KX85 piston comparison

[clmintie]

I put 20ml of caster to 10l petrol. I like to have a little "different length molecule' in the synthetic oil. While the modern oils do a fantastic job, they don't take kindly to sudden shock and a little vege oil can save a nip... Make sense?. Certainly doesn't do any harm and makes me feel warm and fuzzy... (Smells like a racing bike should too... )

[B0000M]

somehting hondas used to have on them was a sticker up on the steering head, telling you what year and modlel the bike is. unfortunately for some reason they stopped doing this, my old 99 had it, and all the previous bikes, but im not sure when they stopped.

[Reckless]

I put 20ml of caster to 10l petrol. I like to have a little "different length molecule' in the synthetic oil. While the modern oils do a fantastic job, they don't take kindly to sudden shock and a little vege oil can save a nip... Make sense?. Certainly doesn't do any harm and makes me feel warm and fuzzy... (Smells like a racing bike should too... )

As you say can't do any harm. Nothing wrong with the old Castor as long as it mixes ok with the TTS etc and doesn't seperate. Smells bueaty as you say!! LOL!!

[krad_nz]

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 think there is only one piston size for a nikisal barrel.
What should I be feeling for with regards to the bottom bearing? I checked for vertical play in bottom end bearing by applying upward force to the little end of the conrod. I couldn't feel any play.

[Reckless]

What should I be feeling for with regards to the bottom bearing? I checked for vertical play in bottom end bearing by applying upward force to the little end of the conrod. I couldn't feel any play.

Thats good all ok then!

I think there is only one piston size for a nikisal barrel.

No there is generally two sizes but I'm not familiar with your model so I could be wrong. The manual will give you a piston size and a bore size then a max measurment the difference is allowed to be. Just make sure your within specs and all is OK!!

[krad_nz]

Thanks mate, good advice.

[camchain]

You'd think there'd only be one piston size for nicasil bore but you can get oversize jobs alright. As Reckless says, check specific model. KTM officially supplies A & B size Vertex pistons, but Vertex actually makes A,B,C,D sizes (As do Pro-X). They only go up in miniscule 0.01mm increments but I figure correct clearances for Nicasil bore must matter otherwise they wouldn't bother with such tiny oversizes.

[barty5]

there are 2 sizes for this bike

[SpikedPunch]

Hmm well that would be a bummer hummer, I've got a perfectly good shiny piston sitting here just waiting to go in. Ah well, I'm talking a half day off work tomorrow to sort some stuff, will try and get into spectrum and engine specialties too if there's time.
Also, upon further research (boy is my face red!) it looks like the kx100 was only rebadged by suzuki for 03 and 04 (they're the only years I can find info/pics for-if anyone knows otherwise please correct me!), would explain why I've had so much trouble finding parts, it's kind of a relief haha. Would add cred to the theory that it was maybe an 03 sold in 05.

[clmintie]

Hmm well that would be a bummer hummer, I've got a perfectly good shiny piston sitting here just waiting to go in. Ah well, I'm talking a half day off work tomorrow to sort some stuff, will try and get into spectrum and engine specialties too if there's time.
Also, upon further research (boy is my face red!) it looks like the kx100 was only rebadged by suzuki for 03 and 04 (they're the only years I can find info/pics for-if anyone knows otherwise please correct me!), would explain why I've had so much trouble finding parts, it's kind of a relief haha. Would add cred to the theory that it was maybe an 03 sold in 05.

FWIW
Grace ran in her new piston today at Sandpit (3.2hrs) and reports no difference in top end, but much crisper off the bottom and mid range... At least you have this to look forward to SpikedPunch. Tracks were fantastic.........

[SpikedPunch]

FWIW
Grace ran in her new piston today at Sandpit (3.2hrs) and reports no difference in top end, but much crisper off the bottom and mid range... At least you have this to look forward to SpikedPunch. Tracks were fantastic.........

Lucky girl !! Jealous! Hopefully sort this shizzle in time for a sunday ride. If it's dry me and krad might go to harrisville on saturday, I'll just be watching this time...

[clmintie]

See you at Harrisville, haven't been for a while and we might be lucky with the weather (Sunday looking VERY WET)

[L Rider]

Hmm well that would be a bummer hummer, I've got a perfectly good shiny piston sitting here just waiting to go in. Ah well, I'm talking a half day off work tomorrow to sort some stuff, will try and get into spectrum and engine specialties too if there's time.
Also, upon further research (boy is my face red!) it looks like the kx100 was only rebadged by suzuki for 03 and 04 (they're the only years I can find info/pics for-if anyone knows otherwise please correct me!), would explain why I've had so much trouble finding parts, it's kind of a relief haha. Would add cred to the theory that it was maybe an 03 sold in 05.

Lol at being red faced!! does sound more like an 03 sold in 05 doesn't it.
Well least now things are starting to fall into place re parts

[SpikedPunch]

Right, twenty eight bucks, same day service, bore all nice and honed. Thanks spectrum and engine specs!
And of course thanks everyone on here for all your info and suggestions, it's been much helpful, don't know where I'd be without KB !

[krad_nz]

Spectrum said that it looked like this piston has been too hot which caused it to nip up. Basically said it was running lean. So time to put the needle back up to the factory position.

An alternative explanation is that it 'cold seized'. Ie: Bike was revved aggressively from cold. The piston heats up faster than the barrel. This causes the piston to start nipping up. Punch did have a tendency to give it death on starting, partly because it was difficult to start when cold. This of course was due to the low compression caused by poor ring seal etc. I like this explanation myself.

The 'cold seizure' is what a mechanic once used to explain what happened to one of the guys son's on his cr80. He seized his bike by giving it death from cold. Some time later with the engine all sorted and nothing else modified the bike is still going strong. His son now lets the bike warm up a bit before giving it full noise.

Apparently the pattern of the scrapes on the barrel can be used to help identify if it 'cold seized'. Take from this what you will, I like the theory.