450s Backfire

[Mrdaviemac 6]

Ok. Topic covered many times before, but does anyone have a solution for throttle off backfire on 2004 450s? Dynojet kit fitted, K and N air filter and brand new genuine carb fitted, recent new genuine muffler. Seems to be running pretty good, plug colour good. Carb adjusted as per Dynojet instructions and tweeked until set as per workshop manual. Any solutions?

[shadetree 5,869]

On 4/14/2024 at 7:20 AM, Mrdaviemac said:

Ok. Topic covered many times before, but does anyone have a solution for throttle off backfire on 2004 450s? Dynojet kit fitted, K and N air filter and brand new genuine carb fitted, recent new genuine muffler. Seems to be running pretty good, plug colour good. Carb adjusted as per Dynojet instructions and tweeked until set as per workshop manual. Any solutions?

solution ?..yeah...but it back to all stock ?..lol. i don't mess with all that fancy crap, all it does is give you trouble !, ( as you are finding out ). there is not one thing that is going to make a utility atv go faster, not even all those after market parts you put on it. other than this info ?, i have no idea ?, as said..i do not waste my time with after market gimics.

[Mrdaviemac 6]

shadetree

Problem solved! Went up a size in the main jet and it has really given the thing a kick in the pants! Plug nice and brown now, runs much better. Pulls all the way to the top. It's not about making it super fast, just livening it up a little, which it has done. Not sure about the USA/Canada spec 450's but the UK ones are notorious for popping back. So much so that gamekeepers and hunters avoid them! Maybe it's a bigger issue with the UK Hondas. But all good now.

Edited April 17 by Mrdaviemac

[shadetree 5,869]

3 hours ago, Mrdaviemac said:

shadetree

Problem solved! Went up a size in the main jet and it has really given the thing a kick in the pants! Plug nice and brown now, runs much better. Pulls all the way to the top. It's not about making it super fast, just livening it up a little, which it has done. Not sure about the USA/Canada spec 450's but the UK ones are notorious for popping back. So much so that gamekeepers and hunters avoid them! Maybe it's a bigger issue with the UK Hondas. But all good now.

glad ya got it solved !. most atv's here in tthe states are made lean from the factory, we can thank the epa for this..lol.

[_Wilson_™ 6,567]

Ya...^^^^ Perfect place for that gas nozzle ? Right up spotted al boars !!! 

[jeepwm69 7,611]

10 hours ago, Mrdaviemac said:

shadetree

Problem solved! Went up a size in the main jet and it has really given the thing a kick in the pants! Plug nice and brown now, runs much better. Pulls all the way to the top. It's not about making it super fast, just livening it up a little, which it has done. Not sure about the USA/Canada spec 450's but the UK ones are notorious for popping back. So much so that gamekeepers and hunters avoid them! Maybe it's a bigger issue with the UK Hondas. But all good now.

 

Not what you want to hear, but those K&N airfilters are horrible for off road use.  They allow a lot of very fine dust into your intake.

 

I ran a K&N on a Jeep for a while.   Noticed fine dust on the carb throat.   They don't filter well off road.  They are made for the race track, not the backwoods.

 

OEM or UNI only on my off road toys.

[Mrdaviemac 6]

K and N filters are good. It's down to proper cleaning and re-oiling the cotton filter. It's the oil that traps the dust, not the cotton. I race off road in Land Rover based vehicles, petrol V8 engines, and never had an issue with poor filtering. Also run K and N in my truck. And besides that, there is very little issue with dust here in Scotland! Rains every day! 🤣