Has anyone used a Mikuni Fuel Pump on a late fifties big twin?

[outboardnut]

I have done a fuel pump conversion a few times using what I call the house shape type OMC fuel pump. But I would like to find a smaller pump if possible. I hear the OMC square fuel pump are not that good. In Max Wawrzyniak book “Cheap Outboards” He says not to use the Mikuni on big twins. According to this web site- the fuel consumption on a Mikuni is 14 liters per hour (3.69841 gallons). Does anyone know the fuel consumption on a per say 1955 25 hp Johnson?
Thoughts on alternative fuel pumps?
https://www.summitracing.com/parts/mku-df44-227

[crosbyman]

my old  merc 50 full tilt pulling skiers  was  about 5g/h   so a 25hp   can’t be much more than 2.5- 3.0 /H

mikuni should work      worked great on a 10hp.

you can always look up  a mikuni or similar  with a higher l/h spec

 

this one looks sturdy…. ask seller for flow rate info

Dromedary 2520227 3085275 Fuel Pump Fits for Polaris Magun Outlaw Predator Sportsman 325 330 400 425 450 1996-2011, Electric Fuel Pumps – Amazon Canada

 

 

 

 

 

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• This reply was modified 3 years, 1 month ago by crosbyman.
• This reply was modified 3 years, 1 month ago by crosbyman.

[Bob Wight]

Here’s a Mikuni with a 31 l/hr flow rate.   I was going to use this one on a ’56 Johnson 30hp but they were out of stock at that particular time.

http://www.nichecycle.com/ncs/categories/fuel-air/fuel-pumps/df52-133-d-fuel-pump-by-mikuni.html

 

Here’s the one I ended up using – it’s for a 17 to 25hp lawn tractor and it seemed to work fine.

https://www.amazon.com/dp/B07MQ44LDX/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B07MQ44LDX&pd_rd_w=geutk&pf_rd_p=8a8f3917-7900-4ce8-ad90-adf0d53c0985&pd_rd_wg=NxFDt&pf_rd_r=314ZSTXDVYPPHQBM6TZ3&pd_rd_r=4343a9cf-77e3-11e9-8772-d5659328fe72

I’d probably use the Mikuni if I were doing it again – probably a better quality pump.

 

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

• This reply was modified 3 years, 1 month ago by Bob Wight.

[outboardnut]

bobw- does the Mikuni 31 Liters DF52-133-D pump have to be oriented in a particular direction?

[crosbyman]

bobw…. that model with the gold mesh was recently a topic of discussion because one user  had issues with the pulse line pushing  some fuel oil mix  to the pump and  it ended up oozing out the gold mesh .

apparently this type was more for  4 stroke type engines   like  lawn tractors   etc… installed  way above the pulse source  source.

just mentionning it in case it does create issues.    the “non mesh” types may be more suited to our  2 stroke outboards

 

 

 

 

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[Bob Wight]

outboardnut wrote:

bobw- does the Mikuni 31 Liters DF52-133-D pump have to be oriented in a particular direction?

Not that I’m aware.  I think it would work in most any orientation, but I would probably set it up so all the inlet/outlet lines were pointed downward.   I think the rectangular Mikuni pump at 14 l/hr would probably work fine as well.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[Bob Wight]

crosbyman wrote:

bobw…. that model with the gold mesh was recently a topic of discussion because one user  had issues with the pulse line pushing  some fuel oil mix  to the pump and  it ended up oozing out the gold mesh .

apparently this type was more for  4 stroke type engines   like  lawn tractors   etc… installed  way above the pulse source  source.

just mentionning it in case it does create issues.    the “non mesh” types may be more suited to our  2 stroke outboards

 

 

 

 

Yes, now that you mention it, I do recall reading that thread.  The round pump was made as a replacement for the Briggs & Stratton lawn tractor pump and it seemed to work fine when I installed it but I do think the Mikuni pumps are better quality.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[drifter]

I had the issue of the Briggs pump oozing fuel out of the gold mesh, only when using the conversion of plugging one side of the valves behind the intake plate, on the smaller OMC motors of the 50’s.

When using the pump on the motors with a modified removable bypass intake plate (like the 7.5 hp models), the pump works great!

[crosbyman]

good to know !  i have modified 5.5hp (58-59)  waiting to go for  a swim….i’ll change the pump for a “no mesh” type  just in case .

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[geary]

Outboardnut,    You might also look at some of the Scott Atwater / McCulloch fuel pumps ?  They had several sizes all the way up to the 60 & 75hp three cylinder engines !  Well made pumps with metal check valves !  The housings are cast aluminum and easy to service !

Geary

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