BF40 Low speed jets

[Navigator]

Hi all,<br />I have a '00 BF40, tiller thats recents begun to sputter and kick at idle. At higher RPM its pretty smooth, but when I back it down to idle, it jumps around and occasionally stalls out. Running on the muffs, it's smoooth at idle, but when in the water, it gets rough. When I give it a little gas, about 1000rpm worth, it smooths out once again.<br /><br />I'm thinking I may have gunk in one of the low speed carb jets. Would running a can of gumout in the tank be a wise first step. I'm trying not to pull the carbs and do a rebuild right now. (Maybe in a few months when things quiet down)<br /><br />Also, if the carbs were out of sync, would this give the same symptoms? Though I've not really documented this, it appears to happen only after the engine is warm. When it first starts it seems to idle fine. But then again, I usually only idle all of 20 feet till I'm away from the dock and I can open her up. I've done all of the obvious, fresh gas, tank is vented fine, bulb is hard.<br /><br />Any suggestions?<br />Thanks,<br />Nav

 

[45_red]

Re: BF40 Low speed jets

What do the spark plugs look like?

 

[Navigator]

Re: BF40 Low speed jets

45_red,<br />I pulled the plugs and they look "normal". No fouling and all cylinders look the same.<br /><br />Nav

 

[coldwaterboater]

Re: BF40 Low speed jets

I have a 03 BF 50 with identical symptons, from the first time I fired it up. I've been waiting for it to "break in" for a year but no change. Dealer went through it, plugs, valves, tore apart the carbs looking for plugged idle jets (they were sparkly clean), checked ignition. Gave it back with a big bill, runs exactly the same at idle, like a badly tuned two stroke. I think one cylinder misses. As far as I can tell, listening to other Honda's, some run smotthly and some don't. Maybe it was the day it was built. If you figure it out I would sure like to know.

 

[kellaig]

Re: BF40 Low speed jets

Hi coldwater & Navigator,<br /><br />i too have had identical problems with a 2002 40. It is still ongoing, try running this motor without a thermostat and see if there is an immediate improvement.<br /><br />If there is, it is heat related problem and Honda australia are going to put in a new computer.<br /><br />I will let you know how I go.<br /><br />regards

 

[Navigator]

Re: BF40 Low speed jets

Well, I've ruled out a heat problem. 3 times now I've gone out first thing in the morning and fired it up. Even when cold, its sputtering and sounds like its missing on a cylinder. For the last 4 years it's run silky smooth.<br /> I'm betting there's something in the carbs.<br /><br />Nav

 

[hondon]

Re: BF40 Low speed jets

While you are out there idleing around, with a pair of very well insulated pliers , start pulling and then replaceing spark plug boots .As you pull them off you should notice a RPM drop and that drop should be somewhat even between cylinders.I would hope that dealer did a valve adjustment and at least a compression test ,if not a leakdown, with that session of service .You may well have carb problems and these triples can be a little tricky.You need to make sure the people you are dealing with understand the basics and have the proper schooling.