Author Topic: dellorto injector pump set up  (Read 514 times)

Offline gil

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dellorto injector pump set up
« on: March 20, 2023, 04:05:28 AM »
Hello Everyone,
I am completing my LE MANS 1 restoration ............however I am unable to find any info regarding the correct injector pump set up/adjustment for Dellorto PHF 36 carbs .
Very little about this subject  is to be found on the 'net'.
It would seem that the correct 'set up' can be achieved through collecting and measuring the amount of fuel squirted  from the pump nozzle  into a container and should be equivalent to   >
20 pumps= 5 CC.

Can anyone confirm this ?

thanks

Offline pressureangle

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Re: dellorto injector pump set up
« Reply #1 on: March 20, 2023, 08:27:14 AM »
There may be a 'book' setting for the pumps somewhere, but if there is it isn't necessarily optimum for your particular bike especially if the intake is not stock.

The simple way to get it close is to close the pumps until you find a deficit, then open them back up a little. The long hard way is to go out and jet the bike with the pumps closed off at steady-state in each of the individual carb circuits; slide, needle, and main jet. If this jetting is perfect for steady-state running, you will be lean when you open the throttle more than a little bit. Then you add in a little pump until you cover the lean effect. This assumes that the slide cutaway and slide pump ramp are what the bike really wants; most likely they are if they're stock.
I fell down that well 40 years ago, and long ago decided that close enough is good enough. Aside from fuel economy, there's very little difference across a broad range of pump settings.
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Offline Cdn850T5NT

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Re: dellorto injector pump set up
« Reply #2 on: March 20, 2023, 01:48:52 PM »
Useful info... Thx
1985 Eurospec 850 T5 NT (Nuovo Tipo - New Type... i.e. Series III)

Online John A

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Re: dellorto injector pump set up
« Reply #3 on: March 20, 2023, 06:41:19 PM »
Iíve never had to adjust that, it was always within the amount . Itís in the Dellorto tuning manual. The pump ramp controls when and how much for a given spot it will squirt. The steepness of the ramp determines the rapidity of the squirt. Again, itís in the manual. I think the manual is on this old tractor . There is a changeable pump jet as well. https://www.thisoldtractor.com/mg_manuals/dellorto_manual_a_guide_1.1.pdf
Yep it was there and the link transferred
« Last Edit: March 20, 2023, 08:24:13 PM by John A »
John
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Re: dellorto injector pump set up
« Reply #3 on: March 20, 2023, 06:41:19 PM »

Offline moto-uno

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Re: dellorto injector pump set up
« Reply #4 on: March 21, 2023, 12:30:04 PM »
  As can only be found in an Italian manual , nothing specific what so ever :) . However the real challenge, (more often than not )
  is to get the pump to actually prime to test for settings ! My favourite method , is with the motor running (and everything removed
  from the mouth of the carb) , take a piece of wood (large enough to cover the mouth of the carb) and whack the throttle open
and then cover the mouth of the carb with the wood. Turn it off, if it hasn't stalled and then check to see if it squirts when opening the
throttle, sounds crude but fast and effective !  Peter

Offline Cdn850T5NT

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Re: dellorto injector pump set up
« Reply #5 on: March 21, 2023, 11:08:30 PM »
  As can only be found in an Italian manual , nothing specific what so ever :) . However the real challenge, (more often than not )
  is to get the pump to actually prime to test for settings ! My favourite method , is with the motor running (and everything removed
  from the mouth of the carb) , take a piece of wood (large enough to cover the mouth of the carb) and whack the throttle open
and then cover the mouth of the carb with the wood. Turn it off, if it hasn't stalled and then check to see if it squirts when opening the
throttle, sounds crude but fast and effective !  Peter
@moto-uno, Peter, you're creating a mega-vacuum by totally choking the carb (from a higher than idle rpm that you've achieved)... choking-off that one cyl... and then main jet, idle jet, and accel pump have fuel brought right to their respective throttle bore discharge points, correct?

Why would you expect that the accel pump diaphragms would not be full and be ready to discharge (without doing this process)?
1985 Eurospec 850 T5 NT (Nuovo Tipo - New Type... i.e. Series III)

Online John A

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Re: dellorto injector pump set up
« Reply #6 on: March 22, 2023, 12:39:43 AM »
https://www.thisoldtractor.com/mg_manuals/dellorto_technical_manual_30-1.pdf
The procedure is in this one, the specs are in another but I didnít look that up for you. The first one I linked to looks like the cover of my book with all that stuff in it and I never looked farther than the cover on Benders site .
John
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Offline guzzista

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Re: dellorto injector pump set up
« Reply #7 on: March 22, 2023, 10:29:22 AM »
Easy way to prime the  accell pump ,(as learned from John Foyston from Eurosport decades ago) is to remove the pump cap and squirt a small plastic syringe full of gas into it
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Offline Stevex

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Re: dellorto injector pump set up
« Reply #8 on: March 22, 2023, 11:58:56 AM »
I primed and set up the accelerator pumps on my LM2 a few years ago. Yes theyre a pig to prime from empty. I did each set up on the bench, not the bike. To prime I also took off the brass screw and filled the system by pouring some fuel down the hole, it still took a while to get them both working. After that it was easy, I adjusted both pumps so they delivered the same amount of fuel for the same amount of bellcrank lever pulls by catching the fuel squirts and measuring it. After that you can adjust each pump the same amount on the bike to get responce how you like.I set up the oumps as per the dell orto manual, cant remember the fuel quantity mentioned now, but theyve worked fine for years since set up. Because of the prime issue, Ive never emptied them since. I just add fuel stab and run it through the carbs for when the bike sits over winter.
« Last Edit: March 22, 2023, 12:00:34 PM by Stevex »

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Offline gil

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Re: dellorto injector pump set up
« Reply #9 on: March 23, 2023, 02:30:47 PM »
good info - keep it coming ,thanks  to all for taking the time to reply

Online amamet

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Re: dellorto injector pump set up
« Reply #10 on: March 23, 2023, 05:09:51 PM »
I inquired about this a while ago. This is from euro carb, the dellortos distributor




Offline gil

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Re: dellorto injector pump set up
« Reply #11 on: April 26, 2023, 09:41:41 AM »
I have now set up my DELLORTOS as per instructions from Euro carb (above) .
This was ,actually fairly easy to undertake with the carb off and on bench , slightly titled , throttle lever pushed slowly/reguarly and held down after each push to make sure that the pump had squirted its load !
Contents collected and measured using  a small graduated syringe.
The pump priming was not an issue , and was accomplished by removal / injection/replacement of a small amount of fuel through the 'pump non return valve" screw .
Road test will follow soon .
Thanks for all the interest and replies.

Offline moto-uno

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Re: dellorto injector pump set up
« Reply #12 on: April 26, 2023, 05:55:43 PM »
 Great news , many happy squirting miles ahead ! :thumb:. Peter

 

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