bluebanshee2

So was finally able to take it to a builder and he said it would be best to start over with stock cylinders then port them at his specs cause he doesn't know what the other guy did. He told me I was running the wrong spacer plate (base plate) for the series of pistons I'm running (795 series). He said i need the spacer that goes under the head. I bought the crank as a set from a reputable atv shop who send me everything I needed. Who's right or wrong so I can return the base plate if needed, Thanks

Do they need the whole bike to see how the crank correlates with the cylinder or do I just tell them I have a 4 mil hot rod crank ?

Doesn't that restrict the air/gas flowing thru? I'm thinking its the porting that is off . It's been running bad ever since the guy ported the cylinders. Some guy from my work who said he worked on banshees did it. it looked like he modified the holes in the old Pistons to fit the porting as well .

As I was was moving the piston up and down I noticed the porting on the intake side is bigger then the holes in the Pistons. Are they supposed to line up ?

yea srry for the bad pic, the piston feels about a 1/4" below maybe a little less but not flush. There is black wet residue (not ashy) that comes from where the pipes meets the exhaust port on the cylinder.

Yea , here's some pics of the lowest spot the piston drops to

I went back to the regular gas cap hose as well. Porting was not touched after stroker installed , I was told with the spacer plate the porting would stay the same. The spacer I have goes on the bottom of the cylinders. I'm running a stock head

It only takes a min or less for the power to come back. I've checked the carb bowls and they are full with gas, even messed with the floats so it would use more gas.We ride in glamis, CA. We went from stock main jets 200 to set us back at zero then 280,300,310,330,340. 300-310 ran perfect with pilot jet at 30, but got the same top speed results. I thought maybe it might be the CDI box but it looks to be in good shape. Ive also thought about changing the petcock to the dual one so both carbs have their own direct hose but they are full with gas when i checked the bowls. maybe bigger reeds? I have stock ones . here's a pic of some of the porting

Coils are brand new from Yamaha dealer, stator from racetech electric, I chrcked the gas cap but haven't ckeaned the petcock. I was thinking it might be the porting. When I took it to the local machine shop he said it had more of a drag porting rather then "dune" porting but he said it would run shitty the whole time if that was the case: ill try and get a pic of the porting when I get home

Recently installed a 4 mil hotrod crank with spacer plate and wisco pistons . Had a dune port prior to 4 mill , also have T-5 pipes, new spark plug wire and caps, and new stator. Bike gets on the power band for about two minutes then loses power. I've tried every kind of main jet ,pilot jet, needle clip, and air screw and get same results. Can't figure out the problem