UK Monster Owners Club Forum .: Technical :. Engines, Clutch, Gears » M900 Carb Leak

Reply
 
Thread Tools Display Modes
Old 28-06-2020, 04:20 PM   #1
Ross090
Registered User
 
Join Date: Jun 2020
Location: Richmond
Bike: M900
Posts: 88
M900 Carb Leak

Hi All,

Just fired up my 1993 M900 for the first time since restoring. It jumped into life almost immediately

All is good except I seem to have a fuel leak at the carbs. The only things I did to them when they were off is open one of the black plastic covers, and I also removed two screws to zinc plate the throttle cable mount. I've also replaced all the lines but I cant see that being the problem.

Do these carbs have common areas of leaking? If so, anyone know where I can source some seals/gaskets locally?

Cheers

Last edited by Ross090; 28-06-2020 at 04:25 PM..
Ross090 is offline   Reply With Quote
Old 28-06-2020, 04:28 PM   #2
manwithredbike
aka Phil
 
manwithredbike's Avatar
 
Join Date: Nov 2005
Location: derry
Bike: M900
Posts: 354
Quote:
Originally Posted by Ross090 View Post
Hi All,

Just fired up my 1993 M900 for the first time since restoring. It jumped into life almost immediately

All is good except I seem to have a fuel leak at the carbs. The only things I did to them when they were off is open one of the black plastic covers, and I also removed two screws to zinc plate the throttle cable mount. I've also replaced all the lines but I cant see that being the problem.

Do these carbs have common areas of leaking? If so, anyone know where I can source some seals/gaskets locally?

Cheers
Where's the petrol coming out Ross, is it at the overflow outlets? Could just be the float valve not seating properly after a period of lay up??
__________________
..
~
manwithredbike is offline   Reply With Quote
Old 28-06-2020, 04:39 PM   #3
Ross090
Registered User
 
Join Date: Jun 2020
Location: Richmond
Bike: M900
Posts: 88
Its quite hard to tell with everything else attached to the bike so I think I will be stripping it down again soon. It appears to be from the left hand carb, but that could be just because its sitting lower when on the sidestand.

It doesnt look like its from the overflow outlets as I have them routed down past the engine, and the tubes were on quite nice and firm there.

Is it possible to test for leaks when they're off the bike and it isnt running or does it need fuel pressure?
Ross090 is offline   Reply With Quote
Old 28-06-2020, 06:41 PM   #4
manwithredbike
aka Phil
 
manwithredbike's Avatar
 
Join Date: Nov 2005
Location: derry
Bike: M900
Posts: 354
Shouldn't be any prob checking them off the bike. The fuel isn't pressurised in the carbs.
It would be useful if you were able to see where it was coming from on the bike though in case it's one of the supply line connections.
__________________
..
~
manwithredbike is offline   Reply With Quote
Old 28-06-2020, 08:06 PM   #5
Ross090
Registered User
 
Join Date: Jun 2020
Location: Richmond
Bike: M900
Posts: 88
Thank you!

I'll take a good look at things when I remove the airbox, hopefully that'll show me if its lines or carbs.

I've found some gaskets on ebay, but they're pricey and a full kit which isn't really what I want. I'll be calling Ducati tomorrow, but I doubt it's something they stock.

Last edited by Ross090; 28-06-2020 at 08:10 PM..
Ross090 is offline   Reply With Quote
Old 29-06-2020, 12:21 AM   #6
Sirc
Registered User
 
Sirc's Avatar
 
Join Date: Jul 2008
Location: guildford
Bike: M900
Posts: 352
to answer your question "do these carbs have common areas of leaking?" - apart from the norm concerning needle valve maladies, they do have one other and that is the float chamber drain plug/screw. It uses a very shallow taper as a means of sealing and this means that they need tightening very carefully as it's only too easy to crack the tapered seat of the bowl casting if over-enthusiastic tightening applied. Hopefully your leak is the more common needle valve failing to seal type as a result of standing etc. Careful examination of float bowl interior will usually be visible if taper seat fractured if you need to check.
__________________
giacca a vento massima
Sirc is offline   Reply With Quote
Old 29-06-2020, 11:48 AM   #7
Ross090
Registered User
 
Join Date: Jun 2020
Location: Richmond
Bike: M900
Posts: 88
Thanks for the info.

I have some seals coming from Ducati, I will be sure to check the casting for any cracks when I have the carbs off the bike again. Hopefully an easy and cheap fix though!
Ross090 is offline   Reply With Quote
Old 07-07-2020, 06:34 PM   #8
Ross090
Registered User
 
Join Date: Jun 2020
Location: Richmond
Bike: M900
Posts: 88
Looks like it was one of the bowl gaskets afterall
..what a job that was!
Ross090 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 07:11 PM.

vBulletin Skins by vBmode.com. Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.