Life isnt fair, at least not today.

[Old Painless]

I travelled a long way to fetch my bike and got it at a decent price as a non-runner.

Just taken the heads off today and found the rear cylinder bores are worn excessively due to lean jetting from wrong size jets and no air filter. One bore has no cross hatching marks and the other has stripes of aluminium off the piston skirt down it.

Looks like i need 2 new pistons and the rear bores either honing or replating.

The base cylinder bore size is 55.00 mm and the max service limit is 55.10 mm.

Seems i have a 0.10 mm tolerance that i can hone within if the most damaged bore can be honed within that spec. Not a lot to play with.

The drag marks on the most damaged cylinder just look like deposits from the piston, anybody know if this is possible ?

[MexicanGringo]

So thats 0.05mm from either side (radius), a 10th isnt a minute amount but if the scratches go deeper, which they probably do, and the excessive wear is indeed excessive, youv got a problem. There was a guy a while ago that left tissues by his cams when doing valve clearances, they worked there way into the sump & blocked the strainer, ended up with a broken conrod & prob scratched bores, he may be able to advise.

Youl probably be advised by other members to buy a new engine off ebay, as its probably cheaper than repairing

[Old Painless]

Always the chance i am buying an engine with different problems to the one ive got.

[CMSMJ1]

How cheap was this non runner?? You can get these bored out to 57mm if you want, your problem is then spending £300+ on pistons....

[paul nc 24]

what bike is it? old painless nc30 or nc24.

[Neosophist]

It's an NC24 yep?

I thought it had the correct 115 jets?

The crosshatching should wear off within the first few miles as its only there to wear the rings in.

Worn bores are signs of lots of miles / neglect rather than jetting.. (it'd have to be really lean and then that'd usually just melt your valves)

If you have a badly scorred bore though it could have been caused by a few things I can think of.

-Something getting in the engine (ie working with carbs off, dropping something in)
-Spark plug failure (lean jetting) causing tip of plug to fall off
-Dropped valve (lean jetting) / valve failure

Problem with the NC24 is getting an oversized piston(s) and a head-gasket.

Hmm... i'd get a running engine from a broken bike, its' going to be a lot cheaper.. make sure you see the engine running first, I picked up a spare NC24 engine for £19.99 on a pallet (delivery was more than the engine) and its mint inside.

It's really hard to say without seeing it.

I'd say it's been ragged without oil in it / owned by numpties.

Of course this is all just speculation from my own experiences..

[Old Painless]

Its an NC24 running 112 and 115 jets iirc either that or 115/118, i cant remember. Either way with no air filter the previous owner has royally mullered it.

What can i say - its an unhappy lump.

It was £360. I will see about getting all the cylinders honed the same size before i do anything else, just means ive got to strip it to bits which is a pain in the ass.

Honing will probably set me back about £50 at my local SPR in Ruddington.

[Old Painless]

He must have heard me praying last night !

Just been to see a guy in Ilkeston breaking a VFR to find he was breaking two and VF400s and a mountain of other stuff besides, it was like alladins cave !

I picked up an engine, under tray, air filter, oil cooler, etc etc for a hundred quid. Today is officially a good day, finally.

[CMSMJ1]

Good arrows!

There is an NC24 engine for sale in Sheffield for £70 at the mo'

I was going to buy it as I want an oil pump - fancy flogging me yours out your dead engine?

[Old Painless]

A couple of pistons and a hone and i will get more than my money back was what i was thinking, you can have the whole engine cheap as it is if you want it, £40 plus delivery ?

Your going to say you just want the oil pump aren't you. lol