GT550 engine life

[old racer]

Interesting. I didn't know that there was an early & late style for the GT750 crank.

The rods were different. The early ones used different pistons also. In 74, they changed the rods to the slotted-top style, and the pistons were modified to include the big thrust washers if I remember correctly.

You are spot on.

[old racer]

Did Suzuki make changes to the crankcase & cylinders to accommodate the new crank?
Can you, for example, use an early crank with a later crankcase?

All cylinders fit all crankcase.

[jabcb]

Someone near me is considering rebuilding a 1972 motor that has a bad crankcase so knowing the options may be useful.
Can you use a 1972 crank + cylinders with a 1975 crankcase?

[Alan H]

Did Suzuki make changes to the crankcase & cylinders to accommodate the new crank?
Can you, for example, use an early crank with a later crankcase?

All cylinders fit all crankcase.

Yes, but they don't work right.
Early (iron bores) barrels fitted to late UK crankcases don't line up ports as Nikasil barrel engines have extra ports cast into the cases and barrel bases. US engines only had iron bore barrels.
There are also differences in carbs, heads, barrel/head shapes and lots of other stuff.
The early heads with early carbs also crash the petrol tap on later tanks as the tanks changed as well.
Sooooooooo.................

Different part numbers on early and late cranks too.
The frames changed, and lots of other stuff including exhausts, wiring, clocks, handlebar controls, even back light unit - at least 4 types of that to make it interesting.

http://www.alpha-sports.com/suzuki_parts.htm" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false; makes interesting research.

[tato81]

...Early (iron bores) barrels fitted to late UK crankcases don't line up ports as Nikasil barrel engines have extra ports cast into the cases and barrel bases. US engines only had iron bore barrels.
There are also differences in carbs, heads, barrel/head shapes and lots of other stuff.
The early heads with early carbs also crash the petrol tap on later tanks as the tanks changed as well....

[/quote]

Are there differences in carburettors? For example, a carburetor from Suzuki GT750 1976 for the USA (iron barrels) and Suzuki GT750 1976 for the Europ (NIkasil barrels)? I can get USA carburettors from 1976 but I don't know if they will be good for my Nikasil barrels. In 1976 in the USA they were also mounted on batteries.

[Craig380]

According to this useful guide: https://www.oldjapanesebikes.com/mraxl_ ... les/page-9" onclick="window.open(this.href);return false;

the carbs from a USA-market 1976 550 should fit any other 1976 550 bike, but they might need a different main jet.