Damaged piston (VFR400)

[EssexDave]

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.

[shifter]

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.

[SV650Racer]

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!.

[Wester]

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.

[shifter]

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.

[EssexDave]

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

[johnnyrod]

It does indeed sound like cobblers. I also fail to see why a valve repair is so cheap compared to a piston repair (whatever that means exactly) as there is a lot of labour in both. Unless it's dropped a valve though it should still run even badly

[EssexDave]

Bike has always been stored in a garage.
I'm going down to the bikeshop now and will see what they say.

Thanks for responses.

[fastdruid]

On the VFR400 the barrels are part of the cases, so to replace a piston you need to drop the engine and split the cases[1].
To replace a valve you just need to pop a head off which you can do with the engine in the frame. Still not a simple job but far simpler than doing anything with the pistons.

To do the same job on the SV would be a fraction of the cost as the barrels are separate to the cases.

Druid

[1] you _may_ be able to drop the sump, unbolt the conrod and pop it out that way, never thankfully had to do anything like that. :-)

[EssexDave]

Ok just got back from the shop.The guy doesn't know what's wrong with it.

What he's done is;

He did a compression test. There is some compression, but not enough for it to run.
He thinks it may be a sticky valve, which he thinks he can cure by using a hammer and "gently tapping" it.

He said, if this doesn't sort it, chances are it will be a piston.

[ThEGr33k]

Hmph, will look forward to finding out what it is that is wrong.

As said though id imagine that it could run on 3 cylinders, my dads old 400 four got him home on 3 cylingers, the 4th had exited the engine! he he. So I cant see why you would have absolutely no start.

What is happening when you go to start it?

[ThEGr33k]

Ok just got back from the shop.The guy doesn't know what's wrong with it.

What he's done is;

He did a compression test. There is some compression, but not enough for it to run.
He thinks it may be a sticky valve, which he thinks he can cure by using a hammer and "gently tapping" it.

He said, if this doesn't sort it, chances are it will be a piston.

I presume that is on one of the cylinders, not all of them :(

[Alpinestarhero]

If its a "sticky" valve, then it would be wise, would it not, to have the ehads off and have everything cleaned, right?

Could it not be a head-gasket (or other gasket) problem? Mind you, my dad had that problem on his VFR, and the engine ran but only on 3 cyl.

I think it is work popping the heads off...its not like its a horrible task, gear-driven cams mean everything just lifts out, no cam chain tensioners etc to worry about and resetting the timing is easy

[EssexDave]

The starter motor sounds like it's on speed. (faster than normal)
That's about it, it doesn't start, simple as.

[Alpinestarhero]

Does it sound like the engine is turning over at all?

[EssexDave]

I'm not sure it's been quite a while since I had the bike, they are taking ages to sort it out. They've had it a week and only done a compression test.

I think it was turning over, but can't be sure.

[ThEGr33k]

Does it sound like the engine is turning over at all?

Suspect sprag?

Did you try to bump it?

[EssexDave]

Yeah I bump started it. Was that a mistake? :|

[yorkie_chris]

The fact that as per your OP it started fine and rode home (did it feel OK?) suggests there's bugger all wrong mechanically.

[EssexDave]

Even after the bump start it rode fine.

[shifter]

I'm finding it very hard to believe that anything valve or piston would prevent it from starting, especially when you have 2 seperate heads and didn't hear anything go bang.
Have you checked all the basics, fuel air and sparks etc?

[EssexDave]

I've checked sparks and fuel. I tried starting it on the reserve too just to be sure.
And yes, I did check the killswitch :p

[shifter]

Now I'm leaning towards a starter fault as well

[ThEGr33k]

Yeah I bump started it. Was that a mistake? :|

No, not at all tbh

Even after the bump start it rode fine.

This is interesting. If the starter spins like mental, does it sound like there is any load on it? If you go and try to turn it over does the actual engine turn over? If not then sprag clutch could have gone... Im not sure if this happens on these bikes.

[EssexDave]

Erm, well I don't have the bike at the minute as the shop does. But I don't think it sounded like there was any load on it. But I can't remember, I've be around quite a few different bikes past 2 weeks with different problems. Bad memory.

[beabert]

Did he put oil down the spark plug hole and do a second compression test?

[EssexDave]

Did he put oil down the spark plug hole and do a second compression test?

I have no idea. Can you explain why you'd do that?

Cheers,

Dave

[yorkie_chris]

Seals up dodgy rings temporarily, if it is still low after that it is valve.

[yorkie_chris]

Even after the bump start it rode fine.

So it's more likely electrical then.

[EssexDave]

Bah, I hate when things go wrong.

[ThEGr33k]

Bah, I hate when things go wrong.


Indeed it sucks ****! I hope it gets sorted soon mate! :thumbsup:

[EssexDave]

Indeed it sucks ****! I hope it gets sorted soon mate! :thumbsup:

Cheers.

[Lozzo]

Get it out of the bikeshop it's in and have someone else give a second opinion. Sounds to me like a knackered sprag which was hidden by a duff battery previously. Your current shop don't apppear to have a clue.

As you said, it ran fine when bump started a week previously, so there's no reason why it won't run properly now.

I'd have another bike shop check out the Reg/rec while they're at it, sounds like it has a charging problem as well.

[EssexDave]

Get it out of the bikeshop it's in and have someone else give a second opinion. Sounds to me like a knackered sprag which was hidden by a duff battery previously. Your current shop don't apppear to have a clue.

As you said, it ran fine when bump started a week previously, so there's no reason why it won't run properly now.

I'd have another bike shop check out the Reg/rec while they're at it, sounds like it has a charging problem as well.

Thanks Lozzo,

Could someone be so kind as to explain what the sprag does?

thanks :)

Dave

[yorkie_chris]

One way clutch, it allows the starter to drive the engine over when the starter is spinning faster, but releases when the engine spins faster.

Full name is a sprag clutch. If they go pop then when you press the button the starter motor will whir without cranking the engine. Some bikes can have issues with them if you let the battery get low and they kick back.

[EssexDave]

Ah that does sound like the problem.
It does sound like my problem. It is like the starter motor is going but not engaging with anything.

[ThEGr33k]

If thats right then I suppose alpine star has the dibs on the idea, he sounded like he was asking about the sprag in a round about way...

Its and easy test, press the starter, if the starter turns and the engine dont then its the sprag.

[ThEGr33k]

One way clutch, it allows the starter to drive the engine over when the starter is spinning faster, but releases when the engine spins faster.

Full name is a sprag clutch. If they go pop then when you press the button the starter motor will whir without cranking the engine. Some bikes can have issues with them if you let the battery get low and they kick back.

Why would a low battery cause kick back. I know on odd occasions I get kick back, not nice! :smt009

[fastdruid]

Why would a low battery cause kick back. I know on odd occasions I get kick back, not nice! :smt009

Because it doesn't quite have enough 'go' to spin the engine past TDC and bounces back again, the sprag doesn't disengage in time and it tries to force back against the starter motor. Early triumphs were legendary for shagging sprags if the battery was low.

Druid

[EssexDave]

Ah, so the first attempt at failing a bump start, and the second successful attempt at the bump start, then attempting to start my bike a few days later = shagged sprag?

Druid do you know what part I need for an NC30?

[yorkie_chris]

Bump starting won't bother the sprag clutch at all. Starting on the button (or failing to) might knacker it though.

[ThEGr33k]

Ah ****e hope mine aint on the way out... Sigh. I sometimes get kick back as I mention.

Will keep an ear out for this. :rolleyes:

[fastdruid]

Ah, so the first attempt at failing a bump start, and the second successful attempt at the bump start, then attempting to start my bike a few days later = shagged sprag?

Druid do you know what part I need for an NC30?

Depends on what's gone, my CD200 broke the pins, in which case you'd need 3 of 28126-323-000 http://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_11691/ or £2.95 each

If you need a new gear thats 28110-MJ8-000 http://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_16324/ or £20

If you need the body then thats 28120-MR8-000, superceded by 28120-MR8-610 http://www.davidsilverspares.co.uk/parts/by-part-number/part_28120MR8610/ 93.60

Rollers are 91101-337-000, springs are 28125-426-000

Anyway, PM me with an email address and I'll send you the microfiche.

Bump starting shouldn't affect the sprag, only the starter motor affects the sprag.

Druid

[Spanner Man]

Good morning all.


If the engine wont turn over on the starter how did the garage manage to do a compression test? I doubt that they ran up the road with it in gear, with someone holding the compression tester running alongside!
Sounds like their talking Beelocks! I would suggest that you get your bike out of there sharpish.

NC30's charging systems are pretty poor, & suffer regular failures or the rectifier/regulator, & the generator. So get it checked out, as a low battery could cause the starter clutch to mis-function.

NC30's have pretty tough engines. However, as the valve shimming procedure is pretty fiddly most garages don't bother doing it. So it is possible to burn a valve.


Cheers.

[ThEGr33k]

Good morning all.


If the engine wont turn over on the starter how did the garage manage to do a compression test? I doubt that they ran up the road with it in gear, with someone holding the compression tester running alongside!
Sounds like thier talking Beelocks! I would suggest that you get your bike out of there sharpish.

NC30's charging systems are pretty poor, & suffer regular failures or the rectifier/regulator, & the generator. So get it checked out, as a low battery could cause the starter clutch to mis-function.

NC30's have pretty tough engines. However, as the valve shimming procedure is pretty fiddly most garages don't bother doing it. So it is possible to burn a valve.


Cheers.


Turn it off of the crank? I have no idea how you do a compression test though to be fair :)

[ophic]

Turn it off of the crank? I have no idea how you do a compression test though to be fair :)
This could explain the reported lack of compression :clown:

[fastdruid]

NC30's have pretty tough engines. However, as the valve shimming procedure is pretty fiddly most garages don't bother doing it. So it is possible to burn a valve.

+1 it is a PITA to do[1] and normally when checked they are fine...

It does make quite difference to starting and running though to have them spot on.

Also balancing the carbs makes a difference and again is a royal pita to do.

Druid

[1] Although doesn't need cams out like the SV as its shim over bucket.

[EssexDave]

I didn't think about the compression test.
That would be why there is no compression if it's not turning over :S

I really don't think I should let them keep my bike.

They want to charge me £50 to tell me i need a new piston..

[yorkie_chris]

Dave I think they're pulling your p*sser.

Turn it off of the crank? I have no idea how you do a compression test though to be fair :)

You screw the tester into a plug-hole, hold the throttle wide open and crank it.

[Alpinestarhero]

Dave, get your bike back off them, they sound a bit un-clever TBH. Can you get your bike to spannerman? I know he has a fair bit of experiance with those little V4's.

good luck, i hope the engine is ok and its something simpler, keep us updated :D

[EssexDave]

Apparently the engine is turning over. :s

[Sudoxe]

Apparently the engine is turning over. :s

Really? From reading the thread, I thought it was you that was being turned over.

Dan

[yorkie_chris]

So they charged the battery and ran a compression test. Ask for what the values were on all pots. And if they had the throttle open when they ran test ;-)

[beabert]

Battery directly to the starter, if it has starting issues.

Need to do it twice if low with and without oil in the bore, as above throttle must be fully open.

[EssexDave]

How hard is it to rebuild an engine given unlimited time and funds?

:p

[Alpinestarhero]

So they charged the battery and ran a compression test. Ask for what the values were on all pots. And if they had the throttle open when they ran test ;-)

good call, you wouldnt expect there to be no compression on any of the 4 cylinders, unless you had just the most aweful luck in the world

[yorkie_chris]

No chance of one of these puppies jumping chain links on timing chain is there lol.

With unlimited time and fund engine rebuild is easier than taking a leak

[Sosha]

No it isn't.

[beabert]

easy peasy as long as you enjoy reading/researching.

[Alpinestarhero]

easy peasy as long as you enjoy reading/researching.

+1

go slow, go careful, check three times, do it once, prepare well and if you are unsure, ask for help or get someone round to help

My dad had no problems refurbishing the top-end of his vfr engine (but then...he is a mechanic with +30 years experiance :lol:). it all looks easy enough though, but if you want to pop valves out and stuff make sure you have the right tools - probably better to hire or borrow than buy outright for just one job, unless its cheap

[yorkie_chris]

No it isn't.

Yes it is. With unlimited fund you say to best builder in the business "I'm sending you a pallet with an engine on it, make it work"

[EssexDave]

I've been thinking about a project bike for a while, and I guess now is as good a time as any to start.

Depending what the problem actually is of course.
Good way to learn too I guess.

[fastdruid]

Personally if it *is* an engine problem I'd get a replacement engine to run and take apart the one you have to learn how it all goes together...

Druid

[beabert]

go slow, go careful, check three times, do it once, prepare well and if you are unsure, ask for help or get someone round to helpYou know its done correctly too, I never like asking for help because i find many others are not as thorough as me, like using just plain oil when the official manual states a mix of oil and moly. Having done the research you find many just plain dont know as much as they thought they do. Best to take advice from many sources and cross reference itn all.

Always read the manual, or several.