Suzuki 2 Strokes

Hi all I recently bought a 1976 GT550 and it came with 2 engines a 1974 and 76 but I don't know which is which . One set of barrels have large transfer ports than the other set . The engine cases as different again on transfer ports . One set has large holes in transfer ports and other is without and clear transfers . Also is there differences with crankshafts . Both engines are both fully dismantled so boxes of bits. I have workshop manual but isn't showing exploded view . I will be getting crank rebuilt once I know which one is the 1976 plus need set of piston and ring kit . I hope someone knows what I mean by vague description . And hi I am newbie to site .

One engine number is 11369 and other is 63849 GT 550 .

Welcome to the forum.

Look at the VINs & compare them to these:
http://www.ozebook.com/compendium/suzi/ ... /page1.gif
http://www.ozebook.com/compendium/suzi/ ... /page2.gif

Suzuki made more motors than frames.
The frame & motor VINs may match at the start of production run for a new model. But gradually the bikes are built with the motor VIN being higher numbered than the frame’s.

Check the parts manuals in the UK.
The EU version of the GT550 was upgraded around 1975 or 1976 to eliminate the exhaust couplers, have nikosil plated cylinders & have more power.

The US version didn’t get these upgrades. So I don’t know how the upgrades impacts your rebuild.

I’ve found old printed parts & service manual are a good place to start. They usually can be found on eBay.

Don't mix the barrels up as it appears you have a late engine with SCEM plated bores and 7 ports, and an earlier engine with iron bores and 5 ports.
Depending on the engine age, there are other differences too. You didn't expect all this to be straightforward did you?
Thread explaining stuff here - https://www.kettleclinic.co.uk/kcforum/ ... it=Nikasil

Thanks for info guys . I've sussed which barrels goes with engine cases . As far as engine no on page with models I can't find mine . One sit of pistons are +0.5 and other set is standard . The barrels with coating won't show surface rust will they but cast will ???

The enging/frame numbers reference only gives the numbers that model started with, not from/to, so if the next year starts with numbers higher than yours then yours is the model year previous. Suzuki were notoriously inaccurate with numbers and tended to take some engines out of certain model runs for racing and development I understand.
The scem plated barrels are much lighter than iron bore barrels as the alloy is plated without a steel liner, as well as the extra ports and rear base studs as described above.

Plated cylinders have longer studs at the rear, cast cylinders have all four the same length.

So the plated liner pistons is the quicker engine due to the extra exhaust ports ??? Or isn't there much in it ??? I've got brand new spannies to go on once bike is built ( long way off ) I can't use the plated barrels as there's a deep groove Down it and port throat damage .

jaybe64 wrote: ↑Thu Aug 12, 2021 1:26 am So the plated liner pistons is the quicker engine due to the extra exhaust ports ???

Yes. The extra 'holes' are called Schneurle ports and create better swirl in the combustion chamber for more top end.

Or isn't there much in it ???

about 6/7 HP.

I've got brand new spannies to go on once bike is built ( long way off ) I can't use the plated barrels as there's a deep groove Down it and port throat damage .

Well, I might have spares, depending on which barrel is poorly. Remind me which bit of the UK you frequent!

East Anglia . Cambridge . Alan The worst one is the left hand side but they all have scoring . Looks like they bashed out piston and hit the inner transfer port . The earlier engine has what looks like corrosion marks as pitted . So if you have the later barrels and price I would like them ( they have the longer back studs and black engine ) many thanks john

Forget the colour black engine as iam sure that's been done by previous owners. Phew looked at a complete set of barrels and pistons minus rings on a commonly used auction site £299 bummer as way out of my price range being I am on disability allowance and that would swallow the whole amount I get . I took out loan to buy the bike which iam now paying back . So if I get a L/H/S barrel I can save for replating .

Dunno about a black engine - they 'should' be unpolished aluminium, but if black floats your boat, then it must be right!. If we all liked the same, it would be a boring world.
I'll have a look and see what's in the stash. If you haven't heard anything by Monday, remind me as I'll have forgotten!!
This is mine with a Nicasil plated bore engine in the IOM.

Hello Alan I will be polishing engine cases as black is so old school . Nice picture . I am getting higspeed Moto GP ones with removable end cans . Well I will wait to hear back from you and if you haven't give you a reminder . I know it's the left I need or a set off you. I see a company in Weston super mare that does the replating . Langcourt.com . Well take care and a big thanks John

I used Langcourts in Feb this year for my 550a and they were very good.turned them round in a week.i have to watch my budget too as im disabled as well.not easy with these old girls ! Good luck amd i look forward to reports of progress .

Vulcanman could you give me an idea as to how much it costs Inc postage ???