yes. pulled engine lots of carbon on top of piston and head cleaned both,
found the oil rings were compressed into groove completely even with the piston, also there was no movement when trying to push in. the compression rings had movement and stuck out from the piston grooves like i have seen in the past. there were no hash marks on cylinder walls and i know that it is needed, is there a way to put back without buying that ball hone
found the oil rings were compressed into groove completely even with the piston, also there was no movement when trying to push in. the compression rings had movement and stuck out from the piston grooves like i have seen in the past. there were no hash marks on cylinder walls and i know that it is needed, is there a way to put back without buying that ball hone
Unstick the rings. Clean the ring grooves in the piston. CLEAN as in hospital clean. Put it back together. Forget about the hash marks. Run the sucker at max revs all the time. Keep the oil on the full mark at EVERY mow.
New rings will require honing slash bore prep. Current rings are already broken in.
Make sure the rings rotate around the piston loosely before putting the piston back in the bore. Oil the rings before reinstalling. Clock the rings 120 degrees apart or whatever the engine manual says to.
New rings will require honing slash bore prep. Current rings are already broken in.
Make sure the rings rotate around the piston loosely before putting the piston back in the bore. Oil the rings before reinstalling. Clock the rings 120 degrees apart or whatever the engine manual says to.
StarTech
Lawn Royalty
- Joined
- Feb 19, 2020
- Threads
- 115
- Messages
- 12,512
Actual ball or flex hones are for breaking the glaze and will make taper and out of round worst. You would need a ridge hone to true a cylinder. and you go pass
0.005 of the current spec you need to hone to the next oversize.
0.005 of the current spec you need to hone to the next oversize.
Awesome! Everyone print @7394 post and attach it to your mower as a reminder every time you use it!!
sgkent
Lawn Addict
- Joined
- Sep 27, 2017
- Threads
- 35
- Messages
- 1,964
check your fuel to be sure that it has not aged poorly. Ethanol can cause issues when it sits. So can gasoline dripping into cylinder, be sure the oil is not being diluted with gasoline. It may not be the MMO that improved things but rather clean oil. I did a scientific study many years ago. Took some carbon chunks off the intake valves of a the CJ7 I had at the time. Soaked each piece, about half the size of a marble in different fluids for a week. Water - zero effect, Acetone - zero effect, MMO - zero effect, GM Upper cylinder cleaner (No longer available except old stock on ebay etc) softened it to like toothpaste in a few hours and completely dissolved it in about 3 or 4 days, Berryman's B-12 - some softening, Traditional Berrymans carb dip - dissolved it about the same as the GM product but different chemical. So based on that I would say it is not the MMO cleaning up your engine.
Really should not throw used rings back in a cylinder. It is a bush type fix. Should be new rings and a Sunnen hone to break the glaze and cross hatch the cylinder. It will also straighten out the cylinder a small amount. The way to test a guide is to pull the keepers and retainers off, then push the valve so it is open may 3/8". Rock the head. Should be minimal movement. If you get say .006 to .008" movement then the guide is worn. Replacing them on an engine of this kind is a real rabbit hole. Also, each guide made will be slightly different where the center line is. So when guides are replaced, the valve seats have to be touched up too. Normally the guides have about .003" to .004" clearance for oil, and half of that is what each side of the stem sees. If the valve rocks .008" then the clearance around the valve is .004", which is so much it will let oil burn and keep the valve from properly seating.
here is a video of a small mower head being properly rebuilt. You won't find many shops that have the ability to do this. They were doing this one for a neighbor. Normally you just buy a new head except valve in block engines. Then find a machine shop that builds go cart racing engines.
Really should not throw used rings back in a cylinder. It is a bush type fix. Should be new rings and a Sunnen hone to break the glaze and cross hatch the cylinder. It will also straighten out the cylinder a small amount. The way to test a guide is to pull the keepers and retainers off, then push the valve so it is open may 3/8". Rock the head. Should be minimal movement. If you get say .006 to .008" movement then the guide is worn. Replacing them on an engine of this kind is a real rabbit hole. Also, each guide made will be slightly different where the center line is. So when guides are replaced, the valve seats have to be touched up too. Normally the guides have about .003" to .004" clearance for oil, and half of that is what each side of the stem sees. If the valve rocks .008" then the clearance around the valve is .004", which is so much it will let oil burn and keep the valve from properly seating.
here is a video of a small mower head being properly rebuilt. You won't find many shops that have the ability to do this. They were doing this one for a neighbor. Normally you just buy a new head except valve in block engines. Then find a machine shop that builds go cart racing engines.
Last edited:
Auto Doc's
Lawn Addict
- Joined
- Sep 7, 2024
- Threads
- 18
- Messages
- 1,510
Hello ACF,
Check on Ebay for a "small engine cylinder hone". (They are very affordable) They have 3- stones usually. You need a fine grit in the 320-400 range, just enough to see a pattern (Watch some videos online to get a feel for it). Avoid a ball hone design, they were good to use for the older cast iron blocks, but not so good for newer engine cylinder designs.
This is not the space shuttle we are talking about.
Replace the rings as a set and follow the service manual procedures.
Check on Ebay for a "small engine cylinder hone". (They are very affordable) They have 3- stones usually. You need a fine grit in the 320-400 range, just enough to see a pattern (Watch some videos online to get a feel for it). Avoid a ball hone design, they were good to use for the older cast iron blocks, but not so good for newer engine cylinder designs.
This is not the space shuttle we are talking about.
Replace the rings as a set and follow the service manual procedures.
- Joined
- Sep 24, 2017
- Threads
- 282
- Messages
- 6,825
FRs didn't have to best air filtration.
Pull your air filter off and check for excess dirt in the air intake.
Pull your air filter off and check for excess dirt in the air intake.