Topic: A little help from my friends... CB550 Mr. Turbo

[Ricky_Racer]

All you turbo pros in bike builder land....

I've got a couple CB550's and a loose CB650 motor lying around, as well as this Mr. Turbo kit for a CB550... They all need to get together. 

Help!

Can anybody ID the model of this Rajay turbo? The tag on the unit doesn't help at all. The tag just says: Roto-master, Serial 0138112, Model 600594-01. I've checked with a couple turbo rebuilding companies and none of the numbers seem to reference anything in their records.

The kit came with a Kei'hin carb but the only markings on the carb are the Kei'hin cast-in "K" symbol and half a paper tag that says "Mr. Turb..." Can anyone ID this carb? I'm sure it is as supplied with the package.

Anyway, thanks for any help anyone can give. I appreciate your time. RR

[TurboD]

Post a close up of the id tag. The carb looks to be a newer style Harley.

[Ricky_Racer]

Thanks, TD. There is no tag on the carb and no model number. Do you mean the tag on the turbo? RR

[Ricky_Racer]

TD, you're a genius! I took a closer look with a magnifier at the carb and found the number SE21. That turns out to, in fact, be a carb Harley used in 1976-78. It has obviously been modified by Mr. Turbo and an adapter fitted to the base, but it does have a Harley application and kits, if I need them, should be available. Thanks, again! RR

[754]

 I bored a lot of those carbs out, def looks like the same body as HD.
 I think if you have some basic measurements of the turbo body, someone will know which series.

[Jim F]

Why not call terry Kizer
He rebuilt my ATP kit. Isn't he in fact, Mr. Turbo?
Good luck
Jim

[Lostboy Steve]

Did you check Majestic Turbos? Theyve done a lot of good work in the past. Even sourcing parts for stuff long dead.

[TurboD]

On the turbo, look inside the exhaust turbine housing intake, there should be a number cast into it (.28 maybe). Also measure the intake on the compressor housing (carb flange). And maybe A close up pic of the turbo id tag.

[Ricky_Racer]

Hi, TD. I took a look inside the exhaust inlet opening of the turbo and found some engraved characters: 1) the number 8 and, 2) 4LAC. I hope that helps with the ID. Please let me know if I can provide any additional info.

I've also attached a photo of the tag on the turbo. Thanks again for your expertise!

RR

[kmb69]

.....
Can anybody ID the model of this Rajay turbo? The tag on the unit doesn't help at all. The tag just says: Roto-master, Serial 0138112, Model 600594-01. I've checked with a couple turbo rebuilding companies and none of the numbers seem to reference anything in their records.
.....
Anyway, thanks for any help anyone can give. I appreciate your time. RR

Did you check with Rotomaster proper? They have a current website: http://www.rotomaster.com

[Mitchell]

I cant help you on the I.D. of your turbo, but please keep us posted this setup is going to be sick nasty on a 550

[Ricky_Racer]

Thanks for the suggestion, Keith. Yes, I called them a couple days ago. Spoke with a long-time tech there and sent him photos and info. He told me that the turbo was no longer made and that I should contact Turbonetics, but their website wasn't any help. I'll try to contact them next week but I'm not optimistic that I'll get much help there.

RR

[Ricky_Racer]

Thanks, Mitchell. I'd really like to bolt a 650 head on a 550 lower to reduce the comp ratio and improve the flow but I'm not yet sure if the exhaust or intake manifolds will fit the 650 head. I may end up just sticking this thing on a plain-jane 550 and see what happens. It's not like I don't have fourteen other priorities right now...    RR

[TurboD]

Ricky yes the tag is of no help, it does not use the normal Rajay ID stampings. It looks to be a 301 series. Rajay made two series in these small turbos 301 and 370.

To start out, the exhaust housing sizing is probably the single most important thing when it comes to putting a combination together. It will make or break how well and or how much power a given setup will make. This said, if the "4" cast in the exhaust is in fact a ".4", this housing will be entirely too large for a 550-650 or even a 750-836. I have used the .4 housing setup on 1000-1075 Kawasaki's, and even they are lazy to spool. On a small engine such as a 550-650, you will want a .28 setup and even then I guess that the turbo will be slow to spool and very late in the RPM band. These old Rayjay/Rotomaster turbos are very inefficient by any measure of todays standards.

The trouble that you will run into today is that most if not all turbo companies and repair shops, simply don't have any experience with this old units. When I started using them almost 25 years ago, the choices were somewhat limited then.

I recommend that you retain a reasonable amount of compression, as you will need it off boost, and to help spool the turbo.

[77F]

+1 on what TurboD said the .4 a/r exhaust housing will be over sized spool slow on 550. The BB25 I've been messing with on 1060cc dohc Honda doesn't see Full positive pressure till 5000 rpm and it's undersized for cc. Measured the exhaust housing on one I have sitting hear that's supposed to be a .4 a/r  as per tag it measures ruffly 2.115 id on exhaust inlet close to wheel.  The b flow compressor inlet measure ruffly 1.605 on inlet  F flow compressor measures 1.845 on inlet hopefully those numbers might help some. Have a bb25 could measure and post specs as well if you would like as well. Half to go get it though lol.

Regards,

Josh

[gpzkat]

Ricky_Racer - I know this is resuscitating an old thread but hope that's OK. I found this post after searching around a LOT on the Web for info about my bike's turbo.  Mine is exactly the same, 16 units before yours per the serial#. 

Did you get the turbo worked on, and if so what info can you share? I believe mine is fine, but I'd like to clean it and check it out, if possible.  I know even the gaskets/kits are rare and expensive.

About the bike, it's an '82 Suzuki GS1100E that was raced at Bonneville. Did 184MPH, was never used stock, so I have all original take-off parts.  But I want the turbo!

Long time since I've had a CB750 but am helping a friend restore his, so I'm still in the game, sorta.  Here's a video of the bike.

[Cb750 Racer]

Agreed with what others said. If you measure of the intake inlet ID I could tell you exactly what trim it if. B compressor is 40mm, F compressor is 45mm at the inlet. .4 AR will be wayyyyyy to large for a 550, I'm wondering if my .4AR turbine housing on my 1040cc cb750 will spool let alone a cb550.Shoot over pictures of your turbine i'm curious to see if it's a B style. To put things in perspective Mr.Turbo would run Rajay F40's on their Hayabusa turbo kits into the 2000's Like others said A b25 would be a much better match. I have a spare if you're interested but you may want to even look into the smaller IHI turbos like the ones that came off the ATP cb550f turbo kits. I rebuild these old RAJAYS if you wish you get your unit rebuilt. It does get pricey though the rebuilt kit alone is around 400$. These turbos are very robust in most cases they get rebuilt without really needing to be.You have to remember these turbos were mostly for aircraft use if they have to rebuilt every hounded hours they wouldn't be nearly as popular. The compressor won't freely spin like a ball bearing turbo these units need oil pressure to really spin freely, most people take that as them needing a rebuilt when THAT'S HOW THEY'RE SUPPOSED TO BE. Words from Terry Kizer himself.

EDIT- Sorry just realized this thread is 4 years old.

[gpzkat]

That's OK and I'm sorry to revive a long dead thread it just seemed that the OP, if still around, might have insight on this tricky issue. But what you said helped a lot, and I thank you (and promise never to do it again).

I put it all together and fired it up after 26 years.  There was very little play, and it spun freely but not easily, just as you say.  It's in the shop getting jetted/dynoed, has a new Mikuni HSR42.  It sounds great and I hope that it tunes up well.

Oh and I picked up a '73 CB750 project so I'm using the forum a lot, it's great.  Here's the cleaned up bike, shot of the turbo side.

Agreed with what others said. If you measure of the intake inlet ID I could tell you exactly what trim it if. B compressor is 40mm, F compressor is 45mm at the inlet. .4 AR will be wayyyyyy to large for a 550, I'm wondering if my .4AR turbine housing on my 1040cc cb750 will spool let alone a cb550.Shoot over pictures of your turbine i'm curious to see if it's a B style. To put things in perspective Mr.Turbo would run Rajay F40's on their Hayabusa turbo kits into the 2000's Like others said A b25 would be a much better match. I have a spare if you're interested but you may want to even look into the smaller IHI turbos like the ones that came off the ATP cb550f turbo kits. I rebuild these old RAJAYS if you wish you get your unit rebuilt. It does get pricey though the rebuilt kit alone is around 400$. These turbos are very robust in most cases they get rebuilt without really needing to be.You have to remember these turbos were mostly for aircraft use if they have to rebuilt every hounded hours they wouldn't be nearly as popular. The compressor won't freely spin like a ball bearing turbo these units need oil pressure to really spin freely, most people take that as them needing a rebuilt when THAT'S HOW THEY'RE SUPPOSED TO BE. Words from Terry Kizer himself.

EDIT- Sorry just realized this thread is 4 years old.