DUM DUM BULLET

So the PT4 is not a work of art!
Program is quite limited and requires being plugged into to the unit to function at all.
But the O2 sensor is still in play so it seems to be doing a great job of trimming in closed loop.
I have just populated the fuel "map" with 75% increase leaving the bottom line at 50%.
Doesent knock and pulls well, I was so happy I put it back on the bench and changed out the oem cam for the stage 2, quick job if you don't use the special tools and don't drop the cam chain or a bolt :cool:
And here's the surprise ,compression has increased bucket loads.
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Compared to the same build with an OEM Cam, which was 185.
So rings have bedded in?
Valves are open longer so more air gets sucked in?
I did it wrong last time?
Or the gauge is buggered?
 
Dool said:
Or the gauge is buggered?
Click to expand...
I vote for this option.
there is no logic in any change of compression due to a cam change. if "more stuff is in the chamber" where actually a valid argument then compression would change every time you change mapping.
and the rings have already been run in (if you use my set)
cheap china shit?
 
So you discount the extra lift and duration of the Cam has an effect on volumetric efficiency?
Stauff gauges would be my choice but I doubt it's the gauge.
Probably Chinese but what isn't?
 
Your are saying the rings were already bedded in but the assembly was fitted to a different engine so they would not have been so.
Since running this set I have had starting issues and low voltage mils( engine warning lights) as a result so I am not so sure.
Anyhow it will be getting topped up with 98ron tomorrow.
 
Re-assessment in the dum dum build.
I, as usual jumped steps and missed some.
The leap to the 84mm piston was a leap to far at the time.
Previously with just a 60cc increase in displacement I had been getting good results and do not think I reached the full potential before going to higher displacement.
As I have already installed the PT4 and am in no hurry to remove it! I will utilise that for moderate ignition advances and fuel increases and hopefully learn enough to determine if a bit more is worth while.

So reinstalling 411 kit, only 1 base gasket, stock head, Stage 2 cam, stock header, decat pipe and Indoori HK muffler .
 
As it stands, so the Bullet has the 411 kit Stage 2 Cam, Indoori muffler( with home made baffle), OEM airfilter with high flow cover.
PT4 and Fx pro plus.
Air Fuel Ratio gauge would indicate it runs quite well( if I knew the gauge was calibrated).
The fluctuations shown on the gauge usually about 1 point or less depending on throttle input etc, the Fx when set to a number above 3( ie off) reduces the fluctuations and it would seem to be integral with the PT4.
I state that also because I have eventually found a Dyno tuner who will work with and has knowledge of the PT.
When making a Booking he asked if I had the FX fitted as well as the PT, saying it was necessary for Closed Loop tuning.
He also must be in demand, I have the next available slot in ,,,,,, October 27th!
Can I wait that long or will I live that long was my first thought, or will I still have 411cc? I might get bored!
Haven't asked the price, I can wait for that surprise :confused:
 
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High Flow airfilter cover, hacksaw a Belt sander and my Dremel changed the OEM( forever).
I doubt this engine will ever use more air than can get through this.
 

This what is commonly called a Hotdog muffler, at 45mm( 1 and 3/4 inch ) the inlet takes the stock graphite gasket and oem clamp is used along with the oem bracket ( that involved welding 2 8mm nuts.
Sound is good and the price is right, A$56 including freight.
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