You have an old obsolite motor. It produces 18 H.P. at
3000 R.P.M. To run a REAL generator and not a toy you buy at Home Depot your motor will have to run at 1800 rpm
because a REAL generator runs at 1800. I don't know if your motor will put out enough H.P. at that rpm. Don't know
if your , cut down , fly wheel will keep the engine turning
smoothly to produce it's rated H.P. how much weight did the fly wheel loose ? Is it still balanced ? Will the
generator you get turn the same way as the motor if it is
direct coupled ? If not you will have to use belts. you need a minimum of 10 H.P. for your gen.
Good luck

i thought that my Kubota D 850 runs at 1800 rpm not 3000 ??
and I was just wondering why the Kubota is used so extensively in the Luxury motor coach industry ?? My plan is to install the Kubota in my bus conversion, that is if i can make it into a REAL generator. By the way who it the conceited nut that replied to my post ??

I'm the conceited nut, that is if that was an insult.
Kubota has a bulk selling policy for their engines and they have been around for over 50 years. your engine will
run at any speed you want it to. ever here of a throttle ?
It HAS to run at 3000 rpm to produce it's rated H.P.
My Kubota service dept. doesn't even list your motor any
more. too old. I took the time from my day to do some
research for you to reply to your post because from what
i've read you have almost no idea of what your in for let
alone any idea for what you have for a motor. I know how
these systems work. I build them and the transfer panels
for each. I use one for up to 15 hours non stop after a
hydro outage. i asked you the first most important questions before any project starts and i get insulted ?
I'm not conceited. I just know more about the subject than
you. you asked, i tried to help, and i get this ? The
Kubota is a very good motor but not one i'd use. When they
break down they break down BIG money, if you can find a
dealer near you. I use industrial engines that run 24/7
untill the world runs out of oil. For your limited use you
will be fine. Don't bite the hand that feeds you. Good
luck and have a good weekend.

I DONT BUILD GENERATORS NOR ENGINES BUT, AS YOU NOTED KUBOTA HAS BEEN AROUND FOR ??? WHAT 50 YEARS. MY UNDERSTANDING FROM NUMEROUS DEALERS, WRICO IN OREGON, BUILDS GENS FOR MULTI PURPOSE AND LUXURY COACHES, MAGNUM PORTABLE LIGHT TOWERS THE LIST GOES ON AND ON. YES THE D 850 IS AN OLDER DIESEL ENGINE AND AFTER SITTING FOR SEVERAL YEARS IN A FIELD IT STARTED UP AFTER PRIMING FUEL SYSTEM. I AM NO YOUNG PUP AND NEWER IS (NOT) ALWAYS BETTER. YES FINDING PARTS IS A PAIN IN THE BUT. THEN AGAIN IF ALL GOES WELL I SHOULD ONLY HAVE A GRAND TOTAL OF $ 1500 FOR WHAT A $ 5000 GENERATOR COST.OK SO ITS NOT NEW !!! NEITHER AM I AND WHEN ONE IS ON S.S.D.I. WE HAVE TO GET THE MOST BANG FOR OUR BUCK AND I BELIEVE/HOPE I AM DOING SO. THAT IS WHY I AM ON THIS AND OTHER FORUMS HOPING TO GET USEFUL AND RESPECTFUL ANSWERS TO MY QUESTIONS. ONE MITE SAY A FEW FEATHERS WERE RUFFLED WHEN I WAS TOLD I DID NOT HAVE A (REAL)GENERATOR. AS FOR MY USE, IT WILL BE MORE THAN ADAQUATE, IF I DONT NEED TO USE BOTH ROOF TOP A/Cs AND EVERY THING ELSE IN THE COACH AT THE SAME TIME. THANKS FOR ALL YOUR HELP. ONEmule

We may have gotten off on the wrong track but as in " real " generator they turn at 1800 rpm. most of the " crap " that is sold in big box stores turn 3600 rpm.
your system will do you perfectly for what you want. you
really don't want a lighting plant that turns 3600. too much noise. As i read it you don't have a generator. you just have a motor and are looking for a generator,right ?
Kubota has been around since 1890. Went to north america
in 1969. Did you forget to turn off your Cap Locks or are
you yelling your head off ? If you can get this going for
$1500 or less you have one hell of a deal. My hat goes off
to you. good stuff. As i said before you do have a good motor and there is nothing wrong with it. It will serve you
fine.

THANK YOU KALINING. YES WRONG START, MY APOLOGIES. I AM STILL TRYING TO LOCATE A GEN END OR (HEAD) I BELIEVE THEY CALL THEM, IF I AM NOT MISTAKEN THE KUBOTA d 850 WILL HANDLE A 7.5 KW. SO IF THERE IS ANYONE THAT KNOWS A COMPANY THAT SELLS THEM WITH A DIRECT MOUNT I WOULD BE GREATFUL. RANDALL

Let me start by saying that the initial response by "Kalining" was indeed very snotty & condescending. I, on the other hand, would like to put in my two cents WITHOUT putting you down or essentially calling your project a waste of time. I have a bit of experience in this area, as I am in the midst of the EXACT same project. I, too, have a D850 that I'm building into a standby generator. A few points of clarification. As the D850 has an intermittent max of 18 bhp at 3000 rpm, it would be suitable for roughly a 10kw generator head. Now, to connect a head to be used at 3000 rpm, you won't be able to direct couple. A belt drive is the likely choice. Should you go with an 1800 rpm, direct couple, according to the power curve for the D850, you'll only have about 13.5 bhp to work with, which won't get you much of a generator. While the 1800 rpm generators are generally more desirable for extended use, the 3600 rpm versions are hardly 'toys'. They are quite suitable for most applications however it would be important to choose your vendor wisely. For intermittent use, they are perfectly fine. The head I obtained is the Voltmaster AR100, a brushless unit which produces 10kw peak, 9.5kw continuous, requiring 18hp at 3600rpm. http://www.voltmasteramerica.com/products/AR100.htm

I got it for a song off Craigslist-brand new.

You could also do one of those rather reliable 1800rpm Chinese ST heads, but you'll of course require a greater pulley diameter variance to step down to 1800 from 3000.

To mount up such a beast, dual groove sheaves are required to handle the load, sized accordingly to match the engine speed with the required rpm of the head. It's also important to size the sheaves large enough to prevent belt slippage.

I have some technical documents for the D850 that I'll be happy to email you upon request, as well as the data sheets for my generator head.

Also-parts for the 'old' D850 are still readily available. Like yours, mine was sitting for a number of years & I just slapped a battery on it & it fired right up. They are VERY reliable motors & if the hours are not too excessive, you should get a lot of use out of it.

Oh, almost forgot another important point. If your engine was not originally set up to drive a generator, (BG designation), then the governor spring will likely need to be changed to a more 'responsive' one, Kubota p/n 19259-56411. This is necessary so the engine will maintain a closer 5% rpm tolerance when under varying loads.

Tis all for now. I look forward to maintaining a dailog on your project & rest assured, I won't be talking down to you on the subject.

FYI-another great web resource is www.utterpower.com

Steve

You may need even more than a double groove for 18 HP depending on the belt size.
Even 3 HP requires a triple in A size.
Machinery's Handbook should have the the sizes and power ratings.
Smaller pulleys require smaller belt sizes, and more belts.
Larger pulleys can use fewer and larger belts.
If you want to do it correctly the design data is out there.

Here is a link that might be useful: V-belt sizes

Hey,
I have been building a generator with a VW rabbit diesel and have quite a bit of luck.

I am using a 20kw st head, coupled with belts.
The belts arent the normal v belts, but instead belts from gates (about 2" wide) and are sycro. The belts are designed to allow the VW rabbit engine to run at 2200 rpm, which was my target RPM because of the hp at the curve on the rabbits torque curve. Down load from Gates the DFProdStd. Its called Design Flex Pro. It will allow you to select the right belt for the stress and horse power. You can order shims for the 42 and 44 mm shafts common on ST Generators

I bought a Pierce adjustable speed governor off ebay. It allows me to have an idle position for start up and shut down, then an adjustment to put it right on my desired RPM (2200). I use pulleys off the engine to run the governor right around 3200 rpm (don't spin a governor faster or there may be internal damage, usually 3600 is max). I used threaded rod and tierod ends from a lawnmower (bought at Tractor Supply) to connect the governor to the diesel injector pump. The guys at Pierce were great. Make sure you have no slack in the linkage, or springs that compete with the movement of the governor (like to pull back to idle).

Lovejoy does make couplers, but be sure and use the right one. I am using a LF-16 coupler which will help with any misalignment and to tapen the vibrations from the engine. I had a problem with torsional vibrations knocking my drive shaft loose. The LF-16 is designed to isolate the engine from the shaft, but in an easy to mount to the flywheel configuration. See Lovejoy's web site for more about the LF-16 (you may not need one the same size as I did). The "normal Lovejoy coupler doesn't kill the torsional vibrations per the engineers. The folks at Lovejoy are very helpful.

I have been able to pull over 45 amps at 220v (9 kw+) for a welder and not had any problem with engine rpm or voltage deviations.

Hope this helps.