Aerox crazy fuel consumption

[GalaxyTramp]

Hi

I have inherited a Yamaha Aerox with the following mods:

Polini 70 CC kit
Polini Variator Kit
Dellorto PHBG 21 Carb
Yasuni Exhaust

The autolube system has been removed and I use premix at around 30:1

The bike performs well but uses more fuel than the space shuttle, no matter how I drive it. Having had it standing for about 2 weeks I decided to rip the carb off to see if I could find the problem.

The insides of the carb and manifold are covered in fuel, despite the engine not having been started. The pipe between the carb and airbox is also coated in a fuel/oil mixture.

Removal of the plug reveals that is is black and oily. The carb has a main jet marked as 60, surely too small?? and an idle of 50 and a choke/starter of 60.

I have attached images to show how fuel/oily things are. The carb jets have had the edges knocked off it seems, but not by me.

The needle is a W7 but if you look you can see a groove around the middle is this supposed to be there? The needle quite easily pops through the center of the brass retaining plate that fits under the slide spring, is this normal? Which way up should this be fitted?

Heres hoping somebody can help with this I feel that I am putting fuel in the tank it is running straight out of the exhaust. the exhaust does not smoke once the engine warms up incidentaly.

Regards

Colin

[clancy]

change the jet and adjust float needle to restrict fuel ? something like that i did on my scooter and it stoped it using as much fuel anyway.
only problem is its gonna want to eat fuel with 70cc etc on it.

i wouldnt of bothered modding it to be honest. but yeah, i think i adjusted the float needle and it stop drinking fuel
____________________
KLX 300r

[GalaxyTramp]

Thanks for the reply

I prob would have left well alone but it came very cheap having just been rebuilt with new crank, cylinder etc. This is not using a lot of fuel, it is using a really stupid amount of fuel, about 5miles to the gallon

What I would like is someone to give me a start on the main jet size. 60 seems to be so small!!

I will set up the float levels when I put it all back together.

Jet sizes anyone!

Colin

[Mr.Ormes]

on my gilera gsm standard carb and bore, im pretty sure my main jet was 58.
____________________
DT 125 1995
Thumpstar 120
Suzuki ZR 50

[GalaxyTramp]

Hmm!

I think that may be way off but thanks anyway. Looking around the web it would seem that something in the 80's or 90's might be close. Perhaps this supposed 60 has been reamed out??

Colin

[evoboy]

Id replace the jets. Who knows whats been going on in there looking at the heads on those jets!

Clean the carb, set the needle, float height and air screw to standard and work from there.
____________________
Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

APT Motorcycles

[GalaxyTramp]

Yes the heads of the jets have been "around the block" I fully intend to change the jets but I need to have some form of starting point before I buy a box of jets. Standard does not exist unfortunately.

I was considering a hotter plug to try to stop the oily build up, any thoughts on that? The plug is as recommended with the cylinder kit (I have the documentation that it came with)

I have just set the float height, it was slightly high.

C

[evoboy]

Main jet seems too big to me from looking at the plug and that its doing silly mpg. My SR50 had a leo vince pipe on it when i got it. It also did stupidly low mpg, turned out someone had gone ott when upping the main jet.

Try a 55 or 57.5 ( no idea what ratio dellorto jets go in ) main and see how that goes?
____________________
Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

APT Motorcycles

[Polarbear]

Doesn't it say in the documentation for the oversize kit what you should change the main jet to?

Other than that I can only suggest a forum for tuned mopeds. There must be some around. Sorry for not being any more help.
____________________
Triumph Trophy Launch Edition

[GalaxyTramp]

Polini cylinder kit just says to go up with the jet sizes, not too much help at all really.

I need to get a look at the Polini PHBG carb kit docs they might be of some help.

C

[mysterious_rider]

you sure it's not a fuel leak? Or leaking fuel out of the overflow or just leaking fuel because the needle is worn?

[Noxious89123]

I can't help you with your question, but just thought I'd make a post to say that your photos rock. I can't get photos that close up without the autofocus on my camera spazzing out big time.

So much of the time people post useless blurry photos, so props to you sir.
____________________
'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi

[baldy]

I think the main jet is too big. The standard air box is really restrictive so you should need around a 50-55. Around 50 is standard. If you run a cone filter and ditch the air box, you will need around a 100 main. They run way better with the standard air box for some reason.

Have you checked the float needle for wear and st the float height? Also the needle should have the clip on the middle notch for the standard setting. It should be fairly secure in the slide and not be able to move up and down separate of the slide.
____________________
One day i will rule the world, just not today.

[GalaxyTramp]

[baldy]

It does look a little large that jet for it's size. I would replace them anyway as they look fairly munched up. As for the needle, it will be able to move side to side a little but not up or down.

If the air box has been drilled then the jetting could be anything.

And yes, it is from experience, i used to fix scooters everyday that some tard had tried to 'tune' and made it run really crappy.
____________________
One day i will rule the world, just not today.

[GalaxyTramp]

Ok so I will replace the needle with another W7, get a 50 - 72 jetkit and replace the idle and choke jets. I need to go a bit larger on the jets because of premixing the fuel am I correct?

Should I be looking to change the size of the idle jet?

Which way up does the needle plate go can you remember?

Do you think I will be on the right track doing this? (Hope so)

Colin

So many questions

[GalaxyTramp]

Anyone got an opinion as to why the carb needle has a groove worn around it. (see image)

I have ordered a new one but do not want this to happen again if it can be prevented.

Comparing the supposed size 60 jet hole with the 60 choke jet does indeed give the impression that the main jet has been reamed out.

Anyone know which way up the brass jet retaining washer should be?

regards

Colin