OzVMX Forum
Clubroom => Tech Talk => Topic started by: William Doe on June 27, 2014, 01:03:15 pm
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What's the go with Chrome bores ? Honda red rockets and YZ 125A models specifically ???
What rings do you run in them , is it std cast rings in chrome bores and chrome rings in steel bores ?
And what about nikasill and other plated bores , what rings can you run in them ?
Thanks Bill
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Chrome bores - cast iron rings.
Nikasil - cast or chrome rings.
You would be very lucky to find a chrome bore still usable.
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Crazy Phil had his red rocket cylinders replated by NZ cylinders & uses wossner pistons in it, he seems to be really happy with their work. The wossner pistons will be using the same rings as any modern bikes
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There were very few actual models with Chrome bores, the 2 you mention may be the only ones.
Unfortunately every plated cylinder that has a Nicasal bore or Electrofusion bore gets called chrome which causes a lot of confusion.
Nicasal & Electrofusion bores use the same pistons and rings as cast iron bores.
The actual real chrome bores can't use chrome rings otherwise they will seize
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early Ts 250 had a chrome bore also.
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Best thing you can do with a plated cyl is to get it sleeved in cast iron. That's what cylinders are meant to be made off.
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Sleeved cylinders don't transfer heat properly. Replating a cylinder is a much better idea.
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Still kicking myself--a few years ago i decided to give my worn out DT1 GYT kit chrome cylinder [1968] one more run as it always went really well & didn't drop off power when hot like the DT1MX cast bore does [that i have]. Anyway--i Fkd up big time because i picked the 'best of the rest' piston & shuffled around all the old rings [assortment] Knowing full well the right ring must be used & bloody well picked the wrong one. They were all used rings & couldn't decide which was cast but possibly none were, in that box in the end. Short story long--it stuffed it in about 100 metres. Might fix it one day.
Another time back in the late "60's at a guess a mate had a 'Starmaker' motor[were they villiers?] in a C15, the second model C15 with Ally tank--good looking bike after the goosneck frame that bent. Anyway, he had a chrome cylinder on it [not sure if aftermarket or came like that but] same story although don't think us budding mechanics knew the implications of running the wrong ring till then. Was an instant learning curve--flat out down our country road & destroyed itself. Damn.
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early Ts 250 had a chrome bore also.
I thought those mid 70's TS250s had a plated bore a bit like the Kawasaki Electrofusion not actually chrome. Could be completely wrong only going on memory from a mates bike.
TZ125, 250, 350 & 700/750 all had chrome bore as far as I know
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the BSA B44 GP had a chrome bore.. in 1965..
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I thought those mid 70's TS250s had a plated bore a bit like the Kawasaki Electrofusion not actually chrome. Could be completely wrong only going on memory from a mates bike.
yup..'76 TS250A had a Nikasil coating of types called SCEM (Suzuki Composite Electro-chemical Material)
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Didnt yz 125C have a chrome bore , I remember Bitd having the choice of buying a 125C or a red stripe elsinore i opted for the elsie as someone said the C had chrome bore which was bit of a a put-off - no rebore's ???
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Sleeved cylinders don't transfer heat properly. Replating a cylinder is a much better idea.
You obviously have never had a sleeve fitted properly.
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Sleeved cylinders don't transfer heat properly. Replating a cylinder is a much better idea.
I reckon so too.
My KDX 175 barrel is buggered and needs replating but you have to give it credit for lasting 33 years on original bore, you won't get a cast iron sleeve do that.
I have a 88 KX 125 barrel that has a steel sleeve fitted, will gladly swap it for a non sleeved barrel in any condition.
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Didnt yz 125C have a chrome bore , I remember Bitd having the choice of buying a 125C or a red stripe elsinore i opted for the elsie as someone said the C had chrome bore which was bit of a a put-off - no rebore's ???
No only the A&B's had the chrome bore's 125 , 250 & 360 .
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Sleeved cylinders don't transfer heat properly. Replating a cylinder is a much better idea.
I reckon so too.
My KDX 175 barrel is buggered and needs replating but you have to give it credit for lasting 33 years on original bore, you won't get a cast iron sleeve do that.
I have a 88 KX 125 barrel that has a steel sleeve fitted, will gladly swap it for a non sleeved barrel in any condition.
I have sleeved quite a lot of plated cylinders over the last 20 odd years and no one complant that they didn't go as well as before. I have also seen a lot of sleeved cylinders that would be worse than the original with realy bad port matching and no interference between the sleeve and cylinder.
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Each time I see a sleeved cylinder that was designed around nicasil they ping their head off once they get hot. Just replate with nicasil and use a commonly available piston of the size you need.
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YZ125A & 250A's had chrome but 360A had a thin liner you could go to 'one' oversize 10 thou officially--of course i'd go more & probably pay the price lol. In fact, come to think, [somewhere] i have a 360B cylinder which 'is' on 1st over. Always planned [still do] to fit it onto RT cases but have to think of a [home mechanic] way of moving the rear stud hole out about 5 mill each side due to the wider reed block. i'll do it oneday.
By the way i'm just listing a YZ250/360A airbox on trademe & looked up what they sell for by just googling it, as you do [$100 it said] & same site is selling a YZ250/360A RH Blinker--just gotta have it for setting up that pass, gosh i'm so happy i found it!! as been looking for years. I'll try to put a link to it. Cheers.
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http://www.gotusedmotorcycleparts.com/product-p/286988.htm try that and see if it works--for a laugh. [RH blinker YZ250/360A]
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for the discerning motorcycle racer ;D :D
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Best thing you can do with a plated cyl is to get it sleeved in cast iron. That's what cylinders are meant to be made off.
Why do you think it is that race all motorcycle engines have changed to plating instead of using a cast sleeve?
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saving weight & for heat dissipation? [i'll swear my chrome cylinder DT1 gyt cylinder just stayed strong to the end--in 1968--till i fkd it in say 2008, AAAAHHHRRRR.
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Lighter, cheaper*, harder wearing, closer tolerances/improved performance, superior heat transfer. Just to name a few obvious reasons all the manufacturers have embraced the plated cylinder technology. The tech was developed through the late sixties into the seventies and seemed to be the engineering solution that made the rotary engine viable.
For over 20 years aircraft engines have used a nickel silicon plating in the cylinders, so we can say it is trusted to perform.
Plated cylinders might have been a exotic thing once upon a time but they are the norm now, ride the waves of change or drown beneath them sounds like the mantra that successful companies adopt to stay in the race.
*Automated production accounts for efficiency and precision that makes plated cylinders better and cheaper.
A repair facility which does not understand the criticality of the process will make a hash of the job.
Rework is often expendsive for one off jobs, but still cheaper than a new OEM barrel in most cases.
Cylinder sleeves have thier place, but no one can argue that the plated cylinder is not here to stay.
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It is quite sad that the good old cast iron is on it's way out. But that's or disposable life style in a nutshell, make it as cheap as possible and when it wares out through it out.
Back in the good old days there used to be strange shops called engine reconditioners and they employed actual people to do the work!
There is no question that a plated bore doesn't out last an iron bore but if you take into account the number of rebores and occastional mishapes like bearing failures, nip up's, eating of foreign objects etc you are way in front with an iron bore.
RIP iron bore and engine shops.
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Cost factor in production is the bottom line ..... bet you they never thought they would be running 30 - 40 years later down the track and still have parts to do so ;)
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my lawn mower had an ally bore--so there haha--now, if i just get rid of the stuffed chrome on my gyt kit cylinder & run a 1st over DT1mx piston kit--i can just see it now, first to the first corner umm & first on the trailer & off home. How do they get away with it on some [4 stroke] mowers, special ally?, lots of oil, or what. Fascinates me. had a kx80 [trade in buggered & dismantled at work, first watercooled one, i must've put a piston kit in it & it was just the fastest best little bike back then & got ridden hard by the kids [raced]. Nikasil was through to the ally around the ports but you'd never know by performance. Even found accidentally [after no symptoms] that the water pump impeller had come unstuck so was just thermosyphoning. Jeez they were good old days.
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my lawn mower had an ally bore--so there haha--now, if i just get rid of the stuffed chrome on my gyt kit cylinder & run a 1st over DT1mx piston kit--i can just see it now, first to the first corner umm & first on the trailer & off home. How do they get away with it on some [4 stroke] mowers, special ally?, lots of oil, or what. Fascinates me. had a kx80 [trade in buggered & dismantled at work, first watercooled one, i must've put a piston kit in it & it was just the fastest best little bike back then & got ridden hard by the kids [raced]. Nikasil was through to the ally around the ports but you'd never know by performance. Even found accidentally [after no symptoms] that the water pump impeller had come unstuck so was just thermosyphoning. Jeez they were good old days.
Had a KX125 barrel (about 08 I think) come in a few weeks back that a poor sucker had bought with the rest of the bike after being told it had a new piston in it. After one ride it had lost a lot of power and to his local shops surprise it had a first over wiseco in the bored out nicasil barrel. Real good buy. Fitted him up with a sleeve and happy days.
Wops shouldn't of done that with cast iron but to late now.
Some of the little 2 stroke weed wacker motors have alloy bore with some type of coating that is not nicasil almost looks like anodised but not sure. It seems to last quite though until they forget to put oil in the fuel.
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It is quite sad that the good old cast iron is on it's way out. But that's or disposable life style in a nutshell, make it as cheap as possible and when it wares out through it out.
I don't see how Nicasil makes a barrel disposable or cheaper, I don't have any costings but I imagine the cost would be very similar
Back in the good old days there used to be strange shops called engine reconditioners and they employed actual people to do the work!
Now we have strange shops called platers that employ people.
There is no question that a plated bore doesn't out last an iron bore
Typo??
but if you take into account the number of rebores and occastional mishapes like bearing failures, nip up's, eating of foreign objects etc you are way in front with an iron bore.
Yes that is a true advantage of cast iron sleeves
RIP iron bore and engine shops.
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I've never had an engine with a plated bore so I'm certainly not in a position to make a comparison however I've read about a guy in the states that road raced an Ossa 250 with an iron bore but used a piston that had a Ceramic coated top and Graphite coated skirt. He never mentioned problems with heat or wear once engine was run in. Engine was fitted with a Yamaha conrod and claimed to be super fast and reliable. I don't hear of people using Graphite coated pistons. Anyone have thoughts on this? I'm not a mechanic so I'd be interested to know if Graphite actually would add longevity to both plated and plain bores and pistons or was it just a passing fad from years ago.
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There are plenty of place that coat the pistons. There seems to be some benifits from it , mainly longevity.
Here is one place to have a look at.
http://www.competitioncoatings.com.au/pistons.shtml
The ceramic on top is there to reduce the heat of combustion going into the piston and the fricition coating on the skirt is meant to cut back on wear and friction. All good in theory but I haven't seen any Dyno proof of big HP gains.
I have seen a Harley with an iron bore and a fully coated piston do 200K before a rebuild. That is well over the norm.
The Wossner piston come stock with a black friction coating on them stock and a few of the Wiseco as well.
I did ask the company above if due to the reduction in heat could we reduce the piston clearance but he wasn't that confident and wouldn't recomend it.