Difficulty tuning HP.61 carb

HP engines (Hirtenberger, AG Austria) tech support. Owned by RJL Industries since 1990

Moderator: SteveM

Difficulty tuning HP.61 carb

Postby djc » Sat Oct 01, 2005 4:51 pm

I have an HP .61 with a slide accelerator pump carb. I am having difficulties getting it to run rich enough. Once it has gone lean it is very difficult to get it to come rich again. It needs to be set very rich, almost 4-stroking, in the horizontal for it to continue running in the vertical while tuning. I have cleaned the carburettor as best I can, however cannot clean inside or through the pump. Is it possible to remove the brass pump from the aluminium carb body for cleaning and/or maintenance. Has anyone else got any advice on how to remedy this problem. I am running a APC 12/6 prop at approx. 12000 RPM on 18% oil, 6% nitro, Coolpower Blue synthetic oil.

Thanks for your suggestions
djc
 
Posts: 2
Joined: Sat Oct 01, 2005 4:43 pm
Location: New Zealand

Postby MECOA » Wed Oct 12, 2005 7:51 am

You must run exhaust pressure to the tank. What type of exhaust system are you using?

To remove the large brass nut on that houses the accelerator pump you need to lock the spraybar from the inside with a small screwdriver or scribe. Be sure to assemble the parts back correctly.

Also a common mistake made is people think that the idle needle in the center of the barrelis a barrel stop screw and screw it in too far thus leaning out the mixture. There is no stop screw on this carburetor.
MECOA
Site Admin
 
Posts: 1095
Joined: Mon Jun 30, 2003 9:48 pm

Postby djc » Sat Oct 22, 2005 7:14 pm

Hi there,

Thank you very much for your help.

The engine is installed with a standard strap on HP exhaust running exhaust pressure. I have now removed, cleaned and reinstalled the pump and have test flown the new installation. With the APC 12x6 I have about 1/2 a turn on the main needle between reaching peak revs and going lean. Prop is running at about 11400 rpm. With the tune just as it hits peak revs from rich the engine has no change in note or change in tach reading from horizontal to vertical and performs faultlessly in flight running smooth and powerfully, with a clean pickup through the whole flight. I am very pleased with the results and performance of this engine.

Cheers

DJC
djc
 
Posts: 2
Joined: Sat Oct 01, 2005 4:43 pm
Location: New Zealand

Postby MECOA » Mon Oct 24, 2005 12:35 pm

GREAT!!!
MECOA
Site Admin
 
Posts: 1095
Joined: Mon Jun 30, 2003 9:48 pm


Return to HP (Austrian) engines Tech Questions

Who is online

Users browsing this forum: No registered users and 9 guests

cron