Honda 40hp vs 50hp

[Navigator]

I am interested in possibly converting my Honda BF40a to a BF50. (Year 2000, Long Shaft, Tiller, No PTT) Is there a reference chart somewhere that I can look at to identify the parts that are different? Is it simply a carb swap and a higher rev limiter? Anyone have access to the microfiche on the 2 engines?<br /><br /><br />Thanks

 

[slufff]

Re: Honda 40hp vs 50hp

I have a 50 with a bad head and the parts man at my dealer checked and the 40 head (I purchased a used one)and the head and valve assembly have the same part numbers in each. He thought the cam was different, as i am going to change them out I also would like any knowlege base input that is available. Thanks in advance

 

[Navigator]

Re: Honda 40hp vs 50hp

sluff,<br />I couldn't really find anyone will or able to tell me the difference in the 40 and 50 hp. They share the same block so I believe it probably just a carb piece since the 50 gets it HP at a higher WOT.<br /><br />The best way is to get the microfische on the engine on Ebay for about 10 bucks and compare part numbers. Its on my to-do list, but I haven't had a lot of time lately since I have a 6 month old youngster <br /><br />If you find out anything, let me know. My goal is to convert my 40 to a 50 and also convert it from a Tiller to remote. (Honda doesn't make a conversion kit so I have to find the parts separately, go figure! )<br /><br />Thanks,<br />Nav

 

[Dman]

Re: Honda 40hp vs 50hp

While this article is a 9.9 to a 15, it might give you some reasons not to do it. Kinda interesting reading.<br /> http://www.smalloutboards.com/modifications.htm <br /><br />D

 

[Skinnywater]

Re: Honda 40hp vs 50hp

My Honda Marine factory manuel is clear that the intake valves are larger, so the head has larger seats. The camshaft is also different as well as the carb jetting and setup.

 

[Navigator]

Re: Honda 40hp vs 50hp

Skinnywater,<br />Thanks for the info. I was only considering the idea anyways, but if the valves are larger, its not worth the effort. I really dont want to mess with the 40 because it still purrs so nicely . I still however, need to change it from a tiller to a remote. ( I dont have the funds now for a new one so I want to convert the one I have already if possible.)<br /><br />Thanks for the info!!!<br /><br />Nav

 

[slufff]

Re: Honda 40hp vs 50hp

I just had head from both 40 & 50 at machine shop and the valves apear to be the same but the 40 uses a cam with a R1 part number and the 50 has a R3 part number. I will post any other info I gather on my quest to solve the water in oil problem I have by swapping a 40 head with a 50. I needed a valve from the bad 50 for the 40 as the 40 came off a blown block and the valve stem was bent when we removed it to grind it. Will post further adventures as they occur. SLUFF

 

[slufff]

Re: Honda 40hp vs 50hp

skinneywater is absolutly correct that the valves are a different size in the 40 and 50 so if anyons needs a 40 head email me at sluff@ yahoo.com

 

[Skinnywater]

Re: Honda 40hp vs 50hp

Yeah, the 50 has a 33mm diameter intake while the 40 has a 32mm.<br />I'm impressed that Honda went to so much trouble to give you 10 extra HP. The camshaft has a higher and longer duration.<br />BTW, you can identify either head at a glance. The BF50 head has a white paint mark from the factory.<br /><br />Another thing I was very impressed with.....When I did my first valve adjustment and saw those hand polished forged rocker arms. This was an extra step that Honda didn't need to do.