400 to 440 jetting w/450r carb

[JTrider]

I recently went to a 440 bore and I'm in the process of breaking it in. My question is I have a 450r carb w/ a 175 main and 45 pilot that I ran on the 400 and it seems to run great on the 440 just like it did on the stock bore? I was thinking I would need to increase the main by moving up to the 440? I guess it doesn't matter? Should I experiment with larger mains?


I openned if up for the first time yesterday and it ran great. No hesitation.

[honda400ex2003]

most likely it will be bigger than that. around a 185 or so would be my guess. i havent really done too much with the 440 jetting though. always better to break in a bit on the rich side instead of lean though. steve

[honda400ex2003]

how is the plug looking also? i have seen machines that do get more efficient when they go a bit bigger like mine did when i used the 450 carb. I run down to a 162 in mine when it is warmer outside. steve

[JTrider]

I haven't checked the plug yet but that will be the next thing I do. I just thought it weird that it wasn't asking for more fuel. I will update as soon as possible.

Thanks again.

[dalejiw25]

"I openned if up for the first time yesterday and it ran great. No hesitation."

Famous last words. Like the old adage - "They run best right before they blow."(Which I can only assume Refers to a lean condition). I would do as Steve suggests and check the plug. Just because it's running great doesn't necessarily mean it's not running lean. Never hurts to go bigger on the jets till you know for sure.

[JTrider]

Bad picture but looks like its on the lean side. Currently have a 175 main. What next? 182 or 185?

[JTrider]

another pic of plug

[honda400ex2003]

i think it looks pretty good... maybe a 178 or 180 would be good also. you shouldnt have to go to a 185. it would be too rich then. just to be on the safe side i think a 180 would be a good idea to try and see how it runs with that. steve

[JOHNDOE83]

heres some info for ya.

http://www.exriders.com/vbb/showthread.php?s=&threadid=441780&highlight=reading

[400exshop]

it looks like you need to go up on you'r jets.

[honda400ex2003]

http://www.jetsrus.com/

http://www.jetsrus.com/FAQ_spark_plugs.htm

the FAQ section on jets r us is a great place to find out about plugs and jetting. that will give you the easiest most effective method of determining exactly how your plug looks against the others. your pictures are hard to tell. I go for more of a golden brown or cardboard brown color with my plugs which is sort of where yours is at by the looks of the pics. steve