Hi There when setting the TPS when swapping to PJ38's does it have to be set on the Dyno or can it bet set to WOT which if I recall is 5ohm??
or is it a little more complicated than that. Many thanks.
If you have access to a dyno, this would be the best bet. But, I didn't use a dyno and still managed to get 76.2bhp out of my motor. (Of course my motor has a lot more than just PJ38 carbs on it...).
Before removing TB carbs from my MC28, I opened up throttle fully while measuring resitance on the TPS. I then removed the TPS and rotated it manually until I got the same resistance. I then put a bit of RTV to hold that position before I plugged it back into the wiring harness. The TPS fit nicely inside that little black box next to the power valve motor.
Great Thanks for the reply Scott. You must have a serious motor to be making 76 . care to share what you've done to it??. I'm goin to Dyno my bike anyway so I'll check the best position for the TPS while i'm at it as I want to do a back to back with some HRC carb's I've got .
Cheers
I'm running wiseco RM125 pistons, 56.0mm (+2.00mm over). These have single rings along with a substantial weight savings over stock.
Cylinder porting is similar to NF5 RS250; PJ38 carbs and coils from RS250; Boyesen high tension CF reeds (from CR125 application, PRO-01); HRC 010 card.
Cases have been cleaned up and filled in places; Tyga lightened MC28 flywheel; custom heads with inserts and center aligned spark plugs; JHa/custom pressurized airbox; Tyga mild-steel pipes with CF silencers.
To get the full 76hp, I have to use VP Racing U2 fuel. Very powerful but nasty, toxic stuff. The motor will make 73hp on AvGas. The dyno numbers are conservative/realistic as this same dyno usually reports 40-42bhp for RS125/TZ125 motors.
I have many dyno run sheets for this bike. But I do remember that installing those RS250 coils (used) and NSR250 plug wires (new) along with NGK B9ECM plugs was good for about 1.5hp.
I use the same wiseco pistons , except mine are not oversize . i was thinking that route before i decided on the 300 . For interest , where does the ring locator sit on those pistons ? Over a port ?
Have tried the iridium spark plugs ?
Can you test on a dyno if ram air is adding to your hp ? or do you only feel it at 200km/h ?
The ring locator pin is in the same location as the NSR's. If I remember correctly, the cylinder height had to be slightly cut do to wiseco's piston top to wrist pin dimensions. The piston model number is 641M05600.
The shop that had done dyno work on my bike has a fresh air fan in front of the bike but I'm sure its not enough pressure to mimic the bike travelling at 200+Km/h. Overall the bike doesn't feel that much different until speeds at about 160 and up. Then, I can tell it still has a bit more pull than without the pressurised airbox.
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. care to share what you've done to it??. I'm goin to Dyno my bike anyway so I'll check the best position for the TPS while i'm at it as I want to do a back to back with some HRC carb's I've got .