piston rings

New seals and check the valves and guides. At that point you can tell if the rings are leaking too.
Steve

blink543 wrote:

Irish Yobbo wrote: Did you do a wet test as well to ensure it's the piston rings? If not, it's a good way to tell if it's your guides or rings.

Do a compression test on all cylinders - you say one is low. Now put a small amount of oil in the cylinder with an eyedropper, and repeat for each cylinder. The excess oil will seal better, so if your compression jumps significantly, you know it's the rings.

It's good to do the wet test on all cylinders, as you will have a comparison to work with. It's not unlikely it will raise the compression on all your cylinders, but if the one reading a low compression jumps up a lot more than the others, it's the rings. If they all stay much the same or all increase just a little, it's more likely to be a valve.

It might be a valve. I'm planning on switching out the top end anyways with a used top because my tach holder snapped off because of my dumbass. So how might I see if the valve seals are good on the other top that I'm switching to? Also it's a bit rusty in the inlet ports of the other head piece I'll send pics later

Once you've removed the head, you've already incurred most of the cost of a ring job. All those gaskets and little o-rings and seals add up quick. You need to diagnose this problem with the motor intact, then decide what to replace. If wouldn't 'hurt' to replace the rings, though (and no, at such low milage you don't have to bore and go to the next oversize unless there's obvious damage to the bore, just a hone and new rings get some more life out of it).

blink543 wrote:

bountyhunter wrote:

blink543 wrote: When I took my bike to a mechanic before he did a compression test and said one of my cylinders were lower on compression. So how would I go about changing my rings? I've looked online and it's kinda hard to find them. Would I replace them with stock size rings or +1 size? It only has like 27,000 miles on it now. 78 kz650b

You need to bore and go up size on the pistons and rings. +1 is 1mm oversize, there are also 0.5mm sets.

I am very surprised you need rings at only 27k miles. Make sure it isn't just valves which it usually is. You get oil crud build up on the valve seat and then the valves don't seat tight.

Well Its blowing blue smoke on start up for a while. So where's the oil burning coming from? I adjusted the valves a few months ago in the summer

Almost certainly valve seals. They need replacing about every 30k miles.

blink543 wrote:

Irish Yobbo wrote: Did you do a wet test as well to ensure it's the piston rings? If not, it's a good way to tell if it's your guides or rings.

Do a compression test on all cylinders - you say one is low. Now put a small amount of oil in the cylinder with an eyedropper, and repeat for each cylinder. The excess oil will seal better, so if your compression jumps significantly, you know it's the rings.

It's good to do the wet test on all cylinders, as you will have a comparison to work with. It's not unlikely it will raise the compression on all your cylinders, but if the one reading a low compression jumps up a lot more than the others, it's the rings. If they all stay much the same or all increase just a little, it's more likely to be a valve.

It might be a valve. I'm planning on switching out the top end anyways with a used top because my tach holder snapped off because of my dumbass. So how might I see if the valve seals are good on the other top that I'm switching to?

You need to change them anyway while it's apart, and lap the valves. The cost is minimal compared to having to tear it down later to do it.

So my rings are shot I did a compression test and cylinders 3 and 4 had a low dry compression at about 135 psi. Then I put oil in the cylinders and it shot up to 180. I dif this when the bike was cold tho. I heard it doesn't make too big of a difference

blink543 wrote: So my rings are shot I did a compression test and cylinders 3 and 4 had a low dry compression at about 135 psi. Then I put oil in the cylinders and it shot up to 180. I dif this when the bike was cold tho. I heard it doesn't make too big of a difference

You're crazy to declare rings holding 135 psi as "shot". Was this compression test performed HOT while holding the throttle wide open?

Blue smoke on start up is more likely a valve stem seal issue than rings.

blink543 wrote: So my rings are shot I did a compression test and cylinders 3 and 4 had a low dry compression at about 135 psi. Then I put oil in the cylinders and it shot up to 180. I dif this when the bike was cold tho. I heard it doesn't make too big of a difference

I wouldn't say shot exactly. It'll run OK down to about 110PSI cold, could take you another 40k miles to get that bad... Rings can get gummed up with carbon which cements them in the piston gooves and causes low compression. There are various snake oil type treatments which may result in some improvement if that's the issue. Just riding hard can provide the quickest result (if it works). All the soak/stuff in the crankcase methods take more time and miles.

But like I said before, if you're going to take the head off anyway, doing the rings at the same time will only add $75-$125 to the expense.

I don't recall if you mentioned it yet, but have you torqued the cylinder head nuts down to spec? As the head gasket compresses and they get loose and this causes low compression and sometimes oil leaks...

Start by reading the engine section in your factory service manual. At the very least you can refer to parts with their proper names. Definitely read through before starting anything.

jackleberry wrote:
But like I said before, if you're going to take the head off anyway, doing the rings at the same time will only add $75-$125 to the expense.

Kawasaki rings for that bike are P/N 13008-059
Best price I've found on real OEM rings are $52/hole, so you are talking about $208 + shipping for a set. There are aftermarket rings though that are cheaper.

jackleberry wrote:

blink543 wrote: So my rings are shot I did a compression test and cylinders 3 and 4 had a low dry compression at about 135 psi. Then I put oil in the cylinders and it shot up to 180. I dif this when the bike was cold tho. I heard it doesn't make too big of a difference

I wouldn't say shot exactly. It'll run OK down to about 110PSI cold, could take you another 40k miles to get that bad... Rings can get gummed up with carbon which cements them in the piston gooves and causes low compression. There are various snake oil type treatments which may result in some improvement if that's the issue. Just riding hard can provide the quickest result (if it works). All the soak/stuff in the crankcase methods take more time and miles.

But like I said before, if you're going to take the head off anyway, doing the rings at the same time will only add $75-$125 to the expense.

I don't recall if you mentioned it yet, but have you torqued the cylinder head nuts down to spec? As the head gasket compresses and they get loose and this causes low compression and sometimes oil leaks...

No I don't have a torque wrench yet. I'll do the test again when the engine is warm. U guys are probably right

Nessism wrote:

jackleberry wrote:
But like I said before, if you're going to take the head off anyway, doing the rings at the same time will only add $75-$125 to the expense.

Kawasaki rings for that bike are P/N 13008-059
Best price I've found on real OEM rings are $52/hole, so you are talking about $208 + shipping for a set. There are aftermarket rings though that are cheaper.

I didn't know I could do after markets

jackleberry wrote:

blink543 wrote: So my rings are shot I did a compression test and cylinders 3 and 4 had a low dry compression at about 135 psi. Then I put oil in the cylinders and it shot up to 180. I dif this when the bike was cold tho. I heard it doesn't make too big of a difference

I wouldn't say shot exactly. It'll run OK down to about 110PSI cold, could take you another 40k miles to get that bad... Rings can get gummed up with carbon which cements them in the piston gooves and causes low compression. There are various snake oil type treatments which may result in some improvement if that's the issue. Just riding hard can provide the quickest result (if it works). All the soak/stuff in the crankcase methods take more time and miles.

But like I said before, if you're going to take the head off anyway, doing the rings at the same time will only add $75-$125 to the expense.

I don't recall if you mentioned it yet, but have you torqued the cylinder head nuts down to spec? As the head gasket compresses and they get loose and this causes low compression and sometimes oil leaks...

Well when the engine was cold I added oil to the two lower psi cylinders and they shot up right away. So Idk what that means? Obviously a good seal.