1977 gt380 head nut torque needed

[angus67]

So I'm slowly getting together a gt380. I've got copper base gaskets, and head gaskets. I have been looking for torque specs for the head nuts. I know many of you have worked in garages and dealers thru the seventies and saw a few of these 2 strokes pass thru.
I'm tempted to go to 25ft/lbs. Seems a average for nut on studs, steel sleeves. It's a alum block, alum head, just like our xs650. I'm targeting low, that way if there is issue, I can snug up to 30#s.
Even the manual doesn't say.
Thanks in advance.

 

[MaxPete]

Hi Angus: I typed in “Suzuki GT380 head torque values” and found the following on a site called:

http://www.suzuki2strokes.com/forum/

You might find something there.

Pete

 

[angus67]

Thanks pete

 

[grizld1]

Jeez Pete that's a screwy board and a screwy thread! Angus, the "torque wrench adapter" they're nattering about is known in the trade as a crow's foot. Harbor Freight has 'em, so do many hardware stores. For tight spots don't be afraid to slim them down some on the bench grinder. The correction for extra length is a simple straight proportion. On your torque wrench, measure from the center of the handle to the center of the drive head. Then put a fastener in the crow's foot, and measure from the center of the drive hole to the center of the fastener; that's the length you'll add to the torque wrench with the crow's foot mounted 180* to the handle. Add that to the wrench length. Correction factor=wrench length/total length. Multiply your torque value by the correction factor. Example: if you have a 12" wrench and the crow's foot adds 1", the factor is 12/12+1=0.923. 25 ftlbsx0.923=23.07 ftlbs. (Ignore the .07; the wrench ain't that accurate).

The trick to getting copper gaskets to seal well is to anneal them and use a good sealant. Unlike steel, copper softens when quenched. With a larger item like a base or head gasket, I hang the gasket on a wire, set a bucket of water under it, and use two propane hand torches with flame spreaders to heat the gasket cherry red. Unwrap the wire from the nail that holds it, and drop the gasket straight into the H2O. For a sealant I like Permatex copper Spray-A-Gasket. HK Copper Coat works fine too.

 

[MaxPete]

Yeah - I hadn't had a chance to actually look at it Grizld1 - it isn't very well organized is it?

Good thoughts on the crows feet. They are inexpensive and easy to use in situations like Angus' GT380 base bolts.

 

[angus67]

I found spec of 26ft/lbs. That thread is all over the place with no reference links. My first hunch was 25#'s. I was only a pound off. The engine is out of the frame, so I don't need a contraption as described, but the torque multiplier is much appreciated.
This gt380 was my mother in laws, and my wife was in utero when mom rode it. It had been sitting in the back yard since my wife was born in 78. It is really crusty, but surprisingly, the tank is rust free. This is my first attempt at a restore.it will be quite a while before its ready to fire. I wanted to seal the engine back up, and get it blasted, and shove it in a corner until the roller is ready.
Thanks guys.

 

[MaxPete]

Superb - what a cool story Angus!

I must say that I’ve always had a soft spot for the Suzuki triples. My riding buddy at Engineerïng school had a 1975 GT550 and I always admired it. That thing had presence, torque, it handled well and was dead nuts reliable plus it sounded cool. I stared at those 3-into-fours for hours as we rode....

Truly, the “thinking-mans” two-stroke.

 

[grizld1]

Congrats on a cool project. I refurbed a GT380 in 1999 and rode it for a couple of years; enjoyed everything about it but the three sets of points to dial in and the gas guzzling. If you mount shocks 1/2" to 1" taller than OE it will wake up the steering and keep the mufflers from grinding asphalt when you pitch 'er over. Right, Pete, the 550 triple was hands down the pick of the litter.

 

[angus67]

The 550 also had a starter. A big plus as I get older. But alas, the 380 is kick only. The 3 points setup looks a bit confusing, hoping to find a conversion someday