Author Topic: CB750 AHRMA Sportsman 750 Racer  (Read 44720 times)

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Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #875 on: January 19, 2019, 10:36:25 am »
i would not like to try and put a lot of power through that !

Why is that?
All you gotta do is do what you gotta do.

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Offline simon#42

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #876 on: January 19, 2019, 12:06:04 pm »
because it does not look very strong , dont worry though you are not putting a lot of power through it .

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #877 on: January 19, 2019, 12:30:32 pm »
Plenty of road racers running hubs just like this making lots more power than me. Far stronger than an old cush drive hub as well.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
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AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline 754

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #878 on: January 19, 2019, 06:50:56 pm »
That's a thick flange hub, some are half the thickness. If you are slipping the clutch vs dumping it, it should be ok..
 Note ..as with all lightweight race parts frequent inspections are necessary..
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Offline 754

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #879 on: January 19, 2019, 06:57:11 pm »
MAD MEL was running dirt track wheels on his turbo Honda and Suzuki.    Both were in a 69 CB 750 frame.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline scottly

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #880 on: January 19, 2019, 08:08:34 pm »

Interestingly, the spokes have not had issue as far as coming loose, though every time the rear comes off, I remove the sprocket and re-tighten the bearing adapter bolts. On my hub, there are 8 bolts, 4 sit in counterbores and 4 are the "pins" that the sprocket rides on. I find that at least half of them have loosened to some extent after a race weekend, despite having lock washers on them.
What type of lock washers? I've found the typical split washers aren't worth a damn, especially with Allen head bolts seating on aluminum. I've had better results with blue locktight and hardened flat washers, with a close fitting ID for the Allen heads. (I have resorted to reaming the washers to size. ;))

Should have said lock nuts. They are nyloc nuts that were provided by the hub manufacturer.
If the bolts are loosening up, it's probably due to the heads deforming the aluminum, due to the very small area of contact, rather than any locking mechanism. The solution, at least for the drive pins, might be to make "Tee" nuts, with a bigger, thicker base, counter-sunk into the hub, with the bolt inserted from the other side, or custom bolts with a similar head.
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Offline NitroHunter

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #881 on: January 20, 2019, 08:03:17 am »
MAD MEL was running dirt track wheels on his turbo Honda and Suzuki.    Both were in a 69 CB 750 frame.

I'd forgotten all about that guy. Thanks for the memory.  8)
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Offline 754

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #882 on: January 20, 2019, 09:10:28 am »
Look up Mad Mel Honda or Suzuki online, a few pics..
 He made double the power we have..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline gschuld

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #883 on: January 20, 2019, 02:16:09 pm »
https://www.rbracing-rsr.com/madmel.htm

Mel has nice taste.😁. Oh, wait a minute, I was supposed to look at the bike.🤔

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Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #884 on: January 28, 2019, 12:27:18 pm »

Interestingly, the spokes have not had issue as far as coming loose, though every time the rear comes off, I remove the sprocket and re-tighten the bearing adapter bolts. On my hub, there are 8 bolts, 4 sit in counterbores and 4 are the "pins" that the sprocket rides on. I find that at least half of them have loosened to some extent after a race weekend, despite having lock washers on them.
What type of lock washers? I've found the typical split washers aren't worth a damn, especially with Allen head bolts seating on aluminum. I've had better results with blue locktight and hardened flat washers, with a close fitting ID for the Allen heads. (I have resorted to reaming the washers to size. ;))

Should have said lock nuts. They are nyloc nuts that were provided by the hub manufacturer.
If the bolts are loosening up, it's probably due to the heads deforming the aluminum, due to the very small area of contact, rather than any locking mechanism. The solution, at least for the drive pins, might be to make "Tee" nuts, with a bigger, thicker base, counter-sunk into the hub, with the bolt inserted from the other side, or custom bolts with a similar head.

Im liking that idea and will need to come up with something like that for sure. Having to get back on those after each race is just another thing and if they loosen too much I may have a bigger problem to deal with.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #885 on: January 28, 2019, 12:32:06 pm »
Couple things from the weekend. I showed my bike at the Garage Brewed Moto Show in Cincinnati in the race class. I didnt win anything but had a good time and some great beer in the process.









I was also following the activities down under at the PI Classic and noticed a few shots of the frame of a CB750 race bike down there that I found quite intriguing.





There is a lot going on around the neck but I like the thought and it seems like it would add some much needed rigidity. I think with my Superbike build that may be something to pursue, and potentially on my Sportsman bike as well.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline Tintop

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #886 on: January 28, 2019, 12:48:23 pm »
That is similar to how Denis @ CMR braces the headstock.  Not sure were the pictures are (which page), but check out how he revised that area on Brent's bike.
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Offline calj737

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #887 on: January 28, 2019, 03:31:19 pm »
Who’s that skinny fella standing next to your bike?  :o ;D
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Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #888 on: January 28, 2019, 04:04:31 pm »
Who’s that skinny fella standing next to your bike?  :o ;D

Just stop it Cal. Still lots of work to do. 2019 has started slower than anticipated.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
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Offline gschuld

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #889 on: January 28, 2019, 05:14:08 pm »
That is similar to how Denis @ CMR braces the headstock.  Not sure were the pictures are (which page), but check out how he revised that area on Brent's bike.

Brent’s bike has had a substantial amount of the factory frame replaced.  Dennis Curtis went to the limits of the class rules about what had to stay stock frame wise for his VRRA rules.  Way beyond bracing😎

George


Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - 2019 Preparations
« Reply #890 on: February 10, 2019, 06:01:06 pm »
After some parts swapping, my cycle x 4 plate clutch system is in and the clutch cable was shortened 5 inches and rerouted. oil change to Motul 5100 forthcoming to complete that upgrade.

New brakes in and ready to rock with fresh race pads. The lever feels so much firmer with the AP unit vs the Grimeca.



More thing on the punch list before first race which is now Roebling Road in Georgia... in 11 days. Things in my schedule changed for the year so had to add a race earlier than expected. Better get moving!
« Last Edit: February 11, 2019, 05:47:20 am by slikwilli420 »
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - Roebling Road in 4 days!
« Reply #891 on: February 18, 2019, 10:02:27 am »
Bike is all set for 2019! Roebling Road is in 4 days. My wife and I are driving from Michigan starting Thursday morning, with an overnight stop in Charlotte, NC then onto the track in Savannah, GA. Too hard to put 14 hours in one day so it will be a little bit vacation as well as some racing. I will practice Friday afternoon, then racing Sat/Sun, then back to the frozen North.

The bike is all set and ready to go with no time to spare. I will fire it this afternoon to bring it out of hibernation and get the new Motul 5100 moving through the system. I have double checked every wire and bolt on the bike and every system looks like a go.

I have a number of changes I am going to make to the bike for this year, after Roebling and NOLA (early March), including a new seat, adding a dash mounted oil pressure gauge, front fender, and a few more refinements. I am also planning on starting to build a new fuel tank. Im going with aluminum and will gas weld it together in my shop. After all the back and forth on my oil tank, I want to try to get my in-house aluminum welding up to speed. It may take longer than going to the welder but it keeps my ability to change things on the fly very much in tact. I have a design that will echo the tank on Brent's racer, as its fairly simple from a shape standpoint, and will hopefully be more ergonomic than my current tank, which I find limits my movement on the bike.

4 days...
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
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AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline Ramrod_Racing

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Re: CB750 AHRMA Sportsman 750 Racer - Roebling Road in 4 days!
« Reply #892 on: February 18, 2019, 10:10:27 am »
See you there!

Offline slikwilli420

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All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - Transmission grinding, WTF?
« Reply #894 on: February 19, 2019, 06:58:33 am »
Threw the bike on the rollers last night to fire it before loading in the trailer, and its making the most awful grinding noise from the trans. Sounds like a can full of rocks. It seems that when I let the clutch out on the rollers to engage the engine, it grinds as if the gears arent meshing all the way and simply spinning past each other. Either way, to make Roebling Road this weekend I need a small miracle. Thank God I have extra trans parts I can swap in. Wish me luck.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline 754

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Re: CB750 AHRMA Sportsman 750 Racer - Transmission grinding, WTF?
« Reply #895 on: February 19, 2019, 07:02:44 am »
 Change back to the old clutch.
 I think you had said you tried a 4 plate..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline bwaller

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Re: CB750 AHRMA Sportsman 750 Racer - Transmission grinding, WTF?
« Reply #896 on: February 19, 2019, 07:32:11 am »
Agreed Frank, first thing to check.

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - Transmission grinding, WTF?
« Reply #897 on: February 19, 2019, 08:07:09 am »
That is definitely step one after work today. I did find that my clutch pack height was too tall, making the pressure plate rub the clutch basket rivets and after I took out one steel (extra steel for early vs late inner hubs) I had eliminated the spacing issue, but the grinding persisted. Im going back to my original clutch from last season to see. Im having visions of it being trans related where something is broken off in the gear set keeping them from engaging. I can swap the clutch back to the original quickly and get on the rollers, but if thats not it, then the engine is coming out.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline Rocketman

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Re: CB750 AHRMA Sportsman 750 Racer - Transmission grinding, WTF?
« Reply #898 on: February 19, 2019, 06:22:46 pm »
Fingers crossed.....

Offline dragracer

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Re: CB750 AHRMA Sportsman 750 Racer - Transmission grinding, WTF?
« Reply #899 on: February 19, 2019, 11:11:49 pm »
I see that Roebling is a non-spectator track. So much for showing up in support of a fellow racer. Shame,  you would be only 2 hours from me down Interstate 95. 

 

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