nc30 engine problems

[mini_me]

ok, now I am having a hard time believing that I have managed to fuck my nc30 engine (the story is below if your interested)

so the whole point of this is now I may possibly need a new engine and does any kind kb'rs have a spare one lying around that they would be willing to sell to mwah? or do they know of any available

and more importantly do any of you fullas have any advice one what I should do and what I shoud look for
cheers
m/m

now the story goes something like this
last weekend I was out riding with my step-brother and step-father and My bike drops a cylinder and refuses to start (now when I say dropped cylinder I dont mean running on 3 with the 4th firing every now and again I mean only 3 cylinders firing but it wouldnt run for any set amount of time) and so I pull the and tank off to have a looksie because I was thinking fuel blockage but there is only so much you can do with a roadside toolkit so I put it back together and try to bypass the fuel pump (blocking off the little pipe that sucks and then manually sucking on the place where that pipe goes and hey presto she fires and runs sweet, lets reattach the pipe and hope she stays running so I take off down the road ahead of the others and I get a grand total of 3.8 km down the road before the same happens again and this time she is truely dead and no amount of coxing with get her to fire (now its trailer time)[insert roughly an hour of laying down in the sun while the others return with the car and trailer]

later that night I have the bike in my mums garage and can look at it a little more comprehensively first thing I do is pull the fuel pump apart but no fault can be found, bugger I'll have to look elsewhere, so I did for until some horrible hour in the morning without any success. The next morning dawns brightly [I know cos I was awake] and after a couple of minutes of tinkering I suddenly remember how I had initally thought it was a fuel blockage and cursing my memory I blew really hard down the fuel line and it seemed to get a little easier after a bit (whether it was jsut cos i blew all the fuel into the carbs i dont know) so i now connect the fuel lines and start to turn her over and she almost immediately fire and purrs away quite happily and the throttle response is just like it used to be right then it be test ride time shoot off up the road to test it (yes very irresponsible I know) but she still isnt running properly and is still misfiring but all 4 cylinders are running. I am now thinking valve clearences and carb balancing will fix the problem so off to a bike shop it goes for a tune up

a couple of days pass and i recieve a call from the mechanic who is telling me that he pulled the airbox cover off and the airbox _full_ of oil (which it definately wasnt when I put it together) alerted to this he ran a compression test and all 4 cylinders where around 65 psi and they should be 165psi so they are _way_ down (i queryied this and he said it was with brand new guages and he also tested 2 other bikes cos he couldnt believe it) so he checked the valve clearences and the came up fine so he stopped at that point wanting to talk to me about what do to

[Warr]

Ohhh thats a bit harsh.
How may k's has the motor done. Might be time to upgrade to its bigger bro, the 750/800

[mini_me]

its only just done 38k
and i know those are the true k's or at least very close because I've owned it since 13k and just the general condition it was in when I bought it told me it was genuine
m/m
ps. I've done oil changes every 5000 religously

edit: oh and I would _love_ to have an rc30 or rc45 just they kinda pricey and hard to come by

[Sketchy_Racer]

i would think that it sounds like a crook headgasket to me but the fact that all cylinders are at 65psi just dont sound right- take it to another shop and get it tested i think i dont think it would even run on that amount of compression?? although it was running like a rats arse when you tested it did it still have a similar amount of pick up that it used to??

just my 2cent

cheers, GLenn

[mini_me]

i would think that it sounds like a crook headgasket to me

no water in oil or vice versa (just did an oil change and checked the coolant)


but the fact that all cylinders are at 65psi just dont sound right-

i know thats what I thought but it was a rband new set of guages and the mechainc double checked it by testing another couple of bikes as well


i think i dont think it would even run on that amount of compression??
although it was running like a rats arse when you tested it did it still have a similar amount of pick up that it used to??

you'd think that - other than the very annoying miss (like it had out of balance carbs it was running like normal)


m/m

[Ixion]

Well, the oil in the air intake could be from blowby down a breather that's taken back to the intake for emission reasons.

The 65psi on ALL cylinders sounds odd - too even. Usually it's like 30 100 60 50 or something, varied.

Only scenario I could put togeher is : initial fuel blockage. Then you partially cleared that but only partially cleared it. Lack of fuel meant it was running lean (though on all 4 carbs ? ). Lean mixture means detonation, and might (maybe) hole a piston. Holed piston on one or two cylinders would sound possible, and account for low compression , and massive blowby. But the even, low compression on ALL cylinders has me stumped. Only guess I could make, is one, or two, holed pistons, and also a blown head gasket between the cylinders. Sometimes the blow misses the water jacket. The blown head gasket would equalize the pressure .

Engine will run on 65psi though - not well, but it will run.

Sounds like the head's going to have to come off anyway.

Bad luck.

[mini_me]

Well, the oil in the air intake could be from blowby down a breather that's taken back to the intake for emission reasons.

The 65psi on ALL cylinders sounds odd - too even. Usually it's like 30 100 60 50 or something, varied.

Only scenario I could put togeher is : initial fuel blockage. Then you partially cleared that but only partially cleared it. Lack of fuel meant it was running lean (though on all 4 carbs ? ). Lean mixture means detonation, and might (maybe) hole a piston. Holed piston on one or two cylinders would sound possible, and account for low compression , and massive blowby. But the even, low compression on ALL cylinders has me stumped. Only guess I could make, is one, or two, holed pistons, and also a blown head gasket between the cylinders. Sometimes the blow misses the water jacket. The blown head gasket would equalize the pressure .


Engine will run on 65psi though - not well, but it will run.

Sounds like the head's going to have to come off anyway.

Bad luck.

hmmm, that could explain it however... being a v4 it would require that both the fornt and rear head gaskets blew in teh same way at roughly the same time
and wouldnt you hear a hole in the piston let only two pistons, The motor is making _no_ mechanical sounds as such it is just missing every so often which is what made me think fueling
I've talked to several people and they are all at a total loss for what it could be
me and my brother are gonna strip down the engine next weekend and see what we find

m/m

[Kwaka-Kid]

Thought i do have a spare engine... your case is not worthy!

I dont think theres any problem. Would love to check it out... Oil in the airbox - how much exactly? Because yeah mine gets quite a fair amount, only becasue of the union breather, was it overfilled with oil? That could help the cause.

Hmmmm... interesting, again, id love to cehck it out.. timing aint shit hot atm with racing tomorrow and too much to do here at home :(

[Ixion]

hmmm, that could explain it however... being a v4 it would require that both the fornt and rear head gaskets blew in teh same way at roughly the same time
and wouldnt you hear a hole in the piston let only two pistons, The motor is making _no_ mechanical sounds as such it is just missing every so often which is what made me think fueling
I've talked to several people and they are all at a total loss for what it could be
me and my brother are gonna strip down the engine next weekend and see what we find

m/m

Yeah, I don't have a lot of faith in the theory. It would need a lot of things to happen at once. Two blown head gaskets? Both missing the waterways ?? Well, 'tis possible I guess.

Though, no, you won't hear anything from a holed piston, except maybe some blowby noise out the crankcase breather. Actually, the term is usually a bit deceiving, on four strokes you don't usually get a nice neat hole in the middle of the piston (seen it, but more common that on two strokes). What happens is that you get detonation damage around the ring lands, and leakage past the rings. No mechanical noises .

If it weren't for the oil in air filter , and above all the low compression readings, I'd say fuel supply. I really wonder about those compression readings.

[Kwaka-Kid]

i have ONCE seen a hole right thru the right rear cyl of a VFR400NC30, first and only time though... really dont expect it.

[mini_me]

i have ONCE seen a hole right thru the right rear cyl of a VFR400NC30, first and only time though... really dont expect it.

lol, had a friend who put the wrong sparkplug in an AG100 and punched a whole through the top of the piston, got his old man to weld a plate over the top of it and away she goes again

[Sketchy_Racer]

Argh! nothing sounds like it should be running bad!!! have you cleaned all carbs and fuel lines etc out?? does this model have a fuel pump? is it working? the fact that it ran better once you blew some fuel into it and it ran better makes me feel like it is a fuel prob

anyways good luck

Glenn

[sAsLEX]

Argh! nothing sounds like it should be running bad!!! have you cleaned all carbs and fuel lines etc out?? does this model have a fuel pump? is it working? the fact that it ran better once you blew some fuel into it and it ran better makes me feel like it is a fuel prob

anyways good luck

Glenn

well i had some trouble with mine and had the carbs off a few times and never found a fuel pump


turned out to be a bugger spark plug that caused it, even though it seemed like fueling from the symptoms

[mini_me]

update: found the side of the motor is covered in oil and it appears to be coming from the side of the head(rear) :S
*sigh* looks like a new motor is the go
its sprayed all on the inside of the fairings
oh and when you turn it over with no sparkplugs in oil comes up through the spark wells

m/m

[Ixion]

May not be as bad as a new motor. Oil coming up the cylinders certainly looks like holed psiton. But i've known that happen and all that's needed is a new set of pistons and rings (and gaskets etc). Of course, there may be other damage, ring chunks can score up the bores etc. You'll know once the heads are off.

[mini_me]

May not be as bad as a new motor. Oil coming up the cylinders certainly looks like holed psiton. But i've known that happen and all that's needed is a new set of pistons and rings (and gaskets etc). Of course, there may be other damage, ring chunks can score up the bores etc. You'll know once the heads are off.

yeah, but there is a big catch 22 in the whoe thing, i need a bike to get to work on and if i dont work i cant pay for the repairs and I *could* spend thousands fixing that motor and i think it works out better to throw a new motor into it and then pull the old one to pieces to have a look at whats wrong with it and if pos fix it up and sell/keep for spare

[Sketchy_Racer]

well dont spend any money yet just pull it down and see what has gone wrong.... it may have blown the gasket near the oil trace and is pumping oil into the cylinders... if its well screwed bugger but sometimes they are better than thought :)

[Ixion]

I'd second that. Y'r not going to know what you're up against until you pull the heads. And most of the work to do that you'd have to do anyway to switch engines. So pull the heads, then make the call. If it is a new engine you've not lost anything, just carry on with the removal. And if it is a simple and cheap fix (and really, you just never know either way until you get into the innards ) , then you're laughing.

[wendigo]

I'll third RG100. Blew a piston in my NC23 after ~130 k (due to buildup of deposits on the valves raising the compression enough to cause detonation), which cost the price of 1 piston + 1 headgasket + 1 set of rings to repair. Can't remember the exact price (couple of hundred I think), but it was certainly shitloads cheaper than going of and buying a new engine. At 38 k there's still plenty of wear left in the motor.

How many cylinders is oil coming out of & what state are the plugs in (ie any signs of little balls of alluminium or the plugs being excessivly worn)? The impression you give is that it's more than 1. I find it hard to believe a honda motor would let go 2 or more cylinders at once.



I blew really hard down the fuel line and it seemed to get a little easier after a bit

If its a diaphram pump like on the nc23 (which in likelyhood it is), I found this means SFA. It's nigh on impossible to blow through the pump. Best plan to test the pump is to pull the fuel hose of the fuel rail, point it into a container & turn the ignition on. Fuel should get pumped out. If none does & there's no clicking noise of the pump working, pump is fucked. I bring this up, coz again I had this problem (at a different time) on the cbr - in my case it was actually caused by one of the screws that go through the end cap (where the power lead goes into the pump) having worn away some insulation internally in the pump & shorting out the pump. It was quite an interesting problem really, because it was only intermittent, and manifested in a number of different ways. To start with the engine would mysteriously die after a couple of k (in hindsight however long it took the float bowls to empty themselves). Leave it for a couple of minutes start her up & of I'd go. At first I though it was carb icing (it was December in Ireland at the time), coz it would only happen when starting the bike from cold, and I could hear the pump clicking for a few seconds whenever I turned the ignition on. It was only when it blew a fuse that I twigged something more was amiss. Again like you I was bloody miles from nowhere & ended up jamming the entrance hose from the pump into the exit hose & limping home.

The moral of this story is to double check that pump. Would be a damn shame to go off & either get the motor repaired or bung in a new one & have exaclty the same thing happen a few hundred k down the road.

Good luck with it anyways.

[sAsLEX]

If its a diaphram pump like on the nc23

I am sure the thing dont have a fuel pump, see http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=15308&d=1125915428, which shows no power to a pump, plus I havent seen one when taking the carbs off mine

[Kwaka-Kid]

alex your like a dog with a bone!

no,they never ever had fuel pumps, but it only takes 10 mins to put on on it which is a semi-common race trick.

[Raven]

Been readin through this thread and I have come up with the only possible explanation I can think of which would explain your lack of cpmpression in all pots like you've got and would also explain your oil problem. I don't know where you have parked your bike but sugar etc in the fuel would explain all your symptons including the misfire. Fouled plugs due to glazed bores and rings allowing blow by. Hope I'm wrong and best of luck.

[Raven]

More along the same lines as before. Check your fuel by putting some on a sheet of glass or anything for that matter that won't absorb it and let it dry. See if you get any residue. I've heard of some real stupid things people have done and some things can be added to fuel to the same effect that are undetectable and will continue to stuff engines until the tank is thoroughly cleaned. I'm not really sure you'll be able to detect anything but it's worth a shot and is cheaper than getting a chemist to check it.