UK Monster Owners Club Forum » .: Technical :. » Engines, Clutch, Gears » I have two problems :-(

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Old 27-05-2020, 09:53 PM   #1
Murray Mint
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I have two problems :-(

As the title says, I have two very distinct issues.

The first is that with the bike level and on stands I am seeing fuel dripping from the drain hole in the carb if I give the bike a bit of a shake. I have checked that the drain screw has NOT cracked the float bowel. The float levels have been set to 14 mm when they are just touching the shutoff valve. from my point of view, the fuel coming out of the drain hole would indicate that the fuel level in the bowel is too high.

The second problem is with the compression pressure. after warming the bike up for around 10 mins, I carry out a compression test. With the throttle wide open and plugs removed and grounded, I crank the engine for about 10 revolutions and I'm getting a reading of 100 PSI, this is very low from the 150 PSI in the manual, has anyone got any suggestions as to what the issue might be?

Thanks for looking.

Murray Mint

Last edited by Murray Mint; 27-05-2020 at 10:07 PM..
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Old 27-05-2020, 10:04 PM   #2
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Hi Murray, I assume you mean 'NOT cracked the float bowl'
Perhaps the needle valves aren't sealing, either worn or some crud in there. Same possible with the seal on the drain screw.
Also check that the floats aren't damaged, if there's a hole in one it won't float. Either that or try setting the floats a little lower.

edit: rather unhelpfully, my 900 manual has no languages other than Italian around the float bowl section, it's in four languages everywhere else, although I'm fairly sure float height isn't mentioned as my Italian is passable as long as no-one is speaking fast at me.

Presumably after ~10 revs the compression has stopped rising?
Try putting a little oil in the bores before re-running the compression test, if the compression comes up, it's rings/bores, if not you need to look at valves: first clearances, then seats.

Last edited by slob; 27-05-2020 at 10:24 PM.. Reason: checked manual
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Old 27-05-2020, 11:20 PM   #3
manwithredbike
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re the compression, are both cylinders roughly equal in pressure, and how is the bike running?
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Old 28-05-2020, 11:40 AM   #4
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Slob, I've always set my float levels to 14 mm and not experienced any issues, ill whip them off tonight and set them up a bit lower.

manwitharedbike, there is no other colour then a RED Ducati now is there!!! :-)
Yes both cylinders are the same and last time i had the bake out it ran well, no problem lifting the front wheel high enough to scare me. :-) The bike has been standing for nearly 12 months so ill get a MOT on it and get some miles covered and try the compression test again. Last year was ment to be the big rebuild but sadly never happened. :-(
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Old 28-05-2020, 02:14 PM   #5
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Quote:
Originally Posted by Murray Mint View Post
Slob, I've always set my float levels to 14 mm and not experienced any issues, ill whip them off tonight and set them up a bit lower.

manwitharedbike, there is no other colour then a RED Ducati now is there!!! :-)
Yes both cylinders are the same and last time i had the bake out it ran well, no problem lifting the front wheel high enough to scare me. :-) The bike has been standing for nearly 12 months so ill get a MOT on it and get some miles covered and try the compression test again. Last year was ment to be the big rebuild but sadly never happened. :-(
lol, yes, red is the fastest of course!
If the bike was running well, as it sounds, i'd not be rushing into any major work until you get round to your major rebuild. Though as Rob said, worth checking out the obvious eg valve clearances etc making sure your openers aren't too tight. Also worth checking the pressure guage. The piston rings could be stuck in their grooves having been laid up though you would prob notice it a smokey as the rings don't get to expand to seal the cylinder wall properly. if so, they might work free with a few runs, or you cold soak them overnight with some light oil.
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Old 29-05-2020, 08:55 AM   #6
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Ok so I think I found the problem. both floats were set to the correct height, 14mm, however I found after taking the carbs off, again...……. I'm getting good at that, and stripping them down, I found that the plunger inside the fuel cut off valve was sticking. with a little playing I managed to free the plunger off and all is now good.

MOT today at four, wish me luck.


Last edited by Murray Mint; 29-05-2020 at 09:00 AM..
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Old 29-05-2020, 10:27 AM   #7
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Good luck.
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Old 29-05-2020, 11:16 AM   #8
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It could be my 65yo eyesight but both tips look like they have slight wear marks. If your fix doesn't work I think I would replace both valves and seats. Good luck !

About the compression figures if it starts and runs ok , and does't use oil I would leave it alone. BTW how many miles has it dpne?
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Old 29-05-2020, 02:04 PM   #9
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the lodger, its done just over 34,000 miles. the bike is due for a full rebuild and refresh soo ill see what the end of the summer brings to see if the compression needs to be addressed.

I will also buy a couple of valves along with a full carb rebuild kit.
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Old 29-05-2020, 08:27 PM   #10
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Bike didn't even make it to the MOT, well geographically it did, but upon arriving at the test station there was fuel pissing out of the nearside carb, needless to say, no MOT today.

I left the bike with the shop to sort out and will pick it up done dusted.
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