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Dellorto PHF36 Tuning

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I'm stumped on the idle circuit on the PHF36 on my 2000 Husky TE-410. Stock jetting according to the manual should be a 170 main and a 60 pilot. That's exactly what I found when I opened it up.

Here is my tuning procedure. Warm up bike. Turn up idle with adjustment screw. Back out mix screw unyil the engine reaches maximum RPM. Turn idle down a bit and make fine adjustments to mix screw. Adjust idle to normal idle RPM. When tuning the mixture screw, I have to open it up 5+ turns. I bought some additional pilot sizes, and even with a 66 pilot, I have to back out the mix screw to 5 turns.

I checked in the carb body, no washers or o-rings stuck in there. I even bought a complete new mixture screw from Guzzino.com, thinking there may be an issue with mine. The one I received was a very different profile and wouldn't even begin to thread in.

Any help or advice or help is greatly appreciated.

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You are on track with the logic. All carbs using a fuel screw adjsut the same way, whether it is a lawn mower or a Ferrari.

The fuel screw should never be opened more than 2.5 turns.

Using your current pilot jet, and the idle at about 1,850, if you close the fuel screw, will it still run? If so, the pilot is too big. If not, and the pilot is way larger (like two or more sizes and you are at normal air density) something is amiss and you should stop adjusting. You would be chasing your tail.

If the bike seems lean, it can be bacause of a air/vacuum leak. This can be a bad spigot mount, bad oring, bad hot start, bad vacuum line, clogged car passage or??? If the bike runs fine off of idle and no issues at WOT, you can rule out a float too low.

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With idle set to 1850 and adjustment turned all the way in, the bike will not idle. Bike runs fine when adjusted out this far and at WOT, so probably not float level. I'm thinking there may be another passage in the carb or in the bowl that needs examining.

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I dug back into the carb again last night.  Blew out all the orifices and jets with carb cleaner again.  I did notice that the emulsifier tube under the pilot jet is mangled.  I can blast cleaner through it into the carb body, but the slot in it is so badly mangled, there is no way I can remove it from the carb body.  Despite the fact I can blow cleaner through it, I still call it suspect.  At this point, I'm tempted to swap to a different model of carb completely, or try to find an un-molested PHF36 to rebuild.  I don't see anywhere else that could be causing a vacuum leak.  There aren't vacuum lines running anywhere, the carb mount seems to be in very good condition, I'm at a loss.  

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Those slots are critical. Unless you can replace the emulsifier, it is toast.

 

I suggest you source a FCR-MX 39 or 40mm

I figured that may be the case.  The saving for a FCR begins.   :rant:

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If you go for the FCR, you want to get one with a removeable intake bell. If you go used, be sure the slude cavity is not too worn out from the slide wheels. Get the MX variant and not the slant. Not sure if the intake bell is removeable or if not, if it'd fit but the lat model Honda FCR's have an improved, Honda only, AP actualtion

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