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Dellorto float nut gasket leak. What's the trick?

Posted: Tue Jul 19, 2011 4:30 pm
by mattcfish
I was installing new floats on my Dellortos last night. The old ones had gotten heavy and had actually stuck in position in the past. I usually reuse the ring shaped gasket that goes on the bolt that holds the float on. I've had a problem in the past where the new gaskets always leak while the old gaskets won't, so I've kept on using the old gasket ring.
Last night one of the old gaskets stuck to the float and was damaged when I removed the nut. I had several new spares, so "no problem" right...? Wrong...there was a puddle of gas under the bike this morning.
Is there something I'm supposed to do to the new gasket to prevent this? Is there a trick other than using a sealer?

On a side note. I tried to use the two methods to adjust float level. The 18mm measurment technique http://www.ducatimeccanica.com/float_levels.html
and Sno Bum's 55cc (ml) per bowl trick. "It is a good idea to check the float adjustment (3.2.2). Here is another method: With the carbs full of fuel, shut off the fuel and clamp the line above the carb. Place a measuring cup under the bowl, and undo the center nut, and let all the fuel run into the cup. It should be 55 cc. Adjust the float if need be, taking this measurement several times, to be sure you are doing it accurately. Officially, from the manual, the float heights are 18 mm, +- 0.5 mm. You will prefer my 55 cc method; or, check the measurement on the workbench."

When I adjusted the carbs the first way I ended up with the floats being just about parallel with the base (like a Bing). But, when I measured the fuel in the bowl (just for curiosity sakes) I ended up with almost 65ml of fuel (that's with all hoses disconected, and just measuring the fuel that trickles out around the loosened bolt). When I tried to go by just the cc's like Bum did, the float had to hang down to 19+mm's and I still couldn't get less than 60cc's. The tang could not be bent any further. I have the latest version of the PHM carbs. Do they have larger bowls?

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Tue Jul 19, 2011 7:09 pm
by esman100
Have you tried grease on the gasket?

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Tue Jul 19, 2011 7:24 pm
by Dave Backmarker
Matt,
I replaced the two nuts on the bottom with milled nuts to the bottom of the bowels that I got from Bevel Heaven. They are pricey but much stronger than the pieces they replace.

I don't know the capacity of the float bowls but I used the Dellorto spec of setting the floats with the 18.5 mm method. If you'd like, please PM me with your e-mail address and I'll send you several pages from a Dellorto tuning guide I found helpful.

DaveM
1975 R90S, 2000 R1100RT

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Tue Jul 19, 2011 10:11 pm
by mattcfish
Dave Backmarker wrote:Matt,
I replaced the two nuts on the bottom with milled nuts to the bottom of the bowels that I got from Bevel Heaven. They are pricey but much stronger than the pieces they replace.

I don't know the capacity of the float bowls but I used the Dellorto spec of setting the floats with the 18.5 mm method. If you'd like, please PM me with your e-mail address and I'll send you several pages from a Dellorto tuning guide I found helpful.

DaveM
1975 R90S, 2000 R1100RT
You mean this? http://shop.bevelheaven.com/detail.aspx?ID=335
Looks like the same 21mm bolts I have. Doesn't say anything about how they are made. Did they have another product? I'm trying grease. We'll see if it leaves a puddle by tomorrow.

I checked my float cc's again today with a more accurate graduated cylinder. I've got about 58cc's in each. Better than 60 but not 55. The float setting is bigger than 18.5 mm (over 19mm) using the Dellorto specified method.

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Wed Jul 20, 2011 12:16 am
by robtg
If the float bowls contain 55cc or 2 gallons it makes no difference. The actual fuel level is the important thing.

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Wed Jul 20, 2011 1:44 am
by mattcfish
robtg wrote:If the float bowls contain 55cc or 2 gallons it makes no difference. The actual fuel level is the important thing.
Yeah, but how do you know where that is? That's where one of those transparent floats would be handy. http://shop.bevelheaven.com/detail.aspx?ID=297

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Wed Jul 20, 2011 2:00 am
by Major Softie
mattcfish wrote:
robtg wrote:If the float bowls contain 55cc or 2 gallons it makes no difference. The actual fuel level is the important thing.
Yeah, but how do you know where that is? That's where one of those transparent floats would be handy. http://shop.bevelheaven.com/detail.aspx?ID=297
That's why I like carb bowls with drain spigots. You put a piece of clear tubing on that sucker, open the petcock, open the drain, hold the tube up alongside the carb, and you see EXACTLY where the fuel level is.

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Wed Jul 20, 2011 12:41 pm
by Dave Backmarker
mattcfish wrote:
Dave Backmarker wrote:Matt,
I replaced the two nuts on the bottom with milled nuts to the bottom of the bowels that I got from Bevel Heaven. They are pricey but much stronger than the pieces they replace.

I don't know the capacity of the float bowls but I used the Dellorto spec of setting the floats with the 18.5 mm method. If you'd like, please PM me with your e-mail address and I'll send you several pages from a Dellorto tuning guide I found helpful.

DaveM
1975 R90S, 2000 R1100RT
You mean this? http://shop.bevelheaven.com/detail.aspx?ID=335
Looks like the same 21mm bolts I have. Doesn't say anything about how they are made. Did they have another product? I'm trying grease. We'll see if it leaves a puddle by tomorrow.

I checked my float cc's again today with a more accurate graduated cylinder. I've got about 58cc's in each. Better than 60 but not 55. The float setting is bigger than 18.5 mm (over 19mm) using the Dellorto specified method.

Matt,
Yes, those are the parts. They're milled. I agree with trying grease too.

DaveM

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Wed Jul 20, 2011 2:55 pm
by RickR90s
"If the float bowls contain 55cc or 2 gallons it makes no difference. The actual fuel level is the important thing".

I would think it does make a difference as 55cc's creates a pre-determined level in the float bowl. FWIW, I find that the 55cc measurement to work just fine. To me, it's a much more accurate method of determining how much fuel is in each bowl.

RPG

Re: Dellorto float bolt gasket leak. What's the trick?

Posted: Wed Jul 20, 2011 3:39 pm
by mattcfish
Major Softie wrote:
mattcfish wrote:
robtg wrote:If the float bowls contain 55cc or 2 gallons it makes no difference. The actual fuel level is the important thing.
Yeah, but how do you know where that is? That's where one of those transparent floats would be handy. http://shop.bevelheaven.com/detail.aspx?ID=297
That's why I like carb bowls with drain spigots. You put a piece of clear tubing on that sucker, open the petcock, open the drain, hold the tube up alongside the carb, and you see EXACTLY where the fuel level is.
I actually thought about doing just that. Anybody done that to PHM's?