XR500 Diesel Bike Farymann 43F

[focodiesel]

The plan is to transplant a Farymann 43F horizontal air cooled single into my '85 Honda XR500. I like this engine because I am partial to undersquare diesels and this is the only relatively small air cooled undersquare engines I know of, If you know of others I would be interested in hearing about them. I have made a deadline of July first to complete this bike by. To incentivize me further, I have a running bet of $100 with a coworker saying I have to ride this bike in to work by July 1st.

http://www.youtube.com/watch?v=zJ8rzD7-7Vc

http://www.youtube.com/watch?v=19qA7lXZqXc

http://www.youtube.com/watch?v=8xpXM0hOaf4

http://www.youtube.com/watch?v=rajAxdUGyOE

Also, is there anyway to embed videos into our post on this forum?

I'd like to here those of you engine savvy peoples' suggestions regarding the flywheel. I need to remove the flywheel that is on the engine now because it is way to heavy, it has an integral fan, my thoughts are to build a lighter flywheel/fan to replace the stock one. So my main question is regarding balancing. Are engines balanced with the flywheel or is the rotating assembly/flywheel balanced separately? Will this engine run without a flywheel? Will I damage anything by trying to run it without the flywheel? Any comments on this subject will be appreciated, so thanks in advanced!

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*Edit- I will be posting links to build videos on this first post for a good reference point, Please check them out:
(Pt. 1) Intro -> http://www.youtube.com/watch?v=zJ8rzD7-7Vc
(Pt. 2) Footpegs -> http://www.youtube.com/watch?v=19qA7lXZqXc
(Pt. 3) Engine Start -> http://www.youtube.com/watch?v=rajAxdUGyOE
(Pt. 4) Last gas ride -> http://www.youtube.com/watch?v=2Z3_9Y-9o2g
(Pt. 5) Teardown -> http://www.youtube.com/watch?v=b9-zLq6AK8M
(Pt. 6) Transmission mod -> http://www.youtube.com/watch?v=6i2lTlpUlUY
(Pt. 7) Clutch mount 1 -> https://www.youtube.com/watch?v=vAoMQpg5hvw

[Stuart]

Reckon you'll need most of the weight in that flywheel to get you compression & ignition. Reduce the weight too much and it may well cause problems. Some metal was taken from mine to make it more throttle responsive but I've no idea how much as I didn't build it.
Hope you win that bet

[focodiesel]

I do suspect that it will take a certain amount of rotating momentum to keep the engine running. Just off the top of my head it seems at higher rpm's the less of a factor this will be, not that that helps me at all because I would like a normal idle...Also If I build a flywheel to be as light as possible but effective at keeping the engine running it will be best to put the main mass of the flywheel at the outermost diameter.

I have a diesel engineering book, I think there is a chapter on flywheel design, I will look at it and if I can find some useful calculations I will post them, in the meantime keep the suggestions, comments, and concerns coming!

[tappy]

I'd be very interested to hear what your book has to say on flywheel design as I'll be putting a different one on my Hatz.

The heavy fan flywheels on these static engines serve several purposes:
1) Sustaining compression / ignition etc at low rpm
2) Smoothing torque impulse loads on starter motors
3) Smoothing torque impulse loads on driven accessories, shafts etc
4) Increasing the engine's inertia so the fuel control can respond before the engine overspeeds when the load is suddenly reduced / lost
5) Cooling the engine
Modifying the engine's crank vibration modes

For (1) I've done a few hand calcs and assuming that an engine cranks at 300rpm when starting, the effect of flywheel mass here is much more significant than at 1200rpm (1/16th in fact). So if it can start OK, then it'll probably idle OK too. If you removed a LOT, then the proportion of gain in the fuel control mechanism would be effectively reduced and it might tend to "hunt" at idle.

(2) If you fitted a decompression valve or a valve lifter then you might be able to remove a fair bit of flywheel mass, but would need a starter motor that spun faster (starter motor's windings tend to limit their speed) or had different gearing.

(3) Most of the transmissions we're using are for petrol engines that have much lighter flywheels so their engine power pulses are more severe. The other cause of shock loading is suddenly throttling off, missed gears etc when the transmission then has to try and "spin up" the flywheel. In these cases a lighter flywheel will actually help.

(4) Not really an issue on bikes - we're already used to making sure we don't miss gear-changes and over-rev etc

(5) There's still some debate, but a couple of us have done independent calculations suggesting that using the original fan-wheel driven cooling system uses a couple of hp. Depending the finning arrangement on the basic engine, and assuming you don't sit idling in traffic, the forward motion of a bike will provide ample cooling for these engines.

[tappy]

Ooops, I missed off (6)!

A given crank, of a given material (most steels have very similar modulus), and a given cross section will have a stiffness, just like a spring.
If you put a particular weight on the spring it will have a particular resonant frequency - just like a pendulum.
If you put a lighter weight on the spring, the resonant frequency will go up.

So, if we lighten a flywheel, the resonanct frequency of the crank - flywheel pair will increase.
Now IF the resonant frequency is already higher than the upper engine rev range, then the frequency will move even further out of range so no damage will be done.
IF however the crank has a resonance below the lower engine rpm - so below idle, then lightening the flywheel may move it into the normal running range in which case it'll do damage very, very quickly.
If your diesel book mentions anything about cranks running "super-critical" then we could have a problem.

As I said - I'd be interested to hear what your book says

[focodiesel]

tappy,

Thank you for your comments on the flywheel issue, they have brought up questions which I will need to research more about. I have skimmed through the section of the book on flywheel calculations and there is quite a lot of material to go over, trust me, I will post all of the formulas and math as I work through it, mainly because I am sure I will need help along the way, so stay tuned for that...I will try to get something posted next weekend, and I will do some research on resonance frequencies as well so I can have an intelligent conversation on the topic.

Keep the questions and comments coming... Thanks!

[focodiesel]

Update: After looking into the flywheel topic I have made the decision that in order to meet my deadline of riding this thing to work before July 1st, I will leave the flywheel as is. This will make the bike 2-3" wider at the flywheel and will make this bike very heavy for a dirt bike but somewhat ok for a adventure touring bike...If my knowledge and machining/balancing skills increase enough and I have the desire to narrow lighten the flywheel in the future I may.

Thus far I have stripped the xr engine and will post pictures/video soon...My plan as of now is to sell the xr engine/gearbox/carbs and go a different route than I had planned. After looking at the dimensions of everything I am convinced that this engine will fit best with the cylinder pointed towards the rear of the bike. Which will put the flywheel at the front left side of the bike. I'm still planing on mounting the engine high in the frame to allow a gearbox to sit under it so I don't have to lengthen the wheelbase. The flywheel spins ccw when looking at it, I am pretty set on using a late model harley transmission (6-speed). To keep the bike narrow I would like to not use a harley clutch which sits outside the drive sprocket, but instead run another sprocket from the input shaft of the transmission to a stand alone clutch on a intermediate jack shaft which will sit below the engine/flywheel and another chain connecting the clutch to the flywheel. The entire purpose of this "divorced" clutch is to keep the bike as narrow as I can.

Stay tuned for updates/pics/videos and please comment if you have concerns over my new strategy.

[pietenpol2002]

Several comments.

1. The 43F has been known to be driven off the crank side (although I wonder if it's only in the electric start version). Would that help any in keeping it narrow?

2. Any chance you could convert it to vertical. It certainly wouldn't be any taller than what you're proposing and would shorten things up such that you might be able to tuck a trans behind it. But, you'd probably be paying your buddy the 100 bucks.

3. The engine-over-trans has been done before as detailed some years ago in this forum. It's the Yanclone 178 mounted atop a Jawa trans in a Jawa frame. If I recall correctly, the "tank" does not hold fuel. Rather, it's simply a cover that encloses the top of the engine. Rather ingeniously done. And as you desire, it avoids lengthening the frame. Having the C of G so high is one of the downsides as I see it.

Done in Minsk as I recall, so use your on-line Russian translator.
http://www.gorod.cn.ua/news_32467.html
http://www.hvilya.com/blog/oshhadlive_s ... -10-25-694
http://www.hvilya.com/_bl/6/58032770.jpg

[gilburton]

Seems to me this method might suit the big trail bikes and also the sports bikes with the delta type frame which is wide enough for the top of the engine to go between the frame rails without modification.

[focodiesel]

Several comments.

1. The 43F has been known to be driven off the crank side (although I wonder if it's only in the electric start version). Would that help any in keeping it narrow?

I pondered that in the beginning, I'm sure it can be done, I don't see that saving width though as I have to put a shaft and sprocket on either side and it will increase the width similarly I would assume.

2. Any chance you could convert it to vertical. It certainly wouldn't be any taller than what you're proposing and would shorten things up such that you might be able to tuck a trans behind it. But, you'd probably be paying your buddy the 100 bucks.

This engine was designed to be horizontal +/- 15 degrees, I'm sure with oil sump re-engineering it could be done, but like you said there's no way working on this during weekends i'd be able to finish in time. This engine is relatively flat and was designed that way, conversely it is relatively long too so I don't think I'd gain an advantage in height and I would loose space for my transmission.

3. The engine-over-trans has been done before as detailed some years ago in this forum. It's the Yanclone 178 mounted atop a Jawa trans in a Jawa frame. If I recall correctly, the "tank" does not hold fuel. Rather, it's simply a cover that encloses the top of the engine. Rather ingeniously done. And as you desire, it avoids lengthening the frame. Having the C of G so high is one of the downsides as I see it.

You are absolutely right, this thing will have a high center of gravity, and even worse it will have horrible gyroscopic effects by having that huge flywheel so high off of the ground, which will mean slow turn in response, but honestly if that is a necessary byproduct of shoehorning in a torque monster diesel into an xr500 I will have to sacrifice some nimbleness. These bikes were never light nor quick around corners anyways, they dominate in a straight line at high speeds like baja type races. I would like to gear this bike to hit 75mph at 2000 rpm! I haven't done math on gear ratios yet so I don't know if that is at all possible so don't hold me to that.

[toyotaracer9]

How much hp is that engine making at 2000 rpm?

[focodiesel]

@2,000 rpm about 8hp and 30 ft-lb, I am planning on turbocharging it as of now so that should "boost" the numbers some.

[focodiesel]

Haven't updated this thread because I am spending all of my time and energy towards the bike in order to meet the deadline...I'm taking many videos and time lapse photography of the work which I will upload in the future. So far I have built a frame jig and am getting ready to start cutting and welding on the frame. I am using an external clutch (PTO off a lawn tractor) which will be hooked via chain to a flywheel stub-shaft mounted sprocket above, and than to the transmission input shaft via a 1/2" v belt. This will be the weak link in the set-up, I am sure there will be lots of slippage, and burning up of belts, but it will have to suffice for now. Eventually I can change the v belt for chain to remedy this, but it will take extra machining/fab which I don't have time for now. So let me do the calculations for what ratio sprockets I need for clutch to engine...
Given:
Rear tire diameter: 25"
Rear sprocket: 50 T
Drive sprocket: 19 T
Clutch pulley diameter: 5"
Trans input pulley diameter: 4"
Trans OD ratio: .86

So...if 2000rpm ( x)((3.14*5in)/(3.14*4in)) (1/.86) (19/50) (3.14*25") =70 mph
2000rpm ( x)((15.7in)/(12.56in)) (1.16) (.38)(78.5in)=70mph
2000rpm (x) (1.25) (1.16) (.38) (78.5in)=70 mph
2000rpm (x) (.551) (78.5in)=70mph
86,507in per minute (x)=70mph
86,507in per minute (60min/hr) (1ft/12in) (1mi/5280ft)(x)= 70mph
81.92mph(x)=70mph
x= .854 underdrive (larger sprocket on clutch, smaller off flywheel)
Just for kicks...
3000rpm (.854) (.551) (78.5in) (60min/hr) (1ft/12in)(1mi/5280ft)=

Top speed of 105mph
I know I probably won't have the hp/aerodynamics/belt grip to ever see this but good to know I won't run out of gearing.

[Diesel Dave]

With 8HP I'd be gearing for 50mph tops..........

[Stuart]

I agree with Dave. You won't see much over 50.

[focodiesel]

I agree with Dave. You won't see much over 50.

You guys may be right, honestly that would be ok with me, but I'm sure I can do better than that. I definitely will not gear my top speed in 6th to be 50. I should have plenty of gears in between for what I'm planning. Guys can reach 50+ mph with 10hp yanclones and cvt's I should be able to hit that with 15hp NA and the possibility of a turbo (20-30hp?) in the future. If I don't like the long legs of the bike, I can swap out sprockets very easily.

[Stuart]

When I rode similar (350cc single) I just made sure it could breath easy & had high Cetane fuel. Free flow foam air filters, corrugated piping, tweaking the fueling, it all helped. Very hard if not impossible to turbo a single.

[XLerate]

I've got some comments, don't know how useful they'll be. I'm planning to shove a 3-4 cyl diesel transverse into my Kawi, spinning a Harley 6 spd with chain drive to rear wheel, possibly selectable for 2WD in a sidecar build. This for long distance touring but also for local short trips on extemely challenging narrow mountain roads with terrible crowns and marginal maintenance.

I want C of G low as possible for the obvious reason that it's at the heart of all handling characteristics. I want C of G correctly balanced front to rear for the same reason, plus for traction. I can't see any good reason to design in a lousy ride, lousy handling, poor traction, inherent danger and known discomforts to build a screwy topheavy rig.

On mine it looks best to stretch the frame [PROPERLY] in order to have all parts 'in the right place'. 'In the RIGHT place' means with easy access for repair/maint, for simplicity of build, with weight sitting as low as physically possible, centered as well as physically possible, with overkill on machine strength and also, hopefully, a good looking and totally functional layout.

So I may need to add an inch or two of frame height and whatever extra frame length it takes to run a chain off engine PTO up to a jackshaft close behind/above engine crankcase, which will run by chain drive downward to my Harley trans, with a chain output from trans to rear wheel. Pretty easy to run small tubes from top frame tubes to bottom as supports for bearing pillowblocks for jackshaft. This will also reinforce frame along the length and height to help deal with diesel torque.

Chain because it's easiest, strongest, most reliable, most available if broke down out on the road in the middle of nowhere, easily repairable with just a master link or two, with the most discreet dimensions. I've never thrown a chain or had one slip but more than one belt has caused me headaches over the years. This design also allows throwing on another drive by simply adding a sprocket to the jackshaft for my possible 2WD arrangement. Jackshaft/trans position also allows for easiest adjustment and dialing in of drive system, the heart of the motion. I like easy.

Stretching the frame 2"-4" or more shouldn't have any adverse effect on handling, may even improve ride. Gives me more room for radiator or oil coolers and tubing/hoses etc. as needed and for other parts fitments as needed. In some cases it gives more room to stretch fuel tank or add capacity as desired. I know for a fact I don't want to build a top heavy, wallowing, ill handling and screwy looking machine to spend many long hours on. I'd also much rather try to do it right the first time.

Lastly, I know from the personal experience of adding a Cummins 4BT/NV4500 to my 46 year old Dodge Town Wagon: it's far more important to get my drive system, suspension and handling RIGHT and LEARN to DRIVE IT than to try to make the assembled parts do what they were never designed for or capable of doing in the first place.

[pietenpol2002]

I dunno XLerate, that combination of transverse 3-4 cyl with a low CG on "extremely challenging narrow mountain roads" could win you the distinction of being the only human known to "lowside" on a diesel flywheel. Be sure to post the video.

http://www.youtube.com/watch?v=sYxU_lYBHpY

[XLerate]

I dunno XLerate, that combination of transverse 3-4 cyl with a low CG on "extremely challenging narrow mountain roads" could win you the distinction of being the only human known to "lowside" on a diesel flywheel. Be sure to post the video.

Well, let's see here: I didn't say how 'low' the low C of G was, and I didn't say anything about driving like a halfwit, did I?

[focodiesel]

XLerate, I don't know if low cg automatically means good handling, think of a low custom harley vs crotch rocket, the sportbike handles much better in twisties than the much lower bike, also longer wheelbase is worse in tight mountain roads compared to a short wheelbase. For going straight, yes longer is smoother. I will agree, lower moment of inertia is better, lower rotating mass... my bike will have a very high rotating mass...which sucks, but to fit this engine in this bike I have decided to do the engine high to keep the normal wheelbase of a dirt bike. If I were to build an ugly as hell superstretch I might be able to fit this engine ahead, or possibly longitudinally up to a bmw/guzzi trans...This bike will be unique, it will have character, it may suck at turning but if I want to go quick up a mountain I will ride my Buell.

I know for a fact I don't want to build a top heavy, wallowing, ill handling and screwy looking machine to spend many long hours on. I'd also much rather try to do it right the first time.

I am building this bike the way I want it, and no I am not building it to be a canyon carver.

Lastly, I know from the personal experience of adding a Cummins 4BT/NV4500 to my 46 year old Dodge Town Wagon: it's far more important to get my drive system, suspension and handling RIGHT and LEARN to DRIVE IT than to try to make the assembled parts do what they were never designed for or capable of doing in the first place.

Could you clarify what you are getting at here?

[focodiesel]

Very hard if not impossible to turbo a single.

Yes I have done some research on this topic, most on this site, I think the general consensus is that many have been disappointed by the results, most using it on yanclones, a few have claimed increased power, either way I am kind of skeptical that I could get a turbo to improve power on a 43f, but from what I could gather the issues are either singles have two long of a duration between power pulses, or the yanmars don't have the displacement or flow to push the turbine into it's efficiency range and it ends up being a net loss, or maybe a combination of both. If the issue is due to the small size of the yanmars, than the 43f might have a better shot at spooling a turbo up as it is some 300cc's larger in displacement. But I do realize a turbo is not guaranteed power.

[XLerate]

Lastly, I know from the personal experience of adding a Cummins 4BT/NV4500 to my 46 year old Dodge Town Wagon: it's far more important to get my drive system, suspension and handling RIGHT and LEARN to DRIVE IT than to try to make the assembled parts do what they were never designed for or capable of doing in the first place.

Could you clarify what you are getting at here?

That last part was just to explain that I had to learn a whole new way of driving with the diesel, even though I've been driving this truck since 1977. So I was trying to say that I expect the same from my diesel sidecar build, having never driven a sidecar or a diesel motorcycle yet.

On the rest there I was just passing on what I'd decided on my own build in case any of it might apply to yours. I don't want you to be unhappy with your results, that's all. Oh, and as for length on mine, I may be able to get away with 2"-3" extra and in addition, it's going to be a 3 wheeld sidecar rig, so not much similar to your 2 wheeled dual sport.

Just want you to be happy right from the jump!

And hey, Pietenpol, sorry if my answer was a little smarmy there... I certainly do respect your opinion and wisdom too!

[focodiesel]

XLerate, I appreciate your thoughts, actually this has made me brainstorm some more... I fixed up the frame to my jig already and am close to moving the swingarm mount. I was going to move it lower to keep the harley trans at the bottom of the frame, but than your comments got me thinking... Could I flip the orientation and mount the trans over the engine and move the swingarm pivot up, after starring at the frame for about an hour and taking measurements this would lower the cg tramendously, lower the moment of inertia by almost a foot, and could possibly allow the use of the stock tank and seat. The cost would be loosing quite a bit of ground clearance because I will have to lower the frame by 4-5". I will contemplate this more tomorrow and make a decision and than run with it.

[Diesel Dave]

One of the most common misconceptions about small engined diesel bikes is thinking the flat torque curve = no need for gear changing, the opposite is true.

For a while I was running both the 500 petrol bullet and the 400 diesel bullet with exactly the same close ratio gearset in the albion box and 18t gearbox sprocket.

I did a mental count of gearchanging comparing 2 days commuting, I actually changed gear nearly 3 times more often on the diesel.

Taking a trip on a flatback recovery truck one time showed the same was true of their underpowered diesel motor setup, lots of gearchanging to keep the motor in the green section of the tacho.

[focodiesel]

One of the most common misconceptions about small engined diesel bikes is thinking the flat torque curve = no need for gear changing, the opposite is true.

For a while I was running both the 500 petrol bullet and the 400 diesel

The rpm range of a diesel is so much smaller than that of a small gas engine, so this would limit the diesel, it makes up for this however in torque (lots of it, across entire rpm range). I think lots of close ratio gearing isn't the be all end all though. If you are driving a loaded tractor trailer and actually using most of the power of the engine to try and accelerate quickest, you will use many gears that have close ratios. But the key here is small power per the job at hand.

You were comparing a 500 gas engine to a 400 diesel which had half(?) the power of the gas engine. If you were comparing the 500 gas to a 1000cc diesel I bet you would have wanted taller gearing to take advantage of the low rpm torque and power of the diesel to reach similar speeds of the gas engine.

[focodiesel]

Well, I successfully won the bet, I rode my diesel XR500 in on Monday, July 1st. It is by no means complete, but I got it "functional" for the occasion. This was one of the hardest things I have ever completed, and in order to meet the deadline I was working 18-20 hour days on this bike for the last few weeks, and was up working until 3:30am before I took it for the first test ride, got 1 hour of sleep, than woke up to ride it in to work. Now that the deadline is over, I can get back into a less strenuous schedule and edit/post some videos that I made along the way. I hope you enjoy my "out of the box" designs. I plan on addressing the issues to make the bike more ride-able, Some were expected, some just had to be experienced. I will continue to capture the upgrades to share with you. Some of the things left to do:
-Electrical: For the bet I just temporarily mounted a motorcycle battery for headlight and taillights, but I plan on adding a large electrical panel on the right side above the engine to house fuses, charge controller, a PLC which I will use to sensor and control a display to monitor vitals (rpm, egt, speed, oil pressure&temp, etc.). Also currently the bike has no alternator so I will have to modify a Briggs and Stratton stator to work under the flywheel. A different headlight, and addition of turn signals possibly. The starter on this engine is 24v, so I plan on having a 24v super-capacitor bank instead of a battery, this I believe will be a better fit for this bike than a traditional battery set-up, plus mechanical diesels need no power to run, if I have electrical issues I can roll start it, which has worked surprisingly well.
-V-belt:I have used a lawn tractor PTO cone clutch, the clutch drives the trans input through a 1/2" v-belt, this slips when to much power is being transmitted, I new this was a week link and so no surprise here. I will be machining the clutch to accept a 50 series chain.
-Gearing, thanks for your opinions on gearing you were right about not gearing too tall, I actually listened and used a .601 under-drive from the flywheel to the clutch, I still think it may be too tall but I am going to add a slightly bigger wheel sprocket 53T vs 50T, and install the chain over the v-belt to eliminate slippage and go from there.
-Exhaust: I rode it in with no exhaust, I plan on building a heat exchanger into the exhaust to preheat the fuel, this will allow me to run oils easier. I also would like to add a spark arrester muffler so I don't get harassed if I take it on trails.
-Backup fuel reservoir: The XR500 used the frame to hold engine oil, but I would like to keep diesel in this area, I'd say it holds about a quart.
-Covers: I plan on making aluminum flywheel and sprocket covers.
-Front wheel: I don't know if it's possible yet but I am going to try and use a 18" rear rim on the front wheel hub. Currently the front wheel will hit the frame at a certain up-travel.
-Lower height: coupled with a shorter front tire I would like to lower the mounting points for the rear shocks to lower overall seat height.
-Intake horn: there is very little space between the bottom of the trans mount and the intake port, currently I just have ss mesh over the intake, I plan on molding a custom silicone intake horn to allow the best flow given the space restriction. Attached to the horn will be a throttle body (emergency kill snuffer), than an air filter.
-Frame disconnect: rear attachment of the engine cradle I used tube disconnects, the goal is to allow easy detachment of the engine for service reasons, I need to fabricate a detachment system for the front down-plate section of the cradle.
-Saddlebags: I would like to build some storage bags to make this bike more useful for grocery parts getting or for touring.
-Seat: Eventually I would like to make a more comfortable seat.

So far I am exceptionally happy with the bike, it works far better right now than I could have hoped. I have made it into 3rd gear so far before the v belt starts slipping bad and I would guesstimate I reached a top speed so far of 40-45mph.

Here is a photo taken the morning of the 1st before riding it to work.


Here is a vid from the original teardown that I got edited today:
http://www.youtube.com/watch?v=-eiGurvx ... e=youtu.be

[coachgeo]

Generally speaking; what country?, state?, city?, province? are you in?

[focodiesel]

Northern Colorado.

[coachgeo]

Northern Colorado.

ahhh... another North American rig. Great.

Sent you a PM about the bash plate that you pulled from the Honda before conversion