Gt550 Pistons

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Raytuckgt
Posts: 59
Joined: Mon May 30, 2016 8:55 pm

Gt550 Pistons

Postby Raytuckgt » Fri Jun 30, 2017 8:54 pm

Gents, I'm going to get my engine rebored but looking at Pistons on eBay they say that there Pistons don't fit Nykasil cylinders , how do I know if my 1975 , M , has these, rgds
Ray.

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Alan H
Posts: 9266
Joined: Fri Aug 05, 2011 6:38 am
Location: Wombwell, Republic of South Yorkshire

Re: Gt550 Pistons

Postby Alan H » Fri Jun 30, 2017 11:36 pm

Firstly, you cannot rebore plated cylinders only the iron bore barrels.
You can have the SCEM (Suzuki Composite Electrochemical Material) barrels replated but it's very expensive.
Easy to identify, the back 2 base stud holes are higher than the front ones, and there are 2 extra ports in the barrels.
Another difference is that the early iron bore barrels have chrome plated rings and the Nikasil/SCEM bore barrels have cast rings.
Pics aren't too good but the difference is easy to spot.
The pistons are different too due to the extra ports.
The top pic shows the extra ports.
You can fit the late barrels to early cases and early barrels to late cases (with correct rear bolts),and the engine will run, but the ports don't match and it'll be way down on power and the carburation will be way out.
Attachments
barrel.jpg
late barrels.jpg
Late type SCEM or NIKASIL plated
early barrels - US import.jpg
Early iron bores
Proof that four strokes are over complicated

Raytuckgt
Posts: 59
Joined: Mon May 30, 2016 8:55 pm

Re: Gt550 Pistons

Postby Raytuckgt » Fri Jun 30, 2017 11:56 pm

Cheers Alan.....
Ray.

Raytuckgt
Posts: 59
Joined: Mon May 30, 2016 8:55 pm

Re: Gt550 Pistons

Postby Raytuckgt » Sat Jul 01, 2017 11:57 am

image.jpg
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Looks like I can rebore these do you agree....
Ray.

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Alan H
Posts: 9266
Joined: Fri Aug 05, 2011 6:38 am
Location: Wombwell, Republic of South Yorkshire

Re: Gt550 Pistons

Postby Alan H » Sat Jul 01, 2017 12:35 pm

Yes. They are the iron bore type. Make sure you measure them carefully before you get them done as it may be the pistons that are worn, not the bores. 1st telltale is the nail catcher if you try to scratch the bores near the top between the bore top land and just below the faces where the piston rings stop.
Chris Appleby is good, just did my crank on the hippo, but have a word with Baz unless you have someone local who knows and understands 2 strokes. Also check what rebore size you need - and can actually get.
Proof that four strokes are over complicated

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PaulD738
Posts: 2894
Joined: Thu Sep 25, 2014 6:57 pm
Location: Warrington Cheshire

Re: Gt550 Pistons

Postby PaulD738 » Sat Jul 01, 2017 3:15 pm

Handy hint #1 keep those cooks matches handy then you can quickly set fire to the bloody thing when it all goes pear shaped :lol:
There rubbish them Jap bikes lad they won't last five minutes! you want to get yourself a nice Royal Enfield!
A quote from my old dad 8-)

I started out with nothing and I’ve got most of it left!

Raytuckgt
Posts: 59
Joined: Mon May 30, 2016 8:55 pm

Re: Gt550 Pistons

Postby Raytuckgt » Sat Jul 01, 2017 7:29 pm

Thank you big help
Ray.


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