I am In agreement with syko on the majority of his post dont like the frankinstein on intake though but that could cure it
there is a linkage on the reverse lever you can adjust if its not too worn out you also might wnat to check the enrichener
(choke) at the carb it could be stuck or if the rubber boot over the 14 mm nut attached to carb(on choke cable) is cracked it could be letting in air .
Pull the carb clean it especially idle jet ,check intake for cracks .If its blowing alot of dark smoke its fuel, fuel air adj and idle drop but if you dont know what youre doing itll never run right I would just adj.fuel air screw 2 1/2 turns out and let it ride.
The tinberwolf is a fun tourqy quad I ride wheelies on customers units at work all the time also be careful when you change the oil filter spray pb blast all over the allen bolts especially the upper left long bolt it has a tendancy to break
and you dont want to go there if it does ther is 2 cases outer and inner the bolt usually breaks even with the inner.
83 YTM 200,84 200X,,85 350X basket case,86 350X parts trike,86 350Xroller needs top end, 86 250SX,