Suzuki GS750. using oil.

[Brendan W]

1000ml = appx. 1 qt pr 200 mi... That's a whole lot.

And some.....
You know it's time to fix leaks when you plant your boot at a stop and it slips

[bob808]

I did not do the leak down ( not intentionally), I just started taking it apart. I already know all the valve specs are within tolerance and will rebed the valves and reseal the stems on rebuilding.

The pistons have not been cleaned they are coated lightly with oil. HUH !
I guessed the gaps looked big ( on the pistons) . But will gap check when required
The bores are great and pistons clean.

I will now take it to the engineer to have the bores measured, its £30.00 for a tool and I dont think the shop would charge much more. Then they can hone or rebore as required, and I know its good.
Worried about them not being round. Thanks.

[Cipher]

What would you recommend?

Castor oil jk. I saw Aberdeen and assumed lowish ambient temperature being combined with short run times to be not allowing oil to flow adequately.

But seriously during your rebuild did you check the play in the valve to guide? Excessive slop would be hard on seals.

As a superfluous aside too light a synthetic runs through my old bike at a disturbing rate. Rotella t6 burns off but t5 mineral does not drop significantly between oil changes.
this is whilst being flogged in a 30 deg. plus environment.

[bob808]

Castor oil jk. I saw Aberdeen and assumed lowish ambient temperature being combined with short run times to be not allowing oil to flow adequately.

But seriously during your rebuild did you check the play in the valve to guide? Excessive slop would be hard on seals.

As a superfluous aside too light a synthetic runs through my old bike at a disturbing rate. Rotella t6 burns off but t5 mineral does not drop significantly between oil changes.
this is whilst being flogged in a 30 deg. plus environment.

Yeah checked all the valve specs, even bought a set of ball gauges. I found my piston ring gaps seem very large. How do I upload pics?

[bob808]

So just a quick update, Went to the machine shop. The barrels are oval front to back, and enlarged bottom to top. The pistons are toast too. So its a re-bore then. Just going to stick to 750cc cos the head has been skimmed previously. Thanks for the advice. Any opinions on IMD Pistons?

[rphillips]

2 smalls, How many and what part of the pistons are worn out? and how much will need to be removed to get the cylinders back straight in both directions?

[Nessism]

I've heard decent things about IMD pistons. While your at it, I'd ask about a simple valve job on the head; lightly cutting the seats and facing the valves is way better than lapping and shouldn't cost too much.

[bob808]

3 thou. Front to back,2 thou top to bottom and 2 thou on the pistons. Took the call at work so he said something else about the pistons and I'm not sure what. Anyway he said that was that and that I needed a rebore. Valve job sounds like a good idea. Should I strip the head before handing it over?

[bob808]

Another thought!


Do I look at the crank,rods ,bearings, the seals on the ends of the crank are fine?

[Nessism]

On 2nd thought...

In all my years here, I've never heard of anyone wearing out a set of pistons and cylinders in 24,000 miles. 124,000 miles, yes. Which is what I'd expect to get out of the engine if it's well cared for. Never in 24k. Something doesn't sound right about that machine shop that took the measurements.

Before going off the deep end, I'd remove the rings from a piston, put it into each cylinder up side down, then take a feeler gauge and cut it between the piston and the cylinder wall. The point of max wear is near the top. Most likely, you won't be able to cut in a .0025" feeler gauge, which would indicate you are okay.

I'd buy a cheap set of new rings off eBay, get a bottle brush hone with 240 grit stones, and get to work. Better check the valve stem seals because it's possible to damage them on install.

[bob808]

I was beginning to think the same thing, with regard to mileage / wear. Only I was thinking perhaps the clocks were swapped, interesting.I will check out the wear on the pistons, and post it on here, soon as I get a chance. .Im off to look at hones.

[Nessism]

I was beginning to think the same thing, with regard to mileage / wear. Only I was thinking perhaps the clocks were swapped, interesting.I will check out the wear on the pistons, and post it on here, soon as I get a chance. .Im off to look at hones.

When doing the feeler gauge test, measure at 90 degrees to the pin, at the bottom of the skirt, about 1" down into the cylinder.

https://www.amazon.com/67mm-Flex-Hone-Cylinder-Silicon-Carbide/dp/B002N36MOA