PHF32AD refurb

V

Various

Junior member
Location
England
Merry Christmas to you all.

Yesterday I went for a Christmas Eve ride on my '76 3CL and after riding along on a twin for most of the ride I finally decided that the carbs need a good looking at and I can't make things worse, so I've started taking them apart (for the first time by me) to see what it's like in there.

I've only stripped the middle carb at the moment, but there's clear evidence that it was left with fuel in for a few years causing all sorts of mess (which hopefully explains the way it runs). I'm planning to replace the following items from Eurocarb on all three carbs, can anybody flag up anything more I might need to consider or flag up anything which looks odd:

Needle: K12
Atomiser: AB265
Main jet: 118
Needle valve and seat :250
Choke jet: 70
Idle jet: 55
PHF pump diaphragm
Non return valve
Fuel banjo filter
PHF gasket set

I'm undecided on replacing the floats, they are covered by a heavy deposit but look basically OK.

The mixture screw looks fine, I will probably leave that alone. I can't see any damage on the body.

This lot add up to ?85 less than a whole new carb, so it's getting close but seems like enough to try and refurb the existing bodies.

Thanks
Matt


 
Matt,

A good clean and carefull setting up can have your engine running well again.  Lots of other things to consider...

Seems you have a 1200, judging from your K12 needles.  The 1200s have very restricted air boxes to comply with noise regulations of the time.  They do work best once the restricting crap is removed from the air box and K1 needles fitted, ie, reverting to stock 1000 specs.

If not punctured, floats can normally be re-used.

Also check slide condition and play in the actuating linkage shafts.  The slightest amount of slop will play havoc on all your balancing efforts.

piet
 
If it has been gummed up it is a waste of time just fitting new brassware and leaving it at that.
They need a few hours in an ultrasonic bath after degreasing and then blowing out with an airline.
Also a waste of time just refurbishing one carb.
It's possible to clean all the tar-like crud off the floats. Try neat petrol.
Personally I would fit 3 x K1 needles and throw out any restrictor plates (if any) in the airbox.
Is it running standard restrictive silencers or Jota pipes?
If running Jota pipes you may want to increase main jet size up to 125 or 130.
 
Thanks guys. I'll be doing all three carbs. The deposits aren't the tar/varnish I've seen in other carbs, it's more like a dry 'scale', a bit like you get inside a kettle. I'll have a go at scraping it (gently) off the float.

I'm interested that the K12 needles seem wrong, as far as I know it's a standard 3CL with original silencers (not the seamed ones and not Jota) and an airbox with nothing in it. So K1 is the correct/standard needle is it? I've ridden about 700 miles on it since I bought it and it has a huge flat spot (hole!) in the mid-range until it gets virtually full throttle, at which point it flies.

The slides have some wear, but not too bad, so I'll clean them up and put them back.

I've just stripped one of the outer carbs and it's in a lot better condition, although still not brilliant, especially the needle.

I also notice that only one of the three carbs actually screws-up tight onto the bracket which connects them, 2 of them move about when tightened - this isn't right is it?

 
All three carbs should be tight on both brackets.  If the brackets are bent or loose, you will have great difficulties synchronising.

Strange that a 3CL should have K12.  K1 is standard for a 1000.  Flat spot should be gone when you're done. 

Heed Grants advice re ultra sonic cleaning... these deposits can take their time.  All passages need to be checked with an air line, preferrably with more than just 5psi pressure.

The deposits on the floats can usually be rubbed off.  As the needles seem to have been replaced with incorrect items, please check the floats, should be marked 10gr.

piet
 
Carby cleaner spray will remove all the gummy fuel deposits and eliminates ultrasonic cleaning imo.

Watch out carby cleaner will also remove your paint so be super careful  :)
 
Jod said:
Carby cleaner spray will remove all the gummy fuel deposits and eliminates ultrasonic cleaning imo.

Watch out carby cleaner will also remove your paint so be super careful  :)
Click to expand...

It works OK on the gummy stuff, but has difficulties removing hard, limescale-like deposits in the fine passages.  Especially the passage from the mixture screw to the tiny opening in front of the slide is affected.  This is often a right bugger to free up.  If this passage is blocked, you can kiss a steady idle good-bye.

A bath in the parts cleaner, a douse of carb cleaner for really stubborn stuff on the outside, and at least 30 minutes in the heated ultra-sonic with a dedicated ultra-sonic cleaner fluid usually do the trick.  Hit each passage with about 140psi of compressed air to make sure.  Even then, it sometimes takes a soft copper probe to dislodge stubborn crap.

piet
 
sfcpiet said:
Matt,

A good clean and carefull setting up can have your engine running well again.  Lots of other things to consider...

Seems you have a 1200, judging from your K12 needles.  The 1200s have very restricted air boxes to comply with noise regulations of the time.  They do work best once the restricting crap is removed from the air box and K1 needles fitted, ie, reverting to stock 1000 specs.

If not punctured, floats can normally be re-used.

Also check slide condition and play in the actuating linkage shafts.  The slightest amount of slop will play havoc on all your balancing efforts.

piet
Click to expand...

Hello Matt,

Was there any sign of water in the float bowls or Main jet cap nut? Just a few ml in the cap nut will kill progression from idle onto main and needle jet...
 
No signs of water, but I suspect it had been re-commissioned shortly before I bought it so anything could have happened in the past. It seems to have spent most of its life in Naples, so should have been warm and dry most of the time!

There is a tide mark on the floats, everything in the bottom of the carb is covered in scale but everything above is not too bad, except the needles which are rubbish all the way to the top.

I'll put new brassware in with K1 needles and go from there. I'll also check the float weights.

Can anybody advise on buying an ultrasonic cleaner? They seem to vary in price hugely and I don't know what the difference is between them.
 
Parking for long periods in very hot weather makes the fuel evaporate, leaving gummy residues which really mess things up.
Can lead to a black tar-like deposit or a green powder as it attacks the brassware.

 
My new brassware has arrived and is genuine Dellorto. Everything is fine except the atomisers do not fit. The new ones measure about 0.07mm larger on the thread OD (compared to the old ones). They start to screw in but soon tighten up too much.

The supplier has taken back the new parts and checked them, they say the parts are fine so it must be a problem with my carbs (all three of them).

Has anybody experienced a similar problem? I can't see what can be wrong apart from the new parts being too big.
 
The new needle jets/atomisers are fine, your replacements will be just the same.  You will need to run a M7x0.75 tap down the bore of your carbs... common problem when working old these old things.

piet
 
Various said:
I'm genuinely surprised by that! But I'll buy a tap and clean up the threads as suggested.

Thanks.

Matt
Click to expand...

Why's that?  Don't like surprises?  Buy Mikunis. :D

Nothing wrong with your threads either.  If you'd find a NOS needle jet, it would most probably fit perfectly.  Just that at some point a slight difference in tooling slipped in... these carbs have been in production for more than 40 years! 

I spoke to a Dellorto representative at the Cologne Intermot show last October, he claimed spares support for these carbs can be upheld for about another 5-6 years.  Existing tooling is seriously worn and will be eventually scrapped.  Main reason for new carbs only offered in such few different sizes, most casting dies have long been re-cycled.  Another chance for the Chinese to step up to the plate... :D

piet
 
Ha ha, no it's not that I don't like surprises. The surprise is that the carb thread is the part which needs altering, I thought it would be the new parts. But what you say makes perfect sense.

I spoke to the parts supplier today and they confirmed that if necessary the bush in the body of the carb can be replaced with a new one for a modest cost (about ?10 (GBP) per carb).

Matthew
 
Seems to me that if the threads on new jets are a bit tighter than NOS jets, the preferred fix would be to run a die nut over the thread on the needle jet rather than tap the thread in the carb body.
 
Maybe Cam. 

But I just happened to have a suitable tap to hand.  I've probably installed 100+ needle jets of the current type to date, no issues.  Old jets still fit nicely, not very much material is removed.  Not that every workshop has a M7 x 0.75mm tap and die laying around... quite a rare size, even over here.

piet
 
Well, it's done. I ran the tap through the holes and there were no problems at all, the new atomisers now fit without fuss. :D

While I was at it I used a 5mm helicoil to repair a stripped thread on one of the air take-off points (PTFE tape had been used around the screw to give it some purchase!). This was fiddly but worked out well.

I also put a small countersink onto the holes in the carb body where the bracket mounts. Five of the screws were not seating fully which made them loose on the bracket, now they are all fine.

No doubt I'll be asking about setting them up properly soon

Matt
 
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