Cagiva Pistons

93 NSR · Borekit Bruiser Joined: 04 Aug 2003 Karma :

after only 500km in all of riding my nice new bike it's blew up. no signs before hands just went and the back tyre is locked solid. Where are the cheapest place to buy a decend quality piston for it and Is it a nikasil barrel or a normal one??

Cheers,
Craig

Scotty · Scooter Boi Joined: 31 Jul 2002 Karma :

500km, what did you do wrong. i'll be running in soon hopefully, and its gonna suck, all 1000khm of it.
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Regards
Scott

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Try PJ Engineering (https://www.prox.co.uk I think). They should do one quite cheap.

Surprised the piston went before you have even finished running it in.

All the best

Keith
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cagiva gezzer · World Chat Champion Joined: 17 Mar 2003 Karma :

Is it "new" new or new to you?

Ifs it new, then shouldnt it be covered by warranty?

If it was being run in at the time, then the seize shouldnt of been cause by you thrashing it, more likely a error in production.

PJ use pattern pistons and i wouldnt touch a pattern piston again. EVER!

I have used two in my supercity. The first one cracked from the port to the base and spun on the wrist pin, causing it to seize in less than 3000km. The second one managed 2000km before its spinning on the wrist pin almost caused it to seize.

They cost me £80 each, i dont know if PJ use the same ones, but stay away from cast pattern pistons.

OE pistons are forged and are much stronger and the shape of them allows better small end cooling, preventing over heating and the spinning i experienced.

I just got one from Mito Mondo ( www.mitomondo.co.uk 01425 650034) for £92.34 +VAT.

The barrel is NikaSil (or the cagiva version) and it WILL need to be replated. Thay can be brought new for upwards of £350 from 3cross, but plating costs £104.00 +VAT from PJ ( www.prox.co.uk 01902 307457) They have just done an excellent job on mine, slightly high tolerances, but a good job overall. About a three week turnaround time.

I think their web page only goes on about cylinder resleeving, noty replating. They dont supply OE pistons, so you have to source you own one and send it off to them with you cylinder.

The cylinder will need painting again afterwards as the blast it.

Best to remove the cylinder and work out why it seized. Lack of lube, powervalve out of adjustment, over heating, head gasket gone, snapped ring, poor finish on ports, etc etc. Each has its own tale tale sign.

Best of luck.

stuart.

Oh, dont even bother phoning three cross for parts. A) you wont get through. B)if you do, the person will know bugger all. C) they havent had major parts for months and wont be getting any for a while.
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"because one stroke isnt enough and four strokes waste two"

93 NSR · Borekit Bruiser Joined: 04 Aug 2003 Karma :

No the bike was new to me. it's only done 11500 ish kilometre's. bout 450 were mine. i think whats caused it is i was low on oil so i used some of my brothers cheap ass stuff. cos it slowed down and stopped in about 3 seconds. I know when a bike is seizing i've had it before on a few bike.
the annoying thing is that it was only last week i went to my local bike shop and said i'd like to put a new piston in just to be sure!!
This gunna be a big one then. once it's done i'm selling the bike, should have a car licence then. 2 out of 2 bike gone bag big time!
Craig.

Scotty · Scooter Boi Joined: 31 Jul 2002 Karma :

Buy a 4 stroke alternative instead if you dont have much luck with 2 smokes.
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Regards
Scott

cagiva gezzer · World Chat Champion Joined: 17 Mar 2003 Karma :

Cheap oil kills engines. Make sure you drain the tank and flush out all of the old oil.

A new small end will also be needed, you will prob find nice smear marks up and down the front and rear of the piston.
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"because one stroke isnt enough and four strokes waste two"

93 NSR · Borekit Bruiser Joined: 04 Aug 2003 Karma :

stripped it today and guess wot. it's not the piston. i've ogt the barrel and head of and if i pull the piston there is up and down movement. at foirst i thort the big end had gone but the bearing seems fine and the pin worn? what do you think?
How much is a new pin and bearing gunna be??
are there any websites where theres a parts list and price guide?

Craig.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

If there is vertical play in the con rod then the big end is almost certainly shot. Cannot remember for certain with Cagivas but on most 2 stroke bike the big end kit consists of a con rod, big end bearing and big end pin. To replace it you need to take the engine out and split the crank cases. Not a job unless you know what you are doing (drop the engine out yourself though).

If the little end bearing has gone badly enough to be able to feel loads of play then there is a fair chance it has damaged the con rod as well.

All the best

Keith
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93 NSR · Borekit Bruiser Joined: 04 Aug 2003 Karma :

i dont really want conrod kit though. can i just buy the bearing on it's own??? i can split and re-align it no problem. the engine is out. just haviing trouble getting the magneto off.
Just found a place that does conrod kits at £50.20 and e-mailed mitomondo.

Craig

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Fairly certain you cannot just buy the bearing. They are matched to the pin and the con rod.

Are you really certain you can accuratly press the crank appart and back together?

All the best

Keith
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93 NSR · Borekit Bruiser Joined: 04 Aug 2003 Karma :

positive, I race Karts and we do our own engines. been doin it for 5 years now. so not a problem at all. my grandad is an engineer. when i get the bearing out i'll try a few bearing shops and see what they say.
Craig.

cagiva gezzer · World Chat Champion Joined: 17 Mar 2003 Karma :

Are you sure youve isolated the play to the big end and its not the small end or the mains?
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"because one stroke isnt enough and four strokes waste two"

93 NSR · Borekit Bruiser Joined: 04 Aug 2003 Karma :

1000% it's in the big end bearing. i've got the crank in my hand and the conrod moves up and down on the crank pin. i've ordered a conrod kit and gaskit kit for £52.00 and £30. it looks like it hasnt been long since it was rebuilt. theres hardley any carbon on the piston and the head is clean. i think its a new one actually.
hopefully it'll be for sale soon.
Craig