weber carb

slacker · Post by **slacker** » Thu Jan 06, 2011 8:06 pm

Hello,
can anyone offer any suggestions on sizes for the weber 44 dcnf 120? I have been reading the forums and also the doc by Romus and Higgy. I'm a newb at this so any direction to help me better understand this weber tuning would be appreciated.

Basically I had rust in the tank of my 1990 750 sport and I have taken the tank off to get rid of the rust and have ordered a carb rebuild kit and have taken it apart and started cleaning it, but I wanted to put it back together with a proper baseline to tune it right. From my understanding the existing jet sizes that are in it are not stock.

Also should I still upgrade the Ventury to 4.5 and drill out two extra holes in the emulsion tube or is that only for the 906 model(it appears this did come with the 906 model emulsion tube)?

And my elevation here is around 1,100 ft but I may occasionally ride up to 4,500 ft.

Here are the specs that are in it:
Main jet 145
Idle jet 60
Air corrector jet 170
Auxiliary Ventury 3.5
Choke 34
Pump jet 40
Starting jet 110F7
Needle valve 175
Emulsion tube F27

slacker · Post by **slacker** » Thu Jan 06, 2011 8:10 pm

and I've already ordered the Grose jet and I have a cheapy fuel pressure regulator that supposed to support from 1-5 psi and I ordered new fuel filter, fuel pump filter, and have an inline fuel filter that will be installed in between the regulator and carb.

higgy · Post by **higgy** » Fri Jan 07, 2011 1:08 am

The 4.5 tall auxiliary venturis are a good idea on any weber,but you can make the one you have work
The modified emulsion tube Romus and I use is strickly for the 906, it may work in the 750 but I WOULDN'T GO THERE YET

First thing I would suggest is get it cleaned up and see where you are. No need to fix what ain't broke

In the mean time you can learn about the weber here.....http://www.webercarburatori.com/?p=handbook
this site has all the info you will need for free, no need to buy a book it won't give you anything more.
Need a pointer or 3 I'm usually around or you can pm me. It is best to put the filter before any regulator or pump if possible, the closer it is to the tank outlet the better off you'll be

BTW where are you located?

slacker · Post by **slacker** » Fri Jan 07, 2011 2:04 am

ok, cool, I'll just put it all back together and get it running again with the new grose jet and order some venturi's. I've had it for about 10 years and it ran pretty good for the first 2 but then I moved and had it parked at my parents house for a couple years and it never ran right again. I've now figured out that it was because of the rust in the tank clogging up the carb. I'd open up the carb and clean it out and it would run for about 30 miles then die out again until it got cleaned again. Took it to a duc shop twice and they never fixed it or told me about the rust so I started taking it apart myself, which has actually been kinda fun to start this new hobby.

Now I'm using evapo rust on the tank and going to follow it up with electrolysis for good measure. Also ordered a new in tank fuel filter and fuel pump filter.

I was just thinking that a previous owner had already modified(so I figured it I already had it off and open to try and correct anything in it now) it cause the sizes on everything didn't match to anyone else's and the emulsion tube was the same size as the 906 one you were showing and by the sizes I was guessing it was set to run to lean(but I'm still trying to figure out how all the sizes relate to eachother). It always had a stuttering until it got above 4000 rpm then it's power would kick in, I just thought that was normal for a duc until I started reading these forums and your doc's. Much thanks for the help.

I'm in Phoenix Arizona.

Post by **jcslocum** » Sat Jan 08, 2011 8:51 pm

Caswell's or Por-15 both make sealers for rusty tanks. they can seal up the rusty bits so it can't come back. Good stuff both of them!!

slacker · Post by **slacker** » Sun Jan 09, 2011 4:16 am

Cool, thanks. I was going to try out the por-15, but I think I'll try that caswell epoxy instead.

slacker · Post by **slacker** » Tue Jan 11, 2011 6:39 am

Didn't know which part of the forum this should go in...
Here's a parts diagram for the 44 DCNF. It's not exactly as our carbs are cause it looks like there are no top studs listed where the air horns mount on the carb.

slacker · Post by **slacker** » Tue Mar 01, 2011 5:45 pm

Just wanted to give an update. I've got the carb rebuilt from an alpha1750 ebay rebuild kit. Had to use a razor blade to cut at the gaskets to keep them from overlapping in the venturi's and also in the intake adapter and also none of the screw holes lined up proper. Also had to reuse two of the small ring gaskets at the fuel inlet cause the kit only came with one when I needed three. After using this kit, it worked, but I'll be getting one from pierce manifolds next time if I need to since their kit looks more complete and hopefully the gaskets will fit better. When I addressed this with alpha1750, alpha responded by telling me that my carb must be counterfeit.

I've degreased the tank with purple power degreaser, then evaporusted it, and sealed with caswell epoxy. Tank looks great now, I'd highly recommend these products. I've got to get my garage door fixed in a couple weeks to be able to start it up to tune the carbs.

Thanks for all the recommendations.

higgy · Post by **higgy** » Tue Mar 01, 2011 7:32 pm

Counterfeit to an Italian would be US or Spanish made. There is a difference between the 3. Best to give the series numbers when dealing with gasket sets,sorry I didn't mention that earlier,could have saved you some issues

slacker · Post by **slacker** » Tue Mar 01, 2011 7:48 pm

so you mean not all 44 dcnf's are the same? Mine says 44 DCNF-120 9E on it.

higgy · Post by **higgy** » Tue Mar 01, 2011 10:43 pm

Not all DCNF's regardless of size are the same,but yes that is the number you need to get the proper parts

BTW I have received a few wrong parts from Alfa1750 and she has always made good and at her expense, unlike Pierce which has a 50/50 chance of the right parts and no chance of return or exchange at all..you buy it, its yours. Also every time I have gotten a quote from them it has always cost me more in the end.
Hope you fair better. I have always gotten the right parts when they are available from Fast Road Cars who has also had parts no one else has from time to time. Anthony always does everything he can to get it if it can be had.

slacker · Post by **slacker** » Tue Mar 01, 2011 11:18 pm

thanks, I'll try fast road cars next time, it's probably worth the shipping then.

BTW, I had a brass float and it looked like your doc was based on a plastic float so I couldn't get the height to match so I set it at 49mm closed and 56mm open with the grosse jet. I couldn't set it at 48mm closed as per the haynes manual cause the float would hit the top of the carb cover. Does that sound right?

higgy · Post by **higgy** » Wed Mar 02, 2011 12:34 am

Level with the carb top is correct

for any float in any carb JFYI

regardless of specification and especially poorly written Haynes manuals

The only time this needs to be changed is when the carb is mounted at some angle other than parallel with the plane of gravity, like hill climbs

slacker · Post by **slacker** » Wed Mar 02, 2011 5:54 am

Ok, sounds good, I'll give it a try. haha, oops, I guess I got offended when I shouldn't have when she told me I must have counterfeit. I just saw how perfectly the previous gaskets lined up and never saw anywhere advertising any other specs other than the 44 dcnf.

weber carb

weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb

Re: weber carb