teamroper 4 Posted December 30, 2022 What can cause my machine to vibrate on first and second gear acceleration? I was thinking a universal joint but now I am thinking a motor mount. Anyone have an idea? Share this post Link to post Share on other sites
Fishfiles 20,147 Posted December 30, 2022 What year and model do you have ?? ---- I am going to guess you have a trx450 from your avatar , maybe a ES cause I can't see a foot shifter in the bad pic ??? And from the decals I would think 2004 I like to jack and block all 4 wheels in the air and run it , sometimes it helps to isolate a noise or vibration ---- check the easy things first --- did you check the oil in your front and rear differentials and change the engine oil and filter lately --- maybe adjust the valves 1 Share this post Link to post Share on other sites
teamroper 4 Posted December 30, 2022 It is a 450s Forman. 2004 Good ideas. I will try them. Yes, the oils are current. The valves were adjusted to specs within the last year. It is a foot shifter. The vibration is only in the low gears and higher rpm. If I start out slow no problem. So for the time being I have a work-around. Thanks for your suggestions. Share this post Link to post Share on other sites
Fishfiles 20,147 Posted December 31, 2022 It could be so many things , maybe a bearing on the rear axle ----- If the engine ever ingested water , it could have bent a rod , it will still run but it could vibrate ---- also if the connecting rod journal is worn the piston will slap around in the bore Share this post Link to post Share on other sites
teamroper 4 Posted December 31, 2022 Thanks for the input. Share this post Link to post Share on other sites
toodeep 1,759 Posted January 2, 2023 Check for any play at the swingarm. I've seen many of them the frame will crack out, spreading it enough, to give the swingarm just a little play under pressure (at first) and give weird vibrations. Share this post Link to post Share on other sites