Dude

Change the needle, as this is causing your mid range burn duwn. The 39PWK carb needle from HPD I think is a bit lean, so go richer by a size or two (I did on mine) and have no problems. Other mods are similar to yours.

To solve the problem, just ride wide open all the time! Works for me!

 

What kind of needle? What size? I heard that I could just file the tip down a bit...any ideas?

 

Brian;
How am I suppose to help you if you don't answer all my questions? What altitude, outside temp., main jet and needle size? Don't plug off airflow at the airbox. Also; how far is airscrew turned out from fully closed? It's true that the HPD ported cylinder likes more clearance. The dealer was only going by Wiseco specs.

 

Brian, If you have the EGH needle, IT'S TOO LEAN !!! On April 6 2001, I burned down mine with a EGH Needle set 1 notch RICH from center, 38 Slow Jet, 168 Main Jet and 1 1/4 turns out on the air screw.
I rebuilt the engine with about .005" piston / wall clearance and replaced the needle with an EEG. I'm still trying to nail down the jetting, I ordered a couple of slow jets from HPD and should have them next week.
I had talked to Rick Ritter after the burndown and he told me that it wasn't uncommon, that the PVT causes some tuning problems with light load / high RPM riding. His suggestion was to jet it as rich as I could stand and still get reasonable throttle response. He also suggested on long steady state runs, to turn on the choke to the first postition to richen the mixture, switching it off a couple of seconds before the end of the run to clean the plug off.

 

Yeah I thought you might ask that.

I will have a look tonight and get back to you.

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Yep That is it! The EEG. Middle clip with spacer.[img]i/expressions/face-icon-small-happy.gif[/img]

 

They must have sent me the EGH...the one that comes standard from HPD with the 39mm carb. That sucks! They told me that they never sell other needles because of this midrange stuff. So in other words if I get the EEG I could keep the main and pilot they sent and this could clear up the midrange just like that? Looks like we will be riding double on the Raptor this weekend...

Could running with the choke on 1/2 help for now?

What about filing down the needle??

Plus, how come it lasted at least two months before melting and now with richer jetting after the rebuild I am getting no color on the plug??


Fasterthangas...I am looking for the altitude and other specs you asked for.

 

Fasterthangas...My buddy just e-mailed me and said we are at 12600 feet. (not sure) I am running the 175 main jet and the 40 pilot. (one size bigger than stock) Temperature is in the high 70's. The needle is set to one notch above the bottom last. EGH needle. Air screw is by HPD "stock" specs...could not reach it tonight. Any thoughts?

 

Keep the file away from the needle. For a couple of bucks, it is much easier to buy the correct one. If you start filing, you will affect the taper, and the harmony between the taper and the length. To me it looks more like science than engineering (Balck magic!)

1/2 choking it would help. I had this when I installed the carb, and did not adjust the choke properly, so it stayed open slightly all the time. Ran bitch rich until I spoke to Mike at HPD about the problems, and he told me what to look for!

I run a 38PJ, and a 170 main. Thinking about the 168 main. Most of my riding is at sea level (slightly above!)

You got a reed spacer?

Had any overheating problems since the mods?

 

The trail mod carb comes with the EGH Needle, while the Race Mod gets a EEG.
The dealer pulled the piston back out and put some more clearance in the cylinder ??? Did I catch that?
What I did was adjust the choke to add a small amount of fuel at the first click.
Filing the needle is risky at best, since you won't have any reference once you start filing.