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 19,667 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 19,667 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 1,732 Posted January 2 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
