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Post by kev on Aug 16, 2015 21:33:10 GMT
Hi I'm hoping you knowledgable guys can help me with my Vespa , I bought it as a non runner about 2 months ago, I have a fairly good mechanical knowledge and thought this would be an easy project , I'll list what I've done below to give you all a bit of background as to where Im at and hopefully you be able to offer advice on how to progress to getting the scoot to start and run correctly .
Firstly I did a compression test which was good , secondly I tested for spark, no spark , so I tested the stator and everything was ok , new cdi ,lead and plug and now we have a good spark.
Next I fitted the cables , brake , throttle and the two cables to the auto box changing mech ( pk50xl automatic )
I then bolted up the carb which was loosely fitted and replaced the fuel line , checked fuel tap was working and also put fresh pre mixed fuel in the tank .
By this time I was ready to fire her up, no joy , so I squirted a bit of fuel in the carb and she started ,but only ran until the fuel evaporated that I had squirted in , I continued with this and as she ran I played about with the carb settings ,I could get the scoot to run ok but by the time I found the ' sweet spot ' the scoot would stall and then wouldn't start , so I went back to where I started and tried from there , the same thing happened ,I'd get her to run but it would eventually stall by the time I'd get her to rev up cleanly with no bogging .
Ive been trying the above now for weeks and yesterday the same happened but the scoot back fired from the carb and a puff of smoke came out of the carb , no amount of coaxing would get the scoot to start ,after 3hrs of this I gave up . Today I bite the bullet and stripped the carb down completely and gave it a good clean , checking all the jet ect , after refitting and adjusting I couldn't get it to start , but after a while I get a back fire through the carb.
Im guessing the timing is out , any ideas how this happened or what way do I go to get my scoot running ?
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Post by henri on Aug 17, 2015 7:36:15 GMT
slipped key on flywheel, to check it is timing squirt some fuel in again ,if it runs its carb ,no pops its electrical an you'll need to go thru the ignition again top to bottom , H
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Post by kev on Aug 18, 2015 21:28:26 GMT
I tried squirting fuel down the carb and it wouldn't start , it didn't even sound like it wanted to fire , looks like I'll be checking the flywheel .
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Post by tzsteve on Aug 19, 2015 15:36:56 GMT
back firing out of the carb sounds like the spark is coming after TDC. check the flywheel aint slipped the key.
if it has, clean it all up lap the taper with some fine grinding paste and clean all the grinding paste off. then refit the flywheel.
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Post by kev on Aug 19, 2015 21:24:17 GMT
back firing out of the carb sounds like the spark is coming after TDC. check the flywheel aint slipped the key. if it has, clean it all up lap the taper with some fine grinding paste and clean all the grinding paste off. then refit the flywheel. Cheers , it doesn't back fire through the carb every time , but it just doesn't sound right when you kick the engine over , I'll check the flywheel on the weekend and report back .
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Post by ray66888 on Aug 21, 2015 14:29:42 GMT
Might be that the stator plate has moved if the four screws are a bit loose. Check the timing marks are lined up on stator and crankcase.
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Post by kev on Aug 21, 2015 20:07:43 GMT
Might be that the stator plate has moved if the four screws are a bit loose. Check the timing marks are lined up on stator and crankcase. Will do mate
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Post by sugarlump on Aug 22, 2015 8:25:40 GMT
I'd pop the head off and check the squish and reset the timing. Presume you cleaned the internal fuel filter when you stripped the carb?
Does the engine turn over freely?
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Post by kev on Aug 22, 2015 8:37:28 GMT
I'd pop the head off and check the squish and reset the timing. Presume you cleaned the internal fuel filter when you stripped the carb? Does the engine turn over freely? Yep the carb was thoroughly cleaned , the engine has always turned over freely and has good compression and I have had it running but very boggy when revved up , I have noticed when I'm kicking it over that sometimes it ' slips ' as in the kick start goes to the floor and doesn't really turn the engine over as well as it should . I was hoping to have a good go at stripping this today but , I'm working outside and rain has stopped play , if the weather improves I can crack on with the job as I want to strip and put it back together in one day ,at least then I won't forget how it goes back together
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Post by kev on Aug 22, 2015 20:00:58 GMT
* Update *
Well I managed a few hours today on the Vespa , it was quiet a job being as it's the Italian version of the pk50 pluramatic ,the Italians call it Automatik instead . Anyhow the key way on the crank was fine no damage whatsoever , I could see this once I got the pulleys off .
But I proceeded to remove the flywheel which was a nightmare ,so that I could check the stator , from the timing marks I could find everything looked ok and I double checked the four screws to make sure they were tight and there was no signs of anything moving or had moved previously .
Tomorrow free time permitting ,I'll attach the drive belt and try and get it started .............I'm not getting my hopes up .
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Post by ray66888 on Aug 23, 2015 13:08:34 GMT
Hello Kev. I have got just about the same problem with my pk100. Cant offer you any advice on the cure as still got the problem. I was thinking check crank bearings are not worn and seals ok Cylinder base gasket and look for leaks from crankcase gasket with dish soap. Make sure the inlet pipe to carb joint is ok - I took my manifold off complete with carb put my hand over the cylinder end of pipe and blew through carb to find any leaks...none Did all the other obvious things, jets, carb slide, mixture screw1 1/2 up to 4 turns out. Compression test was 118 lbs. So if you have more luck than me Let me know, I have given up as I just cant think what to check next. Oh ar you got plenty of fuel getting to carb? Regards ray
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Post by kev on Aug 23, 2015 16:51:25 GMT
Hi Ray , I feel your pain , the most annoying thing is I've had mine running ,ok it wasn't running very well , very boggy and it didn't matter what I did to the carb it still didn't improve matters , I then got to the stage when it started backfiring through the carb , wether that was because of the carb settings were all wrong I don't know .
I then thought to myself it's got to be the carb , so I stripped it and checked and cleaned it thoroughly, now I can't get it to start let alone run , I checked the flywheel key way , the stator timing and alls good , spark is good too,plenty of fuel getting to the carb .
I'm at the point where I'm sure it's something simple ,but being a newbie to scooters I don't know them that well ,I could be missing something simple it's so frustrating .
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Post by ray66888 on Aug 23, 2015 18:22:21 GMT
Hi Kev. I am going to have another go at mine again this week. Will keep you posted if I find the problem. Regards ray
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Post by kev on Aug 23, 2015 19:53:00 GMT
Hi Kev. I am going to have another go at mine again this week. Will keep you posted if I find the problem. Regards ray Thanks Ray , just too add I rechecked my compression today and it was the same as it was before .
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Post by kev on Aug 29, 2015 18:31:14 GMT
Hi all , I still can't get this scoot started , to re cap , I've had this scoot running but once I found its sweet spot the engine would stall and I couldn't re started it without messing about with the carb settings . I've checked the compression and it's good , I've a good spark brand new plug, lead ,cap and cdi unit , I've checked the flywheel key way and it's not slipped ,also the woodruff key is good as is the key way in the crank , I've checked the stator plate timing marks and that's good , I've stripped the carb again ,cleaned it , made a new carb gasket , new fuel line from tank to carb and fresh fuel , I'm getting fuel to the carb and the plug is a little wet , any ideas why it won't start ? I'm tearing my hair out here and I have'nt got much left as it is ,a bit like my patience
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Post by oppinionated on Apr 5, 2016 17:18:33 GMT
Some good advice from Ray (even though it hasn't sorted his issue).
It's a ball-ache, but a complete engine strip-down should really be the starting point.
You don't know what's happened to it and who's done what to it. I would pull it apart and check every part for wear and fit etc.
Replace all the seals (and bearings if you can afford them) and gaskets. Check the crank seal as this is one place that so many older Vespas will have issues. You would be amazed how many numpties have dropped stuff into the inlet !!
Again, it could be a partial blockage in the tank cap....air has to get in, for the fuel to flow out. Even the routing of the pipe can be an issue.
I did recently have a similar issue with my Primmy, and ended up stripping the carb several times and cleaning it out....it had been sat doing nothing for several years though !!
Good luck, and don't give up. If it's broken, it can be fixed.........eventually !!!
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Post by kev on Apr 5, 2016 21:43:28 GMT
Some good advice from Ray (even though it hasn't sorted his issue). It's a ball-ache, but a complete engine strip-down should really be the starting point. You don't know what's happened to it and who's done what to it. I would pull it apart and check every part for wear and fit etc. Replace all the seals (and bearings if you can afford them) and gaskets. Check the crank seal as this is one place that so many older Vespas will have issues. You would be amazed how many numpties have dropped stuff into the inlet !! Again, it could be a partial blockage in the tank cap....air has to get in, for the fuel to flow out. Even the routing of the pipe can be an issue. I did recently have a similar issue with my Primmy, and ended up stripping the carb several times and cleaning it out....it had been sat doing nothing for several years though !! Good luck, and don't give up. If it's broken, it can be fixed.........eventually !!! Grab yourself a cuppa and a pack of biscuits and have a read . vespasmallframeforum.proboards.com/thread/19948/vespa-pk50xl-problematical
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