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Post by daddycool on Mar 3, 2012 20:26:29 GMT
Hi everyone, looking for a bit of advice on my px125. Coming back from Camber sands rally last year, blew a hole in the piston as the autolube had seized up. Fitted a malossi 166 kit and run it in for 500 miles. However, now it rides ok up to 40-50 mph, but heat seizes if I try to run it at 60mph.
Any ideas anyone? Could it be the crankshaft? If so, why does it run ok at 40-50,. but not 60?
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Post by sbwnik on Mar 4, 2012 12:07:03 GMT
Firstly, I'd be surprised if the faulty autolube caused the holed piston, that's a symptom of either running lean or your timing being a long way out. That said, it's fairly unusual for a standard 125 to hole pistons. Would I be close if I guessed that you've changed the exhaust and not given the jetting much thought?
Secondly, repeated seizures on a 166 aren't good. Even if it's only a soft seize you'll be damaging the piston/rings/cylinder set up every time it does it.
My initial guess is that (given you're asking these questions, I assume you're fairly new to this?) the bottom end of the engine hasn't been ported to match the cylinder? This isn't essential, but not only will it make setting up an awful lot easier, but will also give us a baseline to work from.
If you have had it ported, then we need to look at other aspects - what carb and jets are you running, what timing are you set at? On a 166, the very least I'd be looking at would be a 24/24 carb, even in unported mode, with the timing set around the 200 mark. From there, you can get a better idea of what;s happening,
Before you ride it any further, pull the plug and look at it. If there is any suggestion of whiteness about it, pull the cylinder head off and take a look at the piston. If you can grab some photos of the piston and plug and post them here, we can have a better idea of what's happening.
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Post by daddycool on Mar 4, 2012 19:33:25 GMT
Cheers mate, thanks for the advice. I've got a mate looking at it at themoment who seems to think it may be the crankshaft as I know bugger all about scooters! I'll run past him your valuable advice and get back to you as soon as.
Don't want to fork out for a new kit and crankshaft if I don't need to.
By the way, you're right about changing the exhaust. I fitted a Simonini exhaust and was advised by a mate that I didn't need to adjust the jetting while it was still a 125.
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