Suzuki 2 Strokes

6 years after rebuilding the top end on my triple, the head gasket on the centre cylinder has started weeping a little oily crud. And now one of the nuts isn't taking the torque, it just keeps on turning: feels like the thread in the cylinder has fatigued and given way, which has happened before

Even using genuine Suzi gaskets, new spring washers and nuts on the rebuild, the two rear nuts on the centre cylinder would always loosen and need retorquing every 1000 miles. All the others were solid.

So that's it -- I'm getting that stud fixed and the head cut into three individual sections to see if it sorts the head gasket problems. I will report on progress.

Craig380 wrote:6 years after rebuilding the top end on my triple, the head gasket on the centre cylinder has started weeping a little oily crud. And now one of the nuts isn't taking the torque, it just keeps on turning: feels like the thread in the cylinder has fatigued and given way, which has happened before

Even using genuine Suzi gaskets, new spring washers and nuts on the rebuild, the two rear nuts on the centre cylinder would always loosen and need retorquing every 1000 miles. All the others were solid.

So that's it -- I'm getting that stud fixed and the head cut into three individual sections to see if it sorts the head gasket problems. I will report on progress.

Good luck with it Craig,
I put some 12mm threaded inserts into the barrels of my gt500 to replace the aluminium threads..some of the threads had been helicoiled years ago. I just drilled & tapped the holes 12mm, bolted & loctited the threaded holes with stainless bolts then cut them off & filed them flush with the tops of the barrels. Finished them off
with valve grinding paste on an old surface plate to get the tops of the barrels perfectly flat. I flatted the heads off also with the paste/ surface plate...assembled the top end & drilled & tapped the inserts 8mm as Suzuki intended. I realize that the gt500 has studs as well as the top bolts that hold the head on but the 380 just has the heads bolted straight onto the barrels? I would do this repair but just do 2 diagonally at a time so that everything would line up when all four are bolted down. A word of warning if you do this, bolting stainless bolts into the barrels could potentially distort the bore, so I honed my bores before the final build up. So far I've put 300 miles on it now & its running ok.
I'm in Sheffield!

Tim.

Its the only way to deal with the problem, having a fixed head over three separate cylinders is not the best idea.
Remember to cut outside of the fins for the centre head portion, if not it will be too narrow.

I have seen this very problem encountered by another 550 GTer and this is what he did also ( cut the head into 3 parts )

Dave if you're referring to Eric he also got sick and tired of the re-occurring leaks and cut his head up on the 550. Since then hes had no more issues.

Yep .. Eric .. i contacted him to check the fix and he also said thats what he did to fix the head leaking issue and he said dont over torque the head bolts as they like to pull out .

Suzukidave wrote:Yep .. Eric .. i contacted him to check the fix and he also said thats what he did to fix the head leaking issue and he said dont over torque the head bolts as they like to pull out .

I think that's one of the major causes here. Three separate cylinders will rarely give a truly level, even deck for the head to rest on ... one jug will often sit just a tiny bit higher or lower than the others. The sandwich-type head gaskets will remedy some of this unevenness, but not all.

Then when you torque the head down, the studs on the slightly lower cylinder will be subject to more stress. Over time, this will allow a slight 'fretting' motion which can work-loosen the head nut. So you retorque, and this fretting will start again, and eventually damage the threads in the alloy barrels.

My feeling is that converting to 3 individual heads should eliminate the fretting and allow each head to be clamped more evenly by the head nuts, without being affected by its neighbour.

Once our friend Eric had done the mod on his 550 he has had no more issues. Let us know how you get on with it Craig.