Snoops Enfield Diesel Conversion Thread

Take one 1992 Enfield, bought from London. Take one Yanmar L100 404cc Diesel Chinese clone from Nottingham. The result?... thought about building this is beyond me though two reasons spring to mind; a) I'd sold my BMW R1200GS and b) my mate and i are going to Cape Town on it and perhaps a second one sometime in the future.

Oh and then there is the vegoil and 150+mpg. No bike will do better than that. When I took the R1200GS to Greece last year it drank like George Best. OK it was loaded up, and a mate was on the back, but I was dismayed at how much of the money allocated for the trip went on fuel.

My mate set a challenge. Get the bike done and I'll meet you in Serbia. The game was on.

This thread can be used as a guide by others. I'll try and justify the differences between my conversion and others. Some of the guides out there are poor and do not tell you about all the "little" things that have to be done to get this working. I will.

Before I get started my thanks to Danielson for his wisdom and countless replies to my queries. You can find his conversion at: http://www.advrider.com/forums/showthread.php?p=13787924

Let's get started...

Start by removing the primary drive cover. The alternator must come off (three bolts) and then then magnet is held on by the big nut you can see on the left. It's on tight and the rear brake and clutch couldn't cope (wheel turned or clutch slipped). I ended up placing a bar in between the teeth on left cog (behind the magnet) and a bit of the case. When the engine turned it jammed the rod up good.

Then take off the three nuts on the clutch drive and remove all the bits. You should keep the order or don't as I did and then look at the "Peter Snidal" manual. It's worth it in case you have to change them in the future.

The center rod thingy will come out of the clutch center. There is also another long rod inside it - don't loose this.

Now you must pull both left and right parts off together as splitting the chain would be annoying. This requires pullers. A standard three leg will do the left. For the right you must be creative as a standard puller against the outside of the clutch will bend it.

For my first trick, get a piece of metal and drill three holes. Put those bolts you took of earlier back in. Before this though you'll need a bolt in the center and a nut on the other side which you can hold with a spanner. The following picture shows my clutch puller bodge!

Now that the drive is removed you can go ahead and remove all the engine bolts. The gearbox comes out with the engine and you separate later (four bolts).

The engine is likely to drop down.



Hurrah the cast iron piece of shit has been removed! ...

AWESOME. I'm fascinated by diesel conversions and have never really gotten around to learning more about them.

Will be watching with earnest. and interest. ... and maybe with Ernest. Bum's never around when I'm surfing.

Whatever. Lurk is on.

All for this thread. God speed!

With that aside you get a chance to look in detail at one of Britain's worst engineering feats ever.

The shoddy paint job ... they didn't bother with primer. It scratches to the metal real easy and then rusts away.

The electrics ... by Jesus what were they thinking? Arghhhh....



It then came to me that I couldn't remember what any of these wires were for. I'd got a bit carried away removing the engine. No matter, I pulled out the wiring diagram for the Bullet 500 without CDI (my bike model).

None of the electrics matched.

After hunting around I found one that was nearly right from a 350 Lightening or something like that. Most the wires matched just a few were different colours. Looks like Enfield used whatever was lying around the workshop.

As the electrics are simply a lot of the harness can be undone and much of the wiring removed for the coil, many ground leads and so on. Over time I got to know each wire and I overhauled much of it to suit my needs including an AA battery charger and Pano LX3 charger. Later on the Enfield rectifier/regulator burnt both these out.



Here you can see it coming together. I didn't at this stage know that the regulator and rectifier are separate units as they both say regulator on them. I wrongly presumed there was two to share the conversion load from the original Enfield alternator and so I ditched one as can be seen in the photo - the Diesel only does 4A :eek1. An hour later I'd worked it out and installed the other one. Later on when the bike was running this proved to be in vain as the units were tired and giving out as much AC as DC. My AA/LX3 chargers got hot and died.

I then tried a regulator from a C90 at a pricey £14.50 but that gave out 1.6v DC :huh. Then I bought a 4 pin £2.26 job from Maplin which worked beautifully. It's unregulated and unsmoothed but all my devices work up-to 24v so it's ok. The headlight bulb may have a shorter working life. I'll throw up a pic at the end of the thread. The Maplin one is here: http://www.maplin.co.uk/Module.aspx?ModuleNo=19088

This alloy engine weighs LESS than the original petrol. It has a great big wheel on one side which acts as a flywheel and to cool the engine. You ditch the lawnmower start mechanism.

The shaft is 1" with a keyway. You'll need a duplex cog of 25 tooth @ 3/8's pitch milled in the middle to fit the keyway/woodrift. I don't think you can buy them "off the shelf" and I paid a local machinist to do the boring out.

You can see how keen I was to get the right cogs first time over on this thread: http://www.suckindiesel.com/thingy/viewtopic.php?f=31&t=675

Cog cost £4.50 each (WOW!) so cheap I bought two. They DHL'd them for a quid. :eek1 See: http://www.onlinebearings.co.uk/3-8-sprockets-pilot-bore-pr-16278.html



Here is the critical bit - the acceleration levers. Just above the bit in the middle are two bolt holes. A metal piece goes over these and the flopped spring attaches to it. This tries to pull the mechanism to "off".

You have to make a bracket that goes above those four little holes. A spring attaches to these and the end of your throttle cable.

The whole thing does not work by position of lever but by force. When not accelerating the lever goes to a set position "stock" defined by the spring forces. You therefore use adjustment on the throttle lever to set idle.

When you pull on the throttle the spring force increases causing the lever to rotate. The engine picks up speed and the lever moves back towards the "stock" position because there is now more engine force counteracting the force you gave by pulling the spring up via the throttle.

In other words the lever moves clockwise while accelerating. When speed is stable it's always in the same position. A minimal force on the throttle spring stops the engine from dying completely.

The lever does not move much at all. A tiny movement causes a big response in power.

And here's the catch.

You have the throttle spring to consider. Too thin a spring and it will stretch. Too long a spring will give too much rotation at the throttle. Too strong/short a spring will cause instant response at the throttle.

If the spring in the middle is too strong it will eventually stretch your throttle cable, which is always under tension just to keep idle going.

And also...

The bolt to the left is an injector stroke limiter. When idle the engine runs rich. Upon acceleration the lever hits this bolt which has a spring needle in the end. This provides additional force that limits the amount of diesel going in. It is adjusted to give the best power and least diesel consumption. Excess diesel causes excess black smoke and believe me these engines smoke enough already.

You can't really adjust this bolt unless accelerating, which without a load on the engine is really difficult. Also getting to this bolt when the primary cover is back on is impossible. I say impossible, but I have devised a cunning solution as I'll show later.

You'll have to play with these springs. My only recommendation is to use a more significant one then you would think on the throttle side. Get the middle one taught but not rock hard.

It's as hard as it sounds but don't be put off it just takes a bit of fannying around. :)

Considering you only have 4A at max revs you have to think outside the box. The first thing is LED's for;

Indicators, rear light, front pilots, speedo, turn indicator, high beam indicator.

The headlight takes 35W. I've bought 400 LED's to make a new one as I don't think 4A is enough for a HID.

I also ditched the main battery, it's additional weight and yes it'll help when the engine is idle but mostly it's going to be needing power to charge.

I also hooked up my HTC hero at the front (acts as GPS/Music) and bought a 2.1A switch mode car adapter for an Apple IPad. This gives 5V and is efficient as it comes.

Get this, with everything on (GPS/Indicators/lights) apart from headlight and AA/LX3 charger I'm only using 0.67A.

YEAH! This is sweet..

This is the bit that will be getting you in a sweat. You'll probably not get the Enfield 100% straight so start by sticking the engine roughly in place.

Position the primary case on the engine. Make sure it's horizontally level with the engine.

Drill three holes in the primary case and mount to the engine. The forth hole can't be used. You'll need gasket paper behind but leave this to later. These holes are a bit of a pain to get right and I certainly didn't get them spot on.

I was so worried I didn't take any pictures. As I learnt later, don't worry if it's not 100%. If not it just means the engine is rotated a little and that wont matter because your engine brackets can compensate for it.

Go Dawg!

Now that the primary case is reasonably horizontal on your engine get the gearbox bolted in and put the the primary case on that as well.

The following is the part that matters...

The primary case has a spring loaded seal. Your engine height, it's angle and left/right dictates whether this seal presses against the sides and this is easy to see. It should fit bang on in the middle. If compressed it's life is going to be shorter and it means your engine/gearbox drive will be off as well.

So move the engine until;

a) the primary cover sits flat against the gearbox and
b) the seal shows no signs of compression on any side.

When you've done that you know the engine is in the good spot.

Hopefully the engine was lifted from the middle, I should have mentioned that. This means you can make a metal bracket for the gearbox side.

I used 3mm high carbon steel as it's all I could get at the time. A minimum 4mm should be used, others have used 6mm. Mine doesn't flex easily so I was happy to go with it.

The Enfield has two little triangular tabs which most cut off. DO NOT DO THIS. They are part of the frame strength as one Diesel converter found out on his travels. I welded mine to the bracket as can be seen.

Note that I have not used a bracket the full length of the gearbox, primarily so that ;

a) the gearbox can be removed without taking the engine out and
b) what is the point, the gearbox is hardly going to snap.



You might as well split the chain and install a larger sprocket onto the gearbox as well as the original is too small for the low revving Diesel. I went up to an 18 tooth.

Now get creative with the engine mount on the other side. Same deal as before. I used the original Enfield upper parts and welded on a rectangular bit on one with an M8 hole. This allows it to be split and also prevents the mount from snapping should the strength from one side be used.

There was an argument on Dieselbike.net about it so I went with the safe option. It also significantly cuts down the vibes when the engine is running.

Looks like this ...

Here is the bracket I made for the accelerator. Later on I used a stiffer spring on the left than the one shown.



Here is the second bracket that feeds the cable down (see middle of picture). I used a bit of stainless but later changed it as it was flexing under the strain. Note the hole in the middle - I used a cycle adjuster so that I can change the throttle idle and also the spring attached using a cycle clamp bit - the part that's used to pull the rear brake blocks on a bicycle.

Here the engine is mounted. I also used the Yanmar exhaust which is a spot on fit. A piece of alloy was used to bring it out a little bit otherwise it fowls the injector runoff pipe.

This is a cool, worthy project. I love the idea of diesel bike. But I have to say for safety sake, the welds look awful, dangerously so. The "bird poop" looking bead is indicative of low heat and poor penetration. Such a weld will likely fail under load. Take a welding class, practice on some scrap, or find someone who can weld. Your life and that of your mate may depend on it.

I used the battery to ensure the GPS worked. Most the enfield switches / connectors are unreliable and will have to be replaced at some point.

Time to test it out. At this point I was still using the pull start as the technique to the kick start is a bitch and takes practice. In essence you have to kick down and rotate it under the peg a bit to get it started. Pull start is easier but doesn't work with the foot pegs as sticks out too much.

Also at this point there is no way to stop the bike. This requires additional force on the accel mechanism to make it so. I'll come to this later. For now I pull on the mechanism using a spanner




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More tomorrow!

This was a MIG on high yield. It mostly looks crap because I put weld upon weld to ensure it was tough. Plenty of wire was used. I did all sides, reverse etc and didn't bother finishing it off properly as it can't be seen. I hope you wont be proved right but hell if it fractures it's easy to fix.