(1980) Dellorto PHF Question

bclark

bclark

Senior member
Having never previously owned vacuum guages I've balanced the carbs by setting the slide height with a drill bit (1980 triple PHFs http://www.thisoldtractor.com/gtbender/print/dellorto_parts_diagrams_parts_diagram_for_dellorto_phf_carburetors.htm ) - double checking the induction pitch from each with a pipe. However I'm now fortunate enough to have access to a set of mercury gauges [Cheer] although as is there appears to be no vacuum take off points [Boo].

But.. Dellorto list "vacuum take off adaptors" for these here [Cheer]:

http://www.dellorto.co.uk/merchandise/products.asp?CategoryID=2&PartsectionID=21

So does anyone know where these go?
 
Looking down on the carbs at the front left ( engine end ) there is either a vacuum take off tube, most likely interconnected between all three carbs, or a slot headed screw. Either plug your guages straight into the tubes or fit a 5mm adaptor after first removing the blanking screws, try not to drop them under the starter motor  ;)


    Keith
 
Thanks Keith - I've just located the blanking screws as you describe (screw head facing straight up). I took out the left most one, flicked the starter and found vacuum.. cool. This mercury balancer comes with adapters that match the screw threads so thats a bonus.. but what a flipping bugger those other 2 screws are!

I stuffed an old shirt up between the carb inlets to prevent the starter motor filling up on the screws - which along with a magnetic screwdriver worked well. I think I may just wait for the morning to get the right most adaptors in though..

 
Worth getting some vacuum takeoffs to put in your carbs permanently. Not expensive and readily available:

http://www.dellorto.co.uk/merchandise/products_details.asp?PartNo=9679&CategoryID=8&PartsectionID=17

Just join them with some tube when you are done....

Don't like mercury guages - bloody nasty stuff as it stays in your system forever (and I probably have too much already  :( ).

Davida gauges are pretty good and not too expensive.

By the way - does anyone know how to get the cam cover off without disturbing the carbs and needing a rebalance?  I am sure I didn't have to in the past, but can't remember how (must be the mercury  :D )

Pete
 
Why bother struggling? Carbs off in less than10 minutes then remove the cam cover up and backwards. You need the carbs out of the way if you want to do anything in there anyway. Don't be lazy, just do the job properly  ;)


  Keith
 
Maurice,

The rear of the chain tunnel catches on the nderside of the bar that supports the carbs..

Keith, not being lazy really (well, sort of  ;) ). I was trying to get the cover off without disturbing the carbs, as I couldn't find my vacuum gauges (building work going on, so boxes everywhere).  Found the gauges, so all OK now.

By the way Keith, do you find the carbs go out of tune if you remove them complete?

Cheers

Pete
 
poffer said:
By the way Keith, do you find the carbs go out of tune if you remove them complete?
Click to expand...

laverdakeith said:
They go out of tune if you look at them funny...
Click to expand...

Usually a sure sign the linkage shafts and bushes are shot...

If the bushes and shafts are within wear limits, tune does not go off THAT far, always wise to check though!

piet
 
laverdakeith said:
Why bother struggling? Carbs off in less than10 minutes then remove the cam cover up and backwards. You need the carbs out of the way if you want to do anything in there anyway. Don't be lazy, just do the job properly  ;)


  Keith
Click to expand...

Maybe on rubber mounted carbs but not on the earlier clamp on ones.

                                                                                    Dave
 
Remove the top off the centre carb and ease the bank off with a flat tyre iron. If they are real tight back all of the inlet manifold nuts off quarter turn, don't do them back up again untill the carbs are back on aligns the manifolds and makes the job easyer next time. Still sub 15 minutes even with a struggle....


    Keith
 
poffer said:
"..do you find the carbs go out of tune if you remove them complete?"
Click to expand...

As long as there is a little slack in each of the cables (ie. non are holding anything partially open) and the routing stays the same I'm sure you would not need to re-adjust (the relative positions of everything should stay the same).

A good indicator would be the tick-over after the operation - if it ends up different it would be worth rechecking, if it seems the same I wouldn't worry..
 
The spacer/positioning plates on the Dellortos are easily bent when removing/replacing the bank of carbs, not a lot, but sufficient to throw out any static carb settings.
 
Maybe on rubber mounted carbs but not on the earlier clamp on ones.
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Dave, so are you saying that rubber mounted carbs are easier to deal with?  I have a set lurking in the workshop, so could fix 'em up and put them on.

Are they easier to work with (they look a little odd to a 180 person like me, as all the idle screws are on the inside  ::) Nice touch with the ability to fit drain pipes for the float overflows though  :)  They are clean as a whistle, so could be a good option to get back on the road and sort the originals out in winter...

Keith - next time I go near the carbs, I will look the other way  :-*

Pete
 
poffer said:
Are they easier to work with (they look a little odd to a 180 person like me, as all the idle screws are on the inside  ::) Nice touch with the ability to fit drain pipes for the float overflows though  :)  They are clean as a whistle, so could be a good option to get back on the road and sort the originals out in winter...
Click to expand...

Simply indicates the left and right hand instruments have been incorrectly fitted/swapped at one stage... :-\  ::)

Rubber and clamp type are absolutely identical in function, just a few minor differences at the float bowl and main jet holder.

piet
 
I have never had the take the carbs off to get the cam cover off - its easy to take it out on one side - the right as I recall, get the hump past the spine an bobs yer uncle...don't want to cause a stir but it never seemed necessary...just did it a couple days ago. I could go on and on about all the bikes I've done it to but its really irrelevant. 8)
 
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