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 Post subject: GT380 BARREL REPAIR
PostPosted: Wed Jun 17, 2020 5:44 am 
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Still in the Driveway

Joined: Mon May 04, 2020 7:51 am
Posts: 2
Country: United Kingdom
Suzuki 2-Strokes: GT250L 1974
Hi Suzuki People,
I'm a new member and owner of three GTs; 185, 250 & 380, which I am looking to repair and restore.
I have just begun to dismantle the GT380 A (USA import) and found that a previous owner has snapped off an exhaust stud in the left hand barrel, then badly drilled, partly missing the stud, resulting in a large hole which breaches the casting wall.
I have tried to remove the remains of the stud without success so far. In any event, the hole can't be Helicoiled and I assume a welded repair would be too expensive.
Can anyone advise me if a JB Weld repair would be strong enough to secure the exhaust? Alternatively, I will have to replace the barrel, are those from all models the same or do I need to get one from a GT380 A?

Many thanks


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 Post subject: Re: GT380 BARREL REPAIR
PostPosted: Wed Jun 17, 2020 10:03 am 
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Moto GP
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Joined: Mon Dec 13, 2010 4:32 pm
Posts: 3572
Location: southwestern Pennsylvania
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
I don't think the JBWeld fix will last very long.

I have no insight, but a weld repair might be cheaper than you think.

This is my understanding of the cylinders:
The early models (J/K - 72/73) have individual carbs, and the later models (L-B - 74/77) have a bank of carbs. The cylinders for those two groups are not interchangeable.

The use of SRIS also varied. (SRIS recirculates excess oil in the crankcase for each cylinder to the intake for different cylinder.) The early models (J-L - 72-74) have SRIS, and the later models (M-B - 75-77) don’t. The SRIS lines connect to the cylinder near the carb inlet. The models with SRIS have a fitting on the cylinder for SRIS & the models without SRIS don’t.

The bottom line of all of this is:
1) M-B (75-77) cylinders are the same. You can use any of these.
2) L (74) cylinders have the fitting for SRIS. You can use the cylinder if you block/seal/eliminate the SRIS fitting. Don’t know if there is any porting difference.
3) J/K (72/72) cylinders are incompatible.

_________________
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 73 project
T350 69, 71 & 72 project
T250 72
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE


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 Post subject: Re: GT380 BARREL REPAIR
PostPosted: Thu Jun 18, 2020 2:22 am 
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Expert racer

Joined: Mon Dec 01, 2008 2:52 am
Posts: 1225
Location: Manchester, UK
Jabcb is correct. The porting, stud-spacing etc is identical across ALL years but as he said, the earliest J/K model bikes had very short inlet stubs because they had individual carbs, not mounted on a rail. Those short stubs don't work with the later rail-mounted carbs.

If the cylinder is in good nick otherwise, try and find an engineering shop to drill out the stud, ally weld the hole, and drill/tap a new stud hole.

_________________
1976 GT380 - wounded by me, and sold on
2006 SV650S - killed by a patch of diesel and a kerb in Feb 2019
2017 SV650 AL7 - naked and unashamed


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 Post subject: Re: GT380 BARREL REPAIR
PostPosted: Thu Jun 18, 2020 5:38 am 
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Still in the Driveway

Joined: Mon May 04, 2020 7:51 am
Posts: 2
Country: United Kingdom
Suzuki 2-Strokes: GT250L 1974
Thanks Guys,
Very helpful and useful information.


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