Well I've fitted the pipe & put it back together. I made a venturi stinger insert to replace the RS125 one as it's (obviously) suited for a 125 being 23mm, but it's pretty cool as I can machine up any 25mm tube 25mm long & swap it in to test. This one is bored 18mm & tapered with a 9deg cut to 1/2 way along & a 40deg cut on the baffle cone side with a 8mm section at 18mm. I have a formula somewhere but this was just cut as an experiment being a couple of mm smaller than typical for a 100. Looks nice too. Must be worth a couple of horsepower just in trickness.
Having too big a stinger bleed can actually lose some reasonable power.
So off to the dyno. Seemed like a waste as the day disappeared. Maybe I should be out on the road bike, or the trials bike. Weather was sunny & wind calming down. Oh well.
So either way the PC is playing up, she's an old girl. Like there's a stuck key. Finally I get a run. It towers over the old WC barrel, but that is hardly hard. This run had the RS stinger 23mm tube (too big but wanted to see the diff when putting in my venturi one). Touched 20hp, not bad for a first run, bit above 12k & over sharply thereafter so conservative. Had a bit of a dip before peak power, but this was the first run with whatever jet & ignition timing where it landed. next run was up a couple of jet sizes as it was pretty small. I was heading for the van for tool & there was a crash, the weather set in with a storm. Hail etc. The BANG, the PC goes pop. Hmm, that's not good. ctt breaker. phew. But the PC won't start, so it's gone pop. Power surge or just age? Hard to say, but that's the day done. Retd the ign & with jet size bigger to be safe. Did put the restrictor venturi in as it should be better. Not sure if I'll be able to run it up before next test day, but at least it goes & doesn't seem to drool oil.
Hoorah.
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