6/14/12

Dnepr/Ural reduce fuel tips

Hello everybody,
In most of classic bikes owners knows about high level of fuel consumption, but how it can be reduced? Let's try to reduce this level, check out an information below about this process on russian motorcycles Dnepr Ural with sidecar.
There are a lot principes to reduce fuel consumption, like to check out tire pressure or driving dynamics, but this princips can't reduce a lot. The main things, what we look out will be carburators, ignition system and final drive.
Carburators - is used to blend air and fuel. The stock carbs remove and throw out. I suggest to put another ones with diffusor diameter 34 mm, I have used Keihin carbs from Kawasaki ER-5, it has 2-cylinder 500 cubic cm engine, on dnepr/ural engines are 650/750 cubic cm, but don't think about engine capacity, because Dnepr/Ural engines performance is less than Kawasaki. The general parametr is max engine horsepower on kawasaki is 48 hp, Dnepr/Ural 28,32,36 and 45 hp, that means, what carb flow rate (performance) will be enough for Dnepr/Ural engines. Under carb adjustment I putted fuel flow bolt to min level and position of carb needle to min level, under different engines it can vary. Carb bracket consist from 2 parts - rubber and handmade bracket to cylinder head. Of course air flow filter required with zero resistance. If you are using stock air box, you can put in K&N filter for Kawasaki VN1500 (Vulcan) 99-, size/dimension will fit in to the filter box. Check out the image:

Finally, needs to add fuel hose to each carb and gas hawsers.
Ignition system - calculation of ignition moment, stock contactless ignition remove and throw out contact and put in car sensor. The shutter is hand-made. Ignition coil can be used genuine.

Distance from sensor to shutter about 1 mm, main purpose: on shutter must be 2 simmetrical notches to imitate crackshaft frekvence, because camshaft frekvence is less in twice than crankshaft. If you don't want to make it by own, you can buy it on ebay ignition kit.
Ignition module - include ignition control unit and commutator. Control unit is hand-made as well on PIC controller base + octane correction, depening of fuel type using, commutator has been taken from car. Ignition module are located under seat.
Well, last thing has been left is changing stock final drive (8/37) for 9/35, it can be found at ebay as well.
After those moifications overall fuel consumption has been reduced from 13L/100km to 5.5L/100km on driving with sidecar at speed 80-90 km/h.
If there are any questions, comment the post. Regards.

8 comments:

  1. Bloody hell that is amazing difference!
    If I ever get my carbs to stop leaking I will start thinking about this.
    Just got a dnepr mt-11 and wondered where you were in Ireland, I'm in Clare.

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    1. Unfortunately I'm not in Ireland any more, but for consulting I'm available here, now I'm trying to put in carbs from Honda Pan European 1100, there are 4 carbs, but diffusor is the same 34 mm, these modification will not add some horses, but reduce the fuel, reduce exhaust smoke level. Fuel consumtion may vary under engine condition. Pay attention on compression ratio, that should be the same, if there are some differences, you can't adjust carbs precisely.

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  2. Leaking concerns are everywhere and i came to know about this when i was looking for how much does it cost to ship a car. This is an amazing article and i believe every motorbike owner should consider it to get rid of leakage issues.

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    1. This kind of modification can be applied for cars as well, at any petrol/gas engine, but new modern engines already fitted with electronic ignition module, however, if you have classic car and it is used regularly, to reduce some fuel leaking - it can make sense to fit electronic control ignition. Depending of engine size under % value, much more effectively of big-sized engines like american muscle cars of '60s. =) Of course to reduce more there is solution to put fuel system ECU instead of carb or carbs.

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  3. Fantastic article! very well translated, well done!

    Ill try these carbs and an electrical ignition, I'm amazed it doubles the fuel consumption, but this is an excellent guide.

    thankyou very much for writing this.

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    1. U r welcome!!! I forgot to add one thing, I suggest rebuild voltage regulator on transistors, because stock coil based spend a lot of electricity, to prevent low voltage on ignition coil - spark power will be better, generator power 150 Watts is not enough for all electric system. The simplest way put in voltage regulator from car generator.

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  4. ECU can be made under order and published on ebay, if there are some interest, let me know

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  5. I have added video, how it works, follow link http://youtu.be/M1Sey1zxJlM

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