32vm (econo) power jet jetting questions

[Rollingmenace]

Ok guys I have a few questions ...on the 78 intruder 440fc

1> I’m new to the econo jet carb and it kind of confuses me how they operate with the power jets as opposed to the standard VM can anyone give me a brief overview of the power jet operation as it relates to jet size and how it runs compared to a standard VM

2> I’m running at 6000-8000ft the standard jetting calls out for a 25pilot 170main and a 120-130 power jet..  now on a Keihn carb for example as a general rule 1 jet size down for every 1000ft in elevation gain... what would be a good rule on jetting these VM carbs as a baseline.. it seems with the power jets would complicate things slightly

3> would it be worth it for ease of tuning to just swap over to a standard vm carb.. this will be a oval ice race sled and only used to race so ease of tuning on the fly could be a factor

[Interceptor398]

Not sure about the carb questions but the 78 is a great choice to race as it is the lightest of the bunch.

[mswyka]

Checkmarks runs at high altitude.  He would be a good one to check with.

Note that the air exhaust is on the PTO side and so that Power jet is normally run richer.  There was different stock jetting referenced each year of production.  Our Intruder run 25 pilot, 150 main, and 120/130 powerjet.  We run between 500 and 1000 feet of elevation.

[gixxer6]

The power jet carb splits the main jet circuit into two allowing better tuning.  So if you want to switch to a standard VM round slide carb, you would add the PJ and main jet numbers to get the main jet for the non-PJ carb. 

There is good information in the FSM on this subject, its worth the read.