KX85 piston comparison

[camchain]

Hey spikedpunch. My rough guess would be that it may have gotten hot. There's less material & so less dimensional stability around ports & on piston skirt so these bits expand more with heat (on piston pic, scuff marks don't run all they way up to top of piston by the looks of it). Normally would expect probs on ex side (hotter) rather than inlet side though, so may have sucked some dirt in and not overheated. Some of those scrapes look fairly deep and considering nicasil coating is only about 0.1mm it could be an issue.

It's voodoo science how they get a superhard material like nicasil to stick to aluminium, given different materials = different expansion rates etc. I don't know if the coating can stay stable if it's worn through in small parts.

Taylor Automotive off Khyber pass might be worth trying if you're in the city. They have a lot of experience building Porche race engines (which have nicasil bores). I've taken bike parts there before, had bores checked by them.

BTW, I've found I get good results for macro shots with camera set to single point focus. Like me, my camera gets confused looking at shiny surfaces.

Noobi, nice 'burn' with your mappa tassie reply

[krad_nz]

Took those pics with my phone mate. Not too many options unfortunately :P

[camchain]

Took those pics with my phone mate. Not too many options unfortunately :P

Sorry krad - didn't mean to criticise, just passing on to anyone reading thread something I found out after a bit of frustration with my own pics. Good pics for phone cam!

[krad_nz]

Hahah, no worries mate. I wasn't having a go at you.

[SpikedPunch]

I just found out my bike is really an '03, not an '05....Aaaahhh can this week get any more awesome? Better not ask, would rather not know....
FFS, I feel so ripped off

[barty5]

I just found out my bike is really an '03, not an '05....Aaaahhh can this week get any more awesome? Better not ask, would rather not know....
FFS, I feel so ripped off

how did yah work that out???

[clmintie]

home a lot this week with school holidays. .

Sandpit with the kids on Wednesday?

[Midget200]

I just found out my bike is really an '03, not an '05....Aaaahhh can this week get any more awesome? Better not ask, would rather not know....
FFS, I feel so ripped off

Geez Spiked Punch, feck the bastards not telling you! Bad week for you, can't believe it. I definitely want to go new now! The KX at Spectrum is looking better and better!

[SpikedPunch]

how did yah work that out???

Used one of those VIN decoders. 'Just for fun'

[L Rider]

Sandpit with the kids on Wednesday?

He was planning on just taking Brooklyn up with his JR - try to get him riding it. Atlanta isn't at school yet so she's at daycare while i work.

[L Rider]

Used one of those VIN decoders. 'Just for fun'

I've used one of those before when buying Atlanta's quad & it came out with the wrong years - i emailed Suzuki & got correct year.

I must say though before we've brought 2nd hand we've always checked out the year as you can never trust anyone.

[camchain]

I just found out my bike is really an '03, not an '05...

Not having a good run at the moment spiked punch. Try not to be too bugged by year thing, need to keep in mind that new model year bikes are always available months in advance - in previous year.

Not only that, it's entirely possible your bike was a leftover sold in 05 (not a bad thing at all), I'd say it's even likely, given what you were told & that RM100s aren't that common. Without sale docs, bit of an issue when selling though. Best to just be honest about it, and that you were told it was bought in 05. When buying used you're often going off feel for the seller as much as bike, and people appreciate honesty.

I like to know what month bike was sold if I can - there being almost a years diff between Jan and Dec! My current ride is an 07 model but manufactured July 06 (but no sale date docs). Previous one was manufactured Nov 04 but sold Aug 05 (had docs). With bikes that hardly (if at all) change between model years it's when it was bought that really counts.

[L Rider]

Not having a good run at the moment spiked punch. Try not to be too bugged by year thing, need to keep in mind that new model year bikes are always available months in advance - in previous year.

Not only that, it's entirely possible your bike was a leftover sold in 05 (not a bad thing at all), I'd say it's even likely, given what you were told & that RM100s aren't that common. Without sale docs, bit of an issue when selling though. Best to just be honest about it, and that you were told it was bought in 05. When buying used you're often going off feel for the seller as much as bike, and people appreciate honesty.

I like to know what month bike was sold if I can - there being almost a years diff between Jan and Dec! My current ride is an 07 model but manufactured July 06 (but no sale date docs). Previous one was manufactured Nov 04 but sold Aug 05 (had docs). With bikes that hardly (if at all) change between model years it's when it was bought that really counts.

Very true re leftover in shop etc.
We brought a JR50 beginning of this year as they no longer make them. Although it was brought beg 2009 it had just come into the country it was manufactured in 2006 i think as this was last year of manufacture.
However even some shops get the years mixed up - they had said the JR was a 2009 JR50 which is actually isn't.

[Reckless]

Here's some more pix for you..... Note that the pix make the carbon look thicker that it is, as I run my finger over the line between 'shinny' and carbon, it's hard to feel any difference in height...Maybe better described as 'soot' no doubt due to using a blend of TTS and R30. We use 3 air cleaners and chuck a clean one in every ride, often between races in summer. Airbox gets duct taped when very wet.... I realise by leaving it in for 100 hours, I've pushed this piston way beyond what would normally be called it's 'use by date' it's just that the first 30 40 hours were pretty 'gentle'.....

The castor based castrol R will leave more deposits. That piston looks like a typical karting piston on Castrol R. Not too bad. Bit of blow by though, I'd probably run it in a bit harder to get a bit better ring seal. Mind you some of it could be at the end of the 100 hours when things weren't so tight. I do rings 50 hours (measure the piston as well) new piston and rings at 100 for trail riding. This gives two bites at the ring seal and a good look at it, at the 50 or so hour mark. Only $30 bucks or so for rings so a good thing to do.
Why you blending your premix Climintie any particular reason?

Thanks for your help earlier on today Aaron.
Here are a couple more pics showing the bore and piston. You can see some nastiness on the inlet side of things, either side of the inlet port. Aaron suggested that this could be just starting to seize up? Punch mentioned that the bike was feeling low on power and didn't have the topend hit she was used to.

I'm not really sure what to do next. The damage itself can be sorted out but I don't really understand why its happened to begin with. Air filter is cleaned regularly. Clutching at straws below.

Points of interest:

- coolant is meant to be about 0.67 litres total. When we drained it there was only about 0.4-0.5 litres. Maybe caused engine to over heat? There is no overflow bottle on these bikes so it probably should have been monitored frequently but wasn't. I've never seen it steaming or anything however.
- we've dropped the needle one notch from standard to address a serious spooge issue.
- shes running about 32-35:1 oil ratio, Castrol TTS.

Thinking of taking to an engine specialists to get an expert opionion on what to do next.

Looks to me like its not been well maintained in a fair while. The top pin looks like its been very baggy causing the piston to bash about in the bore. Rings lost there tension heaps of blow by. Something may have been in there as well causing that scratch! But its low down and not torn its self through the rings etc. Never trust the last guy many just change rings or pistons and leave the old top bearings in. For the price of a piston I'd always do a 2 smoker as soon as you can afford it after buying it unless the info you have on it is 100% reliable
Wouldn't worry about the shortage of water mate you probably didn't drain it all out the engine anyway!
What to do next!!
YES take the barrel to someone that will give you a good judgement upon if its gone though its Nikasil or not.
Then get them to measure it up and see what size piston you need. You could quite well need a B instead of and A, or visa versa, (which ever is bigger) if your barrels a bit worn. You don't want a piston thats to small rattling round in there.
Get them to feel the bottom bearing in the crank as well! If that's shagged it cold be 1/2 the problem. Hopefully not though.

I've seen worse barrels than that (hard to tell from pics though). As long as the barrels is OK and the crank pin is good, that will patch up and go for ages. Its not a new bike so you can't expect it to be 1000% but it looks like it'll go back together OK!
There was a thread on here recently where we discussed Honing etc and in that there was a good recommendation for a shop that had the proper diamond Hone, maybe camchain knows the book mark to the thread. I personally wouldn't hone it, especially an older barrell with thinner Nikasil, but each to their own! Do your check ups and measure ups, clean it up a bit, fit the new stuff properly, run it in hardish to get it the new rings to seal well and that'll be ok for ages!

[barty5]

Very true re leftover in shop etc.
We brought a JR50 beginning of this year as they no longer make them. Although it was brought beg 2009 it had just come into the country it was manufactured in 2006 i think as this was last year of manufacture.
However even some shops get the years mixed up - they had said the JR was a 2009 JR50 which is actually isn't.

Was told a trick some shops use if the bike has excel rims there is a number on the rim the last number is the year the rim was made, ie 7 = 2007 8=2008 if its a 7 then the bike is an 2008 if its a 8 then the bike is 2009. you get the idea as the rims are made the year before the bike is as they come outa stock. Its not fool proof as rims can be swapped etc but if your told its an 07 and there was a 3 stamped on it youd be asking questions.