Piston Question

[Stralya]

Stupid question #134

OK, I installed my 1196 kit without checking the ring gaps. It has 650kms on it since the re-build and so far so good. Petejw and I are going to rebuild his motor next winter and we will check the ring gaps before installation.

What I want to know is what symptoms should I be watching for on my bike that might tell me if my ring gaps are too narrow and if they are, will I need to buy a new set of rings or a whole new kit?

I'm probably getting ahead of myself because like I said so far so good but I too didn't notice that line in the instructions and with my luck.....

Thanks

Dan
Mildly concerned.

[79XS11F]

OK We all know that everything expands when it gets hot and the rings even if circular get longer and thicker when they get hot. That's why there are specs for ring clearance between the rings and the ring groves and specs for end gaps.
If the ring end gap was excessively too small, the rings, when they expand and get longer, can fully close that end gap. If they need to expand further they will actually increase their total DIA and become VERY tight against the cylinder walls and can remove the honing very quickly, remove too much oil and in a worst case scenario seize to the walls because of the added heat that is created by this increased friction and the lack of oil present because they will have fully removed the oil by their tightness to the walls.
Check your manual on ring replacement and it will tell you in there that skipping this step can lead to engine failure.
Is it a panic situation .. no one can say because no one knows what the gaps were when the rings went into the engine. If it were me I would just be sure to keep the oil good alway full to the mark. There's not a lot else that you can do at this point is there.
Rob

[pggg]

If the bore specs are good the wiseco rings will be too

[Stralya]

That's a relief.

[petejw]

Usually the shop that does the machining
will also check ring end gap,
Stralya, urs is sweet 2 go.

[Stralya]

Thanks mate.

[trbig]

I only took mine the pistons to measure and bore to. Ring gaps will be my responsibility. I could see them doing that if they were assembling the motor for you, but not just as part of the boring job. They aren't resposible for your ring gaps... just the piston to cylinder gap.

Tod

[Stralya]

Well I'll just have to rely on Wiseco engineering then.

[John]

Tod

You may also want to talk to Weisco about a break-in procedure. IIRC they told me to run it up to operating temp, then shut it down for a while, and repeat two more times, and to use a straight weight, non detergent oil.

[79XS11F]

Do you mean for head re-torquing? I was told this by a lad at the local bike shop. He told me to fire the engine up and bring it to full operating temp. Shut it down and let it fully cool and then re-torque the head. Then use the bike for for 100 KM and repeat the re-torque of the head once again with the engine cooled down. DO it again at 500 KM.
This is necessary due to the added compression of this kit. The head gasket MUST be torqued properly and remain torqued properly.
Rob

[trbig]

The Wiseco pamphlet just says to refer to the owners manual for proper break in procedures.



Tod

[79XS11F]

Yeah the Wisco instructions do in deed tell you to refer to your owners manual for proper break in procedures but do keep in mind that that would be for a standard factory piston replacement or a new bike break in. It is more about rev ranges etc during break in.
I spoke to the lad at the shop around the corner because he has done several of these on his own bikes (KZs) that he drag races locally and he told me to do the re-torquing that I described. I can only say that on each time I re-torqued there was head nut movement even if only small amounts.
Any time I checked head torque on my factory sealed XS1100 of years gone by I never saw any movement of the head nuts.
Rob

[trbig]

Every time I have put this thing back together.. even with re-using head and base gaskets.... I have had to re-torque the head nuts at least once, and the exhaust bolts several times. The valve cover screws can usually take a good going over also.

I have heard of the method you describe though with several heating up and cooling off cycles. I was told to do that with my 2-stroke dirt bike also... just never been able to stand it and had to take off on it! lol.


Tod

[MAXIMAN]

John's right. If you talk to Wiseco they'll tell you to get the engine up to Op temp then shut it down and let it cool. They told us an excellent way to seat the rings is on a dyno. Get the motor hot with a few runs then shut it down and let it cool completely. By the time this is repeated 4 or 5 times the rings will seat.

I can tell you from experience that did not happen with me. I had 125 psi of pumping compression only after 50 or 60 dyno runs. I had about the same when I left for Tahoe a couple weeks later.

After I rode to Tahoe and back last year (about 5000 miles) then and only then did I have 150 psi. So who knows if Wiseco is right.

Having said all that...sooner or later the rings WILL seat if the engine was put together properly.

[trbig]

if the engine was put together properly.

Just had to throw that jab in there didn't ya!


Tod