Extract more hp from Merc 30hp 2cyl 2 stroke

[wolfgangb]

Yes, this is an odd one: we have a local juniors class in which predominantly recent 30 hp Merc 2 strokes (2 cylinders) are run.
Hp/rpm differences between competitors appear to be up to 15%. My buddy`s children are running in that class and i would like to help them improve their competitiveness.
Any advice appreciated, before we spend big bucks leading ourselves down the garden path.
Thanks guys,
Wolfgang (South Africa)

[FMP]

I bit off topic but a 3 cylinder in that 25-30hp range was made for a few years. Force by Merc, called an international model the last couple years. Maybe more potential?

[phillnjack]

no such thing as force by mercury. it was just that mercury bought out the force brand... once all stocks were used up and the factory shut down it
stopped being made.
force were low grade motors made on the cheap, they were good for the money and thats about it.

the mercury 30hp will out perform the force every day of the week, it was made by tohatsu and is a brilliant motor that can be modified to give some very high performance.
But I would think if you have a 30hp category then you will be limited to the mods your allowed, if the class is by the engine capacity then you can modify it
and get a lot of power from the motor.
check out the gt30 race class and speeds.

just noticed your in south Africa, this makes it even better as you have plenty of spares for the tohatsu/mercury /mainer 30hp motors.
a force in those parts would be a terrible idea, no parts back up at all....
all the Asian market motors and mods are available to you, depends on how far you8 want to go and what the class allows...

[FMP]

you again


92 lbs triple 6000+rpm range, merc lower

[Capt.Insane-o]

you again


92 lbs triple 6000+rpm range, merc lower

The Force actually ran pretty good and the 18 chopper slides right on the shaft.

The big actual Merc 30 is a heavy poor idling turd. It has a single carb and shares all the internals with the 40-60 triples so you could cut up a triple intake to make it a two carb.

If you have the Tohatsury it's a different animal.

[FMP]

I noticed that tohatsaboo with yet another brand name on it, Korean or Malaysian i think. Who made who, ain't nobody told you.

[phillnjack]

its a force.. force is just the company that mercury owned for a few years till they dropped it in 1996...due to lack of interest in cheapo motors.
you can put whatever stickers on it you like, its still just a force.

a rolls Royce used Lucas electrics, borg warner gearbox, Citroen suspension and bodies made by various companies, but it was still a Rolls Royce.
Today Jaguar is owned by Tata but its still a jaguar as too is Land Rover, but everyone still considers them to be English motor cars not Indian.

the original poster has a far better motor in his 2 cylinder mercury 30hp, it will always be easier for parts availability anywhere in the world.
parts for mercury, mariner and tohatsu are in all 4 corners of the planet.
plenty of after market modification parts i.e reeds available for the mercury as too are props water pump kits, carb kits etc.
and power wise it will destroy the force triple, power to weight goes right out the window on this application.
the merc twin is around 15 pounds heavier, but its weight is its quality....

[phillnjack]

merc 25 and 30 for a long time have been the tohatsu motor.
the other brand name for tohatsu is Nissan, they are nothing like the Malaysian or Korean crap copy motors like hidea etc.

Tohatsu /Nissan is the same motor. different name for different countries.

if you ran a tohatsu you would then understand just how bloody good they are. very strong and bullet proof motors. and very quick.

people all around the world racing the their 50hp motors in the salt and getting them dunked a lot on the zap cats.
more fisherman in the world buy tohatsu/nissan than any other brand.

the Nissan tohatsu have been used by mercury since the late 1980's on their small motors, I have a 1990 4hp branded as mercury with the mercury decals
and the Brunswick /mercury decal.

[FMP]

I think your 4 could be a Force, lol

[Capt.Insane-o]

30 hp mercury weighs 170 lbs.
30 hp Tohatsury is 120 ish pounds

still don't know if he has a real Merc or a rebadge.

[wolfgangb]

Hi, Thank you all for your interesting comments. The class is our local GT30 variant, and it appears now that all and any mods are allowed (politics again). As stated by the local Merc importer, the heavy turds (apt expression!) are indeed Tohatsu manufactured. It does have some unusual features, like a built-up crank (con rod big ends not parted), a totally useless inlet tract with uneven mixture distribution (the standard motor uses a slotted restrictor plate between carb and manifold to overcome this), loads of dead volume between the reeds and the crankcase proper, hence next to no pre-compression. The standard Keihin carb does not even allow adjustment of the float level!
The suggestion to cut up an original triple sounds appealing and doable (even here) and much better than trying to make a purse out of a sow`s ear! After all, Renato Molinari had Autodelta cut a Twister apart to win the SE world championships after protesting Michael Werner`s win with his handbuilt Mercury triple), was it beginning seventies?
Please keep this great thread going, and thank you again for your valuable contributions.
Rgds, Wolfgang

[wolfgangb]

On another note, I am actually a great West Bend, Chrysler, Force fan. That goes back to the `60s, when as a youngster I worked for the German Chrysler Marine importer. I do own a `93 5 cyl Force, being fitted with 5 carbs from a 98 model 90hp Force and a CLE, plus a 98 model 120hp, being fitted with carbs from a 140hp Johnson. I do own the long and short original Chrysler racing lu`s, and did shorten Chrysler tower housings to fit them to both motors. And yes, had an adapter fabricated to fit the Chrysler rlu to the 120hp mercurized Force. Of note is that Mercury after the `95 acquisition of Force expended considerable resources to modernize and upgrade the Force motors with increased bearing sizes, improved electronics etc., only to close them down when design-wise they had reached optimum maturity!
For racing, i am preparing for next year an STV replica, with an upgraded 280XS, with 2to1 and a 1,87to1 Sportmasters. I also collected a 2,4 chrome bore Merc V6 of unknown age. it has an unpainted block and 2-piece cylinder heads with widely-spaced bolts - appears to be an ancient Mod-VP block. Bores are undamaged, although 3 pistons lost their ring-lands. I need more garages LOL, the older I get.
Rgds, Wolfgang

[FMP]

I thought I recognized your name from another site , I remember reading about a fuel injection you had been thinking about building for the Force. Please share some details on all the builds , F5 5 carb included.

[Capt.Insane-o]

Right, you have a Tohatsury. The US version of the 30 hp is the heavy turd.

This spring I was brought a 1978 time capsule Starcraft with a like new Chrysler 105. After some ignition upgrades and service it was probably one of best running motors I got in this year. Quiet, started instantly and ran incredibly well. The young guy was tickled to death as it was his gramps boat. He and his girlfriend logged a bunch of time in it this summer, pretty cool.

[staylor]

For the record- the original firm was Kissel which became West Bend(who made Elgins under a private branding with Sears)- Chrysler- Force. I was given a early 1950s Elgin(West Bend) in the 1980s that was missing a lot of parts. I went to the local Sears store and all the parts I needed were ordered- including small parts like the high speed needle and gaskets. All the parts showed up one at a time thru the mail in little envelopes for around 2 weeks. But I was still missing a prop so I took a flyer and went to a Chrysler outboard dealer. I showed him the motor and he went into his parts and came up with a 6 hp Chrysler prop that was a perfect fit. This little motor ran like a top for the 8 years I owned it after getting it running. Carb had a glass float bowl like an early Holley carb- easily removed with a little clamp when you saw crud building up, then quickly dump the bowl overboard, re-install bowl and clamp and keep on running.....
Doug