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vespa
May 22, 2011 8:26:25 GMT
Post by mikeymoo41 on May 22, 2011 8:26:25 GMT
hi, can anybody help me..i have a px125 with dr180 kit on. ive just got a scorpoin exhaust fitted..1st to 3rd it pulls great..in 4th it dies and wont do more than 50mph..ggggrrrr ive got a 122 jet in a moment..do i need to up jet even more??? is there anybody out there to help. Attachments:
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vespa
Jul 11, 2011 18:28:17 GMT
Post by colin4255 on Jul 11, 2011 18:28:17 GMT
I'm no expert with jetting, but I have a PX 125 with a DR 180 kit and my main jet is only a 114. It runs fine. It still slows up in headwinds and going up hills, but they all tend to do that to some degree or other. Aldo, I am no lightweight!!!
It sounds to me like yours is over - jetted. Jets are only about £3 orn £4 each and the advice I was given was to buy a range of them, 110, 112, 114, 116 and try them all out. They take ten mins to change and you normally find the right one inside 3 or 4 attempts.
Best way is to try and relatively short runs at top speed and 'see' which one feels best and/or seems to give best top speed, then, run it till it gets nice and hot, take it flat out and cut the engine, coasting to a stop, then take out the plug and check it. It should be a nice chocolate brown colour if the mixture is riight. You won't get any sense out of trying this if you run it and take the plug out after riding it normally to a stop, you have to cut the engine while its going flat out and do what the guys call a plug chop. If its pale brown or grey in colour its running too weak. If its very dark brown or black, too rich.
My guess is that the jet is too big and its bogging down as its running too rich. The main jet only comes into playv after more than half throttle anyway so the fact its running fine until you get it into top and it accelerates OK I would suggest the idle jet etc is fine. Poor top speed can just as easily be caused by too big a main jet, as too small a main jet.
The DR kits are not a race kit, only a touring kit really, so don't expect it to go much above 60 - 65 mph in any case all things being equal, but it shouldn't be dying in top.
How long has the kit been on the engine? My DR180 was losing power in top and I was mucking about with jetting, then the clutch exploded, thowing bits into the engine. We split the engine and found it had a missing gudgeon pin clip and a nice big score down the barrell and very little compression. As I was new to scootering back then, I had no idea.
Once I re4placed the kit with a new one, ran it in and sorted out the jetting it works fine, but 60- 65mph is about its limit flat out and to do that it it is properly flat out....
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vespa
Jul 12, 2011 4:46:58 GMT
Post by sbwnik on Jul 12, 2011 4:46:58 GMT
I'd agree. A 116 should be somewhere about right for that - it's what a P2 runs. What exhaust have you on it? With that set up, a Sito Plus or the new SIP pipe would be a good investment IMHO
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