It's a side mount, and I can't get any range out of the throttle. With the cables disconnected, it works fine, full range, with throttle cable attached- works fine. with the shift cable attached, it engages forward and reverse, but way before it should so it never gets to the second stage where the throttle cable only engages.
It sounds like you either have the shift cable improperly adjusted or a shift cable that is out of spec with too much slack where the slack cannot be taken up to the amount needed.
I know on the V4 crossflow engines, you are supposed to remove the shift cable, shift the gearcase fully forward and verify it indeed is in forward by moving the propeller shaft clockwise.
Then install the shift cable with it in full forward position and secure it fully. Then check for slack. incrementally remove slack until it has enough pre-load to not move. If you run out of adjustment and it still has slack, your shift cable is bad and must be replaced.
Return throttle to neutral.
Install throttle cable and verify proper pre-load is present to avoid RPM variation.
Pull spark plugs so you can check reverse. Very difficult to do unless you do.
Spin prop, then shift into forward and verify fully shifted in gear before throttle cable moves. Verify throttle range and return to neutral.
Turn flywheel in the correct orientation about 1/2 a rotation, then try to shift into reverse. Don't force it. If it won't, turn the prop a bit and retry.
Repeat process above for shifting into reverse until it does. Verify throttle has not moved. Then check throttle range and return to neutral.
Thank you!