nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 23, 2023 20:07:23 GMT
Hi guys,first off can I just commend all of you with your knowledge & advice throughout this site which has been invaluable to me over the last few weeks of doing my 1st ever engine split & rebuild,thanks guy's you got me through it,but .....,
So I installed complete bgm gasket & 'O' ring set & & all new bgm bearings throughout,head barrel & piston all good but I did replace piston rings,new gaskets on carb too,new cruciform & selector rod whilst I had it opened up,
Everything has gone back to plan
& All works as it should but I have a spluttery misfire when I open her up through 2,3,4
I've put a new bgm cdi on & also checked timing which is spot on,
Sip rd2 with drilled out air filter & 102 main jet,
Is my next route a new stator ?
Still running on 2% premix so autolube can settle in again,
I'm not huge on mechanical knowledge & this site has been my
Haynes manual,but this misfire got me miffed,
Any ideas guys?
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Post by phattanglo on Apr 24, 2023 6:14:31 GMT
Sounds like fueling somewhere.
On a my 125, I'm only on a 98 main jet with drilled filter and SR2 as I've jetted for a richer lower and mid revs.
I would have said you are possibly running a bit rich, but if you are running on autolube and extra oil in the fuel, that would make it a bit leaner.
The only thing I can suggest is to shut the engine off at the point it starts spluttering and check your plug colour.
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 24, 2023 6:48:17 GMT
I checked my plug yesterday & it was a mid brown but wet,is this because I've over sized the main jet ? or the extra oil in fuel while autolube primes itself again ?
Maybe I need to adjust fuel/air mixture screw ?
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Post by phattanglo on Apr 24, 2023 7:05:39 GMT
Hard to say. Was the engine up to full temp?
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Post by adrian on Apr 24, 2023 8:42:27 GMT
Try another plug, the one you are using might be faulty
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 24, 2023 9:09:25 GMT
Hard to say. Was the engine up to full temp? Yeh the engine got up to full temp,rode around town for 45 mins & it spluttered/missed from start to finish,I would say it was happening as I powered up through 2/3/4 at about half revs stage then it pulled through it |
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 24, 2023 9:13:06 GMT
Try another plug, the one you are using might be faulty This was a new plug but I'll pick a couple more up & try another plug 👍 |
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Post by phattanglo on Apr 24, 2023 9:36:03 GMT
So nearing full throttle it settled down and ran ok?
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 24, 2023 9:40:30 GMT
Yeh once it had gone past the misfire point on acceleration
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Post by scooterbooter on Apr 24, 2023 16:27:10 GMT
When you say mis fire, can you get through that by
A. Opening the throttle all the way
Or
B. Backing off the throttle until you find a sort of sweetspot .
It sounds like jetting but I'd need more info. It's all a bit off a stab in the dark. Have you adjusted your jets? A mid range splutter could well be atomizer. But don't rush into things. Is it a new ht lead? Even a poor connection somewhere can't really be ruled out.
It'll be something you've done probably. Don't take that the wrong way. We all introduce faults sometimes and a rebuild isn't a proper rebuild unless you do it at least twice. There will be a tell tale sign you jus t need to find it. Quick way to check jetting is to hold the throttle open revving away on the stand and pullout choke the engine should start to splutter then gently stall. Repeat with throttle in different positions if you don't stall your too lean . If your to rich you will increase your problem before you stall and you just might think- that's what's happening to me! But to be accurate I'd need more info.
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 24, 2023 20:47:33 GMT
The problem existed before I done rebuild & all jets are standard apart from main jet which I upped to 102 on recommendation from sip to suit sip road2 exhaust,I also put new float needle in while carb was off,
I haven't given it full beans yet as I'm running new rings in but it misses around half throttle but if I keep powering up it stops missing and runs fine,
I've put a new cdi, HT lead,plug & cap on,
One thing that did occur just before rebuild when I was out for ride was doing 50mph was fine but if I gave it a tiny bit more throttle it would just cut out until I let off the throttle,hence I thought maybe I had a dodgy cdi & replaced it for new,
But at moment I haven't taken it back up to that speed so I'm still in the dark
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Post by scooterbooter on Apr 25, 2023 7:30:12 GMT
OK I thinki got it. Have you tried any other main jet sizes, I think you are one or two sizes too big. Have you tried other sizes? If not you must buy a 98 and 100 and try those. BUT THEY MUST BE THE SAME MAKE AS YOU ARE CURRENTLY USING. SO THE SIZING IS CONSISTENT. try that big fella. I don't like recommending stuff so quickly but it seems from what you said that should be your next port of call. My guess and it is a guess at this point is that a 100 mj may solve this issue. Good luck.
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 25, 2023 9:22:50 GMT
Cheers SB,I've just ordered a 98 & 100 mj,will give them a whirl when they arrive & let ya know how it goes,
Appreciate the advice,
Many Thanks
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Post by scooterbooter on Apr 25, 2023 16:29:10 GMT
Good luck let us know how it goes.
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Post by soulboy74 on Apr 25, 2023 19:43:06 GMT
Hi there if all alse fails why not stay standard exhaust l have with the same scooter as you just switch out the cat manifold and put it to the original box ! Drill out air filter and stop there for now 97 main jet sweet as a nut and reliable to boot and your still hit 50 mph what a couple of mph !! It a 125 after all the racing exhaust system is best with a racing type tune up !! Standard keep you moving forward ! Best foot forward soulboy74 🏴☮️ peace
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Post by phattanglo on Apr 26, 2023 5:57:20 GMT
Something to consider, with a drilled filter and better exhaust.
You should also check your jetting at lower revs, as coming from full throttle to lower revs can also cause a seize if your jetting is too lean.
People who are far wiser than me have said, that is one of the most common causes of an engine seizing.
MY 125 is standard with no port work, just a drilled filter and SR2
To give you an example, I changed my jetting so it was a bit richer in the lower revs and after a plug chop I found myself staying with a 98 MJ.
My setup is,
Pilot jet 55/160
Mixer stayed as a BE5
Air corrector 120
Throttle slide Number 8
Main jet 98.
I'm a fat knacker so it's hard to say what the top speed is with these carb changes, but it's probably added 5 to 10 mph compared to the normal Euro spec.
I would say that the engine just sounds happier, as the standard carb setup with the cat exhaust is jetted to run very lean to get through the Euro emissions regulations
The carb has to come off for access if you want to change the throttle slide, but everything else can be fitted in situ.
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Post by soulboy74 on Apr 26, 2023 7:47:30 GMT
Yes sounds like you have found your sweet spot on your tune up 👍 well done mate! Lot of work for just a few mph l have found keeping it close to standard as possible will keep your scooter stress free!! as changes can add extra stresses that your set up was not ment to have!! and can keep you changing out different parts just to keep running well !! It's your own choice!! But Hay a standard will always return you your money back !! Best foot forward soulboy74 ✊
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 26, 2023 9:12:17 GMT
Yeh mine is bog standard too apart from it having sr2 on it when I bought it back in October,I'm not not bothered about having break neck top speed but I just want engine to run as sweet as I can get it,so just need to cure the mid throttle mis & the cut out when it goes over 50,I might just a little play about with the other jet settings mentioned too,
Appreciate all the pointers guys,
It been 36 yes since my last scooter so I'm a bit rusty!
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Post by soulboy74 on Apr 26, 2023 15:59:54 GMT
A standard 125 won't do much over 50 mph if that try your original settings in the carb and move up one at a time it should or only need a little bit up jetting !! and a sip 2 won't get you going faster!! Just a bit!! Quicker through the gear's if that !! I have one but chose to put my original box back on with a granini manifold down pipe to the original box!! Look it up ;; not so tricky to boot! Best foot forward soulboy74 🏴
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Post by phattanglo on Apr 27, 2023 6:26:42 GMT
Yes sounds like you have found your sweet spot on your tune up 👍 well done mate! Lot of work for just a few mph l have found keeping it close to standard as possible will keep your scooter stress free!! as changes can add extra stresses that your set up was not ment to have!! and can keep you changing out different parts just to keep running well !! It's your own choice!! But Hay a standard will always return you your money back !! Best foot forward soulboy74 ✊ You'd think it was a lot of work, but actually including removing and refitting the carb after, it was probably an hour at most. The thing is, it's sort of going back to an earlier spec to reduce stress rather than adding extra stress. Keeping the jetting standard on the cat exhaust model can leave the engine very close to seizing at any time due to it running lean. The changes won't alter the top speed all that much, as I said at best it would be maybe 5mph and certainly no more than 10mph and that would have to be with a light rider, but it definitely improves acceleration which for a 125cc single cylinder engine is about as much as you can expect. Also the E5 and E10 Fuels with alcohol added will make it run even leaner Because the post 2011 model had to get through Euro emissions tests. it's jetted to run lean which is not good for a 2t, especially in the mid rev range and if you fit a sportier exhaust and drill the filter it will be running even leaner, which is definitely not good. So my changes are to reduce the stress on the engine as it runs richer. |
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 27, 2023 6:36:45 GMT
Yeh,I understand px125's don't do much more than 50mph & I'm not looking for more speed,I just want
What I'm riding to run smoother,I did put original 98 mj in last night last night and this made the problem worse,so I'll have to wait for bits to arrive & tinker over weekend,thanks guys
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Post by soulboy74 on Apr 27, 2023 9:19:27 GMT
👍 sounds like you are moving forward witch is good just keep the faith and you will find your sweet spot soon mate !! What the year of your scooter if it's pre cat exhaust it should be straight forward !! Best foot forward soulboy74 🏴
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nick71
2nd Class Ticket
Posts: 15
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Post by nick71 on Apr 27, 2023 11:57:08 GMT
👍 sounds like you are moving forward witch is good just keep the faith and you will find your sweet spot soon mate !! What the year of your scooter if it's pre cat exhaust it should be straight forward !! Best foot forward soulboy74 🏴 Mines a 2008 PX125 so I guess it would of had cat originally |
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Post by soulboy74 on Apr 28, 2023 12:26:32 GMT
It sounds like phatts !! Found a good solution!! Check his set up mate but Hay if you have been and done a rebuild might just need running in period!! Get very messy if you are not a good mechanic with vespa technical skills !! The new ones like ours have many improvements ! and are not restrictions like many other tell you once the cat part is out the rest are all inprovement!! Your never going to hit 7000 rpm on a 125 so CDI is well suited once you have changed the set up you will need to keep on top of your settings and keep changing to suit !! Why not stay standard if all alse fails !! Give phatts a message for his setup advice !! Best foot forward soulboy74 🏴
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Post by phattanglo on May 2, 2023 6:15:05 GMT
The later Chinese cdi and stator setup is adequate for the scoot in a standard state of tune as you're not likely to get past 7k rpm even on a good day.
Just make sure you use the recommended resistor type plug as an ordinary plug will mash the CDI.
If I was tuning the engine and it could exceed 7k rpm, I wouldn't bother with the Reedspeed Zeus CDI.
Honestly I would make a full change back to the traditional Ducati setup with a new CDI, flywheel and stator.
It's more robust, it can be modified to run LED lights well if you want to tinker.
It's tried and tested and hasn't needed to change for years.
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Post by soulboy74 on May 2, 2023 19:17:14 GMT
Yes I must agree with you about the chain part !! As I try to stay standard set up mostly it will do for now!! if you have already started a fresh set up it's a good place to start like most offers it's all about learning every thing vespa !! I was out again Sunday morning ride out and I have easily get 50mph GPS with only the air filter drilling modifications and setting jet to 97 main it's all good and working nicely !! One day l will go full tune up. Best foot forward soulboy74 🏴
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