Finally getting my brother in law to just go for it.
Stock exhaust port was only 15mm as compared to 40mm bore...stifling. He widened it to 22 and ovalized up to 1.5mm at peak. Top speed went from flats 16, to flats 21 With him riding. No other changes. Low speed grunt reduced proportionally to speed change.
Proma circuit pipe is enroute to offset the odds.
Open up the boost a ton, it’s crazy tiny.
Then rejet
It has 3 transfers so I figured good enough for now. We're running a clone carb, already a jetted a bit rich, no marks on jet but looks close to .78mm.
Were crazy about inching up on gains, crazy fun is taking a putrid slow model and slowly working it up.
Is there anyone with a modified port map handy? Worst case we could do the math for next go around
i was messing with a pa50i this summer, freeking opened the ports all up, pa50 ii reeds n intake, pa50ii carb, dos exhaust (very nice) and getting to 45 easy, but was modding the ramp plate angles when my spacer fell down the drain, total bs. Anyways, just copy the pa50ii port map, that should get you to a wopping 30 with the proma.
The pipe doesn't fit either I don't think, the pocket the header sits in is smaller.
Modding a pa-1 is definitely inching up on small gains, haha.... I did one once, that was enough for me, honda really did their homework on restricting it, sooooo many parts have to be reworked it's almost impressive
I got my pa1 up to 55mph maybe faster.
Aux ex ports, decking, multiple finger ports, all with a very modded pa1 reed block
^correct grahm, on the exhaust studs being closer and the slot being smaller. Had to take a grinder to that welded on sleeve on the end of the header and probably narrow the mounting holes.
thanks for all the great responses. good info!
so far ours has a knock of paii carb, 2 petal reed, intake drilled to 12.7mm, and ported to match inlet of 2 petal.
this bike is exactly what we prefer, exhilarating to gain small bits.
-a paii clutch is enroute with extra bits, ramp plate of course.
-proma going on this weekend
afterwards cylinder will get more porting, might get wild..pretty well expendable anyway.
davids pretty big, takes alot of muscle to pull him. we have an express w Athena, proma, vm18, its great except getting off the line.
this bike should be the win for him but, im desperate to find a welder to reinforce the swing, (among others) but not settling for junk.
I have not found stock paii map, felt like I looked everywhere
did you port the main exhaust in combination with aux ports?
Yes I drilled aux exhaust ports
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