Honda ATV Forum banner
1 - 11 of 11 Posts

· Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Cant locate a random knocking from under 2010 420 rancher foot shift. its a hard knock that you can feel and hear, like i said random as hell, doesn't matter what gear I'm in just every min or so decides it wants to knock, as to why i can't pinpoint it. anyone else have this problem. I'm just getting back into the atv world to play in the mud and leaving the mx track for good but of course start off with problems smh
 

· Registered
Joined
·
8,309 Posts
first off,
welcome to the site,
and as for your issue, how about some more info on the atv
how many miles/hours on it
any motor work been done to it
was it ever sunk?
are you original owner or just buy it??


have you done a compression test to it!

when does it make this noise, just idling or do you have to me on the throttle
does it doing sitting still, or does bike have to be in gear and moving?
and pleased try and explain the KNOCK sound better
is it a fuel knock like a timing issue, running low octane fuel,(think fuel pinging ) or like metal on metal sounding??

better info you give us, better we can help you
if you can add a vid with sound, that can help too(like post on youtube and add a link here)
 

· Premium Member
Joined
·
5,072 Posts
Usually a hard knock that you can feel would be swing arm brearings, you tend to feel it through your feet and butt!
 
  • Like
Reactions: retro

· Registered
Joined
·
4 Posts
Discussion Starter · #4 ·
I am the second owner, just bought, not sure of mi./hrs., have not done a compression test yet hoping its just mechanical, no motor work that i know of or hasn't been sunk its snorkeled with 2" lift & 27" tires, however i did get a little water in rear diff. last weekend, drained and replaced fluids. Last weekend was the first time i rode this bike real hard went through some deep water but did not sink it wanted to see what she would do, air box was tight and dry. Fires up and idles fine, bike has to be moving i can feel it through my feet and butt however i would have thought a swing arm bering would be knocking all the time, but will definitely take a look. if i get a chance i will see if i can take a video of the knocking. Not fuel related definitely metal on metal. Bearing would make sense as hard as i was on her the last ride hope thats it.
 

· Premium Member
Joined
·
38,589 Posts
chances are, your connecting rod is bad. with a snorkel on it ?, this tells me it's been sunk at one time or another, maybe not by you ?, but been in deep water/mud..who knows ???. but i'd bet the motor needs to be tore down and gone through.
 
  • Like
Reactions: _Wilson_ and mrbb

· Premium Member
Joined
·
5,072 Posts
I would start with the easiest possibilities first, count the engine out completely for now. A random knock isn’t a typical symptom of engine failure, an engine knock would usually be constant getting progressively worse over time.
I’m not saying it can’t be but I’m saying it’s unlikely.

I’d be looking at lower arm ball joints, swing arm bearings and such before I started digging into an engine. Or of course it could be the rear drive shaft UJ on its way out, be worthwhile checking that, when they go it takes half the engine case with it!
 

· Premium Member
Joined
·
5,072 Posts
Just realised, have you got a stretched swingarm? Lifting a Rancher 420 without the swingarm stretch does blow UJ’s, it’s a common issue.

Some will say it doesn’t cause an issue but mud riding a 420 without the stretch, with a lift and with big tyres WILL eat UJ’s.

If you don’t have a stretch Don Oglesby makes them, you’ll find him on FB, he’ll also back up my info given above.

Hope that helps.
 
  • Like
Reactions: retro
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top