R4 956cc FUEL CONSUMPTION HOW TO REDUCE?

[r4allpourposes]

hello everybody.
I'm wondering if there's a way to MINIMIZE the fuel consumption of my 1990 R4 956cc. I don't care of performance of my "meteor", I've a lot of time!! If you've some tips about modifications or regulations you're all welcome. Please, help :roll:

 

[angel]

What is your current fuel consumption, to start with?

 

[r4allpourposes]

Hi Angel, the fuel consumption is 12/13 km to liter. I don't know if this is a normal consumption, but I would like to bring it to 17/18 (because of the fuel costs). My R4 appear to be in ok condition, no smoke, power ok, 100000 km engine.
There's a way to modify the ignition system?
Thanks

 

[malcolm]

You're at about 37mpg at the moment and want to get over 50mpg (isn't it crazy we're not metric yet here).

37mpg sounds slightly low, but it depends on the type and speed of driving. Driving around town is uneconomical.

Economy improves a lot with condition of the ignition system. New points and setting the timing accurately might help. Also make sure the vacuum advance mechanism on the distributor is working (remove the little tube to the carburettor and suck - there should be no leak in the distributor and the top plate should move).

Check the fuel mixture screw - occasionally people change the mixture to try to correct some other problem. Twist it all the way in and count the turns. Should be about 1.5 turns for a Solex 32 carburettor. Twist it back to where it was if it's close to this.

Driving style - keep your speed down, be gently with the throttle, and try to avoid braking. That'll help.

 

[ade]

fuel economy

if you've got lots of time, its got to be fuel injection, thats the only way....then we can learn by your mistakes! You could build yourself a Megasquirt system, and use throttle bodies from small motorbikes/scooters, but best to use an ECU where you can switch between maps, and have a super economy map. You need to get the injectors as near to pointing at the inlet valves as you can. Rework the exhaust ports for maximum flow and fit larger exh valve if poss. Fit freeflow silencer. Raise the compression ratio to at least 10:1, but keep the engine cool to avoid detonation.

Remove any unnecessary exterior trim, e.g. mirrors ( it must be almost impossible to significantly lighten these cars!), make sure your brakes aren't binding, and keep tyre pressures high...Good luck, Ade

 

[angel]

Ade, fuel injection would be far more expensive than fuel cost in the long run!!!

13 km/liter is 7,7 lt/100kms. This is pretty high with R4 standards, on the other side 18 km/lt is 5.5 lt/100 kms, that is possible on a R4 but only on open road and with an experienced driver and with relatively low speeds.
What type of carburettor do you have?

 

[r4allpourposes]

Fuel Consumption

Hi Angel, thanks for your attention.
I've seen the string: 28IF on my carburetor.
I'thinking if I can replace the main jet with a little one, so I can reduce the consumption. Perhaps my carburettor need some inspection, but my little R4 seen to work.
Some people told me to replace my IF28 with a modern carburetor, more efficient, but I could not know whitch choice to do. Do you agree?
Bye,
MIKE

 

[angel]

In terms of consumption, 28IF is unbeatable because it has no acceleration pump, so it "forgives" a careless right foot.
I do not have enough data for the 956cc engine, however on the 28IF equipped 1108 the main jet size was 91, this is a good starting point. Check also that the float level is correct, perhaps try to lower it a fraction (say 0,5-1 mm) by adding a thicker sealing washer under the float needle valve.
Also check that the crankcase ventilation system is OK, all holes clear, hoses OK, this is rather important.

Remember, as other people have already said, it is not only the carburettor responsible for high fuel consumption, you should make sure that the ignition system (points/timing/plugs) is spot-on and also that valve clearances are set correctly.