batman wrote on 02/16/19 at 18:52:08:So a velocity stack and a drag pipe with a baffle at the end , Jetting doesn't get much harder. Even if you do a good job ,the bike may only run well at a narrow power band near Wide open throttle. The jets you use will need to be more like 55 pilot -155 /157.5/160 main jet and 2- #4 steel washers for the needle jet (spacer mod).Don't expect mileage to be more than about low 40's.
If the velocity stack has been on the bike 3 years ,I'd be doing a compression test/and /or pressure test, to check piston .rings ,cylinder walls and valve guides . A low reading would indicate wear/damage caused be poor air filtration , as these stacks are meant for racing only, bikes that are rebuilt often, not street bikes which log thousands of miles.
The velocity stack was supposed to be temporary but getting this guy to buy parts is like pulling teeth
Luckily fate has left him in a situation where I now have full control of the part ordering/installing
The first order of business was getting a pod filter, it's on the way in the mail
I replaced his stock petcock with an aftermarket one from ebay, the pill shaped o ring sealed up just fine and it's now gravity fed, 3 position, on off and reserve
I also installed a small inline fuel filter
I'll be ordering some mandrel bent pieces as well as a small baffle soon to make him a new exhaust
I took off the exhaust pipe and cranked the engine a few times to verify the valves where all moving, looked into the carb inlet and they where all functioning as they should
The problem kept pointing at the carb slide, i verified there was no leak from the top diaphragm cover by lightly blowing into the overflow tube while sealing the other outlet holes with my fingers, it went up like i expected
I started researching jet sizes and stumbled across a picture of the slide needle with the spring under it.......wait.......spring under it.......
I took the top cover off, pulled out the slide and took the needle plate out of the slide body, there it was, the spring, sitting ON TOP of the needle....
I had taken the needle out a few weeks ago and thought nothing of it, i guess my buddy must have put it on top of the needle the first time he cleaned the carbs a few months back
Thinking about it, the needle would have excessive pressure down on to the main jet, which would starve it i assume
Only time will tell, I'll be picking up a few gallons of gas today to try it out and hopefully get him back on the road