Author Topic: CB750 AHRMA Sportsman 750 Racer  (Read 170580 times)

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Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1125 on: March 15, 2021, 06:12:18 AM »
Another "fun" update is that after I sealed the cases and started putting shifting bits and covers on, I decided to check out my MessnerMoto cam tensioner (can't wait any longer on other solutions and won't go back to OEM) and offered it up to the top case, only to find that it hits the top slider from the primary tensioner system. The only option now is to cut down the primary slider to make room for the cam tensioner system. Since the vast majority of race bikes in the known universe don't run the top slider of any kind, taking some material off the end won't be the end of the world, but does suck to have to split freshly sealed up cases.
Hi Can you take some photos of This? Im going to use the messner cam and primary tensioners aswell thx


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Cases are already sealed up but I cut 1" from the end of the top primary slider that faces the cam chain. I cut it right before the 2nd rivet in. Cleaned up the end on my mill and reinstalled.

I just saw this. Pinged by a forum member. I am pretty sure I designed cam and primary chain tensioner to miss each other. Especially because primary chains and cam chain are also missing each other.

Maybe there is interference of  top 1mm on sides or something like that because of not perfect alignment. I mean I have both tensioners in my engine and they are not touching.

you shouldn't have cut of 1" of top primary chain slider thats excessive and it probably ruined function of top slider! Probably a touch by sanding tool on side of one tensioner would have solved interference problem.

Please if anybody have similar problem contact me....

Yeah Mirko, Im not sure what was going on but I had to make a call. Given that the bike was designed without any top slider, taking material off didnt concern me at all, and now they can both live happily together without interference.
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 - Time for 2021
« Reply #1126 on: March 15, 2021, 06:22:23 AM »
The bike is done! First startup didnt go quite as planned. I have been in this engine enough and each time the bike fires right up after letting the carbs fill with fuel. Well this time was different. I used the rollers so much that the motor started to get really hot and I drained the battery, which meant it was time to push! So I took to my quiet neighborhood street to get a running start down the small hill up from my house. I ended up pushing it back and forth about a dozen times, and had decided to pull in and pull the plugs to dry them out and start the process again. Well, being the stubborn SOB I am, I decided to try and bump it a couple more times on the way back to the house, and the last try it finally caught and I was able to get it going. I ran it gently up and down the street in 1st gear, varying RPM a few dozen times to try and seat the rings. Not the way I wanted to break it in, but it will have to do. I got back to the garage and with the roller battery charged up a bit and a warm bike, it fired right up to double check the timing one last time.

That leaves me here, Monday before the race weekend, the first of 2021. I will be heading out with the Mrs. on Wednesday afternoon with an overnight in Columbus, OH before getting to CMP in Kershaw, SC in the late afternoon on Thursday. Then its back to business as usual, chasing my uncle in S750 for another run at a championship year, as well as getting deeper into my bump class, Formula Vintage. That class has a number of fast bikes from Vintage Superbike and a couple 2-stroke classes. I will be up against GS1000, KZ900/1000, RZ350, RD400 and a number of other hot rods. I held my own against some of these guys last year, and thanks to me busting my butt in the off season, I am about 2-3hp "lighter" than last year, which should help with acceleration, braking and general handling on the bike.

Here's a shot from right after I got the last things buttoned up. I should be able to get some great outdoor shots at the track soon.

« Last Edit: March 15, 2021, 06:30:06 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 Jerry Rxman Griffin aka MuthaF'er

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1127 on: March 15, 2021, 07:41:59 AM »
Great news. Bike looks fantastic. Good luck and stay safe.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline bwaller

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1128 on: March 15, 2021, 08:10:42 AM »
Looks great Matt, we'll be following along.

Penny for your thoughts....I bet you were starting to sweat and worry (maybe even curse a bit) the more you had to push.  ;)

Offline Ramrod_Racing

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1129 on: March 15, 2021, 09:57:11 AM »
I'll do my best to make a nice big draft for you between 9 and 10 in FV on Saturday  ;)

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1130 on: March 15, 2021, 10:35:42 AM »
Great news. Bike looks fantastic. Good luck and stay safe.

Thanks Jerry!

Looks great Matt, we'll be following along.

Penny for your thoughts....I bet you were starting to sweat and worry (maybe even curse a bit) the more you had to push.  ;)

Each time I pulled the clutch and started running I hoped it'd by my last. Perseverance wins the day!

I'll do my best to make a nice big draft for you between 9 and 10 in FV on Saturday  ;)

I'll be out front, just follow me... unless I go in the grass. Think this way, if you're chasing me and I'm chasing Jeff that takes everyone else out of the equation! Hopefully not too wishful thinking. See you Thursday.

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 PeWe

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1131 on: March 15, 2021, 12:48:15 PM »
Really beautiful bike!
If it should have a reg plate, a really nice cafe racer! ;D
Have a really good running 2021!
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Old Scrambler

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1132 on: March 15, 2021, 02:45:12 PM »
Go fast and be SAFE............
Dennis in Wisconsin
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CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
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Offline Sam Green Racing

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1133 on: March 16, 2021, 04:57:00 AM »
It looks to nice to race Willie, it should be in your living room with spot lights on it. Take care and stay safe mate. Good luck.
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Offline RAFster122s

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1134 on: March 16, 2021, 06:25:44 AM »
Safe travels and hope the adventure & racing is trouble free and fun!
David- back in the desert SW!

Offline Ramrod_Racing

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1135 on: March 16, 2021, 01:49:15 PM »
I'll be out front, just follow me... unless I go in the grass. Think this way, if you're chasing me and I'm chasing Jeff that takes everyone else out of the equation! Hopefully not too wishful thinking. See you Thursday.

We shall see! #deepfieldbro

Hopefully your drive will be much dryer than ours.

Offline gschuld

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1136 on: March 19, 2021, 11:35:43 AM »
I can confirm Matt and Ashley are trackside at Kershaw SC, the freshened up engine started right up upon arrival and today is practice day.  New paint looks good👍

Matt is competing in AHRMA Sportsman 750 and formula Vintage.

Good luck Matt,

George

Offline 754

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1137 on: March 19, 2021, 11:27:00 PM »
  Ummmmmm ... stick something on that blockoff dyno plate..in tbe middle ..
 A bottlecap , badge, sticker ...anything.... it really needs it.
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Offline ekpent

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1138 on: March 20, 2021, 08:28:43 AM »
 Good Luck Matt. Look forward to hear how you and the bike did.  Eric

Offline PeWe

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1139 on: March 20, 2021, 10:49:22 AM »
Any Dyno charts?
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline MRieck

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1140 on: March 20, 2021, 12:39:14 PM »
  Ummmmmm ... stick something on that blockoff dyno plate..in tbe middle ..
 A bottlecap , badge, sticker ...anything.... it really needs it.
Yeah......a big JMR Porting sticker! ;D ;D
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Offline PeWe

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1141 on: March 20, 2021, 02:23:32 PM »
  Ummmmmm ... stick something on that blockoff dyno plate..in tbe middle ..
 A bottlecap , badge, sticker ...anything.... it really needs it.
Yeah......a big JMR Porting sticker! ;D ;D
Metal version all over the cover would look really fine ;D
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline gschuld

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1142 on: March 21, 2021, 08:33:53 AM »

OK, I’ll do a little update while Matt is still in racing mode.  Yesterday went really well.  The bike ran perfect.  Zero oil leaks or seepage.  BTW, Matt’s awesome wife Ashley should make any racer proud.  She is a total trooper.  It’s probably fair to say that track life isn’t her natural environment, but she is full on supportive and right there in the middle of it all, from wrestling the engine back into the frame to travel planning, to full logistical and emotional support at the track.  Matt is super lucky to have her as the other half of the team.👍 Go Ashley.

It was quite cold and windy yesterday, especially in the morning.  So much so that Matt elected to skip early practice and just let the tire warmers do their thing.  Race 8 was his first one in Formula Vintage.  Dave Crussell brought out his well prepared big KZ, Will Brint brought the TimsCBX owned and sponsored CBX(both AHRMA Supebike Heavyweight class machines)

I believe Brad Coleman in a gorgeous rare TT2 Ducati https://www.ducati.com/us/en/heritage/bikes/600-tt2  shot out front and stayed there.  Dave Crussell on the big KZ was behind.  Matt and his uncle Jeff Hargis on his big bored sx650 Yamaha(non fairing Sportsman 750 class like Matt) had a close battle for 3/4 for several laps with Matt just behind.  Probably not much more than 3-5 lengths apart the whole 6 lap race.  It looks like around the last lap, Matt got in front and stayed there.  So Matt 3rd, Jeff 4th.  Will Brint came in 5th on his CBX.

After the race Matt found out that Jeff hurt his engine(cylinder head related apparently) trying to stay in front of his hard charging nephew😉 enough that he was now out for the rest of the weekend.

Race 12 is Sportsman(and three other classes including full fairing F750), and for some odd reason, Jeff’s hurt xs650 was the only other Sportsman class besides Matts at the event.  So as long as Matt completed a lap, he won🙄.  But he got a good opportunity to chase the f750 class that started right in front of him.  Matt caught all but one or two of the f750 bikes from behind(👍) and took his top podium finish in Sportsman by a “huge margin”😎

Matt was lucky enough to have the race officials allow his Sportsman class(just him) for today to be run in the same heat the Heavyweight Superbikes.  He intends to race heavyweight Superbikes next year with his new bike being built so this gives him more experience against this class to gauge his speed against them.  He currently appears to be lapping a bit slower than the big KZ, but faster than the CBX.  Dennis Parrish, the current champ, is not at the race so it’s not a full picture, but useful regardless.

Both the CBX and the KZ are likely putting out well over 100(probably up to 130) RWHP to Matt’s current 80.  But he carries a noticeable weight advantage however, especially with the CBX.  Matt’s new superbike in process should have an engine capable of over 100 RWHP as well, but still short of what Dave Crussells big budget DOHC KZ output likely is.

Fingers crossed...   Matt should have two battles with the Superbikes today.
« Last Edit: March 21, 2021, 09:44:47 AM by gschuld »

Offline gschuld

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1143 on: March 21, 2021, 08:38:53 AM »
FWIW, Matt got a good deal on some new leathers.  It seems all his slimming down has caused his current suit to get a bit loose.

Good on you Matt for getting down to real fighting weight.👍

George

Offline gschuld

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1144 on: March 21, 2021, 08:42:01 AM »
Action shot....

George

Offline bwaller

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1145 on: March 21, 2021, 02:22:32 PM »
Somebody is smiling all the way home! Well done Matt.

Offline hondaron

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1146 on: March 21, 2021, 07:32:32 PM »
Congrats thanks for the update and the pictures 😀

Offline ekpent

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1147 on: March 22, 2021, 07:33:30 AM »
 Sounds like a great outing Matt after a winter hibernation.

Offline Ramrod_Racing

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1148 on: March 22, 2021, 12:08:37 PM »
Also, shoutout to Matt for having a spare footpeg to lend me so I could make Sunday's Formula Vintage race after I had one decide to abruptly give up the ghost on me earlier in the day.

Offline RAFster122s

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Re: CB750 AHRMA Sportsman 750 Racer - Time for 2021
« Reply #1149 on: March 22, 2021, 01:12:19 PM »
Congratulations Matt!
David- back in the desert SW!