Honing a two-stroke bore

[PZR]

I want to hone the bore on my 2 stroke (its been sleeved) and give it some new rings. Can anyone recomend someone intelligent in south auckland that wont fuck it up. I can courier it out of town if you know someone real good elsewhere. Also, where is a good place to get some 76mm rings for a good price?

[Motu]

If you don't trust anyone else then do it yourself with some emery tape - then you will know who to blame.

[xwhatsit]

I was wondering whether I should hone my bore when I put my engine back together (4T, mind you), so I did a lot of googling. Anyway, lots of random strange people on the internet (much like you lot) say completely different things -- some are like `you should always hone the bore, otherwise the rings will never seat and they might break and Jesus will kill your firstborn'; others say `honing is just an old wives tale, like polishing ports -- you don't need to do it, the rings will seat by themselves, just don't use any oil on the rings or bore'. What's the story here?

[The_Dover]

i thought this thread was something to do with ixion

[Ixion]

I don't need honing, my boredom skills are already honed to a precision edge. If we ever meet I am sure we will have numerous very long and very interesting discussions. I talk, you listen.

[scott411]

Concept Motors in Pukekohe (used to be DOugs engineering) are good 09 239 0083, thye do all our rebores

[pete376403]

it's always nice to radius (a tiny little bit) the edges of the ports, especially the exhaust port (because it's biggest) - helps ease the rings back in.

[barty5]

ph G K recondtioner in panmure 54 Jellicoe rd they do all our machine work and a lot for different bike shops in auck 5705336

[Motu]

it's always nice to radius (a tiny little bit) the edges of the ports, especially the exhaust port (because it's biggest) - helps ease the rings back in.

Bottle brush hone on a cheap 7.2V cordless drill gives the best finish.The drill is so gutless it gives the perfect speed to do a 45 deg crosshatch and not fast enough to catch the balls in the ports.

[PZR]

Concept Motors in Pukekohe (used to be DOugs engineering) are good 09 239 0083, thye do all our rebores

Thank god my first intelligent response, I was beginning to get worried
Cheers 411

[PZR]

Bottle brush hone on a cheap 7.2V cordless drill gives the best finish.The drill is so gutless it gives the perfect speed to do a 45 deg crosshatch and not fast enough to catch the balls in the ports.

I could do that if I only had a bottle brush hone

[PZR]

I don't need honing, my boredom skills are already honed to a precision edge. If we ever meet I am sure we will have numerous very long and very interesting discussions. I talk, you listen.

Say what? Huh! Did someone say something? Sorry I wasn't listening

[PZR]

I was wondering whether I should hone my bore when I put my engine back together (4T, mind you), so I did a lot of googling. Anyway, lots of random strange people on the internet (much like you lot) say completely different things -- some are like `you should always hone the bore, otherwise the rings will never seat and they might break and Jesus will kill your firstborn'; others say `honing is just an old wives tale, like polishing ports -- you don't need to do it, the rings will seat by themselves, just don't use any oil on the rings or bore'. What's the story here?

One thing about opinions is everyones got one. But thats just my opinion of course.
To hone or not to hone? That is the question. Is it better to have honed than never honed at all?
Its certainly hard to get a hone est opinion.

One things for sure, no motor of mine is ever being reassembled without oil. Your thoughts above may be valid depending on ring type and bore construction. You cannot hone a chrome or nikaseal bore for example. Honing was very common and effective for cast iron rings and bores in old cores

[terbang]

i thought this thread was something to do with ixion


Yup I thought so too but then realised it was 'Honing' rather than 'hooning' a two stroke bore..

[xwhatsit]

One thing about opinions is everyones got one. But thats just my opinion of course.
To hone or not to hone? That is the question. Is it better to have honed than never honed at all?
Its certainly hard to get a hone est opinion.

One things for sure, no motor of mine is ever being reassembled without oil. Your thoughts above may be valid depending on ring type and bore construction. You cannot hone a chrome or nikaseal bore for example. Honing was very common and effective for cast iron rings and bores in old cores

Yeah, I know. That's why I was interested to hear what KB thinks -- for better or worse, I do trust (in particular) Motu and Ixion's opinions over the average punter.

FWIW, the advice given was to put the rings in without oil and without a hone -- for only the first few strokes there is no oil, and they bed in super-quick -- oil apparently gets there pretty quickly. Apparently this is what BMW tells their factory engineers to do, yada yada yada. Does sound pretty scary though.

I'm keeping my old rings as they look (and measure) mint, so I don't think I really need to hone anyway. I'll be using oil though ;)

G'luck.

[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.