Crankcase full of fuel

Elworth · Post by **Elworth** » Sat Nov 22, 2008 8:35 pm

Hi Guys...this is my first post to the site as up till a few months ago i didnt have a bevel in the garage. Well now I do,,,, a beautiful orginal condition 1985 MHR has joined my 1098s and MTS...

All was goiing well until yesterday. I noticed the bike was leaking a mixture of fuel and oil. I couldnt see where it was coming from so off came the fairing and I started the bike. She fired up first press of the starter...BUT... then I noticed oil/fuel dripping out of the clutch sde engine casing.,,,very strange...I pulled off the cover and fuel oil poured out...OK...so now Im worried...I look at the oil inspection window...it was full to the brim...hmnnnnn...so I drained the sump....12 litres of fuel and oil later she was empty....I usually leave the fuel tap on when the bike is standing but now have a sneaking suspicion that the vacuum fuel cock that sits near the front cylinder carby is the problem....Has anyone ever had any experience or heard of such a problem

MartinMille BANNED · Post by **MartinMille BANNED** » Sat Nov 22, 2008 11:19 pm

Welcome to the Forum

Yes I had that a long time ago , reason being the rubber on your needle and seat gone hard and will no longer seal or some dirt in the float bowl is getting stuck on the rubber seat causing the needle to stay open and flooding cylinders and the fuel washes past the piston rings , replace both carb needle and seats and that should be the end of your problem
You may have to buy the full kit and I'm sure that Steve sells them in his store !

Elworth · Post by **Elworth** » Sun Nov 23, 2008 1:51 am

Hey thanks Martin....Hmmmnnnn thought that may be the case ....I will get in touch with Gowanlochs in Sydney to get some spares...Cheers Alex

Post by **BevHevSteve** » Sun Nov 23, 2008 1:54 pm

welcome to the forum. Yes you need to rebuild your carbies [float needle valves for sure along with seal kits and mos tlikely pump diaphrams. Your fuel taps might need ebuilding as well.

Please don;t leave your taps on any longer!!!

Yes I stock all the dellorto bits you may need. Please support this forum by buying parts frm us at Bevel Heaven www.shop.bevelheaven.com

Elworth · Post by **Elworth** » Tue Nov 25, 2008 2:15 pm

Thanks Steve....Strange that the carbs had a full kit put through them less than !2 months ago...and the bike has only done about 1500 klms since then...is it normal to have to go through such a process that often...? cheers Alex

abmartin · Post by **abmartin** » Tue Nov 25, 2008 4:40 pm

Mine were on the bike for almost 30 years before I had any problems. You may want to first make sure there is no dirt between the fuel inlet needle valve and its seat. This would allow the carb to overflood. Another possibility is a leaky float which would pull the needle valve open and again overflood the carb. Shake the float assembly to see if one of the floats contains fuel. Replacement is the only option in this case.

Sometimes fuel from an overflooding carb can collect on top of a piston and the resulting hydraulic lock at the compression stroke can bend a connecting rod.

Bruce

Elworth · Post by **Elworth** » Tue Nov 25, 2008 4:57 pm

Hey Thanks Bruce...

Yep...checked the floats and made sure there are no holes in them or sticking needles...flushed out bowls etc...All seems good ... I spoke to Mike Soderland from Gowanloch motorcycles here in Sydney today and he indicated this issue can sometimes result from something as simple as leaving the taps on when you have a full tank of of fuel..especially if the bike is left standing for a few weeks... Luckily the motor has very few kilometers (13000klm original motor) and I only ran it for about 30 seconds or so before I noticed the oil fuel mixture seeping out of the cluctch side engine cover...It could have been a much nastier result if I just ignored it and rode the bike with over 12 litres of oil and fuel slushing around in the crankcase....seems Ive dodged a bullet this time...so will keep an eye on it .....Phew!!!!!

machten · Post by **machten** » Tue Nov 25, 2008 5:00 pm

"Sometimes fuel from an overflooding carb can collect on top of a piston and the resulting hydraulic lock at the compression stroke can bend a connecting rod"

I once mistakenly left the fuel cocks on on my darmah and must have had a bit of grit in the front cylinder needle and seat which did exactly that. When i went to kick start it, I gave my ankle a real tweak. Fortunately no damage done (to the rod, anyway).

Vince · Post by **Vince** » Tue Nov 25, 2008 6:09 pm

Once cought,I NEVER leave the taps open when it goes to the shed,there is one of the Laverda blokes in Canada,doing a rebuild after bending a rod from excactly this.

Elworth · Post by **Elworth** » Tue Nov 25, 2008 10:45 pm

well i feel suitably scolded now...

the long term bevel owners should take pity on a guy whose other dukes have automatic taps and fuel injection...anyhow come the weekened my old girl will be back in action and "open taps" will be the order of the day

as she winds her way down the open sweepers of the far south coast of Nsw...fingers crossed for good weather...

Vince · Post by **Vince** » Tue Nov 25, 2008 11:01 pm

Keep an eye out for snow,the Sydney Laverda club run missed it by 1 weekend,were is summer?

Elworth · Post by **Elworth** » Wed Dec 03, 2008 4:48 pm

well...thanks guys for all the feedback on my crankcase full of fuel issue.... I can report that after after a full oil change ...a new clutch side engine cover gasket and oil filter the MHR fired up intstantly and ran like the swiss watch she was designed to be....I have to say that despite also having a couple of belts in the garage the "old girl" is just a joy to ride .... the throb of the Conti's...the asthmatic draw of the Del Orto's and the monstrous torque make each ride a memorable experience ... Cheers to Ing Dr T....the man was a genius....Cheers Alex

Post by **BevHevSteve** » Wed Dec 03, 2008 8:36 pm

Glad to hear that all is well.....

Tim Hesford · Post by **Tim Hesford** » Wed Jan 21, 2009 8:02 am

I have just acquired an 84 MHR. It too has a crankcase full of fuel. It was also left with the taps on (by my mate the plonker). However after draining the sump and putting fresh new expensive oil in I am heart brocken to find its full of fuel again and the taps were off! Has anyone had any experience with the vaccume tap leaking? Ive got the tank off and there doesnt seem to be any evidence of either tap leaking. Maybe my mates been at it while I wasnt looking!

Spub · Post by **Spub** » Wed Jan 21, 2009 9:11 am

While leaving the taps open will certainly cause this problem, I had an issue with a leaking tap that was not leaking fuel on the outside, but rather through the hose to the carb. It helps to have clear, transparent fuel line to make sure your taps actually turn off, but sometimes the leak is so small that it is hard to detect even with clear line. The "sugarcube" taps all look alike from the outside, but have different ways of fixing the rubber gasket in place. On some designs the gasket is prone to distorting/dislocating, causing a leak.

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Crankcase full of fuel

Crankcase full of fuel

Crank case full of fuel