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Post by alanc on Apr 12, 2015 13:37:45 GMT
hi guy hope someone can help
I'm building a 1970 sprint veloce with a 1974 sprint veloce 3 port engine I've installed 12v electronic ignition a 20/20 carb 160/be3/102 main jet. it starts second or third kick no problem ticks over and revs just fine. when I ride the scoot it goes up through the gears no problem 1st, 2nd, 3rd, up to about 60 kph but when i shift to 4th gear the revs drop right down and the pickup is very slow almost nothing it's like driving a car and going from 3rd to 5th gear. this is going up a very slight incline. when i turn round and come down the incline it picks up through all the gears up to 80kph but once it gets to 82ish it starts spluttering and missing at full throttle.
any Ideas or suggestions are greatly appreciated as i've been tearing my hair out for a couple of months now and I'm desperate to get the scoot MOT'd
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Post by henri on Apr 12, 2015 17:28:33 GMT
go down a main jet size ,an maybe try a be5 atomiser ,an wheres it timed to , i think i'd set it to 19 btdc an work from there ,
did you build the engine yourself , maybe somebodys stuck a different 4th gear in an scoots struggling to pull it an get on the power , specially uphill ,
which lectronic kit did you use , as memorys saying the sprint veloce's a small taper crank unless changed so a px fly wont fit , pk will or a converted px with pk centre . H
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Post by alanc on Apr 12, 2015 19:05:50 GMT
thanks for the reply
timing is set to 18 btdc, didnt build the engine myself but was a bit of a state and i didnt hear it running as it was out of the scoot, was beginning to think the same thing about the 4th gear, ignition is bajaj
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Post by henri on Apr 13, 2015 8:14:40 GMT
baja lml , are pretty much same deal, they can be a bit down on spark compared to piaggio, as it will rev in 1st-3rd reckon your pick-ups good for now , an if jetted right should just bout pull in fourth with a bit of patience an no uphill , will look out my jetting guides an notes from trying to get stevievespas sprint engine running better , the threads are on here somewhere , from memory we put it back to stock for a sprint in a 20/20 carb body an it was pants , messed about an ended up sticking a set of lml px150 jets in i had kickin round the shed an it was loads better , in my defence i had a crippling hangover that day ,was crosseyed an just couldnt remember how/do the maths to work out the right pilot jet an was just guessing an swapping jets fairly randomly , sorry stevie, but it worked , H
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Post by alanc on Apr 13, 2015 9:28:49 GMT
thanks Henri I've ordered px 150 main jet 150/be5/98 will see what happens and let you know
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Post by alanc on Apr 16, 2015 11:29:57 GMT
ok new jets arrived have put in the 98 main with 160 air be3 atomizer. running a bit better in 4th pulling up to 70kph but still struggling to get to 80kph then starts spluttering missing and dies close throttle to 3/4 and it picks up again
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Post by henri on Apr 16, 2015 16:33:44 GMT
still too large on the main , dont forget altho called a "sprint veloce" (itey for sprint fast) , there a smaller engine in power to a px , an run smaller carbs , 20/17d's if memorys working , i'm not sure if the veloces a 3 port motor ,think there still 2 port ones , a sprint runs a 20/17d an 102 main an be1 atomiser , a super a 20/15d an 88 main an be1 atomiser , a be1 is a slightly richer 1 than be3 , an the sprint runs a 140 air , super 160, i cant find any figures for a sprint veloce as yet , what carb body number do you have ,its stamped/cast in near where throttle cable goes in , h
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Post by henri on Apr 16, 2015 16:36:52 GMT
oops ,just re-read original post n got my answers , erm, will think on it but i think i'd go n try a 96 next n pull the plug n look at the colour its giving you , it sounds over-rich , but best have a look n be sure , as very-very lean can give same effects , H
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Post by alanc on Apr 16, 2015 20:33:31 GMT
cheers H will order a 96 and see how it goes, it is a 3 port sprint veloce engine i've checked the engine number. the plug is a nice golden brown so it's not rich
Alan
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Post by henri on Apr 17, 2015 8:46:30 GMT
how old n blocked is the exhaust ,an how olds the fuel, as if plugs golden the mix should be ok ,but as it wont run past 3/4 revs the plug colours just showing the pilot circuit n atomisers right . needs to run for 1 1/2 minutes over 3/4 to check main jet . h
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Post by alanc on Apr 17, 2015 19:44:47 GMT
hi H the exhaust is a replacement only done about 4000 miles from a px 125. the one that was on it had bits of something floating around inside. have ordered a 96 and a 94 main jet, hopefully they'll be here tomorrow. definately thinking it's a main jet problem,,,but i could be wrong
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Post by henri on Apr 18, 2015 7:35:33 GMT
it got better going from a 100 to a 98 , so reckon your on the right track , need to get it where it will run long enuff to put colour on the plug n tell you where its at , bit hit n miss till then .
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Post by alanc on Apr 22, 2015 14:42:36 GMT
hi H
have cleaned the carb and it's running much better no spluttering at full throttle. however it only gets up to 75kph have tried putting the 102 main jet back in but no difference 75kph max. feel like something is holding it back
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Post by henri on Apr 22, 2015 15:08:19 GMT
just because the cases/engine number comes back as 3 port doesnt mean the barrels a 3 port , ive seen 2 port barrels stuck on 3 port cases before , but should still do better than 35mph , where did you time it too , might be worth advancing it 2-3 degrees ,or until it pinks an then backing off a bit , H
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Post by alanc on Apr 22, 2015 20:47:42 GMT
have had the barrel off H it's definitely a 3 port, it's timed to 18 btdc, started at 22btdc then worked back
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Post by henri on Apr 23, 2015 8:47:51 GMT
22 is the original stock timing ,an 19 is where most electronics are timed to , most retard 1-2 degrees from stock to compensate for modern fuel , as your scoot is revving out in 1st to 3rd gears ,unless your changing up early ,we can rule out a limited cdi or a cdi thats not advancing the timing with rev increase , you put the ignition on an i'm guessing its a new cdi so should be good ,do you know anybody with another cdi you could borrow an fit for a test ,just to rule a cdi fault out of the equation ,
an as there wouldnt be any case marks ,how are you timing it , by strobe an your made marks , as the ignition point is as the zig-zag magnets on inside of fly cross the leading edge of pick-up , sorry if i'm "tryin to teach me gran to suck eggs" , as the carb changes arent making greast improvements my minds wondering if ive sent ya barking up the wrong tree . an theres ignition/spark scatter in higher revs/under load .
think maybe its time to go back to basics an rule out bad ht lead connections/ht cap/wiring-soldering-coil on stator faults/dodgy pick-up/fuel starvation an the other "usual suspects" for lack off oomphh , H
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Post by alanc on Apr 23, 2015 13:14:09 GMT
cheers H lots of stuff there, am time with my own tdc mark which is spot on checked it with the head off and a strobe light. all of the ignition is new cdi ht lead etc, will go back to basics this weekend will start with moving the timing from 18 to 19 see how we go
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Post by alanc on May 6, 2015 8:05:16 GMT
latest update
have reset tdc took the head off to get it bang on tdc reset timing to 18 btdc using strobe light scoot now running terrible no power took plug out and it's completely black with soot way to rich. need weather to get better so i can get her out and test some more
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Post by henri on May 6, 2015 15:30:45 GMT
which way did you have to move the timing if any to get true 18deg btdc , retard/clockwise on stator ,advance /anticlockwise , as no power/bad start/tickover is a too much retarded usually ,
stock sprints is 22 ,i think veloces the same , so if where it was,was better an more advanced ,say 20degrees btdc i'd stick it back there an try n sort ya jetting from there,til its showing good colour on ya plug an then fine tune the timing a bit for optimum performance , its a bit of a juggle really ,get timing to where ya can get rough jetting ,then fine tune timing an finally nail down exact jetting , H
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Post by alanc on May 7, 2015 8:27:45 GMT
hi H am I right in thinking that I need to turn the mixture screw out inorder to lean the mixture
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Post by henri on May 7, 2015 8:40:50 GMT
in to lean it , out to richen , wind in all the way ,then back out 1 1/2 - 2 turns an start from there , is it a 7mm hex head or a straight screw one , screws are coarse thread 1's an 1 1/2 turns out , hex heads are fine threads an 2 1/2 turns out as a starting point , ok ,
an i got caught tother day by a replacement spring being too big , wouldnt wind right in before spring coils compressed an stopped it , wound back out 2 turns an it was bogging ,was on leanest pilot jet n pullin my hair out before sussing it , H
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Post by vespasco on May 8, 2015 18:59:27 GMT
hi guy hope someone can help I'm building a 1970 sprint veloce with a 1974 sprint veloce 3 port engine I've installed 12v electronic ignition a 20/20 carb 160/be3/102 main jet. it starts second or third kick no problem ticks over and revs just fine. when I ride the scoot it goes up through the gears no problem 1st, 2nd, 3rd, up to about 60 kph but when i shift to 4th gear the revs drop right down and the pickup is very slow almost nothing it's like driving a car and going from 3rd to 5th gear. this is going up a very slight incline. when i turn round and come down the incline it picks up through all the gears up to 80kph but once it gets to 82ish it starts spluttering and missing at full throttle. any Ideas or suggestions are greatly appreciated as i've been tearing my hair out for a couple of months now and I'm desperate to get the scoot MOT'd I remember my first P200 motor. ChNging from 3rd to 4th was the same. I had to really rev it out in 3rd and change to 4th. I soon got used to it. Id guess if its spluttering and missing at hi rpm in 4th then you may need a larger jet!? Not enough fuel. |
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Post by alanc on May 24, 2015 12:08:11 GMT
ok took the scoot out yesterday to try different jets all was going well after trying 4 different jets scoot cut out like it was out of fuel then wouldnt start again. now not getting a spark aaaaaahhhhhhhhhhhhhhh. if I hold the HT lead and kick it over with the plug out I get a mild jolt through my hand but not enough to give a spark.  ? Any thoughts H? |
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Post by henri on May 24, 2015 20:22:42 GMT
mild jolt ,if it aint gettin ya break dancin it aint right , first stop ,condenser , then ht coil , an then ignition coil on stator , but before all that keep it "KISS " , thats " Keep It Simple Stup" , no offence meant , check ya ht lead is well connected at coil n ht cap , wire from stators got good connection at coil , coils got good earth. its worth unscrewing ht lead an cuttin 1/4" from end an re-fitting ,new plug/ht cap , all the cheaper simple stuff before we go in depth more costly ,but as where in the cheap seats a new condensers only pennys ,an the old ones still useful , you can throw it at doubters/pigeons/ well just out anything ya fancy ya can hit , H
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Post by alanc on May 30, 2015 8:49:28 GMT
cheers H will have another go this weekend I have noticed that the flywheel is slightly scrapping agains the stator could this be a possable cause?
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Post by henri on May 30, 2015 15:48:06 GMT
if stators scraping on fly ,that means too little clearance 1 side an prob too much tother ,an if damaging the laminates coils sit on can cause too little or too much voltage to be produced by the affected coil, if its scraping/damaging the ignition coil an lessening the voltage produced that will lower the high tension/spark voltage an could be your problem , an check ya points gap, too small a gap=weak spark , ok , H
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Post by alanc on May 30, 2015 21:32:16 GMT
cheers H will check that out. it electronic so no points
Alan
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Post by alanc on May 31, 2015 15:33:41 GMT
still no joy
went and got a multimetre checked the voltage at the cdi from the stator = 4.4v that was kicking it as hard as i could with the plug out
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Post by henri on May 31, 2015 18:00:27 GMT
no where near enuff to build a decent spark, i think youve found ya problem , H
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Post by alanc on Jun 6, 2015 21:16:01 GMT
new stator,coil and piston rings arrived hope to get them fitted tomorrow will let you know how it goes H
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