muggy running too hot...

[drunkmunkey6969]

What clip is the X7 running on? Is it running an air filter or not? Hole in the panel or not?

Heat:
Check jetting throughout the rev range, not just main jet.....where is he holding the throttle, what revs is he riding at in 4th?
Re-check TDC first with positive stop, then set timing, then strobe....do NOT trust timing marks.
Check squish gap (As Sean says 1.2-1.5 is best - over 1.7 will cause problems - the closer to 1.2 the better)
Check compression ratio - machine bowl or change cylinder head to low-comp version
Check flywheel and cowl are a tight fit to each other for max air flow
Check ring gap and replace worn rings
Remove any obstructions to cooling efficiencies (splash plate etc)

[byron]

NO NO....to keep the heat down ,you need a tighter squish........

ahh.... didn't realise that. how does that work ?
i had originally had it about 1.3, but it was pinking then too... i shall fit a thinner gasket again...

tried all clip positions on all needles
no filter
no hole in panel
I made the timing marks in the first place, I have rechecked them, and the timing with a strobe; no, i never take any note of the marks statically
it's a new piston, rings etc. ring gap was ~ 0.25mm
I'll check the fan efficiency etc again.
but I think the slide is the thing that'll make the difference, it is probably around or just above ¼ throttle that he is riding...

thanks for the ideas

[sean brady scooters]

please read and check this out matey...
http://scooterotica.org/forum/viewtopic.php?f=5&t=9439

[byron]

please read and check this out matey...
http://scooterotica.org/forum/viewtopic.php?f=5&t=9439

ahh thanks. a good read

[sideout]

Fuel/oil percentage?

[byron]

Fuel/oil percentage?

that's fine afaik
but will change that for a known good mix if the next steps don't work
thanks.

time to change your signature ??

[Special X]

I've never known an X7 be anything but too weak in the midrange throttle opening on a Muggy. X13 would be better. Change to a 40 slide, reduce idle jet to 50/52, Tighten the Squish, set timing to 18 BTDC, and should be better. If it's a MK1 Muggy then the reaper heads supplied were dire . . . too high compression and the squish area not matching the piston. A properly machined head would pay dividends here. Keep the theoretical compression down to about 9.5 to one.

Good luck.

[byron]

thanks again.
slide and needle change is next then

[sideout]

time to change your signature ??

Too right! Any suggestions