too. Splitting the cases probably tomorrow.. Sturgess Cycle in Hamilton, worth the visit, and they have a really nice Thruxton on the floor too - they're a triumph dealer as well..
 
Engine is stripped, no suprises... A few scuffs here and there, tiny amount of wear on the shift forks..Now I need to find someone to press the crank apart so I can do the seals... Thinking about having the connecting rods checked/balanced at the same time..

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And for the the chaos minded, the reason I stripped it down to the cases.. This may be an indication for why I need to sand a polish a lot on the rightside engine case...
 

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Haven't managed a whole bunch of work on the GT lately, partly due to this

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Almost doubled my work space. Total size is now 12 by 20.. All thats left to do is side it in the spring..

But anyways, working on cleaning up the cases,

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Got the crank seals ordered last week and i'm waiting for those and the pistons / rings to come in so I can send out the barrels and crank for some machine shop work.. I'm also trying to find some information on a crank shaft / case mod to enable the option of running premix without cooking one of the outside bearings, I don't know which bearing or flange needs to be drilled but i've read generalities that indicate that it could be a problem.. If anyone has some direction on this I would appreciate it... I do plan on running the oil pump but I would like the option of running premix you never know.. A thanks in advance for any input... regards..
 
The way the Suzuki triples are designed, I wouldn't consider running premix at all. If I remember correctly, the roller bearings on the right side run in tranny oil, so no biggie there, but the stock system works pretty well, so premix seems like more hassle than it's worth. The middle bearings are pressure fed by the pump, I can't see how any modification to the system would work as well as stock.
 
I slowed down for 2 minutes and had a look at the cases and I see what you mean about the crank oiling.. Thanks..

To get this up to date, i've got the cases all cleaned up and ready for reassembly

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Made a puller and removed the rotor from the crank and the transmission side big end bearing, so thats ready for seals as soon as they come in.. Took three attempts to get the puller right..

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I've also done some work on stripping down the bike that was sitting outside, thats not going well but whatever, it sat outside for 20 years..

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And finally the highlight of my week, parts came in from Suzuki..

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Waiting for my crank seals to come in and once the cylinders are ready and i'll start reassembly :) :)
 
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