SR50R 70cc airsal & Yasuni Z jetting?

Hi I’ve read up on the jetting & I was told to start at an 80 for my SR50R piaggio engined scooter, It’s spec is:

Airsal 70cc sport
Yasuni Z
Malossi stock type filter.

So my main question is I read it’s 8-12% for a kit & 5-8% for an exhaust, so as I have both do I start at a 17% (10+7, in the middle) increase over a 10%?
Because I have both pipe & 70cc kit?
Thanks!

 

This states that the formula is 5 x carb size?

5 x 17.5 = 87.5 so start at an 88 main jet then down?

https://www.google.co.uk/amp/s/www....y-determine-the-carburetor-main-jet-size/amp/

 

Sounds right to me!

 

Odd, I ordered all the parts from pedparts & he told me to start at an 80? Sounds low to me.

 

Might be best to stick to 80 then because pedparts are sound, unless another member knows differently?

 

no- only me finding that guide above really, I'm going to modern scooters tomorrow morning to buy the jets so im sure they will advise me too.

 

Well I ordered the wrong size jets, so I went to a local shop to buy some just to get started, I bought 80-90, 90 was WAY too big, 80 was also too big, I tried my stock 53 just to test it & it was obviously too lean, I just wanted to know it’d run & Rev, so, 68-78 jets ordered & hopefully will be here tomorrow.

 

Now I’ve tried 78 & 76 jets, I’m really not sure if my plug is telling the truth, I know it’s only reliable to do a plug chop at full revs on a new plug so I’ll try that tomorrow I’m pretty sure it’s still bogging on the 76.

 

If you have the standard airbox on then 76 is on the high side - i'd guess more around 65-68.

That guide that said 88 was talking about a setup with a sports filter which needs a way richer mixture than airbox.

 

Ahh i see, so is one way of testing it’s too rich could be to run it tomorrow with the 76 jet & no air box?
Then that’ll tell me it’s still too rich if it takes off & revs cleanly at WOT?

 

Then I’ll work my way down to the 68 in 2’s

 

Yeah sounds like a good plan to me

 

Well I’m getting a little lost here, I got a new plug, held it pinned up the road- cut the throttle & it was as white as white could be, clearly too lean with a 72 jet, tried again with a 74 same, now I’m back up to a 78 & thinking of trying an 80 once again!! Wft

 

Thats surprising, I just noticed you have Malossi sponge in there too - I think that lets more air through than standard sponge so will be slightly higher than I'm used to. Every setup is different though, even things like altitude make a difference to jetting.

If it likes 80 i'd stick around there, better to be a bit rich than too lean - especially while running in a new kit.

 

I’ve just tried again & put some sealant round the reed block & the part between the carb, I think I had an air leak that’s why I was struggling to get a decent reading on the plugs, so I now have two clean plugs, one I use to warm up the engine, then when it’s nice & warm I chop the plug for the other one & pin it for 30 seconds cut the engine & check, so far I’m back to a 76!