gt250 identification help

[ga2wheel]

hello, need some help identifying what exactly I have so I know the parts needed to rebuild.
the title shows it as a 77 gt250
engine serial is 50796 which I don't think is a 77
cylinders with the carbs that clamp to the rubber mounts not directly to the cylinder. and has the ram air covers.

a crank with 2 different sized wrist pin diameter, obviously rebuilt at one time with the wrong year rod. which years had the 16mm which had the 14mm?
any information would be greatly appreciated, want to rebuild and would hate to part it out but need more info on what exactly this basket case consists of.

[jabcb]

The starting frame & motor VINs for 1975 are here: http://www.ozebook.com/compendium/suzi/ ... /page1.gif
and 1976 are here: http://www.ozebook.com/compendium/suzi/ ... /page2.gif

You may have a 1975 bike that was first titled in 1977. Sometimes they did that back then.
Also look at the frame VIN. If its close to the motor VIN, then likely you bike has the original motor.

Some general info about vintage Suzukis is here: http://www.suzukicycles.org
and GT250s is here: http://www.suzukicycles.org/GT-series/index.html

The 73 thru 75 GT250s are quite similar. For 76, Suzuki redesigned the motor for a bit more top end performance.

[ga2wheel]

thanks.
have another question. the cylinders when from carb bolt on to a rubber mount bolted to clamp on the carbs. are the cylinders essentially the same if you remove the studs?

[jabcb]

The cylinders are different. The porting was changed.
The cylinder heads are also different. They switched from a separate head for each cylinder to a one piece head for both cylinders.

[ga2wheel]

the frame is a 77 but it is not the original motor. from what I can tell it is a 75 motor. which still had the ram air covers for the head.
it does have the larger clamp on carbs. which I assume started is 75 or so?
either way only one cylinder is worth recording, the other is maxed out. and I need to rebuild the crank so both rods wrist pin diameter match.
by the way...the tanks was pretty rusty. tried the molasses and water soak....and it worked well. not as good as 3 gallons of metal rescue but good enough with an inline filter. only downside...smells like ass after 4 weeks

[jabcb]

See Service Bulletins GT-30, GT-32 & GT-35
[url]http://www.ozebook.com/compendium/ ... 027-33.pdf
http://www.ozebook.com/compendium/techb ... 034-39.pdf" onclick="window.open(this.href);return false;[/url]

Check the number of transfer ports to determine if you have 73-75 or 76-77 cylinders.

You have a 75 crankcase per the VIN.
Suzuki changed which crank main bearings are fed by the oil pump, so you can also determine if you have a 73-75 or 76-77 crankcase by the RH oil lines.

Another important difference: the 73-75 crankshaft has 3 main bearings but the 76-77 crankshaft has 4 main bearings.

There are several different alternator stators with different timing marks. Would be a good idea to use a dial indicator to sort through this. Also read about the timing variations in the service bulletins.

You might have a mix & match combo motor:
76-77 cylinders & carbs
73-75 crankcase & heads
one 73-74 piston + connecting rod
one 75 piston + connecting rod
(piston & connecting rod part #s changed but I don’t know what the difference is.