Damaged piston (VFR400)

I'm looking for a general opinion before paying out a shedload for a repair the bike may not need.

The story is;

This VFR400 NC30 was owned by a guy before me for 7 years, used at the weekends etc.
I purchased the bike on around 22,000km.

From June this year I have done 19,000km and the bike is now sitting on 41,000km. It was serviced when I purchased it, and had a check over in August, all seemed fine.

Late october, I'm out on the bike and it won't start. Battery is flat.
I bump start the bike, ride home and leave it for a day or two. Still wasn't starting. I figure it needs a new battery (and possibly something electrical meaning the battery isn't getting charged). Regardless, I purchase a new battery, fit it, look forward to a days ride, and nothing, bike won't start.

Leave it for a week, get in contact with a local bike repair shop who now have the bike. They say that either, one of the valves is damaged, or a piston is damaged. Now, the quote for the valve repair is around £50. But the piston is £400-500.

The bike showed no signs of problem before it wouldn't start, and has been fine all year. A lot of the mileage has been commuting to and from work (60 miles a day round trip)

My question for you guys is, does a damaged piston sound resonable? Obviously it could have happened over time, but I was fairly sure that the VFR engine was bomb-proof and things like this were hard to manage.

Should I be getting a second opinion on the damage?

cheers
Dave

[ophic]

I can't see how damage to the engine internals and the electrical system could be related.

I think if a piston was failing you'd know about it, it wouldn't be running normaly and then just not start. It would start on the other 3 cylinders even with no compression on the fourth.

If its dropped a valve then starting would be hard if it would run at all.

Why not go down to the repair shop and ask to be shown the damage?. To see valve damage you would have to remove the airbox/carbs and look down the inlets at the very least.

If the valve is damaged then £50 is far too cheap for repair - you cant repair a valve!.

Can't really help much myself but you may want to ask over at 400greybike.info.
Failing that wait for YorkieChris :P.

[fastdruid]

1) Sounds like the normal NC30 reg/rec / alternator problem
2) Sounds iffy, although possible would be unrelated to the starting problem.

Forget getting it fixed, just too expensive. NC30's in general are bullet proof, engine failures are few and far between and so engines are cheap.

I got a 20k engine (for an NC35[1]), with carbs for 120quid, another 60quid on a service kit/oil and jobs a good un.

Druid

[1] 2nd gear started jumping, would have cost more in parts than the replacement engine.

If it had dropped a valve it would surely hit the piston and would make a mega racket when you tried to start the bike?
And reading back over the OP I also think Reg/Rec.
If you have valve or piston trouble then i'm sure there would be noise and smoke and i'm sure you would not be in any doubt that there was something wrong.

[yorkie_chris]

Dropped yeah but bent or burnt not necessarily.
Compression test it.

The bike shop claim to have done a compression test and I'm not sure of the exact results as they left a message with my parents.

The bike was literally fine, no difference to the previous 6 months before failing, which was clearly electrical.

It does sound different when I try to start it now, I jsut don't see how sitting around not running would damage a piston.

The concensus then is to ask the shop to show the damage?

[fastdruid]

Well if it was stored outside there is a chance that water could get into the combustion chamber, rust the sidewall and you end up with very low compression.

I got my SV spares engine due to that (and then bought a s/h set of barrels for 20quid).

Druid