How much should I jet up on my stock 660 for airbox lid removal? It was running lean with the new HMF slip-on and changing jets to 145-150 ( 5 over stock on both) and adjusting the airbleed screws to 2 1/2 turns out as the instructions say. I did the airbox lid removal to see if indeed it proved I am lean ( have popping, but I am not able to guess how lean it is) and with the lid off it won't even pull the wheels. BTW, changing exhaust and jetting made a huge performance gain.

Thanks

Allen

 

I would start with 165/170. You may want to up your pilot to #25 or 27.5.

 

Thank you.

If we leave the lid on, should we go 3 sizes smaller than the 165-170?

I am surprised they sent so small of jets with the muffler. We did open the divider in the snorkle, if that matters.

It sure runs great ,even with the lean condition, with the muffler swap. Best $217 we spent so far.

Allen

 

Did you do the dyno jet kit? They recommend cutting the flaps in the snorkle. But, pulling the lid is where you get the major gains. Be aware that Dyno jets flow more fuel than mikuni jets so they are not apples to apples.

I am not sure what the delta is from lid off to lid on, but when I first pulled the lid, 165/170 mikuni jets is what worked for me.

 

Thanks again.

No dynojet kit, just 2 jets.

The jets that came with the mufflers were Mikuni's and the HMF literature that came with the muffler/ jets said to remove the 140 and put the 145 in, and the 145 swap up to the 150 supplied. I believe the jets came from HMF as the box label ( ups) shows it came direct from HMF and not the seller.....

I started this thread thinking if I knew how much the lid removal changes jets ( say 5 sizes) then I would know it was safe to go say 10 and be fatter and not too fat as I could lean it by doing box lid mods or sock replacement to lean it back down.... sort of makes sense to me..lol

I will buy the 165-170 pair and give it a try.

Allen

 

Unfortunatly its usually not that easy. Jetting is trial and error. All bikes behave a little different and people ride at different temps and pressure. So, don't put the front plastic on until you romp it down the street a couple times and make sure it runs OK.

Good luck!