350X pulling problems, help inquired

[lisnup65]

I have a 350X that pulls extremely bad. The frame has seen some of the standard welding on the lower left frame due to stress crack, but it was repaired before breakage. Some basic measurements show that the frame appears to be straight.

I put a swingarm({A} 4" extended DuraBlue axle, new carrier bearing) on and took the machine out for a ride. It had a serious pull to left. During a wheelie the pull to the left is duplicated which tells me that its all in the rear end. The tire pressure was checked and both tires have the same 3lbs of air pressure.
For testing purposes I then changed the swingarm to the extra one that I have.({B} factory axle, factory carrier with new bearings). The machine now pulls extremely hard to the right. On a paved surface you literally have to fight to keep it straight. Both ways the pull seems about the same. During a little 10' wheelie, my direction can change as much as 40 degree's.

What am I missing here as I am pretty sure the frame is not the culprit as the machine pulls opposite ways with different swingarms. Any input or guideance is appreciated.


Thank you in advance.
Dave

[hrc200x]

Maybe the swing arms are bent? How are the swing arm bearings and axle bearings in each swing arm? The most common problem would probably be tire pressure. Maybe try reversing the tires. I also found this out about tire pressure gauges. If you hold it strait down and check the air, the gravity helps pull the gauge with numbers out further than if you were to hold the gauge strait up. At least thats what happened when I use my gauge.

[Joel85350X]

I would try switching the tires first, it sounds like you have a different sized tire on each side.

[lisnup65]

Maybe the swing arms are bent? How are the swing arm bearings and axle bearings in each swing arm? The most common problem would probably be tire pressure. Maybe try reversing the tires. I also found this out about tire pressure gauges. If you hold it strait down and check the air, the gravity helps pull the gauge with numbers out further than if you were to hold the gauge strait up. At least thats what happened when I use my gauge.

The bearings are all new. I thought tires also, so Igrabbed my trusty old spider tracs and mounted them up also. Same results occurred. The swingarm that caused the machine to pull left was on my other 350X and it rode straight so I must assume that the swingarm is relatively straight.

I am wondering if the swingarm pivot bolt mounts in the frame could be oversized from a previous owner. 3mm off at the mount would transform into a lot more at the end of the swingarm. Does this sound logical?

Maybe I need to make some centering washers.
Hmmmm??!!

[MR ATC]

with such low air pressure its not an accurate way to determine and have them be perfect with each other. if switching tires l to r or r to l had no effects and if one swingarm pulled to the left and another pulled to the right then the frame/swingarms probably are not bent. it would guess that you are on the right track with the swingarm pivot mount area this is a common area to wear out on 350X'3 and i reinforce this area by welding 1/8 washers to solve the problem