today i went to fastline to pick up my regulator and oil and see the hrc 28sp.
anyway all went well and got home a little early so i decided to fit the regulator and check everyting is ok
all went well and the bike is now charging at the correct rate so i decided to give it a little clean when i noticed a little oil dripping from my lower fairing, so i took the fairing off and saw that the exhaust gasket at the header was dripping oil so i thought i would whip the chambers off and replace the copper gaskets for the sake fo a few quid!!!!!!!!!!
now for the bad bit
i looked up the exhaust port of the lower chamber to see a nice clean piston and exhaust valve ,
but when i looked up the exhaust chamber of the upper cylinder the piston is very badly scored as if it has slightly seized, what should i do, i have only ridden her twice and warmed her up propper both times,
im gutted and dont want to get rid of the bike but also dont want to ride it incase it go bang!!!! help please!!!!!!

Sorry to hear that Phil. Looks like its barrels off & a new top end rebuild kit from Gavin at Jap4. If its seized, it sounds like it has, you may need to hone out the barrel as well. Probably some more experienced guys on the forum can give you more detailed / better advice.

When I get back from my travels, I'll be being doing the same inspection through the exhaust port when I clean the RC Valves. I've no idea what I'll find yet!

Good luck.
_________________
Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

Wonder if the carbs needed rejetting after fitting the new Tyga cans?
_________________
Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

i havent rode it with the cans on and there is no way i have done this.
the engine still runs fine its just in the back of my mind andi dont think i should be paying for the repairs!!!!!

if it were me i whould wip the top end off and have a good look at it mate. mite be helpfull to post some photos. what mods have you done on it?

Does it look/ feel like big deep ridges vertically along the piston? Do the rings look like they`re being held in by the scuffing?
If it seems like it was running okay before you noticed this, I would guess that it`s not that bad.
I think I would at least take the offending cylinder off & inspect it. You can leave the head in place, saves you a head gasket. You may even be able to re-use the base gasket, though it will probably need replacing.
You`d be suprised at what you can clean up from the piston and cylinder.
Have you got much experience of pulling engines apart?
If you`ve only just got the bike (from Fastline)? Perhaps you`ll want to try getting them to fix it under warranty?

if you paid so much for it, take it back and get them to sort it! must be some kind of warranty?

Yes they gave me 2 months warranty and they said something about putting a 2nd hand piston in, which i wasnt happy about as i want both top ends rebuilding, i would be tempted if i had paid 1500 for it but the bike cost me 4000 and i want it right otherwise its going back!!!!!!!!!!!!!!!!!!

is there anyway of telling what pistons are in my bike without taking it apart? i just want to get all the parts priced up so i can give them the option to fix or money back!!!!!!!!!!!!!!!!

Not unless you are really lucky and can see the marking top of the piston through the spark plug hole!

Even then, depending on the piston, some have no mark! The bike is almost bound to be rich too, so the crowns will probably be black anyway.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

isnt there a stamp on the cylinder which will indicate what pistons are in it!
cheers phil

Yes, but you can't be guaranteed that it has the correct corresponding piston!

Look in the parts manual, it will tell you (a) what goes with what, and (b) how to identify the parts.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!

Phil, a top-end rebuild kit for an MC28 (piston, rings, pins, bearing, gaskets) costs £85 in the UK.

Be careful with second hand pistons. I used to rebuild many 2 stroke engines (admittedly Stihl chainsaw & disc cutters and not NSRs), many times a piston looked fine on its skirts (no scores or marks), but the ring grooves wear which allow the rings to ramp up and down inside the grooves, which can then continue on the path to seizure.
_________________
Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

not a chance on this earth am i paying £4000 for a bike going out on it once ( which it broke down on me ) and fitting a second hand piston,

i want 2 new top end rebuild kits or my money back!!!!!
and then ill see what the bore is like when i get the cylinder off, if thats f**ked i want it replating or a new one!

so they only sell you a bike for 4k and give you 2 months warrenty, what do the 6k bikes come with? if i was you i would contact them and ask if they would pay for new piston and rebuild kit and do it yourself for peace of mind, shame you didnt query the secondhand piston before exchanging the cash for bike. if yours is like this what are the other bikes there selling like?