Starting point for setup of Dellorto PHM rebuild

schwim · Feb 27, 2011

Hi there everyone,

I've got a Dellorto PHMzs carb that I'm rebuilding and I need some help with what jets to start with for my area.

Elevation: 1,500 ft
Temp range: 75-90
Bike: 2001 470 with Lineaweaver X2(IIRC) cam and Big Gun slip on (it's the bike that the wonderful members of the UHE gave me at Force Ride 2005)

I've got the carb apart and looking at it, there's no obvious signs that it's the reason why the bike doesn't want to run. Since it's out and apart however, I'm going to try to set it for the area before putting it back together.

MJ: 190
Idle: 35
Needle: K51 Clip is 3rd position down from top
Atomiser: 272 DR
Mixture screw: 2 1/2 out
Idle screw: 5 out

I would very much appreciate any suggestions concerning changes in the settings/jets/needle.

Two things of note:

1) During disassembly, I came across a recessed jet/screw that I just can't remove. I was able to break it free and it turned approximately two to three revolutions, but then tightened back up. I seem unable to thread it all the way out of the barrel.

2) I've not been able to pull the needle and seat, as I'm not able to remove the float arm. I tried tugging on the exposed portion of the float arm pin, but it doesn't want to move. I didn't try much as I didn't want to round over the exposed part.

Thanks in advance for any assistance provided!
json

berger · Feb 27, 2011

viewtopic.php?f=7&t=1762&p=13849#p13849

Or you can just crate the bike and ship it to me. Then pick it up at F4 :wink:

schwim · Feb 27, 2011

Wow, talk about a custom-tailored thread

I only wonder if the less restrictive exhaust might change some of the jetting?

Any insight on removing the float arm pin and my stuck jet?

berger · Feb 27, 2011

schwim said:
Wow, talk about a custom-tailored thread I only wonder if the less restrictive exhaust might change some of the jetting?

Any insight on removing the float arm pin and my stuck jet?

Get on the pin with a good pair of dikes, twist and pull. The jet you can try some penetrating fluid, work it back and forth with a properly fitting screw driver. If you can blow carb cleaner and compressed air through the jet you may not need to remove it. (remember, it used to start with that jet).

schwim · Feb 27, 2011

Well, I can't find a schematic that names that particular jet so I don't know if it's one that Joe mentions needs to be drilled.

Besides, I don't think my OCD will allow me to leave it in there. I'll grab some blaster and have a back-n-forth party.

Davo · Feb 27, 2011

OCD?

Get the bike in the crate Json. :lol:

schwim · Feb 27, 2011

b.b.bu.. but the jet won't come out!

For the love of God, don't you all understand? There's a threaded object that refuses to turn! Archimedes would not stand for this!

berger · Feb 27, 2011

schwim said:
Well, I can't find a schematic that names that particular jet so I don't know if it's one that Joe mentions needs to be drilled.

Besides, I don't think my OCD will allow me to leave it in there. I'll grab some blaster and have a back-n-forth party.

Pilot/Idle jet?

schwim · Feb 27, 2011

berger said:
schwim said:

Well, I can't find a schematic that names that particular jet so I don't know if it's one that Joe mentions needs to be drilled.

Besides, I don't think my OCD will allow me to leave it in there. I'll grab some blaster and have a back-n-forth party.

Click to expand...

Pilot/Idle jet?

I'll let you know.as.soon as I get it out of.there

berger · Feb 27, 2011

I was saying that it should be the pilot jet or what some call the idle jet. I think that may be an emullsion tube, that was under the pilot jet. Some came with them, some not.
By the way, that carb came off an 2000 FC 501 I believe.

Disclaimer,
I may not at any given time know what the hell I am talking about

Taffy · Feb 28, 2011

that'll be the CD1 (one) jet you found Json. if it won't come just leave it in there, at least you have one and unless you have good lubricant and excellent screwdriver fitment I'mm afraid you'll have the head wrenched off PDQ.

as far as the pivot pin goes well if you're buying some fresh stuff from dell orto anyway you may as well add the pin as well. we just snip them in the middle and then bend them enough to push them out.

regards

Taffy

zaga · Feb 28, 2011

Hi Shwim

Pay atention to Taff's advice, leave the CD1 jet on its place and don't take the pin out, your just avoiding problems.

As for the setup of the carb, when you say idle screw, I think you mean the pilot screw, your problem is the 5 turns out setup, it should be 1,5 or 2 +/-

:cheers:
ZAGA

schwim · Feb 28, 2011

zaga said:
Hi Shwim

Pay atention to Taff's advice, leave the CD1 jet on its place and don't take the pin out, your just avoiding problems.

As for the setup of the carb, when you say idle screw, I think you mean the pilot screw, your problem is the 5 turns out setup, it should be 1,5 or 2 +/-

:cheers:
ZAGA

Thanks very much for your help. How am I going to replace the needle and seat if I don't remove the float ARM?

zaga · Feb 28, 2011

Hi

Why do you need to replace it ?

schwim · Feb 28, 2011

Well I don't think I've ever rebuilt a carbon that I didn't replace it. My list of things to leave is growing. I'm nearing the point at which I could have just left it in there

zaga · Feb 28, 2011

Thats a goog idea.. :mrgreen:

I'm saying this because I never needed to change that in a dellorto.

:cheers:
ZAGA

Taffy · Feb 28, 2011

i just put a post up today saying that we have gone to 50% new cloat valves now. the springs are getting towards 10 years old and as weak as kittens. more and more owners are going to moan about: 'rich', 'flooding' 'fuel dripping' etc.

to remove that pin snip it carefully at the halfway point. push one half out and pull the other.

regards

Taffy

schwim · Feb 28, 2011

zaga said:
I'm saying this because I never needed to change that in a dellorto.

The only Dellortos I've ever worked on were these:

And due to their age, they always needed a new needle/seat. I'm not used to working on a carburetor that's not older than I

Taffy sir, thanks very much for all your help. I'll add the pin to the list of the stuff I need. I may just need to buy a new slide as there's not a machine shop in my area that I would trust to perform the modification in JoeUSA's thread.

Taffy · Feb 28, 2011

without looking I think I recall you're on about a 4.5mm slide cutaway. you can't buy it. they come 4mm or 5mm. it's 3 minutes work with a file to turn a 4 into a 4.5.

regards

Taffy

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