Cylinders fitted with liners.

[stevo as b4]

Can we talk about cylinder liners, the pro's and cons of, especially related to if your bike/engine left the factory with a coated/plated alloy bore.

And also if you had the parts sat around to build up an engine with either a liner conversion to the OEM cylinder, or use a newly replated cylinder instead, what would you do?

Especially if your kind of going down the tuning road, trying to get more power and still have reliability.

I've been around long enough to know there's performance engines that are very highly tuned with both types of cylinder bore, but are there any stand out overwhelming reasons why one is always better than another for pushing past factory spec and performance levels.

Oh and yeah we are talking two stroke here just to be clear. Experts give me your wisdom please.

[sickpup]

I can't think of a single bike in the last 20-30 years that didn't have liners, became a necessity with Aluminium engines.
No doubt there are some but can't think of any.

[temeluchus]

I imagine the aftermarket use iron liners as they don't require the plating process needed for alloy cylinders, rather than iron liners actually being better.

[temeluchus]

Just checked a bunch of 2017 japanese fours and none of them had iron liners.
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Some shite cruiser. Now with guns and FREEDOM!

[MarJay]

[redeem ouzzer]

Most modern engines use trick coatings directly onto the aluminium because liners are heavy. The drawback with coatings is when they’re damaged there’s no rebore facility and some of the newer ones can’t be replated like nikasil can.

I don’t like the idea of fitting liners into cylinders that were originally plated. There are other design considerations like rates of expansion and piston choice to consider, which are quite different between lines barrels and those originally designed as plated.
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Be a REAL MAN!

[Tankie]

Plated blocks instead of cast iron liners are used because aluminium conducts heat better than a block with iron liners, as stated if a plated bore is damaged or worn out then the whole block has to be plated and repaired ( welded and re-plated ) .
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Always learning, everyday is a school day

[monkeyman]

Only real difference is that its going to weigh a lot more with liners, will be a lot cheaper is you blow it up though
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Im not the best, but im in the top one
RM 250, Husky TE610, K1 GSXR 750

[Pete.]

Nikasil plating is harder than a Moss Side bouncer. 30k miles and the honing marks still in it. No need for iron liners any more.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[stevo as b4]

Thanks everyone!

I was always an advocate of modern plated bores on high performance two strokes anyway.

The real reason I asked is that I think my KMX has been re-build with a sleeved cylinder conversion instead of a re-plate. It starts and runs well, but is apparently about 10% down on its performance figures, and we don't think the liner is helping.

I've only done) ~500 miles on a nicely run in top end, but as my plans are involving tuning a bit, its only going to get more of a barrier to performance as it gets modified.

Think I'm decided that I need to replace the top end with the factory spec set up and run a plated bore how it should have been originally.

The linered cylinder would make for a nice off road motor for green laning etc.

[monkeyman]

10% down on power?!? So 3hp lol is that using the seat of the pants dyno

If you really sure that you have problems, do yourself a favour and keep the liner. 2 stroke blow up regularly and you can probably get the liner sorted for £40 each time
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Im not the best, but im in the top one
RM 250, Husky TE610, K1 GSXR 750

[mattsprattuk]

In for the "CLEARLY I meant nikasil as it's a type of liner. I'm right and you're all idiots" reply.
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Pete.]

[stevo as b4]

The missing performance is from a dyno run taken at the rear wheel. Before you ask it was a smooth road tyre fitted and pumped up hard too.

Oh and though it's not the case on bigger fatter bikes, on a 100kg 125, 3bhp can make a fucking big difference to performance or how it feels IMO.

[mattsprattuk]

[Pete.]

[MarJay]

I have heard that replacing nikasil plating with a steel liner can cause problems to do with heat transfer and different rates of expansion. I think it's best to use Nikasil on a nikasil bike and vice versa. This is why RGV and RS250's are a pain if you have bore scoring.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[sickpup]

Not had many modern engines apart so not really run into much cylinder plating.
Early plating had problems with flaking especially on two strokes round the ports and port bridges. Manufacturers found it hard to get a consistant layer over edges on the coatings.
Cars had had coatings on Almuinium since the 70's but these tended to rev lower than bike engines.

Nice to learn something new

[temeluchus]

[MarJay]

When I were a lad:

It was difficult to re-coat re-bored (two stroke) nikasil plated barrels. THAT was when you used to get inconsistent finish and thickness. However there are companies that claim to be able to do it nowadays, and I've not heard anything to the contrary.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[monkeyman]

Where does your tuner think the HP gains are going to come from by buying a new cylinder?

I'm struggling with the concept that if you have good compression that you are loosing 10% due to a steel liner

As as far as I'm concerned, In the dirt bike world the only disadvantage of a liner in the weight

What are you using the KMX for?
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Im not the best, but im in the top one
RM 250, Husky TE610, K1 GSXR 750

[Pete.]

[MarJay]

[monkeyman]

Granted the weight issue isn't much of an issue on a dirt bike. The point I'm trying to get at is. It's rediculas spending money on a new barrel when he has a perfectly serviceable barrel

i don't think the heat transfer issue if it really exists, is a problem on dirt bikes. The barrels really don't last that long anyway in comparison to a road bike. I've had bikes with liners(previosly a niclosil barrel) and ones without and have not seen any evidence they last any longer or make any different power. What make the difference to me is that it is so much cheaper to sort a borked iron liner

The only reason I can think that you would make less power is if the ports hadn't been matched properly. Which would be problem if not done right for both methods of refinishing a borked barrel.

I'm more inclined to think the apparent loss of power is a dyno issue or there is another problem with the bike
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Im not the best, but im in the top one
RM 250, Husky TE610, K1 GSXR 750

[monkeyman]

If the top end is in good condition then the places to look are

- exhaust, is the correct expansion pipe fitted to your bike. The pipe is actually matched to the barrel.

- is your jetting correct (this is a black art on two strokes) consider the possibility your tuner may be inexperienced on two strokes

- air leaks, have your pressure tested your bottom end

- KMXs are getting on a bit, the carb and particularly the slides and needle jet can get warn and from all the vibration resulting in the jetting being thrown out

- does the KMX have a mikuni "TMX" carb? if so throw it out and get a Keihen
____________________
Im not the best, but im in the top one
RM 250, Husky TE610, K1 GSXR 750