Rs 125 cilinder wall has scratches

[Runeazn]

I recently bought a rs 125. Wanted to check up on the engine state, so I went to a motor shop to let them look at my cylinder and they suggested to get it replated. Though the motorcycle ran fine, I only opened the cylinder to check the state of the piston. In first case I wanted them to polish the wall till they said they wouldn't because it was damaged too much. When I feel it with my finger they feel like really thin grooves. Deeper then the honing grooved but I think just as deep as 1200 grit sanding paper? These grooves probably happened because of overheating, the coolant hose was teared. I'll place some pictures.

Also I'm ready to pay for a new cylinder, though it's cheaper not to, but an whole engine rebuild is worse. So I'm trying to get a good judgement. The kits I'm looking at are mitaka or italkit. I'm not looking at replating because it's even more expensive than a mitaka top end kit.

[Boxing]

The shop is mechanics, they know best. Get it re-lined and stop being cheap.

[Runeazn]

[Copycat73]

[robertw95]

Im guessing the rs cylinders are nikasil plated and not steel lined then? Re bore out the question
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07 Dt125r, sv650s k8, zx6rr 04

[Copycat73]

[Runeazn]

[Copycat73]

To hone the Aprilia RS 125 cylinder you need special diamond tooling to cut thorough the tough nikasil coating,for this we use our sunnun precision honing machine

(£40.80 Including VAT at 20%)

then you got pistons, rings .. gudgeon pin c clips, gaskets...
wot u get in that kit like ?

although it don`t look fantastic is you sure its fcuked...
did you not compression test it before strippin ?

this may be of interest
https://www.pjme.co.uk/
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Whatever I post I have no citation and no intention of providing one..
caveat emptor

[robertw95]

If its steel plated i'd regard a re bore as standard 2 stroke maintenance certainly is on the dts, send it to an engineering company such as pjme which is highly recommended and they supply correct over size piston/rings for the cylinder

If nikasil from my limited knowledge i thought the only option is re plating?
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07 Dt125r, sv650s k8, zx6rr 04

[Runeazn]

[robertw95]

I dont think thats an unreasonable price mate, rs125s are known high maintenance bikes if not properly looked after and often bought by 17 years who thrash the bike
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07 Dt125r, sv650s k8, zx6rr 04

[Runeazn]

[robertw95]

If it is nikasil then re honing isnt possible im pretty sure, what mileage is the bike on? You sure this piston kit includes a cylinder seems strange to me?
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07 Dt125r, sv650s k8, zx6rr 04

[Runeazn]

[robertw95]

Ok so your doing a top end rebuild that kit has piston rings etc and are known reliable rebuild my dt twice using there kits no problems.

The cylinder hower needs replated after that damage to get rid of those scores, had a look on pjme and a re sleeve says £103 + vat I would get in contact and confirm this is right for your model of bike so under 200 for a complete new top end seems decent to me

I'd also be checking the spark plug to see how the engine is running possible overheating caused that or lack of oil
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07 Dt125r, sv650s k8, zx6rr 04

[Runeazn]

[robertw95]

Im only guessing here never dealt with nikasil bores before but if its iron/steel lined and scored but you cant feel the marks you can re hone the cylinder removing the marks this may be possible

Just me but id prefer to have the standard cylinder re plated by pjme just for piece of mind and fit a new piston rings etc then you know the engine hasnt been thrashed.

I had considered one of these bikes before but looked into it before buying these bikes dont make 33bhp as many claim probably closer to 28ish which is impressive for a 125 but it will require maintenance to keep it in good working order
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07 Dt125r, sv650s k8, zx6rr 04

[Runeazn]

[Kickstart]

Hi

That barrel looks OK, except above the exhaust port which looks a mess.

You can get barrels replated. Think there are 2 people in the UK who do the actual replating. Cost is around £100 + vat (but then you need a piston, gaskets, rings, etc as well). Not sure whether they will post to the Netherlands, but posting to them should be easy enough.

A cast liner can also be fitted, although personally I am not keen on this; only experience was one being supplied by Aprilia UK under warranty which was a mess. Others have had no problems with them. Cost is similar to replating although in future you can then rebore them.

The Mitaka kit is a possibility. Some people have issues with them (think PJME supply them with alternative rings), and based on reputation you might lose a little performance.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Runeazn]

[Kickstart]

Hi

Suspect they might be closed until after the new year.

I would suspect that barrel can easily be repaired, but a Mitaka kit to keep the bike running for now might be a simple solution

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Runeazn]

[Kickstart]

Hi

The plating on the barrel is very hard but very thin. If you wear through the plating then the barrel will be wrecked and replating / fitting a liner will be the only solution. From the pics I can't tell whether above the exhaust port the plating is damaged or whether that is just the remains of a piston smeared on top of the plating

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[stevo as b4]

If a plated bore doesn't suffer a seizure or the plating flakes off, I was always under the impression that you can keep re-using them and you never hone or sand the bore, just check the dimensions before fitting a new piston kit every 8000miles?

I would like to think that a good plated bore would last 2-3piston and ring changes without wearing the plating out?

I certainly would not choose to fit a liner to a high specific output motor that has an original plated bore.

I'm soon going to put the KMX125 on a dyno, but I'm not expecting much as it was re-build with a steel liner which may or may not reduce performance depending on how well it was fitted and how well it conducts the heat away?

[Runeazn]