Topic: Turbo Billet Block CB750 Hits the Dyno!

[gpzkat]

Not sure I'd go drilling yet, but then again I'm not a carb expert and I left it to a guy with a dyno who could measure fuel/air ratio etc.  He installed a O2 sensor.  I bit the bullet, it cost me some $ but I would just have been stabbing in the dark.  Good luck whichever way you go.

[MRieck]

 If it is to rich it will fall on its face too.....just something to keep in mind.

[754]

Drill 2 or 3 times if you have to... it s way better than too big one time..

[Jim F]

Do you have a shop with a dyno that you can check your air/fuel and jet it accordingly?

Jim

[Cb750 Racer]

If it is to rich it will fall on its face too.....just something to keep in mind.

That's definately a fair point. The AFR guage would pin 14:1 or leaner before breaking up. That's at about 5000rpm just creeping on 1lb of boost so it's leading me to believe that it is leaning out. Sorry no update on drilling a 300 jet yet was figuring out a clutch fiasco on my busa that's up next!

Drill 2 or 3 times if you have to... it s way better than too big one time..

I bought nearly a whole jet kit from Sudco Mikuni so I'll just sacrifice one of the smaller units just to see what happens. I don't think I would have the balls to drill the jet if it was my only

I didn't think people even approached the 300 jets sizes so I thought I was going a bit crazy swapping needles trying to make the 250 work but that really does seem to be reasonable afterall. I have a 4.5 float needle installed so very unlikely it's starving on that end.


Not sure I'd go drilling yet, but then again I'm not a carb expert and I left it to a guy with a dyno who could measure fuel/air ratio etc.  He installed a O2 sensor.  I bit the bullet, it cost me some $ but I would just have been stabbing in the dark.  Good luck whichever way you go.

Do you have a shop with a dyno that you can check your air/fuel and jet it accordingly?

Jim

I do but I really don't trust the operator. First time over there We put my mr.turbo gpz900r on the dyno and he straps the bike by it's fork oil transfer tube(not sure exactly what its called but if you have a 900r you know what I'm talking about) and essentially just blows my seals out right away. Then come first pull I tell him the bike has no rev limiter and to try and keep it below 10krpm and right away takes it to 12-13k rpm  Then my wastegate was sticking and he insisted for whatever reason against all logic that turning the wastegate screw in reduced the boost. I heard he was pretty good at FI tuning but I'm not letting him within arms reach of my stuff anymore. Told the owner the only way I'm going back is if I'm the operator.

Sorry replied out of order didn't realize until I was too late

[Don R]

 Any updates on the turbo project? And bump so it's easier to find.

[Cb750 Racer]

Any updates on the turbo project? And bump so it's easier to find.

Hey Don, Sorry the end result is still much of the same since my last post. After playing with the fueling every way possible, I'm nearly certain that my afr's are perfect transitioning into boost, I ended up going down on the main noticing that a split second before the bike was cutting out I was seeing 9's on my afr guage. Dialed it back to a 240ish main jet just to test down from the 310ish just to test. With a 30% difference in fuel I should have some sort of quantifiable results right? The afr's were better at about 12.0 but still at 6k the bike still just falls on it's face. I'm beginning to think it's more an ignition issue and I may be actually set to the wrong map. Over the winter I'm gonna get the programming module for ignition and go from there. If I do still end up having fueling issues I'm gonna swap over to an S&S super B with a thunderjet which would actually allow me to mount the carb closer to the turbo as well.

[scottly]

but still at 6k the bike still just falls on it's face. I'm beginning to think it's more an ignition issue and I may be actually set to the wrong map.

What ignition are you using? If it's a POS Power Arc ignition, try something else. They gave up on it...

[gpzkat]

Just some FYI - my GS1100E Mr Turbo had a Super B long type for Bonneville runs, but it was completely frozen and not usable. After research and with major budget constraints (i.e. I'm a cheap SOB) I got an HSR42 for about $220.  The tuner said it wasn't ideal, it's restricting power but the bike has so much I'll never tap into, so no issue to me. 

It really works well on the street.  I put a deeper float extender on it.  I had rigged up an electric fuel pump and the tuner told me no need, although working fine, he removed and ran about a dozen dyno runs, no problems there either.  The bike had a huge plumbing valve for a fuel tap and automotive sized fuel line on it when using the Super B.  I put a new OEM one on.  The original turbo kit came with a Facet-type pump I think, I've seen on eBay with sticker that quadruples the price evidently. There was an automotive AC Delco fuel pump in the box of parts I got, but wasn't on the bike. Also a methanol tank that I guess I'll sell, it's pretty decent.

So with a cheapo HSR42 for a HD and standard fuel line I'm not having any problems, but I'm not racing, just street riding with an occasional blast into turbo land.

Oh and it has Dyna coils and ignition, never had to fiddle with it, it just started and ran fine so I got lucky there. Good luck!

Hey Don, Sorry the end result is still much of the same since my last post. After playing with the fueling every way possible, I'm nearly certain that my afr's are perfect transitioning into boost, I ended up going down on the main noticing that a split second before the bike was cutting out I was seeing 9's on my afr guage. Dialed it back to a 240ish main jet just to test down from the 310ish just to test. With a 30% difference in fuel I should have some sort of quantifiable results right? The afr's were better at about 12.0 but still at 6k the bike still just falls on it's face. I'm beginning to think it's more an ignition issue and I may be actually set to the wrong map. Over the winter I'm gonna get the programming module for ignition and go from there. If I do still end up having fueling issues I'm gonna swap over to an S&S super B with a thunderjet which would actually allow me to mount the carb closer to the turbo as well.

[Cb750 Racer]

Turns out I'm a dumbass and may have finally cracked the code to the hsr42 carb. I put a thunderjet in the carb with results being much of the same. Turns out I've had the vacumm port in the rear open for the past several years trying to tune this thing which should be plugged off. This vacumm port should only be used for a vacumm operated petcock or a vacumm operated switch. Certainly not OPEN TO ATMOSPHERE  . Only figured it out after buying my first harley the other day. Oh well you live and you learn I'm gonna block off that port and retune it this weekend will keep you posted with the updates.


In other news I finally met the Gentlemen who machined Mike Riecks Billet blocks at Rice O Rama a few weeks back. Very cool guy he said mine was the first one he's seen in the wild beyond Mike's bike which was sad to hear. Unfortunately he said that due to lack of interest he had to stop making them due to the fact he only could get material cheaply by buying 30 or so blocks at a time. The overhead essentially pushed him off from making more. He did give me the information required to make my own in the future and I may be taking him up on it if there is more interest. Of course will talk to Mike before going any further definitely don't want to step on his toes by any means.

[newday777]

In other news I finally met the Gentlemen who machined Mike Riecks Billet blocks at Rice O Rama a few weeks back. Very cool guy he said mine was the first one he's seen in the wild beyond Mike's bike which was sad to hear. Unfortunately he said that due to lack of interest he had to stop making them due to the fact he only could get material cheaply by buying 30 or so blocks at a time. The overhead essentially pushed him off from making more. He did give me the information required to make my own in the future and I may be taking him up on it if there is more interest. Of course will talk to Mike before going any further definitely don't want to step on his toes by any means.

I wonder if I met him and didn't know it. I was there.
Did you have your bike there in the show? If so I didn't notice it.  I had my K5 there with Brad's greenish K4.

I'd love to get one of those blocks......

[PeWe]

The billet block look really good and match the head very well! 
It costed some, but the alternative is not for free either.
Finding a good looking stock cylinder block with no fin damage, remove sleeves, bore for bigger sleeves plus a wider done bore at the bottom, ca 5mm deep 1.25mm wider for o-ring and sealer.  Possible when using CycleX 74.5 mm sleeves, perfect for 70mm pistons.
(Too thin for 71.25mm pistons my billet block has)

Make sure both top and bottom are flat with smooth surfaces for RCS and MLS gaskets.
Assemble the sleeves, bore them + final hone.

My 970cc cylinder had to be milled 1mm (84mm height) to match the NOS JE pistons I have bought rather cheap. Upper 2 oil o-ring indentations milled too when they disappeared.
My nearby shop did not charge me for all extra job doing the extra details to mill the wider part at top for sleeves 1mm deeper.

My Billet block is on vacation until I have cracked the carb jetting using a stock cylinder with 970cc pistons.

Cb750 Racer, you are not alone with long ongoing carb issues
My Mikuni TMR have filter adaptors, but they do not cover the pilot air jet which explains the never ending rejettings. Installed filter via hoses connected to the holes this year when finding out.
Hopefully the final dyno next week to verify the good jetting that did not work before.
Tried same setup twice, plugged and semiplugged pilot air jets sabotaged from idle to 4000rpm.

CB750 owners are very impressed when they see the billet block. Other bikers too
No issues with eventual oil leak between 1-2 and 3-4 that can happen if sleeves are not completely sealed at the bottom with tight fitted o-ring AND sealer as Hondabond or Wurth Super RTV or similar on top.

I have a slow onging engine build that has got its upper case bored to welcome the Billet block as an alternative.

Here how well head and billet block match each other, especially K6 and 392 heads.
My K2 head has a small stick out.

Soon 6 years after delivery and around 25.000km I can only say that the Billet block is well worth the investment.

Thanks again Mike for making this possible with delivery

[newday777]

 
The ultimate motor for the 750

[MRieck]

The billet block look really good and match the head very well! 
It costed some, but the alternative is not for free either.
Finding a good looking stock cylinder block with no fin damage, remove sleeves, bore for bigger sleeves plus a wider done bore at the bottom, ca 5mm deep 1.25mm wider for o-ring and sealer.  Possible when using CycleX 74.5 mm sleeves, perfect for 70mm pistons.
(Too thin for 71.25mm pistons my billet block has)

Make sure both top and bottom are flat with smooth surfaces for RCS and MLS gaskets.
Assemble the sleeves, bore them + final hone.

My 970cc cylinder had to be milled 1mm (84mm height) to match the NOS JE pistons I have bought rather cheap. Upper 2 oil o-ring indentations milled too when they disappeared.
My nearby shop did not charge me for all extra job doing the extra details to mill the wider part at top for sleeves 1mm deeper.

My Billet block is on vacation until I have cracked the carb jetting using a stock cylinder with 970cc pistons.

Cb750 Racer, you are not alone with long ongoing carb issues
My Mikuni TMR have filter adaptors, but they do not cover the pilot air jet which explains the never ending rejettings. Installed filter via hoses connected to the holes this year when finding out.
Hopefully the final dyno next week to verify the good jetting that did not work before.
Tried same setup twice, plugged and semiplugged pilot air jets sabotaged from idle to 4000rpm.

CB750 owners are very impressed when they see the billet block. Other bikers too
No issues with eventual oil leak between 1-2 and 3-4 that can happen if sleeves are not completely sealed at the bottom with tight fitted o-ring AND sealer as Hondabond or Wurth Super RTV or similar on top.

I have a slow onging engine build that has got its upper case bored to welcome the Billet block as an alternative.

Here how well head and billet block match each other, especially K6 and 392 heads.
My K2 head has a small stick out.

Soon 6 years after delivery and around 25.000km I can only say that the Billet block is well worth the investment.

Thanks again Mike for making this possible with delivery

Per....you are most welcome. Can you post pics regarding the TMR's and air jet situation?? Thanks!
Mike

[MRieck]

Turns out I'm a dumbass and may have finally cracked the code to the hsr42 carb. I put a thunderjet in the carb with results being much of the same. Turns out I've had the vacumm port in the rear open for the past several years trying to tune this thing which should be plugged off. This vacumm port should only be used for a vacumm operated petcock or a vacumm operated switch. Certainly not OPEN TO ATMOSPHERE  . Only figured it out after buying my first harley the other day. Oh well you live and you learn I'm gonna block off that port and retune it this weekend will keep you posted with the updates.


In other news I finally met the Gentlemen who machined Mike Riecks Billet blocks at Rice O Rama a few weeks back. Very cool guy he said mine was the first one he's seen in the wild beyond Mike's bike which was sad to hear. Unfortunately he said that due to lack of interest he had to stop making them due to the fact he only could get material cheaply by buying 30 or so blocks at a time. The overhead essentially pushed him off from making more. He did give me the information required to make my own in the future and I may be taking him up on it if there is more interest. Of course will talk to Mike before going any further definitely don't want to step on his toes by any means.

If I had seen that I could have told you that. 99.9 percent of carbs or manifold nipples should be sealed off as they are generally for carb synch, etc.
 As for the Billet Blocks.....yes...the material had to be purchased and I had to absorb that cost which was significant as each raw block weighed about 70 lbs. I also had to pay for the initial CAD design. Luckily I was able to pay for the machining as I sold the blocks but they  didn't fly off the shelf. 95% of them went overseas.....I guess that is where the money was/is.
 Anyway....I'm not sorry I did it but it was a real labor of love for the CB750 and those who own them. I could do it again for a run of 10 (at least) I think BUT I'd need deposits AND conformation from my machinist that he would be willing to do it. Keep in mind pistons and plating are extra and I refuse to use old pistons even if they are NOS.....you need  modern pistons which hold close tolerances.
 The set up would not be cheap....that I am sure off BUT the block is very tough and you'll wear out pistons before the Nikasil coating. They have been proven by years of endurance racing by a customer of mine in Switzerland who bought 2 blocks. One of the nice benefits is they are very robust and really make the engine more rigid.

[PeWe]

The billet block look really good and match the head very well! 
It costed some, but the alternative is not for free either.
Finding a good looking stock cylinder block with no fin damage, remove sleeves, bore for bigger sleeves plus a wider done bore at the bottom, ca 5mm deep 1.25mm wider for o-ring and sealer.  Possible when using CycleX 74.5 mm sleeves, perfect for 70mm pistons.
(Too thin for 71.25mm pistons my billet block has)

Make sure both top and bottom are flat with smooth surfaces for RCS and MLS gaskets.
Assemble the sleeves, bore them + final hone.

My 970cc cylinder had to be milled 1mm (84mm height) to match the NOS JE pistons I have bought rather cheap. Upper 2 oil o-ring indentations milled too when they disappeared.
My nearby shop did not charge me for all extra job doing the extra details to mill the wider part at top for sleeves 1mm deeper.

My Billet block is on vacation until I have cracked the carb jetting using a stock cylinder with 970cc pistons.

Cb750 Racer, you are not alone with long ongoing carb issues
My Mikuni TMR have filter adaptors, but they do not cover the pilot air jet which explains the never ending rejettings. Installed filter via hoses connected to the holes this year when finding out.
Hopefully the final dyno next week to verify the good jetting that did not work before.
Tried same setup twice, plugged and semiplugged pilot air jets sabotaged from idle to 4000rpm.

CB750 owners are very impressed when they see the billet block. Other bikers too
No issues with eventual oil leak between 1-2 and 3-4 that can happen if sleeves are not completely sealed at the bottom with tight fitted o-ring AND sealer as Hondabond or Wurth Super RTV or similar on top.

I have a slow onging engine build that has got its upper case bored to welcome the Billet block as an alternative.

Here how well head and billet block match each other, especially K6 and 392 heads.
My K2 head has a small stick out.

Soon 6 years after delivery and around 25.000km I can only say that the Billet block is well worth the investment.

Thanks again Mike for making this possible with delivery

Per....you are most welcome. Can you post pics regarding the TMR's and air jet situation?? Thanks!
Mike

Mike, a link to my project thread for my K6.
Some pics describing it all.
http://forums.sohc4.net/index.php/topic,180468.msg2210907.html#msg2210907

[Cb750 Racer]

In other news I finally met the Gentlemen who machined Mike Riecks Billet blocks at Rice O Rama a few weeks back. Very cool guy he said mine was the first one he's seen in the wild beyond Mike's bike which was sad to hear. Unfortunately he said that due to lack of interest he had to stop making them due to the fact he only could get material cheaply by buying 30 or so blocks at a time. The overhead essentially pushed him off from making more. He did give me the information required to make my own in the future and I may be taking him up on it if there is more interest. Of course will talk to Mike before going any further definitely don't want to step on his toes by any means.

I wonder if I met him and didn't know it. I was there.
Did you have your bike there in the show? If so I didn't notice it.  I had my K5 there with Brad's greenish K4.

I'd love to get one of those blocks......

Yes I brought the bike to the show but was very late. Will be on time next year. Your cb750's were gorgeous though I remember seeing them right up front.

Thank you for the input PeWe! I'm slowly knocking things off the list to getting the bike completely situated. The billet blocks are an order of magnitude better than the stock block if someone's looking to go anything over 836cc's. The block rigidity will even help with crank flex as the billet block makes the cases far more rigid when all assembled.

Turns out I'm a dumbass and may have finally cracked the code to the hsr42 carb. I put a thunderjet in the carb with results being much of the same. Turns out I've had the vacumm port in the rear open for the past several years trying to tune this thing which should be plugged off. This vacumm port should only be used for a vacumm operated petcock or a vacumm operated switch. Certainly not OPEN TO ATMOSPHERE  . Only figured it out after buying my first harley the other day. Oh well you live and you learn I'm gonna block off that port and retune it this weekend will keep you posted with the updates.


In other news I finally met the Gentlemen who machined Mike Riecks Billet blocks at Rice O Rama a few weeks back. Very cool guy he said mine was the first one he's seen in the wild beyond Mike's bike which was sad to hear. Unfortunately he said that due to lack of interest he had to stop making them due to the fact he only could get material cheaply by buying 30 or so blocks at a time. The overhead essentially pushed him off from making more. He did give me the information required to make my own in the future and I may be taking him up on it if there is more interest. Of course will talk to Mike before going any further definitely don't want to step on his toes by any means.

If I had seen that I could have told you that. 99.9 percent of carbs or manifold nipples should be sealed off as they are generally for carb synch, etc.
 As for the Billet Blocks.....yes...the material had to be purchased and I had to absorb that cost which was significant as each raw block weighed about 70 lbs. I also had to pay for the initial CAD design. Luckily I was able to pay for the machining as I sold the blocks but they  didn't fly off the shelf. 95% of them went overseas.....I guess that is where the money was/is.
 Anyway....I'm not sorry I did it but it was a real labor of love for the CB750 and those who own them. I could do it again for a run of 10 (at least) I think BUT I'd need deposits AND conformation from my machinist that he would be willing to do it. Keep in mind pistons and plating are extra and I refuse to use old pistons even if they are NOS.....you need  modern pistons which hold close tolerances.
 The set up would not be cheap....that I am sure off BUT the block is very tough and you'll wear out pistons before the Nikasil coating. They have been proven by years of endurance racing by a customer of mine in Switzerland who bought 2 blocks. One of the nice benefits is they are very robust and really make the engine more rigid.

it's certainly a labor of love I don't think anyone will get rich manufacturing blocks for these bikes. Your block is hard to improve on as it's everything you need and nothing you don't. I think I'm going to shift my efforts towards suzuki bandit 1200 blocks to start. Using 7 series aluminum and a similar nickel plating as I think there's currently a bigger demand on a product like that. Eventually working back to cb's and applying the same methodology (if people even want them)

That being said I knocked another issue off the list last weekend. I started the bike and was letting it warm up. I put my hand over the exhaust then over the wastegate dump and there was exhaust coming out of the wastegate at idle. Pulled off the top and the wastegate has an 8lb spring in it so it certainly shouldn't be opening. Once I pulled the gate off I realized I forgot to install the gate valve seat  . Got that installed and the bike is radically different from before. I have to rework the jetting completely. While I'm still having issues building boost I finally got passed that 6000rpm wall and rev'd the bike to 8000rpm before it was leaning out. Definitely still very sensitive. Tried adjusting the thunderjet but any added fuel was pegging rich on the Guage. One of these days it'll put down some impressive numbers on the dyno

[Cb750 Racer]

Finally got the bike on the dyno now that I have one readily accessible at work. Ended up narrowing down the issue I was having with the bike not revving correctly down to the powerarc ignition. On the dyno we found out the bike wouldn't Rev past 5000rpm but it would build up boost, 7lbs at the peak. That being said it made 70hp to the wheel at 5000rpm. I'm going to ditch the power arc and have a dyna s ignition on the way just to get it going. The next dyno video should be up within the next couple weeks. Sorry for the delays

Sohc Cb750 horsepower record is in the scopes

[scottly]

but still at 6k the bike still just falls on it's face. I'm beginning to think it's more an ignition issue and I may be actually set to the wrong map.

What ignition are you using? If it's a POS Power Arc ignition, try something else. They gave up on it...

I warned you about the POS Power Arc almost 2 years ago.

[Tracksnblades1]

Looks good.

Gotta start somewhere.

Patiently waiting to hear it climb onto the pipe…😇

Oh, “boost”  🤪. day dreaming again…😁

[seanbarney41]

Dang dude!?  What's it like workin' for Kaplan?  How's the pay?  Quite a place he has going there, I would expect it to be pretty exciting place to work!

[Cb750 Racer]

but still at 6k the bike still just falls on it's face. I'm beginning to think it's more an ignition issue and I may be actually set to the wrong map.

What ignition are you using? If it's a POS Power Arc ignition, try something else. They gave up on it...

I warned you about the POS Power Arc almost 2 years ago.

I wanted to believe my 500$ was well spent. Learned the hard way

[Cb750 Racer]

Looks good.

Gotta start somewhere.

Patiently waiting to hear it climb onto the pipe…😇

Oh, “boost”  🤪. day dreaming again…😁

Thank you! Was breaking up a bit down low but it will get dialed in once I get a proper ignition on it

Dang dude!?  What's it like workin' for Kaplan?  How's the pay?  Quite a place he has going there, I would expect it to be pretty exciting place to work!

He's a great guy I was in IT for years and he pulled me away to come work for him after buying a few of my sohc4 bikes. It's definitely cool a new challenge everyday I wouldn't change it for the world.

[newday777]

A friend and I were just talking about riding down from southern NH to see the museum sometime soon. Lots of cool stuff in that motor. Can't wait to see it.

[Cb750 Racer]

A friend and I were just talking about riding down from southern NH to see the museum sometime soon. Lots of cool stuff in that motor. Can't wait to see it.

Stop by anytime! Friday is the best day as all the techs will still be on duty.

On another note, the ignition was the problem. I just threw a dyna s ignition on the bike and it made 106rwhp @10krpm 6lbs of boost. Going back on the dyno to dial it in more this weekend. Going to turn it up to 12ish pounds of boost and aim for that 130 number on pump gas. Video coming soon!