Honing a two-stroke bore

[Motu]

Pretty standard to use very little oil on rings these days,but smearing them in oil is a hard habit to break - modern rings have such low wall tension they need all the bed in help they can get.We used to assemble compressors dry when I worked on them - there is no power stroke,and that is what seats rings.

[F5 Dave]

Just to add in, you should not use a expanding finger type hone in a 3 stroke [Ok that was a typo but looks funny so I left it in] as could get stuck in a port & the unthinkable happen. But can use long stones set up in lathe, but a ball hone as said is the best. You can ball hone plated cylinders to remove glaze, but I wouldn't anyway, just some scotchbrite is fine.

Only a real light hone is required. I've done my race engines literally hundreds of times without hone, but they don't do big miles in between inspection, then I often only use some emery. Compression always comes up real well.

Spend some time on a new bore chamfering the ports & finishing with fine emery or I have a ciggy size oil stone.

[Danger]

Don't forget to trim the base gasket so that it matches the cylinder or the base and does not protrude. Sometimes the bottom of the cylinder can be touched up to match the base as well. Free hp.

[PZR]

Don't forget to trim the base gasket so that it matches the cylinder or the base and does not protrude. Sometimes the bottom of the cylinder can be touched up to match the base as well. Free hp.

Would you mind elaborating a bit as I am not quite sure what you mean??

[Rhino]

Would you mind elaborating a bit as I am not quite sure what you mean??

This is a trick I used when building racing 2 strokes for a number of years. Put a base gasket on the crankcase and make sure that it is trimmed to fit the area of the transfer ports without sticking into the port area.

Take the same gasket, turn the cylinder upside down and place it on the bottom of the cylinder. Once again check that the casting for the port is not visible inside the gasket. If it is, you need to grind the bottom of the port passage back to ensure that no step is left when all is assembled, otherwise you are being robbed of horsepower.

[PZR]

Thanks for that I will check it out

[Buddy L]

otherwise you are being robbed of horsepower.

Bugger if only i new about this two weeks ago, might not have been pasted by ArcherWC on the last lap on the rodney mx on the weekend.


Another handy tip -004
only found on KB

[F5 Dave]

Ahh, for all you know that little lip causes some turbulence causing the remixing of fuel & air otherwise about to fall out of suspension of the gas stream in the transfer ports.

Remove it & you end up with a wet-but-lean mixture & your throttle response falls off along with peak power. On top of that the lowering of the primary compression ratio will decrease scavenging at out of pipe frequency revs so you don’t hook up as well.

He'll pass you the lap before & gain admiration of the trophy girl who has a thing for 8th place riders & wouldn't consider a 9th placer & you'll come back to a flat on the trailer & the dog will have run away.

[ok I might be kidding]

[Buddy L]

[ok I might be kidding]

NO, thats pretty much what happened, don't now about the 8th and 9th im no champion, i was gunning for the tail end charlie most of the races.

[cheese]

Could be the fact that you ride a 125 and he is on a 250..........

[barty5]

Just to add in, you should not use a expanding finger type hone in a 3 stroke [Ok that was a typo but looks funny so I left it in] as could get stuck in a port & the unthinkable happen. But can use long stones set up in lathe, but a ball hone as said is the best. You can ball hone plated cylinders to remove glaze, but I wouldn't anyway, just some scotchbrite is fine.

Only a real light hone is required. I've done my race engines literally hundreds of times without hone, but they don't do big miles in between inspection, then I often only use some emery. Compression always comes up real well.

Spend some time on a new bore chamfering the ports & finishing with fine emery or I have a ciggy size oil stone.

rebuilt heaps a bike but none with plated bores just about to do my yz426f so your saying i should go over it with a scotchbrite litely??????????

[F5 Dave]

Only if you have a bunch of glaze to remove. Otherwise no, fine as is. Do inspect the plating in a decent light.