Servicar speed

All flathead topics
Post Reply
Posts: 7
Joined: Mon Mar 01, 2010 6:02 am
Bikes: 73GE
Location: spokane

Servicar speed


Post by northapt » Mon Mar 01, 2010 2:33 pm

I've owned two servicars in the past and was hoping to put up another. They're fun but dirt slow. I know I'll never get one up to todays freeway speeds but would like to do 50 without trouble. I know they don't breath well (my 73 had a little Tiliston that looked like it should have been on a lawn mower) I was thinking about using a Mukuni. I've heard of using a taller motor sprocket, etc but didn't want to build a stroker. I was hoping you folks had some tips.

Anyone have trouble with the unleaded gas? Should I look for hardened valve guides..if anyone even makes them?


Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: Servicar speed


Post by Cotten » Mon Mar 01, 2010 3:09 pm


Your flatty never needed lead.
Tetraethyl lead was used to increase octane for vehicles with very much higher compression, and run at a lower cylinderhead temperatures.

And nearly all guides on the market today are quite soft.
They are most compatible with modern coated valvestems

Please remember why the MOCO made the machine with a snotty little carb.
It accents the torque aspects of the motor. You can put a larger bore on to accent the horsepower aspects, but you will have to rev uncomfortably just to leave a stopsign, shortening its life between overhauls.


Posts: 2685
Joined: Sun Jun 06, 2004 5:14 pm
Bikes: '31 VL, '34 VD, '45 WLA, '47 WL, '49 FL, '51 WL, '58 ST (Hummer), '71 GE (Servi)
Location: Lonoke, Arkansas

Re: Servicar speed


Post by FlatHeadSix » Mon Mar 01, 2010 3:35 pm


the words "Speed" and "Servicar" should not be used together in the same sentence, but you can get them to run a little faster on the highway.

Your best carburetor choice is the Linkert DC-2 that the factory installed on them from 1959 to 1965. Watch carefully when buying one on ePay or other web sites because the DC that fit the 45 flathead engine was "left-handed", the float is on the opposite side of the DCs they put on the big twins.

The servis usually came with a 23 tooth engine sprocket, for more top end you can install a 27 tooth and you may even get by with a 29 tooth if you normally drive where the roads are flat. When installing the larger engine sprocket it is sometimes neccessary to also install a 100 link primary chain so you stay within the adjustment range of the slots under the transmission.

My '71 servi is quite happy at 55 mph, all day long.


Posts: 7
Joined: Mon Mar 01, 2010 6:02 am
Bikes: 73GE
Location: spokane

Re: Servicar speed


Post by northapt » Mon Mar 01, 2010 10:07 pm

Thanks for the tip. Are the Linkerts hard to find with the left handed bowl? Anyone run a Mukini? I see where they're a popular choice for the 45 and easy to find..
Flathead..thanks for the tip on the sprocket. I bet you pay for it coming away from a light?

I see since you have a 71 you no-doubt have that god-awful alternator hanging off the frame and run by a rubber belt. My 73 had that. I am looking at bikes right now in the 60-73 range so I get the hydraulic brakes. If I see one like that, I'll try to find a 12 volt generator to work since i'm not running all the police electrics. I would guess the pully uses the same bushing in the timing case.

Posts: 521
Joined: Tue Feb 03, 2009 10:05 pm
Bikes: 1938U,1949FL,1961FL,1968XL,1979FL ,1958 FL, 1965 BMW,1975 Honda CB750

Re: Servicar speed


Post by steinauge » Tue Mar 09, 2010 3:01 pm

I use round slide Mikunis on all my HDs OHV and SV on account of they work well and are cheap-bought 2 38mm at the swap meet last week for 15 dollars.You can buy a plug and play Mikuni kit for your trike from the 45 restoration company.Part # MCK-1,price 225 dollars,518-459-5012.

Posts: 7
Joined: Sat Oct 29, 2011 7:10 pm
Bikes: 55 servicar
81 rigid shovel,73 ironhead hillclimber,98 softail for resale<POS new bike

Re: Servicar speed


Post by dwightlightnin » Wed Nov 02, 2011 1:36 am

My 55 servi came with a mikuni and is a 1 kick wonder after i leave it inside the house overnight.I changed gears from the 22 and got a 31 and still only cruise at 52 mph.I have to downshift to get up hills but this time of year when there is ice and snow on the roads I don't want to haul ass anyways.

Posts: 821
Joined: Tue Aug 03, 2010 7:10 pm
Bikes: 2008 96" Fat Boy TC
Location: New York

Re: Servicar speed


Post by kitabel » Wed Nov 02, 2011 2:32 pm

There are things that will restrict your top speed, even when the gearing is slowed down (27 tooth motor sprocket).
1. still have the box on it
2. really big rear tires
The tiny M-16 (1936-58), DC and Tillotson (1959-73) manifolds are smaller than the carburetors. You need an M-88 manifold, only used on solos 1936-52.

Post Reply

Return to “Flathead and Servicar”