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Post by jimmycliff on Sept 27, 2011 7:26:48 GMT -5
Hi,
I have a '95 NTV 650. Whilst riding the other day, the engine lost power and cut out. I was low on fuel and was actually about to stop to fill up.
I switched to res and tried to restart but couldn't. The bike would turn over but wouldn't fire. Eventually flattened to battery trying so walked it home (mercifully only a couple of miles).
Today I checked the fuel system for blockages and replaced the filter. The system seemed totally fine while doing this, fuel running clean and fast at each point.
I put the tank bank, refueled (and turned the tap to 'on' lol), but still no joy.
I then checked the plugs for spark and they are all fine too. They are quite dirty, though, considering how new they are (I replaced them a month ago with the correct gap).
Basically, I have noticed an oil leak around the rear cylinder head. The coolant level is fine but the block is pretty wet with oil. It's not leaking very fast as I have been checking the level regularly and it's hardly dropped.
I changed the oil and filter when I changed the plugs and I overfilled it a tiny bit (10ml or so). I put the specified 2.6 litres in but that seems to have been too much. But only slightly.
I guess my question is do you think the rear head gasket has gone? I know it sounds like it has but would the gasket going cause the bike to lose power and cut out the way it did? Would overfilling the oil even by a tiny amount cause the leak/the gasket to go?
Apologies if any of these are stupid questions - I'm relatively new to all this.
Thanks in advance,
Jimmy
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Post by Jake on Sept 27, 2011 9:47:08 GMT -5
Unless the gasket was already about to fail it’s unlikely that overfilling with oil by this small amount would have caused a problem.....If the gasket had already failed however, then overfilling with oil wouldn’t have helped...... The fouled plugs may be a clue. The chart below indicates: "....an over-rich, air/fuel mixture. Check for a sticking choke, clogged air cleaner, or a carburetor problem - float level high, defective needle or seat, etc. This may also be attributed to weak ignition voltage, an inoperative preheating system (carburetor intake air), or extremely low cylinder compression....."www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htmAnd low compression could be caused by the failing gasket on the rear cylinder. But it could be just an intake air leak, carburetor or choke problem if the plugs are carbon fouled.... www.hawkworks.net/manual/4.html#4-2-troubleshooting
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Post by jimmycliff on Sept 28, 2011 6:49:54 GMT -5
Hey Jake,
Thanks for replying so fast. Looking at the chart, it looks like the plugs are carbon fouled so maybe it is an intake air leak or carburetor problem.
What do you think about the oil leaking from the head of the cylinder? Is this an indication that the gasket is gone/going?
I'm not a hugely experienced mechanic but I have the manual so can do a tertiary inspection of the float needle etc on the carburetor .
Just to clarify, loss of compression would account for the cutting out and inability to start would it not?
Thanks for your help
J
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Post by Jake on Sept 28, 2011 9:22:32 GMT -5
Carbon fouled plugs could also be the result of low compression....If its leaking oil from the cylinder head then the gasket has probably gone. I don't know if it's low compression that's stopping the bike from starting....You could try nipping up the cyclinder head bolts to try and seal the leak temporarily. But if the gasket needs replacing then I'd get that sorted out quick.... Normally, you'd warm the engine up before doing a compression test. But your bike won't start..... You may not even have the equipment do do a compression test.... www.hawkworks.net/manual/3.html#3-10-cylinder-compressionYou need to get the bike to a dealer/mechanic to try and figure out exactly what the problem is.....If you've already cleaned the plugs and the bike is not starting then it could be a carb problem or something else.... The only other thing is, did you fully recharge the battery after you'd flattened it?
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cyril
Full Member
Posts: 58
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Post by cyril on Sept 29, 2011 6:13:26 GMT -5
Hi Jimmy.
A slight over fill of oil should not cause the engine to stop suddenly.
The engine has a breather system and excess should either blow out down a drain tube, or be recirculated into the induction side of the engine to be burnt off.
You do not stipulate which part of the head is leaking oil. The very top bit (above the inlet ports) is the rocker cover with the cams, rockers, and valves. This quite often weeps, if the seal has hardened, or is displaced. Although messy and is not indicative of an engine problem, and can be resolved either by removing, cleaning and reinstalling, or replacement, not a difficult nor expensive part.
The bit directly under the ornamental cooling fins, or at the base of the barrels would be more expensive, i.e. an overhaul seal kit.
If your oil seems the right colour, and not milky, then there is probably not a gasket problem, as the Coolant (being less viscous, and at a higher pressure) will leach through the gaskets faster than oil will.
Your discoloured plugs could be for many reasons, fuel mixture, sticking choke, oil coming up past the piston rings in the cylinders, or coming down from the head past the valve stem seals in the head (a frequent problem on old fords. Escort mk2, Cortina's, Granada).
I stopped using the choke on my bike last year, the carbs are rich at idle anyway, just hold the revs up to 2K for about 30 seconds, until it will idle itself.
My bike is 22 years old, and starting to smell a little smoky on start up, so the Valve stem seals are on my winter 'to do' list.
Low of compression is unlikely to cause your bike to stop suddenly, unless a piston ring gave way, and i am sure you would have noticed the noise.
An engine needs, Something to burn, A means of combustion, and motion to do the sucking, and squeezing.
You have the motion, you said you have the sparks, that only leaves the Fuel.....
Once you have a good charged battery, it would be worth draining off the carbs, to flush out the bowls. crank the engine, and see if the carbs refill with fresh fuel, this should prove the fuel pump and cut off valve. The carbs are higher than the lowest part of the tank. The pump may have malfunctioned, or the electrics to the pump may have misbehaved.
A friend of mine has replaced the electric fuel pump on his Africa twin with a Car type pump, (his bike would cut out before reaching half empty) it is a mod on their web sites, you have to be careful of the flow rates, and pressure types, ie one for a carburatted engine, not fuel injected.
For me i would drain the carbs, and see what comes out, Check oil and coolant levels, and condition, pull the plugs, and turn engine over driving it from the back wheel in a high gear, to check for excessive stiffness. If that is all ok I would crank the engine to check the fuel pump is actually doing its job of pushing fuel up to the carbs. Hopefully this will get you going again.
If not, it should help isolate the fault, i wish you luck. Chris
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Post by jimmycliff on Sept 30, 2011 6:07:40 GMT -5
Thanks for the thorough replies, guys - it's great to get such detailed advice.
Chris, I think you have it with fuel. I phoned a garage this morning and the guy told me to check the fuel pump was operating and perhaps try tapping it with a spanner whilst turning over. (I had novicely negated to check the pump when I did the filter.
After a couple of taps, she started and then started another three times without taps.
So I think that puts the pump in the frame. I have ordered and aftermarket one and will look at the electrics this afternoon.
A friend suggested spraying the connections with WD40 and wrapping them in self-amalgamating tape. Does this sound like a good idea?
Thanks again for taking the time to help me out. It's most appreciated.
J
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Post by jimmycliff on Sept 30, 2011 6:08:36 GMT -5
P.s. I think the oil is indeed coming from the rocker cover so I'll look into that one too.
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