View Full Version : Rikuo Engine Build

02-02-2012, 06:34 PM
Good Evening Everyone,

Hope everybody is having a good week so far. Tomorrow is FRIDAY!;)

Some of you know that I am restoring a rare 1958 Rikuo RT 750. Its really rare. We believe only two or three ever made it to the States. That being said I thought it would be nice if I shared with you some pictures of the inside of a Rikuo engine. Over the last few days, I have been building the bottom-end of the Rikuo. I know almost all of you have never seen the inside of one of these rare engines. So here tiz:









Before I tore the bike down for the restoration, I fired her up to hear the engine. Sounds just like any Flat Head Harley... As I was pulling the engine down, I was very happy to see very little wear, and made notice to the quality of the internal components. Very nicely done! The crank spins happily on roller bearings, with helical cut gears that drive the oil pump, as well as four individual camshafts. The ignition system is powered by a battery, which is re-supplied by the engine mounted gear driven generator. A very interesting machine to be sure. Hope you guys enjoy the pictures!

Take care:cool:

02-03-2012, 08:30 AM
Thanks for the pics, I'll be following this with great interest.

02-03-2012, 11:52 AM
Do Harley parts interchange?

Steve Slocombe
02-04-2012, 04:39 AM
Dear Denis and John, I have a Rikuo parts book from the 1950s which still uses the Harley part numbers from 1932 when Rikuo bought the license to make the bikes. I have several customers from Japan buying VL parts which I believe are going into Rikuo big twins. I am not very familiar with the Harley small twins, but Denis' pictures show a motor which looks like many Harley parts are still interchangeable.

02-09-2012, 10:16 AM
Hey Steve

I would be very interested in exploring the idea of interchangeability between the two manufactures. I have pretty much everything I need for the engine, but I do need some items for the chassis. Could you direct me to any of your contacts in Japan? We have one or two but haven't had much luck buying anything from them. The most important item is the exhaust system. I believe its completely different than the Harley version. Someone at some point replaced the system on my Rikuo with a 1200cc version. The header pipes are dinged up too... Please let me know if think you can help.


Steve Slocombe
02-10-2012, 04:48 AM
Dear Denis, my Japanese customers seem to speak only part numbers, and if they are buying from me then I guess the parts are not available over there. On the exhaust, the Rikuo parts book shows the front pipe and all clips with the Harley part numbers, with just the rocket ship muffler having a 1951 part number. I'll try to get the manual, and a grubby Owners Handbook, digitised for the AMCA Virtual Library, but this could take a while.

02-16-2012, 05:58 PM
Hey Steve

Just looked at your post... Any help would be great!! Engine is done and sitting happily in the frame this afternoon. I'll post up some new pictures. Regarding the exhaust, are you thinking that a Harley header and muffler will be correct for this model? I haven't found any information that the Rikuo exhaust is the same as any Harley-Davidson exhaust. Maybe I missed something? If its true that there is a Harley exhaust that matches the Rikuo, then that will completely change my parts search!! Our Team is heading up to Millwauke tomorrow, so I will broach this subject with their Archives people. Really looking forward to it!!

Thanks Steve, keep in touch!

02-16-2012, 06:42 PM
Good Evening Everyone!

I hope everyone is doing fine and your week is going fine. Its almost Friday! I've had all sorts of fun this week with my beloved Rikuo. I'm DONE with my engine!! Its sitting happily in the frame. I took the time this afternoon to takes some pictures for you. I'm working away to get the gearbox together. I've got the drive and driven assemblies together and in their case, and all things are spinning in the proper way. The cuts on the gears all look nice and sharp, so I'm in good shape there. I had a chance to do further research this week as well, and have come to an interesting conclusion. This may be the only Rikuo RT-750 in the United States. I believe that Troyce Walls of Florida has a 1957 1200cc version, but I have yet to find anyone with a 1958 RT-750. Wooof! So I had a chance to take a few pictures this afternoon.






And here is a picture of the gearbox...........


I'm really happy about the way this bike is coming together. She's looking sharp!

Hope you guys like this pics! If you have any new Rikuo intel please send it my way!!

Have a great Evening.


02-16-2012, 07:51 PM
You are doing a really nice job Denis! Not to sidetrack your thread (too much anyway), here's a shot of a Rikuo engine that I saw at the Deeley Museum in Vancouver, B.C. last spring.


02-16-2012, 07:58 PM

Hey Cory

So.... is that a ummm... what is that? (I know its a engine you sorry frackin knuckle heads!!) Its completely different to what I have.. Do you know what model, year, production that you had a chance to find out about? It seems to me that Rikuo of all things equals rare. There is not sadly much left... Really interesting picture bro. Thank you.


02-16-2012, 08:05 PM

I'll go through my photos again but I'm afraid I didn't get the write-up in this picture and I've forgotten the year. Not much help eh? It seems to me that it may have been early 40's. If I get there again while this display is on, I will get some more info. Every once in awhile a Rikuo comes up for sale. I've seen a few over the years in Walnecks.

02-19-2012, 07:24 PM
Ok Cory

Let me know if you find out anything.

Take care my Friend!

Mitch and I put the Worwick back in its rack last week. Safe and Still. She's in good hands.

02-19-2012, 09:41 PM
I'll for sure keep it in the back of my mind Denis. If I don't make it before the display changes, I'll bug somebody else to pay attention if they happen to get there.

It's good to hear the Warwick is safe and sound! :D

08-22-2013, 11:04 AM
Dennis, & All,

There are two Rikuos lurking hereabouts.

One is a 1957 RQ750 (45ci) with a three speed trans, hand-shift, foot clutch, and total-loss engine lubrication. This is in contrast to your RT with four-speed foot-shift, hand clutch, and re-circulating lubrication. My oil tank is in the left "Fat-bob" whereas the RT incorporates the oil tank (or "bag" in Harley parlance) under the seat. This bike is currently about halfway through a nut/bolt restoration. Hope to have it ready for the Vintage Meet in October, but that ain't likely this year, I fear.

I think most RQs and RTs were originally the soft blue metallic candy color you have painted yours, although an old Rikuo expert - through a friend of mine there - tells me that the dealers or factory would paint the bikes any color a paying customer wanted. That in mind, my RQ is going to be the soft red candy metallic that I found on most of the tin against the bare metal.

The other Rikuo is a blue (old repaint) 1958 VL1300 (80ci). It now has a new top end and is running/riding great. It would not be had I not managed to purchase a great big transmission gear - using the original HD PN as found in the Rikuo parts book - from VL Heaven some years back. I don't know if that was Steve or not, but thanks if so.

As a side note, I bought a spare 750 engine several years ago only to find out a couple days ago that it is an RT engine with the pump on the bottom, and is actually quite a bit different from an RQ lump. Cam cover and pump, etc., are obviously different, but even the heads and jugs are slightly changed from the RQ. I have a broken fin on one of the RQ's cast cylinders and had hoped to use the one from the spare motor. Argh. It's always some damn'd thang.


08-22-2013, 11:10 AM
Fortunately, this engine toured with the Deeley collection. Saw it in Tampa several years ago. Then I was mostly interested in Honda 250/305 dry-sumps, one of which Deeley has a fine example in original-paint pale red metallic.



08-22-2013, 05:43 PM
Hi Dennis; A Rikuo engine was sold at our antique MC meet here in southern ontario(paris) in june.The VIN was Rxxxx.It sold for acouple of hundred bucks.Wish i took some photos........John

08-22-2013, 10:14 PM
You are doing a really nice job Denis! Not to sidetrack your thread (too much anyway), here's a shot of a Rikuo engine that I saw at the Deeley Museum in Vancouver, B.C. last spring.


Turns out this engine is a Kurogane. It reads from right to left クロガネ.
There is some connection between Kurogane and Rikuo, but I think is mostly that both built machines for the IJA.

08-23-2013, 09:45 AM
You're doing a great job! I look forward to seeing more of it. I doubt this is the same as yours, but... don't forget the Rikuo that was on the "I Love Lucy" show that Fred and Ethel was going to ride from CA to NY.

Have FUN!

08-24-2013, 12:04 PM
Ya know, I have for a couple of years now thought that bike (Lucy Show) was a Rikuo Type 97 myself. A closer inspection of the cams cover in the large poster of that scene I have on the shop wall, though, causes me to think it's a Kurigane as well.

The IJA might have used "Type 97" as a spec number for certain military vehicle categories, as I've seen references to a Nissan Type 97 as well.

09-22-2013, 09:57 PM
Haven't seen much action on this post since I joined so I thought I'd bump this up with two photos I took of a Rikuo 750 at the National Motorcycle Museum in Anamosa, IA yesterday.

http://img.photobucket.com/albums/v493/bikamper/2013-09-21122722_zps6f811304.jpg (http://smg.photobucket.com/user/bikamper/media/2013-09-21122722_zps6f811304.jpg.html)

http://img.photobucket.com/albums/v493/bikamper/2013-09-21122735_zpsffe74c38.jpg (http://smg.photobucket.com/user/bikamper/media/2013-09-21122735_zpsffe74c38.jpg.html)

Good luck on the restoration. I hope to see more pics of it.

09-24-2013, 08:39 PM
Thanks Michael for bringing this post up again. I finished my Rikuo a few months ago and its now on display in the Museum on the first floor. I took a few pictures for you this afternoon. She really turned out nice! I finished the restoration with the muffler which I found through a friend in Japan, Masaki Tanimura. He also sent me a 1/12 scale model of my Rikuo from his shop in Japan. He was a great help to me in finding the last bits to complete the job. I'm really happy the way it all came together.

I hope you guys can make it out next month for the annual Barber Vintage Festival! Its going to be a real blast this year. Here is a link to the website so you guys can take a look. Myself, Chuck Huneycutt, Mitch Cobb, and the other riff-raft will be there and would really love to see you guys too! Here is the link: http://www.barbervintagefestival.org/

And here are a few pictures of my 1958 Rikuo

http://i1205.photobucket.com/albums/bb423/jdenismccarthy/92413RikuoImage11200_zps72007c3b.jpg (http://s1205.photobucket.com/user/jdenismccarthy/media/92413RikuoImage11200_zps72007c3b.jpg.html)

http://i1205.photobucket.com/albums/bb423/jdenismccarthy/92413RikuoImage21200_zps6f82ec29.jpg (http://s1205.photobucket.com/user/jdenismccarthy/media/92413RikuoImage21200_zps6f82ec29.jpg.html)

http://i1205.photobucket.com/albums/bb423/jdenismccarthy/92413RikuoImage31200_zpscf36a5c2.jpg (http://s1205.photobucket.com/user/jdenismccarthy/media/92413RikuoImage31200_zpscf36a5c2.jpg.html)

Take care


09-25-2013, 01:30 AM
Denis ,great job on the bike ,are they tool boxes at the rear of the oil tank??Rob

09-25-2013, 08:34 AM
GREAT JOB! Looks fantastic! This may sound like a silly question, but what does a Rikuo sound like? Does it sound like a regular "Flathead" engine? Like a VL for example?

09-25-2013, 08:38 AM
Thanks for posting the new pics, Denis. I was surprised to see the Rikuo in Iowa after reading this thread.

03-10-2019, 09:24 PM
Hi Cory!
I believe that the motor you posted a pic of is not a Rikuo, but a Kurogane. Rikuo couldn't satisfy the Imperial Army's need for motorcycles, so a 2nd factory was put to work to churn out more bikes. The Kurogane (meaning "Black iron") was based on the H-D VLH 80 CID engine and are in many ways different from the Rikuo. Like the timing cover on the depicted engine (the lettering says "Kurogane") which hasn't a tin cover and looks quite different. The Kurogane is a kind of improved copy of the Rikuo.
Regards, Kim Jarre
Oslo, Norway (Born in B.C.!)
Membership #25693

Steve Slocombe
03-12-2019, 05:26 AM
Dear All, my digitised copy of the 1953 Rikuo parts book, showing nearly all Harley part numbers for the small twin and big twin versions, has been with the Virtual Library for a while, and I hope will soon be uploaded.