Author Topic: Turbo Billet Block CB750 (Read 1113 times)

Cb750 Racer · « **on:** June 28, 2018, 06:47:24 pm »

Figured this was the correct section for the engine build thread. Just got a majority of the engine parts I needed from Ken over at Cycle X. He really hooked it up for me thanks again Kenny!

He got me a nice set of early cases and bored them for the JMR billet block.Also had the main bearing alignment repair done. Really clean job I must say. Stock weight crank with all the bells and whistles as well.

The transmission was undercut and also had the clutch hub rebuilt and balanced.

Cycle X lockup clutch was the only solution that make sense but Kenny came through with a 1 off extended kick shaft so that I can still use the kickstarter. The electric starter and flywheel will be removed and the Cycle X external charging system will take its place.

The engine will also use one of Messnermotos new cam chain tensioner which is rumored to start shipping within the next few weeks. Cycle X heavy duty primary chains will be used as well.Rods are still undecided Carillos maybe? I'll have to talk to Mrieck about it when I pick up my billet block within the next week or two.Also have a RAJAY FB40 in the mail with a custom adapter for a Mikuni HSR42 in the make from "eli" on the forum. Anyone got a Megacycle 125-N-T3 sitting around? Interested in a turbo cam for this beast.

dragracer · « **Reply #1 on:** June 28, 2018, 09:08:29 pm »

Nice start to what will be a fast project.

MessnerMoto · « **Reply #2 on:** June 29, 2018, 04:46:05 am »

Nice collection of parts;)

Cam chain tensioner should be ready by the end of next week.

slikwilli420 · « **Reply #3 on:** June 29, 2018, 05:27:18 am »

Quote from: MessnerMoto on June 29, 2018, 04:46:05 am

Nice collection of parts;)

Cam chain tensioner should be ready by the end of next week.

Whats the final cost? Id like to pick one up for my racer for next year. Feel free to PM instead of clogging up this thread.

Cb750 Racer · « **Reply #4 on:** July 01, 2018, 06:17:44 pm »

The porting god has blessed me. I'm not sure if a cleaner head exists.Go to JMR if you want only the best
Thanks again Mike for really helping me out taught me a lot today in the short time that I was there. Hope he doesn't mind me posting these photos I snuck them in for my personal pleasures

Picture I snapped while Mike was assembling the head. Also have a Megacycle 125-N-T3 on the way. I'm so excited to get this engine together it's been 3 years since I've had the bike on the road.

754 · « **Reply #5 on:** July 01, 2018, 06:45:16 pm »

What size is the bore ?
There is a set of 71.25 flat tops on for sale right now.

Cb750 Racer · « **Reply #6 on:** July 01, 2018, 08:07:40 pm »

Quote from: 754 on July 01, 2018, 06:45:16 pm

What size is the bore ?
There is a set of 71.25 flat tops on for sale right now.

72mm. Sad to see that setup go. That would have been one badass ride.

PeWe · « **Reply #7 on:** July 01, 2018, 09:41:08 pm »

Nice tech porn pics! What about an inlet port view? Head port job is always interesting.
Guides are stock steel?

You will add additional case breather? Modification of the clutch cover works fine on mine. I should have been aware of this for 35 years ago.
http://forums.sohc4.net/index.php/topic,172703.msg2010515.html#msg2010515
I saw that mod a video of Mikes bike.

Cb750 Racer · « **Reply #8 on:** July 02, 2018, 11:31:55 am »

Quote from: PeWe on July 01, 2018, 09:41:08 pm

Nice tech porn pics! What about an inlet port view? Head port job is always interesting.
Guides are stock steel?

You will add additional case breather? Modification of the clutch cover works fine on mine. I should have been aware of this for 35 years ago.
http://forums.sohc4.net/index.php/topic,172703.msg2010515.html#msg2010515
I saw that mod a video of Mikes bike.

Only pics I have at the moment sorry PeWe. The inlets were just as nice I can assure you that

The guides are from yamiya in Japan link is : http://www.yamiya750.com/index.php?main_page=index&cPath=21_249_51
Extra breathers will be crucial I plan on adding a catch can/air oil separator under the tank with lines coming off of the cam sprocket cover. I havnt done anything yet though so my plans might change a bit over the next month.ill keep you posted I've been watching your thread closely

PeWe · « **Reply #9 on:** July 02, 2018, 12:35:51 pm »

Ok, I cannot resist to compare port job with my head that is done 35 years ago. I'm sure the know-how has developed how to create a good port, not only removing as much alu as possible.
Nice breather is shown here as you might have seen. More CB750 tech porn

http://forums.sohc4.net/index.php/topic,158461.msg2006076.html#msg2006076

Cb750 Racer · « **Reply #10 on:** July 02, 2018, 03:01:10 pm »

I'll get you some pictures PeWe. Theories have certainly changed/improved over the years. I was too excited to see it and just kick it with Mike that I didn't get too many pictures.

RAJAY FB40 just arrived from Germany. Shout out to "eli" on the forum did a tremendous job making an adapter plate to fit my Mikuni HSR42 and the turbo looks super clean. Can't go wrong with NOS

This turbo should spool around 6000rpm with the Megacycle 125-N-T3 cam but not certain on exact numbers. I guess time will tell

NitroHunter · « **Reply #11 on:** July 03, 2018, 04:05:26 pm »

Wow that looks great. Perhaps that "B" Turbine, even with the .40 housing, will get to spooling up even lower rpm-wise at moderate load. I think it should be a great road combination. At one time I had toyed with the idea of that F40 set up coupled to a B25 turbine for my street cruiser, using the 108 LC F-2 cam. The thinking was quick spool for very short bursts before the backpressure became an issue. So I'm excited to see how your system works out.
What retainers and springs are those, are they coated?

Cb750 Racer · « **Reply #12 on:** July 03, 2018, 09:40:00 pm »

Quote from: NitroHunter on July 03, 2018, 04:05:26 pm

Wow that looks great. Perhaps that "B" Turbine, even with the .40 housing, will get to spooling up even lower rpm-wise at moderate load. I think it should be a great road combination. At one time I had toyed with the idea of that F40 set up coupled to a B25 turbine for my street cruiser, using the 108 LC F-2 cam. The thinking was quick spool for very short bursts before the backpressure became an issue. So I'm excited to see how your system works out.
What retainers and springs are those, are they coated?

My thoughts exactly Nitro. I figured the "B" series turbine with the .4 housing should be reasonably quick spooling while not choking the setup too much at higher rpm. You're setup would be a mid range rocket that would certainly have any Busa owner thinking "WTF?". I'm very exited to see how this all works out as well

The springs are standard kibblewhite springs nothing special. The retainers are the "super-cooling" F2 retainers from Kenny over at Cycle X. Figured the holes will aid in cooling the valve guides which has always been a problem with these F2 heads. They really are Top-Notch!

Here's a few more pictures of the turbo. Not the best angles but porn is porn i guess

Also just got my hardwelded rocker arms and coated rocker arm shafts in the mail today from Cycle X. Great deals just keep falling in my lap. Thanks again Ken for hooking it up!

Ordering the final components for the build tomorrow which is a set of APE Pro Street rods and a cam chain to fit with the Messnermoto cam chain tensioner. I also may have a TOP SECRET Primary chain tensioner in the works as well but I guess we'll have to see how things line up time wise.

PeWe · « **Reply #13 on:** July 04, 2018, 03:23:06 am »

Good looking parts!

My K6 got rocker arms from CycleX this spring, marked WebCam.

bear · « **Reply #14 on:** July 04, 2018, 07:23:06 pm »

Consider cryo-ing that extended kick shaft.
They bend far to easily as is.

Cheers,
Brian

MRieck · « **Reply #15 on:** July 05, 2018, 03:49:50 am »

Quote from: bear on July 04, 2018, 07:23:06 pm

Consider cryo-ing that extended kick shaft.
They bend far to easily as is.

Cheers,
Brian

I recommended inserting a sealed bearing in the lock up spacer.

Sam Green Racing · « **Reply #16 on:** July 05, 2018, 10:36:45 am »

CB750 Racer, ya should have seen the inlet ports that Mike did on mine, they looked like they might swallow the carbs, haha.

bear · « **Reply #17 on:** July 06, 2018, 06:31:49 pm »

Quote from: MRieck on July 05, 2018, 03:49:50 am

Quote from: bear on July 04, 2018, 07:23:06 pm
Consider cryo-ing that extended kick shaft.
They bend far to easily as is.

Cheers,
Brian
I recommended inserting a sealed bearing in the lock up spacer.

Yep..that sounds like it might be a workable fix.
Either way the issue does need to be addressed before final assembly.
Combining both options could be well worth while.

eli · « **Reply #18 on:** July 07, 2018, 01:31:32 pm »

I'm happy you like the turbo

754 · « **Reply #19 on:** July 07, 2018, 01:35:55 pm »

Quote from: MRieck on July 05, 2018, 03:49:50 am

Quote from: bear on July 04, 2018, 07:23:06 pm
Consider cryo-ing that extended kick shaft.
They bend far to easily as is.

Cheers,
Brian
I recommended inserting a sealed bearing in the lock up spacer.

Did you mean bushing on the shaft ? It appears you can't slide a bearing on.

Ilja · « **Reply #20 on:** July 08, 2018, 02:26:14 am »

Looking good! A lot of nice parts going in.... and I´m jealous of that lockup clutch with extended kickstart shaft!
The stock clutch works also quite good with heavy springs, but with a drawthrough setup which is more agressive I think the lockup is a good idea.
I also have a lockup clutch on my Kawasaki as it slipped over 15psi.

Now that I think about it.... that extended shaft with spacer would make my kickstarter clear my footpeg!

Cb750 Racer · « **Reply #21 on:** July 13, 2018, 11:28:45 pm »

Quote from: Sam Green Racing on July 05, 2018, 10:36:45 am

CB750 Racer, ya should have seen the inlet ports that Mike did on mine, they looked like they might swallow the carbs, haha.

Send some pictures if you have any I'd love to see em!

Quote from: 754 on July 07, 2018, 01:35:55 pm

Quote from: MRieck on July 05, 2018, 03:49:50 am
Quote from: bear on July 04, 2018, 07:23:06 pm
Consider cryo-ing that extended kick shaft.
They bend far to easily as is.

Cheers,
Brian
I recommended inserting a sealed bearing in the lock up spacer.

Did you mean bushing on the shaft ? It appears you can't slide a bearing on.

Correct not really any space for a sealed bearing. The shaft is thicker than stock so I think cyrogenically treating it should be sufficient.

Quote from: Ilja on July 08, 2018, 02:26:14 am

Looking good! A lot of nice parts going in.... and I´m jealous of that lockup clutch with extended kickstart shaft!
The stock clutch works also quite good with heavy springs, but with a drawthrough setup which is more agressive I think the lockup is a good idea.
I also have a lockup clutch on my Kawasaki as it slipped over 15psi.

Now that I think about it.... that extended shaft with spacer would make my kickstarter clear my footpeg!

The softer clutch pull really made the lockup clutch attractive. The extended kickstart shaft was just the icing on the cake.

I don't think this engine will see more than 10psi often, race fuel just gets to be a hassle for longer rides.

APE Pro Street rods just came in they look absolutely flawless. My 96 link DID 219FTH should arrive any day now which is the last part needed before assembly.Still in search for a ATP turbo intake manifold for a cb750 still offering 100$ finders fee for anyone who can source one.

Ilja · « **Reply #22 on:** July 14, 2018, 04:09:20 am »

Quote from: Cb750 Racer on July 13, 2018, 11:28:45 pm

Quote from: Sam Green Racing on July 05, 2018, 10:36:45 am
CB750 Racer, ya should have seen the inlet ports that Mike did on mine, they looked like they might swallow the carbs, haha.
Send some pictures if you have any I'd love to see em!

Quote from: 754 on July 07, 2018, 01:35:55 pm
Quote from: MRieck on July 05, 2018, 03:49:50 am
Quote from: bear on July 04, 2018, 07:23:06 pm
Consider cryo-ing that extended kick shaft.
They bend far to easily as is.

Cheers,
Brian
I recommended inserting a sealed bearing in the lock up spacer.

Did you mean bushing on the shaft ? It appears you can't slide a bearing on.
Correct not really any space for a sealed bearing. The shaft is thicker than stock so I think cyrogenically treating it should be sufficient.

Quote from: Ilja on July 08, 2018, 02:26:14 am
Looking good! A lot of nice parts going in.... and I´m jealous of that lockup clutch with extended kickstart shaft!
The stock clutch works also quite good with heavy springs, but with a drawthrough setup which is more agressive I think the lockup is a good idea.
I also have a lockup clutch on my Kawasaki as it slipped over 15psi.

Now that I think about it.... that extended shaft with spacer would make my kickstarter clear my footpeg!

The softer clutch pull really made the lockup clutch attractive. The extended kickstart shaft was just the icing on the cake.
I don't think this engine will see more than 10psi often, race fuel just gets to be a hassle for longer rides.

APE Pro Street rods just came in they look absolutely flawless. My 96 link DID 219FTH should arrive any day now which is the last part needed before assembly.Still in search for a ATP turbo intake manifold for a cb750 still offering 100$ finders fee for anyone who can source one.

That intake manifold shouldnt be very hard to TIG up by someone, or do you want to use original parts?

Cb750 Racer · « **Reply #23 on:** July 14, 2018, 12:26:03 pm »

It's more of a space issue. With the coils and catch can under the gas tank I'm really running out of room for the fuel pump/regulator. The standard ATP manifold doesn't use the stock carb boots the outlets are actually angled to match the head allowing the intake to sit closer to the head. I'm hoping this will push the turbo/I take far enough forward to allow me to mount the pump/ regulator in front of the battery box. Space is very tight really trying to fit 10 pounds of #$%* in a 1 pound bag

Cb750 Racer · « **Reply #24 on:** September 12, 2018, 08:34:59 pm »

Little update on the build, It's been a few months

USPS ended up loosing my 96 link DID219fth after 3 weeks shipping time and kept hesitating to declare it lost. Ended up costing me a month of time which really sucks but finally got one in my hands after ordering 3 under different names and addresses.

The 96 link DID 219FTH that's sold on Ebay is not endless which is my current setback thankfully MRieck has a tool on the way to connect the chain identical to factory.

The Megacycle 125-N-T3 came in a little while back as well the Intake lobes are a bit violent

The build will slowly start to come together over this month i'm still in search of an ATP turbo manifold if anyone is thinking of lightening their collection

Still offering a 100$ reward to anyone who can source me one.
Also looking for a 5/16 pingel petcock for a 1975-76 cb750ss gas tank if anyone knows the correct model please shoot me a pm it would be greatly appreciated.

Ilja · « **Reply #25 on:** September 22, 2018, 02:05:51 am »

Is that the special "turbo cam" from megacycle? With no overlap but more lift?

Nice...

MRieck · « **Reply #26 on:** September 22, 2018, 06:17:22 am »

Quote from: Ilja on September 22, 2018, 02:05:51 am

Is that the special "turbo cam" from megacycle? With no overlap but more lift?

Nice...

Yes....the Norris turbo profile. Very interesting to look at.

Ilja · « **Reply #27 on:** September 23, 2018, 04:58:41 am »

They look like my z650 / gpz 750 turbo cams... but those are shim-under-bucket ones so without rockers / rocker-ratio.

I see that the specs show only 5 degrees reduced duration on intake and exhaust, but the shape op the sharper lobe says that it will hold the valve open less long around maximum lift.
I think it will feel very strong throughout low and mid for a turbo-charged engine with this cam thats for sure.
I think classic lower compression pistons (8:1) are also needed with this timing.

But I'm curious to see what it will do on top-end, I don't know if it will be better, worse or the same... hard to predict.

MRieck · « **Reply #28 on:** September 23, 2018, 03:07:30 pm »

Quote from: Ilja on September 23, 2018, 04:58:41 am

They look like my z650 / gpz 750 turbo cams... but those are shim-under-bucket ones so without rockers / rocker-ratio.

I see that the specs show only 5 degrees reduced duration on intake and exhaust, but the shape op the sharper lobe says that it will hold the valve open less long around maximum lift.
I think it will feel very strong throughout low and mid for a turbo-charged engine with this cam thats for sure.
I think classic lower compression pistons (8:1) are also needed with this timing.

But I'm curious to see what it will do on top-end, I don't know if it will be better, worse or the same... hard to predict.

We'll see.

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Author Topic: Turbo Billet Block CB750 (Read 1113 times)