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need help bf 40hp wont start cold

J

jtrow

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i have a 2006 bf40 hp honda that will not start when cold, have rebuilt carbs still no change. once it does start it will recrank and start fine all day long, let boat sit over night and i have to crank crank crank to get it to restart next day any help would be great. i have also replaced the bay-starter solinold valve.
 
jtrow said:
i have a 2006 bf40 hp honda that will not start when cold, have rebuilt carbs still no change. once it does start it will recrank and start fine all day long, let boat sit over night and i have to crank crank crank to get it to restart next day any help would be great. i have also replaced the bay-starter solinold valve.[/QU
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Yeah, the by starter you replaced IS the choke. A couple of things come to mind with a problem like this. One is; does the engine have good compression? If the compression is generally low on all cylinders, it could cause the fuel not to vaporize easily on cold starts but then, after warm up, the engine might start more easily.

The other is intake leaks. If you have poorly sealed intake connections ie: carb mount gaskets, intake manifold gasket, or an unintended hole somewhere, you will pull in excess air volume and lean out the mix. I don't imagine it would be a hole since the condition improves after warm up. A warped or badly gasketed mating surface may leak badly when cold but "self seal" when the components get hot.

Obviously, you could do a compression test to eliminate the first possibility. There are several ways to find a leaking intake. Usually, even though they do seal up a bit when hot, they will still leak some and you can find the leaks by spraying carb cleaner at suspected areas while the engine is idling. If the engine speed up while spritzing a given area, that is where it is leaking. This can be a bit hazardous to do so use caution and keep a fire extinguisher close by if you decide it's something you want to try.

Sometimes though, problems like this can be the result of something much simpler. Like contaminated or "bad" gas. Make sure that is not the case before starting to dig too deep.

Good luck.
 
While you are checking all the things that Jimmy suggested, check a couple of other things.

First...check the jet size number on the outside of the top carb's fuel bowl, just above the drain. On the flat spot there should be a number engraved....either 80 or 75. If it is 80, you should get a new bowl that says 75.

Also, check your new bystarter... the numbers printed on the top will begin with either an CL or an HG. The CL is the older bystarter. The HG will match up with the newer (#75 bowl).

Part # for the new Float Bowl is 16130-ZW4-F01. The part # for the new bystarter is 16023-ZV7-H01.

If you have all the most current pieces....

You may have to recheck all the passages in the float bowl of the top carburetor.

Make sure you are using the proper spark plugs...NGK DR7EA.

Make sure the idle mixture screws are set properly. For that model and year, should be 1 5/8 turns out.

You should also vacuum balance the carburetors.

You did not say if this motor is new to you, so you may not know, to start the engine, after squeezing fuel bulb, you just should turn the key to start...not advancing the throttle.

Mike
 
so i checked compression and i have 125 to 130 on all 3 clys at wide open throtle in my world on cars these are good #####???????? right
 
Honda typically lists a compression pressure for their engines for when they are NEW and that is the baseline you would use for determining if you have low, normal or high compression readings. I don't have that pressure spec on me but I use a formula to get close to what it should be when I'm working on something that I don't have the specs for. The math says that your engine should develop about 155 psi. If that's the case, then your readings should mean that the engine, while not perfect, is sound. The important thing is that they are all well within the 15% rule as compared to each other. So, it does not appear that too low compression is causing your hard starts.

Did you check all the stuff hondadude put out there for you? Ignore his advice at your own peril.
 
The book says 199 @ 500 rpm with a maximum 43 lbs variance.

Just recently had twin 40's in with 1200 hours and the compression was 215. After a carb job, they ran great.

It is possible that your gauge is reading low or the motor was cranking slow. Make sure you have all the spark plugs out when you crank it.

Mike
 
going to remove carbs and have found a someone to dip them in a ultrsoinc mechine im thinking i did not get them clean buy just taking apart and blowing out with carb cleaner and blowing air throw passages.
 
If you are taking them off, be sure to check the bowl jet size as I discussed earlier. If the engine is running good once started, concentrate on the top carburetor. That is the one that does the work for starting.

Blowing carb cleaner and air through the passages works fine...as long as you check for flow through all the passages when you are finished. I generally use something like brake clean.

Honda does not recommend dipping since it harms the outside of the carbs. They recommend using an ultrasonic cleaner....which has basically a solution of water and a cleaning solution (that is not much different than Dawn liquid detergent).

Mike
 
ok so im back to working on carbs now and checked the carb bowls and my top carb has a#80 on it and i have a cl cg6bystarter. so do i only repace the top carb bowl float or do i repace all 3 on carbs, the 2 lower carbs do not have # on them.
 
If I am reading correctly, you have the CL bystarter, then that is ok. You should change your bowl a
16023-ZV7-H01 Float Chamber Set. That chamber has a slightly bigger jet for starting purposes.

Once you change it, you should check/adjust the vacuum balance of the carbs.

Mike
 
Check that the "breather tube" (91401-ZW4-H00) is correctly inserted into the muffler cover. There s/b a mark on the tube to indicate depth of insertion. I accidentally yanked mine out a couple of inches and starting was very difficult.
 
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