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Discussion Starter · #1 · (Edited)
I just recently bought two 05 400's (both relativity low hours), one had a 45 pilot put in (not me, former owner had dealer do it) while the other one is stock.

Both start right up but continue to cough / stall for a good 10 minutes if not longer in 50 degree weather.

Air filters are clean.

If I feather the throttle above normal idle they will keep running but this is bordering on ridiculous how long these take to warm up.

I see the choke mod on here calls for a 42 so not sure why dealer installed a 45 pilot but 45 seems to make no difference compared to the stocker.

Maybe 1st thing I should do is check the valve adjustment and then proceed back to the carbs if they are not off at all ?

All the Hondas I own through the years were always cold blooded but these 400's win the cold blooded award for sure!

The warm up time length (In no rush) really does not bother me though and my main goal is to get them to stay running on their own with out having to keep feathering the throttle constantly.

I did not try warming up with out airbox lid on but would suspect that would make the problem even worse since they are lean to begin with from factory, I will try that today though...
 

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Check the Valves yes.
Mine has a 42 pilot in it and its better than stock but not great in the cold weather we get. Is the pilot jet at all dirty? If it is it could be causeing the problem. It dos not take much to clog it.
 

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Discussion Starter · #3 · (Edited)
Check the Valves yes.
Mine has a 42 pilot in it and its better than stock but not great in the cold weather we get. Is the pilot jet at all dirty? If it is it could be causeing the problem. It dos not take much to clog it.
Thanks Dave....

44 degrees right now

I just went out and tested the 45 jetted one with airbox lid off, huge difference it made, it still is not perfect but so so much better then it was which means of course it is too rich with lid on.

This 45 may work out well though, and maybe even better then the 42 in mod because the colder it gets the richer you need it so when its 20 or 30 out I simply put lid on to richen it up some.

I wont know till spring/summer now if the 45 will be too rich for those temps though.

I will eventually update on here if my assumption is correct on the colder/hotter weather.

I will check the pilot but the former owner just had the carb gone over when the shop put the #45 pilot in so it really should not be dirty at all .

Also ...Will still check the valves among everything else to clean and check, both of them in decent shape but not my kind of shape, I can tell both were never maintained very well and would have been pretty beat if the same owners had owned them a few more years, neither one knew how to work on them at all, so its rip apart time on both, at least no big deal if I forget how something is routed or forget where a bolt goes having two of them...:D (am selling the one though once done with maintenence on it)

I hope this helps others when they do a search.
 
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