First run on veg oil...not great

[Diesel Graham]

I just tried a 50/50 mix of veg oil and diesel in my enfield.
There was a sudden increase in power, but I have noticed that under load the engine randomly loses power.
When the power fades, if I open the throttle more, it loses even more power kinda like its flooding, if I close the throttle, it picks up, then suddenly its back to normal again.

Can anyone shed light on what is going on here? I know others are using this fuel, but maybe I have missed something?

Graham.

[oldbmw]

In France the pump diesel is about an 8-10% mix. it burns slower than UK diesel, but idles and pulls better at low revs. at high revs it smokes more, I think because it then does not have time to burn. Try a 10% mix, then 20% and so on to see which mix your engine tolerates best.

[oldbmw]

In France the pump diesel is about an 8-10% mix. it burns slower than UK diesel, but idles and pulls better at low revs. at high revs it smokes more, I think because it then does not have time to burn. Try a 10% mix, then 20% and so on to see which mix your engine tolerates best.

Veggie oil developes less power than clean petroleum oil, also runs cooler. So much so can lead to carbon build up. Is why engine smeat for veggie oil often have steel coverings over the pistons to slow the heat loss through the aluminium.

[Diesel Dave]

Your fuel mix is settling out, this happens if you don't use the bike a lot.

Veg oil carries a little oxygen and if you are overinjecting then you will see a small increase in power. - Warning - if this is the case and you see a trail of black smoke when hill climbing then you MUST back off the rack setting or you risk a seizure. I have yet to find a single Taurus/Greaves motor with this set correctly from India

Loss of power like you describe only comes from a lack of fuel and I suspect that you may have some air in the system or the settled veg oil is solidifying and causing starvation.

At this time of year in the UK 50/50 is too rich.

If you are willing to knock up a copper wrap fuel pipe around either the exhaust or barrel this will help a lot but you will need a smaller 'starter' fuel tank with a switch over tap.

keep the faith

Dave

[Diesel Graham]

Thanks Dave,
I have used the bike every day this week although only short journeys, it does seem like starvation and I guessed veg oil is too thick so I drained it and refilled with diesel and all is well.

The first thing I did to the bike was to lower the max inject setting as there was excessive black smoke, I set it to a point where it is very clean, but with no power loss, this worked ok on my 4x4 so I just applied the same principle.

Graham.

[sbrumby]

Had anybody noticed the rules for useing veg oil had changed in the UK on the 1st of July, it used to be you had to register & send in monthly returns, but now as long as you use less than 2500 litres in a year you dont need to do anything.

[Diesel Graham]

It's good that the law has changed, but I'm sure we all paid our duty on fuel anyway Ha-Ha.

[henryprice535]

Graham
I have come across this problem and I have nailed it down to fuel starvation, if you are using the standard petrol tap (on an enfield) they do not allow enough flow through, I have ended up putting a 1/4 ball valve tap in which gives plenty of flow and don't have this problem any more.

Generally noticed whenhaving a long run a full revs, the engine gradually dies away, left to tick over/or run at low revs you then can get it to pick up.
I found oud by putting a clear fuel filter in the line, normally it's full, but after the long run, it empties, tick over it fills up again,

worth a try.

Henry

[Diesel Graham]

Henry, thankyou that makes perfect sense, I did see the ball valve on your bike, I now understand why you did that.

Graham.

[Diesel Dave]

I'd agree with Henry that there can be a lot of surge in the fuel line.

I run fine with the aftermarket plastic petrol tap but I know that Jochen removes the tap completely on his conversions and just uses a 90 degree BSP fitting.

I would be tempted to check the injection system for a few things though, look at the volume of returned fuel from the injector - if it's a lot then the injector could do with a rebuild as fuel is getting behind the pintle into the spring chamber.

Also check the injector pump, it comes apart easily and look very closely at the internals, I've seen rusted and weak springs and precision internals with rust specs, I tend to use metal polish rather than grinding paste to redo the seats in the injector and pump as this gives a better finish and seal but takes a lot more work to get right.

All this said - the engine will run with all the above faults, it just won't be as effecient as it should be.

Keep the faith and it will all come good in the end.

Regards
Dave

[Diesel Graham]

I am no stranger to diesel pumps although I haven't looked at one so small before. I guess it might be worth a look inside and I have been thinking I should check the spray pattern on the injector.

Is it possible to find timing info and tappet clearances anywhere? Greaves will not reply to my emails and I can find nothing on the net relating to that engine.

[Diesel Dave]

Graham,

Mail me off - board and I'll send you a copy of the CD I have with the Greaves manuals scanned onto disk

Regards
Dave

[gordon160]

http://www.youtube.com/results?search_q ... +motorbike

start off with the [72 jawa] it explains how veggie oil needs heating
then checkout the rest how to start royal enfiels ect

http://cgi.ebay.co.uk/Vegetable-oil-Hea ... dZViewItem
ebay no 260163439845 incase its sold checkout the above links hope they can be of some help they are of General interest anyway

gordon160
i have no connection to the seller on ebay

[Diesel Graham]

Thanks Gordon, I've already seen those you tube videos.
I looked at the svo heat exchanger and have already considered something similar but more simple.
I thought maybe a coil of copper wire inside the exhaust would suitably warm the fuel but have not started playing yet.

Right now I am wondering whether my blocked fuel filter is the cause of the veg oil running problems, or if the veg oil is the cause of the blocked filter???

I need to find some sort of filter to fit before I start experimenting again. I am looking at some combined filters and water seperator units, these are nice because they have drain and bleed screws built in.

Graham.

[gordon160]

Hi just a few ideas, if the viscosity of the fuel is wrong you can warm the fuel up or warm the air before it goes in the cylinder

Your idea of heat exchanger is good but the copper wire should wraparound the exhaust not go inside the exhaust. If you put the wire inside the exhaust it would restrict the flow of the exhaust and cause a power loss
However I think the easiest way is have a small tank of diesel fuel start the engine on diesel fuel then switch over to veggie oil when the engine is warm
This would make the heat exchanger unnecessary

A see though fuel filter for sale at most car part shops would do as a temp type cure,you could disconnect it to drain out the water if you see water in the filter then when every thing was working well look for permanent cure if the problem persists
Hope these ideas will be of use

gordon160 PS if you get it up and running please update your post

[Diesel Graham]

Well, the new filter is on and diesel is flowing again, but I think veg oil is too thick for the 10 micron filter without being pressure fed.

My next job will be to fit a pulse pump in the fuel line which operates by crankcase pressure. These are well known for being a weak point in a petrol system, but I only need the slightest pressure so it may just work. Anyway, it needs no modification to fit so thats a plus point. I find that veg oil will flow if I simply blow into the tank, it will even start from cold, its just a pressure/flow issue with the thicker fuel.

[Diesel Dave]

Graham,

Runner 2 stroke scooters use a small pulse pump operated by crankcase pressure pulses.

Are you thinking of taking a pressure feed from the breather pipe on the rocker cover?

Point of caution, I did manage to trap the breather tube once, I had folded it over to get it out of the way and then forgot to return it.

Anyhoo the result was lots of oil bleeding out from the rocker cover gasket, also there was some oil blown out of the flywheel side main bushing into the fan casing. I suspect any restriction to the breathing by fitting a pulse pump may have similar issues.

You could possibly consider pressurising the tank, a small electrical compressor in the toolbox (the ones they sell for blowing up tyres in car accessory shops). You would need to arrange a pressure cut off for the electrical supply and I'm not sure what effect this might have on the diesel return line.

Regards
Dave

[Diesel Graham]

Thanks Dave,

I am already going down that route with the pulse pump. A friend at work races go-karts and he has a pump for me, the rotax engines use the same pump. I have not yet found the crankcase breather, but I might rig something to the inlet manifold and try out in case there is enough of a pulse available there.

I have just ridden a far superior bike and I think anything I try on mine will still fall short of the performance and smoothness of the Price-Part's diesel. His engine is far superior to the greaves and hardly vibrates at all, it also accelerates like a petrol and feels a lot lighter.

[Diesel Dave]

If you liked the Chineese Yanma motor, then you should like the Hatz IB40, another HP (11) and a lot smoother except at idle - the new conversions even carry a 20t gearbox sprocket making 65 a reality.

Or even better the V2 Punsun - the new ones are 25HP so that's 7 more than the petrol 500 Bullet. Should make a great sidecar hauler too.

All the best
Dave

[Darren]

Might be worth considering a small 12volt fuel pump?