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Gordo
02-05-2009, 02:40 PM
I think this came up a long time ago, but I couldn't find the old thread.
Since I no longer race APBA Factory 1, I would like to re-jet to a more realistic air/fuel ratio on my carbed HP 500. Does anyone remember what jets I can change to that would not turn the transom black every time out?
Thanks,
Gordo
Blue Thunder
02-09-2009, 08:07 PM
77p and 93s would be a good start Gordo. Those came with staggered jetting if I remember correctly.

BT :sifone:
Clustergear
02-09-2009, 10:34 PM
Transom black every time out? Bad power valve ??
Gordo
02-10-2009, 11:47 AM
Replaced the power valve a number of times over the years. The carbed HP500 came from Merc Racing set very rich. When we were racing APBA Factory class we couldn't touch the jets. Now that Factory racing has ended I'd like to change jets. Once upon a time there were a couple of guys that had re-jetted the HP500s' that had posted their jet-testing results.
Clustergear
02-10-2009, 01:47 PM
I am going to to be cutting the choke horns off may carbs and putting PV check ball kits this weekend, if you don't have an answer by then I'll post my jetting for you when I get them apart. I think I have it written down but won't be back at my shop till tomorrow. How are plugs after running not letting it idle. Only take a couple of back fires on cold start to screw up a PV. Bad PV or one that has too high number and low manifold vacuum at idle will really dump fuel at idle and low speed. I picked up an F2 boat, when I when for teat ride I said the guy don't smell the gas fumes and back of boat was all suttie. Got it home checked manifold vacuum and put lower numer PV's in no more gas smell at idle and clean boat, left jetting the same.
Knot 4 Me
02-10-2009, 02:28 PM
You could give Nickerson a call. My guess is they have done a few HP500 setups.
Clustergear
02-11-2009, 07:14 PM
Merc 13549A12 Blue carb
Primary port 81
Stbd 75
Secondary port 89
stbd 93

I just took mine apart I have set same in primary but have secondarys
port 91
Stbd 95
Griff
02-11-2009, 09:24 PM
Gordo, when you do this, give me ring or send me a PM. I have a complete jet assortment pack with pairs of almost all sizes.
The black transom is usually from idle or slow speeds. Especially true on your boat with no swim platform.