Kubota Diesel Motorcycle

[coachgeo]

Throwing things out into the wind to see what I might catch.

I'm back to the diesel motorcycle project started in around 2008. Life got shitty for awhile and things got sidelined. Am stubborn though and have muttled thru the crap and back at it now.

base bike..... 1997 Triump Tiger Dual Sport w/non working 3cyl petrol engine.

Here same type bike dieselized by a Kohler/Lombardini. Mine which will have a Kubota engine.

www.youtube.com/watch?v=k7BqPBvVuyY
Intend going with a CVT though. This fellow has done that on a few other Tigers and bikes as well.


Got at a reasonable price Kubota D722E 3cyl 719cc engine from a refer. Rated at around 18hp continious and 20hp peak. It runs fine. It will need to be rebuilt but I'm hoping; just a "refresh rebuild" is all it needs. While at it; or step by step afterwords, I want to bump up the output with only reasonable affect on engine's future life. I'd like to get it to around 25ish hp continuouse ?

Am needing advice and guidance and hoping forum membes might assist.

. What do you folk feel is the best combination of parts and pieces to achieve HP bump to around 25 horse

. Where am I more liable to find these parts at a reasonable cost.

. Do any of you have connections that can bring cost lower?

. What should I do during the rebuild and what can wait till later? Don't want to do things twice if I can.

. Do any of you have access to CVT's particularly used/reconditioned?


Engine has no bellhousing nor a stub shaft on the flywheel:

. Where would I get a stub shaft to mount to the flywheel for either a CVT Drive pulley or a chain and sprocket (got two different ways to explore CVT use- direct drive from crank or via jackshaft, chain and sprockets to add rpm adjustments )

I traded a second motorcycle to a fellow in TX who is a master Mechanic/fabricator. In return he is the one who will build this engine and the bike.

Thanks in advance!! I know thats a lot of quetions right off the bat.

George Jessup
Springboro OH
coach- gymnastic sports

moderator suckindiesel.com/thingy (diesel motorcycle discussion forum)
moderator benzworld.org/forum/unimogs (MBenz truck discussion forum
moderator burnveg.com/forum (Waste veg. fuel discussion forum)

 

[coachgeo]

Re: Diesel Motorcycle

did some editing and hopefully better organized the opening post soooo giving her a little bump 2 da top

Thanx in advance

 

[South 40]

Re: Diesel Motorcycle

Hey Coachgeo

That is going to be a really cool project, can't wait to see it finished.

To answer some of your questions:

A turbo will give you the most bang for the buck.

You can also have the injector pump and injectors rebuilt and have the pressure raised a bit, this will add a couple more ponies.

You could take some measurements and have a couple thousandths ground off the head and block but you need to make sure there will be enough room for the valves to open.

I am not sure how thick the cylinder wall is on these engines, but going one size bigger on the pistons and rings would add a few ponies also.

Adjusting the timing on a diesel isn't easy, so I am not sure I would attempt that unless you have someone that really knows what they are doing.

Now the problem with all my suggestions is that engine will need a complete rebuild or it won't hold up.

If it were me and I were going to build a project like that and expect it to perform like the one in the video, and you plan to ride it like that, I would go ahead and get the whole thing rebuilt top to bottom.

The last thing you want to do is pump up the power and get out and try riding it like the guy in the video and have it lock up or come apart on you.

Best Regards

Paul

 

[coachgeo]

Re: Diesel Motorcycle

Hey Coachgeo


To answer some of your questions:

A turbo will give you the most bang for the buck....

If it were me and I were going to build a project like that and expect it to perform like the one in the video,... ...

Thanks for the info. Yeah Turbo is an obvious must.

Engine used in the video Tiger is a non turboed, 1000cc. A turbo 722e will sit at approx. same HP as that one yet be around 50lb lighter. w/ CVT tranny instead the Harley Ultima in that one..... it will be another 20lbs lighter. Adding; subtracing really I guess , Im also another approx 30-50lb lighter than the rider on that one. Am 150lb soaking wet; thusly Im a lighter than most any adult male that might sit on the seat.

Buttttttt. that being said.... no do not intend to ride like that. It will be a commuter and scenic trail adventure bike. My ONLY desire for speed is ability to cruise at 70-75mph when on fast moving Hwy so not to get run over by other traffic (cagers). Don't expect to ever go beyond that speed either. . Most time will take 2 lane route. This will help keep trip milage to around 100mpg

Curtis in TX will have not problem timing the IP.

ATGAT
All The Gear - All The Time, saves riders lives and bodies!
Gear: proper riding- pants, gloves, boots, Airbag motorcycle jacket - all with approved padding, and helmet

 

[South 40]

Re: Diesel Motorcycle

Well it should run forever on a tank of fuel, lol.

 

[skeets]

Re: Diesel Motorcycle

I remember reading in one of the HD forums where someone did that useing an industral diesel and I think he used a soft tail. Was a nice job but after that it kinda fell off the map. Im not sure how the counter blancing of the diesel and how it would torque the bike. There is something about 3 cyl motor on the brit bikes that curbed the torqueing of the frame. I m sorry to many mile and to many bugs kinda fogs the brain sometimes. That should be an interesting project ,just rememebr we LOVE PICTURES

 

[coachgeo]

Re: Diesel Motorcycle

I remember reading in one of the HD forums where someone did that useing an industral diesel and I think he used a soft tail. Was a nice job but after that it kinda fell off the map. Im not sure how the counter blancing of the diesel and how it would torque the bike. There is something about 3 cyl motor on the brit bikes that curbed the torqueing of the frame. I m sorry to many mile and to many bugs kinda fogs the brain sometimes. That should be an interesting project ,just rememebr we LOVE PICTURES

Diesel bikes are alive and well. See suckindiesel.com

 

[coachgeo]

Re: Diesel Motorcycle

Hey Coachgeo
...I am not sure how thick the cylinder wall is on these engines, but going one size bigger on the pistons and rings would add a few ponies also....

Oversized engine rebuild kit

http://www.kubotapartsdealer.com/overhaul-kit-d722-e-25mm/

one area calls it a .25mm ..... another says .5 so not sure which it is.

when thinking of rebuilding with oversized piston's what's the Pro and Con's to do this compared to adding turbo

PLEASE CORRECT ME IF I'M WRONG

PRO's to doing full rebuild with oversize pistons instead of refresh engine and turbo it
1. you end up with a new engine
2. adds some HP


CON's
1. potentially cost more than combined cost of "refresing engine" (new bearings) and adding turbo
2. adds less HP than turbo would?
3. lowers engine longevity?
4. lowers fuel milage?
5. adds weight

 

[Apogee]

Re: Diesel Motorcycle

Rebuild the engine stock and add a turbo. The only thing you will need to do is turn up the pump and modify the timing. Will give you more power and should live a very long time if you keep the boost reasonable. Also, the turbo adds coolness factor...

You won't see much increase in punching out it. If the bores aren't tapered then leave it std bore, hone it and dump new parts in it. If you have to bore it, go the first size oversize (.25mm) that way you can still rebuild it again down the road if you need to.

The 722 block is not sleeved so if you punch it out to the max you will be replacing it down the road on a future rebuild. Also, you will lose strength in the cylinder walls and no telling what will then happen if you decide to turbo it. You want to keep as much strength in the upper cylinder walls as possible.

You should be able to find the turbo parts off of a Bobcat (I think).

Weight and mileage will be non-factors as the oversize parts won't affect either in a noticeable way. Adding the turbo will be more $$$ in the long run. If it were me, I'd do a full rebuild then add the turbo down the road. That way, if it makes enough power stock, you will already be set to go. If it doesn't, then it will be ready to take the increased cylinder pressure the turbo will add. Life will be longer sans turbo but then it won't make as much power...everything in life is a trade-off.

Just my $.02,

Steve

 

[coachgeo]

Re: Diesel Motorcycle

Thought ya'll might appreciate the info passed on via the Diesel Motorcycle board on this topic

My engine (D377 in a Kawasaki Vulcan 800 bike) is completely stock running 10lbs boost and turned up to 4k rpm , their is no need to rebuild for low boost. Turboing the engine is much easier than an entire rebuild not to mention just because you bore it out doesnt really give you a whole lot of power, its usually about balancing, raising compression and revving the piss out of them.

for now I would buy a small turbo make an adapter and put a return fitting on the oil pan.If it isn't broken , break it .toyotaracer9

Re: US engine Reefer unit as a source for diesel engine?

Unless the engine has alot of blowby, leave the internals. If the cyl/pistons are scored/worn, the rebuild would be a must. Boring out to an oversize will not give a noticable increase in hp. A td02 turbo and adjustments to the max rpm and max fuel screws will make a decent hp increase on a budget. I had 15psi and 4k rpm on a stock kubota, customer is still running this set up. Install a pyrometer and watch egts and you will be safe. Stock cast pistons will melt around an egt of 1500 degrees f.

 

[coachgeo]

Re: Diesel Motorcycle

engine and CVT off a polaris have made their way to TX for this project.

Goal is to install CVT as if it was a chain driven divorced transmission. Why? Will allow installing the bulky CVT primary clutch deeper under seat instead of jutting out from the flywheel begging to be dropped on etc. End result a much more narrow bike. Granted this bulkiness mounted to flywheel would only be a few inches more than 3" belt drive set up it would require to run a Harley Ultima divorced tranny which is the more typical conversion combination.

Might consider shaft drive to keep CVT tucked away behind engine (flywheel facing rear tire) as the Diesel Track bike does.. buttt if that is only way to tuck the CVT out of harms way.....$$$ will probably force me to stick with conventional; AKA back to putting the Primay CVT pulley on the flywheel facing left side to turn sprockets for left side chain drive rear wheel.

 

[fast*st]

Re: Diesel Motorcycle

Not sure if Kubota and JD use the same bellhousing pattern but the JD yanmar 3 cyl 25 hp engine used in the gator already has the CVT drive. Just trying to think how you'd get enough spread on it.

 

[coachgeo]

Re: Diesel Motorcycle

...Just trying to think how you'd get enough spread on it.

Spread? Spread as in distance between clutches for belt to fit? Or, gear ratio spread? or?

 

[skeets]

Re: Diesel Motorcycle

Just wondering if you were to use a wing frame and shaft drive,, I don't know much about what your trying to do..was just a thought

 

[coachgeo]

Re: Diesel Motorcycle

Just wondering if you were to use a wing frame and shaft drive,, I don't know much about what your trying to do..was just a thought

Obstacle that has been run into with shaft drives and CVT is the limits posed by the set in stone gear ratio of the shaft drive. With a chain drive you can adjust the sprocket sizes to best match the RPM's & range of ratios with CVT.

A Goldwing final drive is a thought. One reason why is; as I've been told, they are often discarded and/or sold cheaply after converting a Wing to a Trike. Would have to do a lot of fabricating to get (single?) swing arm and final drive onto the Triumph Tiger frame though. Also to really do it right to avoid obstacle mentioned above; you would still be best to go from CVT to chain and drive the shaft with that in order to maintain the ability to change sprockets to allow for tuning ratios to best match the desired goals.

 

[coachgeo]

Re: Diesel Motorcycle

So far sticking with chain drive

Build pics and info below

http://suckindiesel.com/thingy/viewtopic.php?f=31&t=829&p=17494#p17494

 

[coachgeo]

Re: Diesel Motorcycle

If you didn't pop over to the build thread.......... am in need of a used oil pan for my Kubota engine (D722). I can trade the large capacity Carrier oil pan for it if you could use it.

Also need different exhaust manifold. Is there a center dump one? Mine is flywheel side dump and it is in the way of where an engine mount has to go. Fan side dump will be just as bad. Will be adding turbo eventually too.

For shits and grins......... so we know our options.......... are there any different intake manifolds?

 

[coachgeo]

Re: Diesel Motorcycle

If you didn't pop over to the build thread.......... am in need of a used oil pan for my Kubota engine (D722). I can trade the large capacity Carrier oil pan for it if you could use it.

Also need different exhaust manifold. Is there a center dump one? Mine is flywheel side dump and it is in the way of where an engine mount has to go. Fan side dump will be just as bad. Will be adding turbo eventually too.

For shits and grins......... so we know our options.......... are there any different intake manifolds?

Anybody got idea where to locate used parts?

 

[KTMrider]

Be sure to post photos!

 

[coachgeo]

Re: Diesel Motorcycle

Be sure to post photos!

pics in links provided