shift kit grabing chain

I would guess it has something to do with the chainline.With that many gears you are really changing the chainline.In 4th is it centered with the front sprocket?If not contact Jim at SBP he will help you.

Sounds to me like your derrailer needs adjusting.

Ride around with engine off and shift through the gears a lot of times while peddling hard.
If it skips out of gear, or to a gear that it's not supposed to be in you need to re- index your shifter/derrailer

Your cable is probably stretched over time and either need adjusting or replacing.

Don't flip out... Don't blame the kit. It's usually something you need to be aware of doing to keep it adjusted, aligned or tweaked to make it just right.

Go here and review how to adjust that derrailer..It will help
Derailer Adjustment

I've had a shift kit for 2 1/2 years and have overcome every conceivable problem there is..It's a great add on if you know and understand how to keep it running right.

TiM

if the chain from the jack shaft to the chain ring is loose it can cause the two chains to bind up and miss shift.

Front jackshaft to chain ring loose usually chucks pedal chain off front sprocket when in higher gears.

i would bet it is the cable index needs to be adjusted.

meaning that the shifter on the handle might be set @ first gear but your derailer is not quite laying the chain in first gear.
it may be in between 1st & 2nd.
cables stretch so it tends to move.

have the bike so the rear tire is in the air.
use your hand to crank the peddles while looking to see the difference between what gear it should be in & where the chain is trying to track.
usually there is an adjustment screw on the shifter (also known as the indexer)
you may or may not have to tighten the cable @ the derailer.
try hand peddling through all the gears even though if the first & last gear are good the rest should be fine.
unless you are using a using different indexers to derailers or cassette. (the cassette is your gears on the rear tire)

after an adjustment may lead to another adjustment when you are riding it that day.