carb issue or soemthing else ?

[br4inl3ss]

hello.
since automn is starting soon i started to get my scooter ready. ( its not the mechanical nightmare i had ! its a new to me 2020 Scootterre Bistro 50 )

i'm buying fairing right now. but i tried to start it and i remembered i had this issue since i bought it ( didnt had time back then ).

so the issue is that it won't stay alive on its own. even if i hold the gas at 1/4 1/2 3/4 or full, after some second it will die.
the only way to keep it alive both at idle of holding gas, is by activating the accelerator pump. be it twisting throttle a bit or pushing it with a screw driver. pushing it and holding it, it will die eventually after some seconde. it must be pumped.

this is with both the stock carb ( Hualong PD18J ) and my Glixal 20mm. at first it seemed better with the glixal, but after 2-3 minute of running ( palying with accelerator pump, ofcourse ) it isnt any better.

this scooter was maintained by the stealership and the previous owner never touched it. iirc even valve lash have been adjusted not long before he store it. its a 2020.

oh i almost forgot.. i tought it was a clogged carb at first.. nope. i completly cleaned it and everything is like new. can even see fuel going through all the passages freely. the jets were clogged to hell tho.

what can the issue be ?

[GrumpyUnk]

Could it be some insects have set up a colony in the muffler or exhaust? Could the outlet from the fuel tank to the petcock be getting clogged with detritus inside the fuel tank? Does the petcock supply adequate fuel to the float bowl? You can skip ahead to testing with a hanging fuel supply like an IV tank feeding the inlet on the side of the carburettor. Two t's if ANZUK. Or British. Assuming autumn, indicating south of the equator.. no?
The accelerator pump adds fuel... but it will run out of fuel as it is refreshed/refilled over time by a small passage in the bowl. The pump side of the diaphragm gets fuel from the float bowl, but I do not remember the details. It is not a direct feed, and I think takes time... so essentially you are running out of fuel, either the jets or the float bowl is being emptied.
tom

[br4inl3ss]

Thanks Tom.

i forgot to mention about fuel supply. damn adhd.
the fuel supply is in excellent state. sucking on the vacuum hose i see fuel flowing extremly well on the fuel hose.

its Québec, in Canada lol. usually i wait till mid - late April, but since i have to change most of the fairing... gotta start now.


ima check if bowl get emptied, but its not related to hose or petcock or tank because the flow is extremly good.
probably the float height, or it stick ( wasnt sticking on the bench ).

[br4inl3ss]

ohhh i think i found an issue.
after spending 2h45 on the phone with both scootterre stealership and scootterre technicals ervice, it end up it is NOT the stock carburetor.
it is an amazon PD18J ( same size ) but different jetting, different top ( metal brass color vs plastic black ).
the PD18J that came with the scooter have a 34 idle jet, and a 75 main jet.
io cannot call them again for multiple reason so i searched on scootterre website, and they sell all the needed jet to tune it ( they even sell a 80cc kit for that scooter when you buy it new ). they have one jet that says "GICLEUR D'ORIGINE 88" in the 50-80cc parts cathegory. in english it means "ORIGINAL 88 MAIN JET".

i fint 88 a little big for a stock 50cc, but whatever. ima try tp upjet to something close to 88 and try.
i dont see how the main jet can affect idle, but apparently according to multiple source, and most are RELIABLE source, they can.

[br4inl3ss]

update, it doesnt change a thing.

i then tested with my phbg 19 ( 38 pilot jet and 85 main ) the issue is still there but its WAY better.
so much better that sometime it will keep running at idle for 20 second or so without my help.
but it still doesnt fix the issue. its also never the same. one start i need to play with throttle, another start it idle on its own after revving high for 2-3 second like in the video ( no choke ).

i dont really have access to shits to check for vacuum leak right now, but if at least i can get a sure confirmation that the ENGINE itself seems in good condition, ill be happy for today.

[br4inl3ss]

update.
its possible a wrong valve gap. as my other engines.

my feeler gauge, a high quality one ( OEM TOOLS 44025 ) the last one made in USA in the late 80's before they switch to china crap ( i know china can do high quality when they want, but they can also make the worst ) and lower the price. mine was 130, newer ones are like 20-50$.

but... i asked many time if .01 , .1 , .001 were the same. they always said yes. since i knew 0.0 and .0 were the same, i tought 0.0 , 0.00 , .0 , .00 were also the same without asking myself why its so weird.

a friend, a mechanic, jsut asked my feeler gauge because he cant find any of his 4 sets. he asked if mine do 0.07, i said yes. i drop the tool at his garage door, and 3h after he call me back sayign thats not the right one. i asked the hell he was talking about. he said its 0.007 and he asked 0.07. i thenr ealised i was wrong this whole time. we had a huge talk and he had th same shit sory up to 5 or 6 years ago because he always got the same aswer too. always from "reputed" mechanics ( bmw shitcedes volks kawasaki and so on. mostly big mechanics but also independent ones ).

so once again, those "mechanics" were terribly wrong. it match everything ive seen in my life in stealershio and most small garages. mercedesc ant put back the proper fireing order the customer must redo it itself, gm cant
put the right spark plugs in, bmw says there is NO head gasket its a rubber sheet ( gasket word doesnt exist ), dodge saying thier 3.9 5.2 5.9 legenday engines doesnt have any camshaft position sensor ( and i know they d, i was a american v8 specialist because i get this fu***** adhd ). yeah trust me, i will NEVER listen to "professionals"anymore. pretty sure my friend wont either. he have seen the same shit everywhere taking customer comming from thsoe stealership. and its not a local one, they're mostly all like that.

anyway. now i know my valve gap was never done properly. i knew it was strange that in the rare decent video of 139qmb valve gap adjustment, the feeler gauge didnt look like half a paper sheet ( aka 0.004 ), but we're not supposed to doubt about "professionals" sayings.
)
so i bought a cheap one on amazon ( 9$ with a 4$ coupon ). ill find a better one that fit my needs and taste ( VERY picky with my tools ).

fake "professionals" plus the fact we sometime have to work with both metric and imperial system from time to time, some job needs both, and a ADHD that the Québec health care system refuse to help with.... well... no words.

a "professional", the most reputed one in the state, jsut fixed my android tv twice, its still not fixed. and last time he said " if there is still an issue go with another shop i cant do anything ".
ill order the led stripe and do it myself. i'm done with "professional".

anyway.... ill check valve gap when i receive the tool... or maybe ill use 0.020 + 0.021 for a 0.041 which is in the 0.04 - 0.05 range per the ScootTerre manual. my OEM TOOLS only start at 0.002 not 0.02. it does have 0.020 and 0.021 tho the last ones and the bigger ones.

[GrumpyUnk]

AFAIK you can stack the blades and the thickness should add up to the desired measurement.
0.01 is the same as .01 is the same as .0100 ...
I do not seek professional help on my vehicles unless forced to. Getting too old to crawl around as much as I did decades ago. Some "techs"(in quotes for a reason) are under the impression they are the only ones with knowledge and disregard whatever a 'customer' tells them. When I encounter that, I either shut up and go with the flow, or decide to take my business elsewhere. I overheard one 'service writer' telling another person that it took up to 3 days to perform a recall that has a book time of 2 hours. In short some people are arrogant, will not admit to being ignorant about ANY thing at all, and get irate if you point out their misconceptions.
Had one tell me my car needed ball joints when it went in for the mandatory CO inspection. He thought he could force me to get new ball joints. I pointed out he was doing the test incorrectly, per the shop manual, and he told me to get out.
In short, it does not pay to attempt to communicate with a lot of "techs" as they use their employment(being employed as a "tech") to bluster when they do not know what they are talking about but do not want to appear ignorant to a customer.
I share what knowledge I have, until I found out a 'consultant' was using me and my knowledge to bump up his billable hours. I quit helping someone who was being paid to KNOW stuff he did not. He was taking the salary under false pretenses. He wanted to bill extra for a couple days when a leased computer was being returned, extra money. The lease money was paid upfront, paid for the system, and the money was used to finance the system so we could use it. It was paid off, completely, and payments were all profit. He was greedy, so I completely erased all the disks, took things apart, and left them for him to put back together. After all, he was a 'professional' who was supposed to know all that.... Why should he take even more advantage of my abilities when he would not give a few days time for me to export all the data? A 'taker'. Had enough of them.
tom

[br4inl3ss]

thats exactly the same shit i deal with everytime i talk with a "professional". they know less than me at 5y when i had no idea what a tire was. at 11 i knew what the whole car was and while i didnt know all the functions and how they work, i was able to put a whole car in parts and reassemble everything in a week. at 12yo, thats extrem. and the "professional", globally, i'm not sure they could do that.

anyway.. bad feeler gauge/gap was the issue for my ScootTerre bistro 50. but not for my rat bike. maybe its not gapped perfectly. ill redo it later.

oh both the phbg and the crappy cvk carb that came on it works now. the phbg need a severe tune, but its working.
its so rich with the phbg that it start like brand new even at 2C without coke. and the idle is like at 3k rpm or so and i cant lower it at all. but hey i think it have a 38 idle jet ( someone told me phbg need bigger jets compared to a cvk of the same size ) but now at least the choke change something ! before the choke was completly useless no change at all. now if i pull it the rpm drop, it sputter like no tomorrow, white smoke, then stall. its doing the job he should.

thats such a fucking good feel to ahve that amazing phbg carb working. ill have to see if it die on quick throttle action as before, but i'm confident it will be fine with a proper setup now.

do you know if a pwk would be even better ( for whatever reason... better throttle response, easier tuning, bla bla bla ) ? jsut wondering i keep my dellorto !

[br4inl3ss]

ok so i tested back with its carburetor. its working !
it need a tune ofcourse ( choke doesnt seem effective but it start very fast in cold weather ? )
ofcourse ill have to install a tach on it.

ive learnt the other day that ScootTerre direcly, and the dealerships, do sell a 80cc kit available when you buy the scooter................... which include the exact carb that i have on it.........
maybe ??
the exhaust sounds exactly the same as when i had my 81cc (50mm). mine wasnt leaking for 3-4 days when freshly mounted. maybe ??
the acceleration even tho the carb isnt properly setup ( a 19mm with a 75 main jet ), seemed close to my 81cc on the rare day it identified as a WORKING scooter ( twice a year at best ). MAYBE ??

the previous owner ( he looks like a very big liar ) said it was 100% original 50cc.

if its a 50, then i can tell you it have extremly high compression because ive never rode a 50cc that perform that good. not even a 2broke wasp ( stock, ofcourse ).

wondering if you know a way to be sure without opening the top end ?
i have a inspecton camera. the form of the top of the piston may tell IF its different than stock, but ive seen many different aftermarket stock style piston. and the size isnt gonna be easy to know using a camera with limited movement because its a tight fit in the sparkplug hole.
the stock piston on the donor motor i have ( on the rat bike ) is a dish piston. so yeah thats not a good visual indication.

[aeroxbud]

Shouldn't it say somewhere on the cylinder the size? You might need to remove the covers to find it.

[br4inl3ss]

i was trying to avoid this. but hey its better tjan opening the engine
i had 3 72cc and 2 81cc cylinder that had no indication at all, just like stock 50cc cylinder.
it has less than 5000 km on it i'm trying to NOT touch it as much as possible.
but yeah... i have to check exhaust gasket so i have 60% of the job done to remove the shroud.