Running in new piston

[vicvega]

Any advice on running in a new piston, GT kit had a big seize up, my fault not the kit, so have had it cleaned up with new piston, do I need to run it in as new? If not wots best.

[jonny snatchsniffer]

why did it seize ?

[Rich_T]

Yes, is the short answer.

Running is covered in the build manual, ideally 500 miles if you're new to it. The main thing is lots of town riding, give dual carriageways and motorways a miss and keep it off the over run. If you're confident in the rest of the bike and you have a good chamfer on the port edges (don't forget this after a rebore) you can usually get away with 100 odd miles to knock off the edges. It might be an idea to up the jetting to 100-102 main (if you are PHBL25 through the airbox) and lift the needle all the way too keep it rich for a while, this will also require you to keep a clean spark plug during the rich/run in period.

[vicvega]

Got carried away and thrashed it too long, too far and too soon, couldn't let a mate of mine on a PX show me up.
It was still rideable but was just waiting for the right time to get it how it should be, probably best to run it in as if new then. It's a 206 running with a 30 mikuni & a JL, I can't think what the jetting is without looking but if anyone has any good set up advice be welcomed.

[Rich_T]

Did you just replace the piston or did you take to the next oversize? Remember a 206 only has two oversize bores, 66.25 and 66.5 so try not to over cook it. On a TMX30 we used between a 220 and 230 main with a JL3 don't recall the rest of the settings but start rich and work down.

[Jazzy]

hi rich,
a mate has a small block gt kit.
with a JL3 and delly 30 what jetting should he run,

Ta

[Rich_T]

Hi Jazzy,

I would not say exactly what to run as there are fractional changes. Where to start is as follows:

Dellorto VHSH 30 flat slide with cable choke conversion Part number: 53003 (c/sunk screw may need to be shortened to fit)
Settings for open mouth with JL3 or KRP3 expansion chamber. Suggested jetting between 125-135 main jet, DP262 (or DQ262) emulsion tube, U2 needle, 55 slide, 35 idle jet, 35 idle emulsion tube (the idle jet and idle emulsion tube are now supplied as one part). Timing set at 17 degrees BTDC.

I do not have settings for PHBH30, so if anyone does have this information I would be grateful to know and add it to the manual. additionally, if you are looking for a low cost PHBH28 carb then try Ebay for a RS125 Aprilia carb, they also have the idle and air screw on the right side if the carb is going to be fitted on the R/H side of the engine where the engine mount usually obstructs the access (useul tip).