Petrol in crankcase.. lots of it.

[dirty30-2008]

Hi all.
Bike hasn't been used for a couple of years since it last disgraced itself ( broken exhaust valve on No.3). In that time I replaced the valves on that cylinder courtesy of RO, did the carb modification and shimmed the needles.Bike was recently treated to new needle valves and seats, Li-tek seals. Bike was a runner and had light use before laying her up. Although I have started her infrequently I had a problem the other day. She started then clonked. Hydraulic locking up.On removing the plugs cylinder No. 2 was full of petrol/oil mix. Something told me to drain the oil which spewed a highly diluted mix of oil/petrol, over 4.5 litres. Haven't drained it all either as I didn't have a container big enough. My fuel tap in unmodified so no fuel should flow until there is a draw from the engine. For this amount of petrol to bypass /work itself into the crankcase I feel it has to be carburetter related but the tap remaining open?
I can only assume that the valves are not sealing enough when the float level rises. I was meticulous about setting float height to 6.8mm but noticed that that the spring in the new needle valves is stronger than the original needle valves.My first port of call maybe to re-use the old needle valves.
Has anyone had a similar occurrence and did you manage to find the root cause.
Cheers....
Rob.

[CMSMJ1]

Ballache!

It's nearly always something carbs related and so I would be looking at whether it is sealing floats properly. Some crap or the like in the seat of the needle.

[dirty30-2008]

I replaced the needle valve and seats as sets supplied by RO. As I said before the spring on the needle seems really strong compared to the originals and I set the float height as Haynes advise,tipping the carbs until the tang of the float is loading the spring. These were spot on. Could it be that the float pressure is insufficient to seal against the pressure of the spring? The cone on the needle valves look unworn,I.e. no indent on the rubber.
Certainly is a ball ache.

[Variablevalves suck]

Probably both the float on the cylinder that's full and the fuel tap not sealing so feeding fuel into cylinder.
Take the fuel line off and check it's not dripping.

[dirty30-2008]

Had a look in the tank and what petrol that is left is below the height of the filter so its drained about 3litres of petrol. Tap is gonna be checked as it must have flowed past without the vacuum being generated.I cut a fairly accurate measure from a credit card and set the Keyster needle valve kits until the tang is just touching the spring but not compressing it ala the manual spec 6.8mm. I put the originals back in as a comparison and they sat significantly lower as the pin on the old spring is shorter, barely 2-3mm above the lip of the carburetter. Don't believe I have set them wrong or is my method flawed?

[dirty30-2008]

Okay, had a little time and I have checked the fuel tap and nothing flows until I draw a vacuum, so I am satisfied all is good there. I have re-checked float heights with the keyster needle valve and seats in and these all match. Carbs are back on.
Given the above , how would that quantity of petrol find its way to the crankcase? Surely if the carbs are flooding the petrol would vent through an overflow or does it trickle into the head , sit on the piston/bypass the rings ( which are probably shot given the mileage). The reality is I've changed nothing. Pot No2 was the only one hydraulically locked when investigated though that doesn't rule out that the other cylinders weren't allowing petrol into the crank also.
Anyone with a take on this would be welcome.

[Suzuki416]

You have 2 issues - these are really common.

1. Leaky fuel tap on the tank - CMSL have spares
2. Floats not sealing allowing the fuel from the tank via the leaky tap to drain past.

Fix both

[dirty30-2008]

Am I missing something? I believe the tap to be good as no fuel flows until I draw a vacuum, hence my assumption the tap is functioning normally. As for the needle valve not sealing, they are all renewed in pairs as supplied, no reason to think they are faulty. I thought that maybe the float is not exerting enough pressure on the spring pin in the needle valve, thereby not sealing. Has anyone had similar problem with the keyster kits? I may put the originals back in to see if this addresses the issue.

[Suzuki416]

Am I missing something? I believe the tap to be good as no fuel flows until I draw a vacuum, hence my assumption the tap is functioning normally.

Yes that is your assumption, However on the basis that your sump is full of fuel, I think its safe to assume that your 'assumption' is flawed.
The fuel tank supplies fuel to the carbs after the tap. if you have fuel at any point after the tank then the tap ISN'T working exactly as it should.

As for the needle valve not sealing, they are all renewed in pairs as supplied, no reason to think they are faulty. I thought that maybe the float is not exerting enough pressure on the spring pin in the needle valve, thereby not sealing. Has anyone had similar problem with the keyster kits? I may put the originals back in to see if this addresses the issue.

You are still getting fuel into the sump ... It is coming through the Carbs from the tank. That means the fuel isn't shutting off in the carbs (as well as the tap). Therefore you also need to fix the carbs.

[dirty30-2008]

The tap was tested with the tank off the bike. When the tap was off no petrol flowed. When it was either ON or on RES it only flowed when I applied a vacuum as it would be generated by the engine. Surely that says the tap is good.
As for the needlevalve and seats, that is where I am guessing the issue lies. What I was asking was if anyone had replaced their needle valve and seats with the Keyster kit only to find that the float does not seal if set as per the 6.8mm. My earlier post mentions that the spring in the keyster kits is significantly stronger than the original in my estimation and the float may not exert enough pressure on the tang which presses on the spring pin allowing more fuel into the bowl.To overcome the resistence in the spring I would need to reduce the float height incrementally.
Also the resting position of the float with the old needle valves and seats in was noticeably lower than with the new sets in which by contrast are rather springy.
So...has anyone had difficulty setting up the keyster kits? Sure I could resort to putting the originals back in, but thought she deserved new ones after 125,000+ miles.
Cheers.I'm open to all theories on this one.