Honda Kubota MK5

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Tim
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Honda Kubota MK5

Post by Tim » Sun Feb 09, 2014 1:12 pm

The staring point for me is creating the front engine mount , Similar to the last 3 diesel bikes I have made. This is allows for easy attachment to the front frame down tube with a good provision to adjust the position of the engine in the frame left to right for the belt alignment .

The engine is a D850 Kubota 3 cylinder engine , I purchased from a trailer refrigeration unit . The modification modification include replacing the standard water pump with a remote electric pump . This will reduce the overall width of the engine by around 100 mm.

I have reduced the flywheel diameter and weight by fitting one from a z482 engine this will lighten the flywheel if this will work . I will engineer the build so if necessary I can fit the original .
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A mock up defining the position of the top bar of the engine mount
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Making a card template ready to transfer to the Aluminium 5083 specification plate . The added lump on the right is in case for clearance reasons I need to shift the starter motor to the rear of the engine if I have to use the larger original Flywheel
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The Aluminium 8mm plate is easy to cut with a bandsaw using a blade designed for wood!
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Checking the right engine plate fits
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The top mounting tube in place, I am not pleased with the looks of the left plate and will come up with a different design
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The new reworked left mount
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I have tapped (M8) thread in the cylinder head and made a bracket that will be welded on to the top box tube
.
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Now the rear engine mount . The photo shows the blank plate , the old engine mount frame so I can cross mark the position of the mounting bolts. The plate is long so I can pick up a mounting for the alternator later on .
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The rear bracket drilled and fitted ready for the weld on plates to mount on to the rear Alloy plates I have yet to make .

The next stage is to prepare the Superdream frame ready to take the engine . ......... ......to be continued .
Last edited by Tim on Sat Apr 25, 2015 8:13 am, edited 2 times in total.

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Re: Honda Kubota MK5

Post by pietenpol2002 » Mon Feb 10, 2014 1:54 am

Tim, you clearly don't let grass grow under your feet or for that matter, the tires of your bikes. The MK4 is hardly complete and you're on to the next. Looks as though you're off to a great start.
Is the plan for a CVT on the MK5?
Also, the smaller D750 used in the B1700 HST tractors had no water pump, relying instead soley on thermosiphon. The link below is an example with the dynamo placed where the water pump would normally be housed and a belt tensioner where the dynamo or alternator is now placed. I suppose if you were wanting to save space, weight and the draw from an electrically driven water pump you could go that route and plate off the pump opening. However, the D750 timing cover would not be interchangeable with yours.
Is the 850 externally balanced with the 3 lightening holes in the flywheel like some of the other 3 cylinder Kubotas? If so, you might have to stick with the original.
Keep up the great work.

http://www.tractorbynet.com/forums/atta ... -hst-2.jpg
Ron
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Tim
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Re: Honda Kubota MK5

Post by Tim » Mon Feb 10, 2014 6:04 pm

Hi Ron
The race is to try and build it in a week, commitments depending . The MK5 will be CVT , having driven one last year I really like them . I now put a much lower rated spring in the CVT so it changes through the range at a much lower engine RPM at around 2000 rpm. I have also played around with a system that mechanical overrides the cvt to allow you change down the ratio manually for overtaking or just needing the engine at max power output. It worked well but it fell apart , a bit of reengineering required when time is available .
Interesting regarding the thermosiphon sadly I think the radiator will be lower than the top of the engine how ever I will fit electric pump but try switching it off and see what the temperature does.

I recon you right about the changing the flywheel , I have fitted a 2 cylinder Kubota flywheel which does also have 3 holes but I recon the are in a different position by about 15 degrees . I will proceed with caution and run trials to see the effect and if the vibration is unmanageable .
I was worried about clearance between the front wheel and starter hence using a smaller diameter to increase the gap .

Thanks for the ideas
Cheers Tim

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Re: Honda Kubota MK5

Post by coachgeo » Mon Feb 10, 2014 7:29 pm

pietenpol2002 wrote:...the smaller D750 used in the B1700 HST tractors had no water pump, relying instead soley on thermosiphon. The link below is an example with the dynamo placed where the water pump would normally be housed and a belt tensioner where the dynamo or alternator is now placed. I suppose if you were wanting to save space, weight and the draw from an electrically driven water pump you could go that route and plate off the pump opening. However, the D750 timing cover would not be interchangeable with yours. ....

http://www.tractorbynet.com/forums/atta ... -hst-2.jpg
hmmm wonder how close the D722 is to the D750 hmmmmmm.

BTW the link does not work. Might only appear if your a member of that forum? I got it to appear via cut and paste though and putting it here for archival
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D750_B7100 HST 2.jpg

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Re: Honda Kubota MK5

Post by Blunt Eversmoke » Wed Feb 12, 2014 11:16 pm

A lighter flywheel will have less problems ticking the engine over when idling if you are also decreasing the static CR on your engine (if you plan to turbo- or supercharge it).

Other than that, great work going on with the mounting provisions for the engine - they seem both space efficient and good-looking to me.

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Re: Honda Kubota MK5

Post by Tim » Thu Feb 13, 2014 5:59 pm

Smaller flywheels

Hi
I wonder as well if it's going to upset the idle and may give the starter motor a hard time as it will store have less momentum?
The CVT pulley will add a bit but I will design in the ability to revert to the original just in case! I will post you the outcome . I don't intend to turbo or super this one (yet) and it will have stock compression ratio. Thanks for your positive supporting comments , I really appreciate the comments.
Cheers Tim
image.jpg
This weeks work includes machining the tooth pulley blank to replace the existing rear sprocket.
This is a simple operation as the 122 tooth m8 20 mm with pulley in the taper lock option is an exact fit over the sprocket boss on the rear wheel , it doesn't often happen like that ! The machining is only needed to lighten the pulley by about 1 1/2kgs by thinning it to around 4 mm thick and cutting sufficient clearance for the 4 attachment bolts that hold it on the rear hub. Using a 112 tooth and 22 tooth front pulley a 1695mm belt is a perfect fit not requiring modification to the swinging arm or the need a belt tensioner. The Center to Center belt calculator from the belt manufacture tells lies , it caused problems for me previously so check the length needed with a piece of string before ordering the belt,

image.jpg
This is the manufacturing of the jack shaft that will mount the CVT pulley and the secondary drive 22tooth pulley
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Checking the cvt fits on to the reduced shaft (19mm)
The next job on the jack shaft will be to cut the 5mm keys lot with slot milling cutter .

The jack shaft bearings are for a 25mm shaft but the 2 flange holes for the bolts are 16mm diameter so I make a bronze bush to reduce them to 12 mm and then fit a 12mm shoulder bolt with a m10 thread. I will then ream the 10 mm hole in the engine plates to make them a snug fit .

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Flange jack shaft bearing with the bronze reducer
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The shoulder bolt fitted in to the flange ready for mounting onto the engine plates
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This is the lucky recipient bike I will transplant the engine into 250cc Honda Superdream
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60 minutes later it stripped down ready for the diesel d850 engine.
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The old Honda engine weights in at an impressive 64 kgs
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The Kubota with complete with alternator weighs in at 82 kgs
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To make the rear engine plates and jack shaft mount I have copied the Mk4 template
Last edited by Tim on Mon Feb 17, 2014 6:22 pm, edited 1 time in total.

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Re: Honda Kubota MK5

Post by Tim » Mon Feb 17, 2014 5:56 pm

image.jpg
The shoulder bolts holes are reamed to ensure minimum slop .
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Boring the 32mm hole for the jack shaft
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The rear engine plates fitted for the first time , note. The front down tube marked for cutting to make clearance of the cylinder head
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Offering the motor into the frame and checking the essentials all line up .
The top gauge is used to set the position of the end of the crank in relation to the CVT unit
The large tremal is to check the distance centre to centre of the crankshaft and jack shaft @ 320mm .
This is V important or the CVT will not function correctly . The additional bearing on the shaft is there as I may need to put in additional shaft support as the length of the shaft may create too higher loading on the inner bearing and shaft . Subject to testing I may not have to fit it .
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First view of the engine in position
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This side looks much nicer , may be the exhaust will need to route via the other side to make it look more interesting?
I think is going to be quite wide but I think it has the potential to look Ok . I may need to mount the alternator higher and move it closer to the centre of the engine to clear the rear brake .
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Back to the rear wheel , using the old sprocket to cross mark the fixing bolts
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The toothed pulley fitted to the rear wheel .
I now need to stew over it to tweak the position to ensure things like the oil filler can be accessed, weight distribution is reasonably balanced and the CVT will fit.

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Re: Honda Kubota MK5

Post by Tim » Wed Feb 19, 2014 7:33 pm

The speed of the build will slow now as I need to source all the ancillary parts . It's only now you can mess around with things like radiator position , exhaust routes etc
image.jpg
Should the exhausts go left?
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Or right?
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A lot of engine, it needs to be uncluttered as possible .

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Re: Honda Kubota MK5

Post by coachgeo » Thu Feb 20, 2014 6:14 am

unless you ceramic coat the exhaust I would consider keeping it away from the CVT side. If I understand things right a CVT looses even more efficiency as the rubber belt gets hot etc. Just something to make you go hmmmmmmmmmmmm

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Re: Honda Kubota MK5

Post by Tim » Thu Feb 20, 2014 7:06 pm

Hi
Yep I will go for a sweep to the left or offside as this side is looking a bit chunky and the sweep of exhaust will hopefully soften the angular look......


I am waiting for parts so to days efforts were on the fiddly bits such as the throttle and stop control .
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The back wheel assembled and fitted with the drive belt
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The throttle cable , due to the lever working in reverse I needed to use the outer of the cable to move the lever
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I needed to modify the mounting for the electric actuator stop control as it only moves about 10mm but can apply a considerable force , as my finger found out!
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The inlet manifold needs to be cut and rotated 90 degrees to allow the air cleaner to clear the tank. The next stage is to TIG weld it back together .
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This will be the alternator bracket that will hang it from the rear of the engine .
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The alternator fitted with using a 612 mm SPZ belt , the additional wires are connected to the stator windings to feed the rev counter .
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The next task being mounting the radiator , I am using a 19 row 285mm wide oil cooler , but its going to be a tight squeeze as I want the angle similar to the engine and still clear the tank .
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It just clears the engine by 5mm . I will have to move and relocate the fuel tap forwards and on the other side to miss the air cleaner
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The radiator is a very tight fit , it's 3rows deeper then the other builds as the engine will have a higher heat loss requirement than the smaller 500cc z482 engine . The last big battle will be fabricating a cover for the CVT unit , this is likely to be formed in plastic .
Last edited by Tim on Wed Mar 05, 2014 8:54 pm, edited 2 times in total.

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Re: Honda Kubota MK5

Post by Tim » Sat Mar 01, 2014 6:23 pm

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Exhaust time , a battle to keep sufficient Clearance from mudguard and oil filter
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Drilling and cutting through where the pipes blend
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All 3 cylinders plumbed in ,
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The finished exhaust , tack welded now ready for fully welding , I will buy in a reducer to fit the pipe to the silencer . The white template above the alternator is a play to I improve the rear of the engine and lose the squareness . I am think of taking a patent out on my organic silencer mounting bracket.
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Next is modifying the fuel tank. For the new feed and additional return line
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New outlet soldered in to position the existing point fouls the radiator outlet
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The only air filter that will fit and look ok is the old axiam unit . It's all a bit condensed around the radiator area
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The exhaust fitted for real , the last part being the wiring and plumbing so I can fire it up ,
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The near side will require making a cover for the cvt unit but I will leave this until its completed a test run
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A view showing the width of the bike .
So here's the video of the first very reluctant starting of the MK 5 !
http://m.youtube.com/watch?v=aiV5W-63fCM

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Re: Honda Kubota MK5

Post by Curtis in Texas » Sat Mar 29, 2014 3:46 pm

Outstanding Tim! Been following this and rooting for you.
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Re: Honda Kubota MK5

Post by pietenpol2002 » Sat Mar 29, 2014 7:11 pm

Are you certain you need that silencer Tim? Sounds awfully nice straight off the header pipe. How about a video or 2 of you accelerating through some turns without the silencer? That my friend, would be pure auditory porn.
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Re: Honda Kubota MK5

Post by alexanderfoti » Sat Mar 29, 2014 7:39 pm

pietenpol2002 wrote:Are you certain you need that silencer Tim? Sounds awfully nice straight off the header pipe. How about a video or 2 of you accelerating through some turns without the silencer? That my friend, would be pure auditory porn.
I have a straight pipe on mine.

It sounds really nice, but its very loud, see:

https://www.youtube.com/watch?v=sVlqtp3levM

Its a bit quieter since this as the intake has been lengthened which has reduced a lot of the induction noise, but the exhaust noise is still there :)

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Re: Honda Kubota MK5

Post by Tim » Thu Apr 03, 2014 7:34 pm

pietenpol2002 wrote:Are you certain you need that silencer Tim? Sounds awfully nice straight off the header pipe. How about a video or 2 of you accelerating through some turns without the silencer? That my friend, would be pure auditory porn.
Well I will give it a try this weekend. Subject to the weather I am planning its inaugural test drive . The motor being from a fridge compressor at present only revs to 1200 rpm but a play with the governors should sort this .
I have I visioned there being problems using a lighter flywheel and starter motor but as yet seems ok as yet and it's snappy to respond to throttle changes .

Any hoo I will attempt to record the event and post it up !

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Re: Honda Kubota MK5

Post by Tim » Thu Apr 03, 2014 7:34 pm

.
Last edited by Tim on Thu Apr 03, 2014 8:11 pm, edited 1 time in total.

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Re: Honda Kubota MK5

Post by Tim » Thu Apr 03, 2014 8:10 pm

alexanderfoti wrote:
pietenpol2002 wrote:Are you certain you need that silencer Tim? Sounds awfully nice straight off the header pipe. How about a video or 2 of you accelerating through some turns without the silencer? That my friend, would be pure auditory porn.
I have a straight pipe on mine.

It sounds really nice, but its very loud, see:

https://www.youtube.com/watch?v=sVlqtp3levM

Its a bit quieter since this as the intake has been lengthened which has reduced a lot of the induction noise, but the exhaust noise is still there :)
Hi Alex
Nice looking bike you have built! The MOT guy might not be so keen on no silencer, however the turbo bike isn't at all noisy without one but I guess that's the effect of the turbocharger . The poor starting turned out to be a faulty heater plug but the engine is showing signs of excessive breathing , I guess a blast up the road will soon indent if what's really going on .
Cheers Tim

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Re: Honda Kubota MK5

Post by alexanderfoti » Thu Apr 03, 2014 8:18 pm

Tim wrote:
alexanderfoti wrote:
pietenpol2002 wrote:Are you certain you need that silencer Tim? Sounds awfully nice straight off the header pipe. How about a video or 2 of you accelerating through some turns without the silencer? That my friend, would be pure auditory porn.
I have a straight pipe on mine.

It sounds really nice, but its very loud, see:

https://www.youtube.com/watch?v=sVlqtp3levM

Its a bit quieter since this as the intake has been lengthened which has reduced a lot of the induction noise, but the exhaust noise is still there :)
Hi Alex
Nice looking bike you have built! The MOT guy might not be so keen on no silencer, however the turbo bike isn't at all noisy without one but I guess that's the effect of the turbocharger . The poor starting turned out to be a faulty heater plug but the engine is showing signs of excessive breathing , I guess a blast up the road will soon indent if what's really going on .
Cheers Tim
Thank you indeed Tim, will you be at the big knock this year?

He didn't seem to mind but it is quite loud. I have been thinking about a small silencer.

Yes I have found that the turbo really quietens the exhaust down.

Fingers crossed there no issues with your rings? Maybe try some water injection to free them up if they are the cause of the blowby

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Re: Honda Kubota MK5

Post by Tim » Thu Apr 03, 2014 8:33 pm

Hi Alex
I am a sado fair weather biker so subject to weather I aim to bring the turbo MK 4 and the 3 cylinder mk5 bikes and if rebuilt in time the original mk3 Kubota engine bike to the big knock . I did rebuild the top end and assessed the bores as being in really good condition , maybe the rings are worn but the seemingly good compression and now much improved starting doesn't point at this ???? Worry if its a moisture, cracked water way in the head /block . I will monitor the water level when it goes on the road .

Cheers Tim

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Re: Honda Kubota MK5

Post by pietenpol2002 » Fri Apr 04, 2014 1:30 am

I have a straight pipe on mine.

It sounds really nice, but its very loud, see:

https://www.youtube.com/watch?v=sVlqtp3levM

Its a bit quieter since this as the intake has been lengthened which has reduced a lot of the induction noise, but the exhaust noise is still there
Nothing quite like the sound of a big single. Thanks for sharing it. And Tim, please do post your inaugural launch.
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Re: Honda Kubota MK5

Post by coachgeo » Fri Apr 04, 2014 3:27 am

Tim wrote:.....
Why did you remove the water pump? Does it not stick out no more/less than the crank pulley you put the alternator on?

download/file.php?id=1981&t=1

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Re: Honda Kubota MK5

Post by Tim » Sat Apr 05, 2014 6:52 am

Hi there
The thinking being the bowl shaped pulley they use effectively adds around 80mm to the width of the engine at a point that stcks out visually . In addition I didn't want the shape of the belt run ie crank , alternator and pump triangle to dominate the looks of the engine . I have added a purely for looks alloy plate to enhance the pump area to match the cam cover shape . So being honest aesthetics is the main factor . However if The electrical pump has problems or can't keep up I guess the pulley one will magical reappear !
I am thinking the poor old battery is in for a bit of a whumping as the glow plugs, water, pump and cooling fans are all live when cranking over, I guess cold weather would be the issue ?

Its the big day today when it ventures out from the workshop for the first test , I will post a video if possible !

Cheers Tim

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Re: Honda Kubota MK5

Post by alexanderfoti » Sat Apr 05, 2014 7:42 am

Tim wrote:Hi there
The thinking being the bowl shaped pulley they use effectively adds around 80mm to the width of the engine at a point that stcks out visually . In addition I didn't want the shape of the belt run ie crank , alternator and pump triangle to dominate the looks of the engine . I have added a purely for looks alloy plate to enhance the pump area to match the cam cover shape . So being honest aesthetics is the main factor . However if The electrical pump has problems or can't keep up I guess the pulley one will magical reappear !
I am thinking the poor old battery is in for a bit of a whumping as the glow plugs, water, pump and cooling fans are all live when cranking over, I guess cold weather would be the issue ?

Its the big day today when it ventures out from the workshop for the first test , I will post a video if possible !

Cheers Tim
Great, look forward to that video! Always a moments occasion when going out for the first ride!

With regards to the electrical load, you could wire a relay that cuts power to everything else when cranking, like some bikes have for the headlight?

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Re: Honda Kubota MK5

Post by pietenpol2002 » Sun Apr 06, 2014 1:34 am

In addition I didn't want the shape of the belt run ie crank , alternator and pump triangle to dominate the looks of the engine .
I do like the clean and uncluttered look you get on that end of your engine Tim. It's unfortunate if you have to bring back the water pump. My solution was to utilize 2 shortened Goldwing timing covers seem below just taped in place for mock up. Breaks up the triangulation a bit and joins the angle of the downtubes. I have to soda blast the covers yet to get the finishes to match. I also bent up some angled aluminum on the brake that will serve as belt guards and are yet to be mounted.
April 4 Honda-Kubota 006-2.jpg
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Re: Honda Kubota MK5

Post by coachgeo » Sun Apr 06, 2014 2:55 am

meez and ol Curtis been going round and round last two days via the net about side load on the crank bearing of the Kubota diesels. Basically there is NO end crank bearing. Just a bush and an oil seal. Thus for longevity in reality with these Kubota engines we should all be using a roller bearing support of some type on the stub shaft prior to any pulleys, sprockets etc etc. Seems most all OEM projects that use these engines are designed with NO side load. Geny's, Excavators, tractors, etc etc...... are all built inline with the crank. So for us when needing to put in a stub shaft support bearing the issue that arises from that is the additional width. Add on top of that in my case the additional width of CVT.... grrrrrrrrrnn

Have you considered sideloads at all in your build?

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Re: Honda Kubota MK5

Post by pietenpol2002 » Sun Apr 06, 2014 1:43 pm

Seems most all OEM projects that use these engines are designed with NO side load.
I don't think you have anything to worry about Coach. The 482 and 722 are virtually identical with the exception of cylinder count, and most of the 482s built were used in side loaded applications. The vast majority of truck APUs utilize the 482 and all are side loaded in driving the generator and compressor. Mine came with the pulley still bolted to the flywheel. It's not uncommon to see those engines running strong at 8,000 hrs having never been opened. Additionally, most use a poly-v belt arrangement that requires far more tension than you will be loading with a CVT. Below is an example.
482 Poly V.jpg
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Re: Honda Kubota MK5

Post by pietenpol2002 » Mon Apr 07, 2014 2:51 am

George, looks like our 2 posts should be moved to this topic.

Kubota and Side loads on the crank (Ultima's CVT's etc)
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Re: Honda Kubota MK5

Post by Tim » Mon Apr 07, 2014 5:28 pm

pietenpol2002 wrote:
In addition I didn't want the shape of the belt run ie crank , alternator and pump triangle to dominate the looks of the engine .
I do like the clean and uncluttered look you get on that end of your engine Tim. It's unfortunate if you have to bring back the water pump. My solution was to utilize 2 shortened Goldwing timing covers seem below just taped in place for mock up. Breaks up the triangulation a bit and joins the angle of the downtubes. I have to soda blast the covers yet to get the finishes to match. I also bent up some angled aluminum on the brake that will serve as belt guards and are yet to be mounted.
April 4 Honda-Kubota 006-2.jpg
A crafty move that really looks great and visually draws eye from the triangle . Nice work, well done you !
I have still to guard the cvt once it the bikes passed it initial trials. Breaking with tradition I hope to make reusable moulds and play around with thermoforming plastic sheet . At least if it works it might me useful for other cvt users /fabricators .

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Re: Honda Kubota MK5

Post by Tim » Mon Apr 07, 2014 5:29 pm

pietenpol2002 wrote:
In addition I didn't want the shape of the belt run ie crank , alternator and pump triangle to dominate the looks of the engine .
I do like the clean and uncluttered look you get on that end of your engine Tim. It's unfortunate if you have to bring back the water pump. My solution was to utilize 2 shortened Goldwing timing covers seem below just taped in place for mock up. Breaks up the triangulation a bit and joins the angle of the downtubes. I have to soda blast the covers yet to get the finishes to match. I also bent up some angled aluminum on the brake that will serve as belt guards and are yet to be mounted.
April 4 Honda-Kubota 006-2.jpg
A crafty move that really looks great and visually draws eye from the triangle . Nice work, well done you !
I have still to guard the cvt once it the bikes passed it initial trials. Breaking with tradition I hope to make reusable moulds and play around with thermoforming plastic sheet . At least if it works it might me useful for other cvt users /fabricators .

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Re: Honda Kubota MK5

Post by Tim » Mon Apr 07, 2014 5:46 pm

coachgeo wrote:meez and ol Curtis been going round and round last two days via the net about side load on the crank bearing of the Kubota diesels. Basically there is NO end crank bearing. Just a bush and an oil seal. Thus for longevity in reality with these Kubota engines we should all be using a roller bearing support of some type on the stub shaft prior to any pulleys, sprockets etc etc. Seems most all OEM projects that use these engines are designed with NO side load. Geny's, Excavators, tractors, etc etc...... are all built inline with the crank. So for us when needing to put in a stub shaft support bearing the issue that arises from that is the additional width. Add on top of that in my case the additional width of CVT.... grrrrrrrrrnn

Have you considered sideloads at all in your build?
Hi there

My Kubota z482 was from an Aixam microcar and it was all ready fitted with the cvt arrangement with a belt between the engine and reduction box . I assumed this would have been with in Kubota specification when the car was new. Going back to the days when I used to service combine harvesters the power from the engines was all extracted via belt . Most didn't have out rigger support and some were in excess of 100 bhp . The are obviously limits and it would be good practice to run the line of load as close as possible to the supporting bearing . In fact on my 482 is about 100 mm from the bearing , time will tell I guess !

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