Submarine GS

[Greg Masters]

I think that you've got to accept that it's totally fecked.

If you have new oil in the motor, drain it and sell it as it now the most valuable part of your bike.

 

[BlueBird]

I think that you've got to accept that it's totally fecked.

If you have new oil in the motor, drain it and sell it as it now the most valuable part of your bike.

not yet its not, will put fresh oil in and run it again see how i get on,
I havent got the right dti to measure the tdc but to be honest it runs that smooth i am thinking that the stroke is ok.

 

[Greg Masters]

not yet its not, will put fresh oil in and run it again see how i get on,
I havent got the right dti to measure the tdc but to be honest it runs that smooth i am thinking that the stroke is ok.

Even with bent rods, the stroke will be OK. But bent rods will mean that the piston deck height is wrong and, maybe, the way the pistons run up and down the bore could be twisted. CR will be well down too.

 

[Bendy toy]

Agree the endoscope is only approximate.
You can get an more accurate comparison with a long posi tipped screwdriver down the primary plug hole. Put a ring of PVC tape around the screwdriver shaft and check opposite side is the same. If in doubt use a DTI.

If still in doubt whip the cylinder off and have a proper look.

 

[Pukmeister]

I doubt most DTI's will have enough travel to measure full piston stroke, just detect TDC.

It won't measure a bent conrod either, unless you remove the rod and sit it on a surface table first.

 

[Bendy toy]

Piston stroke won't have changed but if a rod is bent, its piston will start and stop lower down the bore. Bent rod is effectively shorter.
So compare piston TDC height left to right. If a piston is lower at TDC (stops short) it's likely the rod is bent.

 

[snaponphil]

Piston stroke won't have changed but if a rod is bent, its piston will start and stop lower down the bore. Bent rod is effectively shorter.
So compare piston TDC height left to right. If a piston is lower at TDC (stops short) it's likely the rod is bent.

Only real way to check is remove the cylinder heads & use a straight edge or DTI guage to compare piston heights at TDC in comparison with the top of the cylinder barrels.. ( not a job for average DIY either)

 

[alex_rsa]

Won't a compression tester show up a difference or is the result likely to be too small to register?

 

[Greg Masters]

Won't a compression tester show up a difference or is the result likely to be too small to register?

No and yes

 

[Bendy toy]

If the piston is starting and stopping short the compression ratio will be lower, but a bent con-rod might only be a mm or two so serious damage could still make only a small difference in pressure readings.

Easiest accurate method is DTI comparison of TDC height with a known good engine. You'll have to work out a reliable datum point to use on each engine - probably take off the rocker covers. THE BEST option as already posted is to take the cylinder head off and measure the deck height from the head gasket face to piston top. It's then a small further step to take off the cylinder and physically look at the con rod.

If a con rod is bent at least you'll be able to be sure the big end shells are replaced. If its not bent they could still be hydraulic damage to the bearing shell. As mention earlier, some engines can crimp their big end shells with "only" piston/valve contact. Water is even less forgiving.

 

[BlueBird]

Update

So yesterday I changed the oil and filter and ran it up to temp 5 times before I was happy with what was coming out. final fill up with fully sythetic oil,new plugs and took it for a ride seems to ride ok,took it to a couple of local respected bike techs and they say it sounds fine.
although the fuelling seems a little lumpy on tick over with it "hunting" a bit,also going along on a steady throttle at around 2-3k its unsteady, also seems like there is a flat spot at at around 4.5k which wasnt there before.

I,ve had the throttle bodys and battery disconnected for a couple of days,
I think there is a "reset" procedure which I will look for and carry out.

 

[Pukmeister]

Is it possible that there is a little dampness in your throttle position sensor? Its a vital component in telling the fuel injection/ignition maps how much demand you are asking of the engine, and if the signal goes awry then it isn't going to run smoothly. Perhaps pull the three-pin connector from the TPS on the left hand throttle body and give it a squirt of WD40, I don't think its wise to pull the sensor apart and clean it.

 

[BlueBird]

https://www.youtube.com/watch?v=FIdhylMpUqE

https://www.youtube.com/watch?v=EqvmwyMSGII

 

[Bendy toy]

Running the engine with a little water in the system won't do any harm it's also the only way to boil off the water. The oil is designed to emulsify water. Obviously I'm not talking about serious mayo.
But working an engine with bent con rod(s) could score the crank bearing journals if it doesn't throw a rod.

 

[Greg Masters]

<iframe width="960" height="720" src="//www.youtube.com/embed/EqvmwyMSGII" frameborder="0" allowfullscreen></iframe>

If that's how it is now, change the oil again!

If the rods are bent, you're probably into another engine anyway. But if you did 80 miles home, you'll probably do thousands more.

 

[BlueBird]

Why, There aint no water in there.

<iframe width="960" height="720" src="//www.youtube.com/embed/EqvmwyMSGII" frameborder="0" allowfullscreen></iframe>

If that's how it is now, change the oil again!

If the rods are bent, you're probably into another engine anyway. But if you did 80 miles home, you'll probably do thousands more.

 

[Greg Masters]

Why, There aint no water in there.

Which oil is that fecking colour????

 

[BlueBird]

Brand new oil !

Which oil is that fecking colour????

 

[Greg Masters]

Brand new oil !

Mazola?

 

[SteveM]

Crisp 'n dry