piston rings

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

No eBay APP ID and/or Cert ID defined in Kunena configurationStock size.

If money is tight...
Otherwise, get original Kawasaki rings...13008-059 RING SET,PISTON,STD

MANUAL?
Steve

BTW, make sure the valves are adjusted properly before attempting to perform a compression test. A lot of idiots never adjust the valves and before long the clearance is gone and the valves don't close properly (leading to poor compression). Also, if the bike hasn't run in a while you can not perform a proper compression test anyway.

When rehabbing a bike that has sat for a year or longer first thing to do is make sure the valves are adjusted and then focus on spark and carbs. Get the bike running and then perform a proper Italian tune up on it. After a good hard tank of fuel is run through the engine THEN you can try that compression test. You will see a significant increase in compression at that point compared to testing a barn find bike that hasn't run in a while.

Nessism wrote: BTW, make sure the valves are adjusted properly before attempting to perform a compression test. A lot of idiots never adjust the valves and before long the clearance is gone and the valves don't close properly (leading to poor compression). Also, if the bike hasn't run in a while you can not perform a proper compression test anyway.

When rehabbing a bike that has sat for a year or longer first thing to do is make sure the valves are adjusted and then focus on spark and carbs. Get the bike running and then perform a proper Italian tune up on it. After a good hard tank of fuel is run through the engine THEN you can try that compression test. You will see a significant increase in compression at that point compared to testing a barn find bike that hasn't run in a while.

Should probably add 'change the oil' to that list as well (before the italian tune up bit). Would also be an appropriate time to add seafoam/MMO/whatever to the crankcase.

jackleberry wrote:

Nessism wrote: BTW, make sure the valves are adjusted properly before attempting to perform a compression test. A lot of idiots never adjust the valves and before long the clearance is gone and the valves don't close properly (leading to poor compression). Also, if the bike hasn't run in a while you can not perform a proper compression test anyway.

When rehabbing a bike that has sat for a year or longer first thing to do is make sure the valves are adjusted and then focus on spark and carbs. Get the bike running and then perform a proper Italian tune up on it. After a good hard tank of fuel is run through the engine THEN you can try that compression test. You will see a significant increase in compression at that point compared to testing a barn find bike that hasn't run in a while.

Should probably add 'change the oil' to that list as well (before the italian tune up bit). Would also be an appropriate time to add seafoam/MMO/whatever to the crankcase.

I'm not a big fan of oil additives. Some MMO in the gas tank is a good idea though. It will help loosen up any carbon in the ring grooves. Back to the oil, if someone wants to flush out any sludge that may have accumulated I'd simply put the bike on a 1000-1500 mile oil change schedule. Use a high detergent oil like diesel engine oil too. This method will get rid of the sludge slowly and not dilute your oil. The problem with oil additives that reduce viscosity is that you can't get all of them out during the change.

Regarding your question about +1 size, that's probably for the next larger sized piston (first overbore.) If you're on stock bore, you want stock size piston rings.

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.

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

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

Smoke on startup is probably valve guide seals.

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.

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