Author Topic: CB750 AHRMA Sportsman 750 Racer  (Read 197150 times)

0 Members and 2 Guests are viewing this topic.

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #775 on: June 25, 2018, 01:31:14 PM »
Don't know where the drain plug is on a CB750 and you may have already thought of this, but it is convenient if the tech inspectors can see that it is safety wired without removing the pan.

I have thought about that and with the way the pan is, I can either drip it down a bit or figure out a way to put a small inspection hole in the side. They have those bore camera deals at tech now they can use. I have to wonder how often oil on the track is drain plug related vs other issues like thrown rods, overfilled engines, etc.
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 bwaller

  • Really Old Timer ...
  • *******
  • Posts: 7,449
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #776 on: June 25, 2018, 02:58:14 PM »
They're cool with it inside the frame rails?

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,046
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #777 on: June 25, 2018, 03:10:35 PM »
If you have an access hole to inspect the safety wired drainplug, does the access hole need a saftey wired cover?
 Or can you just use a rubber plug ?
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

  • Really Old Timer ...
  • *******
  • Posts: 7,449
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #778 on: June 25, 2018, 03:41:13 PM »
Some assn's allow a plug. Some also want the plug removed in the rain. This means someone somewhere has to decide when it is wet enough to remove the plug. Then if the rain ends quickly the belly pan is useless.


Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #779 on: June 25, 2018, 04:00:25 PM »
They're cool with it inside the frame rails?

Plenty of guys run them like this. Hell lots run roasting pans and zip ties. Oil containment is vague at best not stating what the pan covers, only what capacity it needs.

No idea on inspection covers but it would need to be wired, no rubber plugs.
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

  • Hot Shot
  • ***
  • Posts: 392
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #780 on: June 25, 2018, 05:45:17 PM »
Mine is inside the frame rails and have had no concerns expressed by any tech inspectors.  I have a rubber plug at the back to remove should it be required, but can't recall which organization wanted it now.  I do duct tape over it to help ensure it stays put.  Mine is held on by 6 plastic wire ties, 3 each side.  It is very secure and don't have to worry about vibration cracking it. 

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer - BOTM! Vote for me!
« Reply #781 on: June 29, 2018, 04:04:19 AM »
Please don't forget to cast your votes this month for the racer over in the BOTM section of the forum. Thanks guys!
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 scottly

  • Global Moderator
  • Really Old Timer ...
  • *****
  • Posts: 17,466
  • Humboldt, AZ
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #782 on: June 29, 2018, 07:56:58 PM »

Given the comments about weight bias on my bike, I am thinking about a shorter gas tank. I will go with glass as that is in my capabilities to do myself and then I can easily tweak the design to suit. I will be able to put the form on the bike and sit on it, so a perfect fit should be easier to achieve. That means a new seat as well, but should be well worth the effort. I have also noticed with my current tank, that while I like the look, its very wide and square at the back, which keeps my outside leg from hugging the bike in a turn.
Don't sell yourself short, Matt. The way the oil tank turned out, shaping aluminum looks to be well within your capabilities, even if the welding isn't. ;) Go for an aluminum tank.
My complaints about the Seeley tank are similar: it's too long and too wide at the back. I also don't really need a 5 US gallon capacity. ::) 
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline simon#42

  • Old Timer
  • ******
  • Posts: 2,701
  • liverpool
Re: CB750 AHRMA Sportsman 750 Racer - BOTM! Vote for me!
« Reply #783 on: June 30, 2018, 01:56:44 AM »
buy a cheap inverter plenty of people make them or see what you can turn up secondhand , having seen the other stuff you have done a tank will be no problem

Offline turboguzzi

  • Old Timer
  • ******
  • Posts: 4,118
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #784 on: June 30, 2018, 09:57:41 AM »
The pan is silk, willi....

Well played Frank, very well played.
that's pretty much how i build my pans, i just more outside for more coverage / volume.
Our techs dont allow plastic ties to hold it, either build some ears that are held on to various engine covers screws or aircraft clamps on frame tubes. on the pan i put some riv-nuts.
we need to have more capacity than 1qt, so i built a small deeper area next to the 4-1

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #785 on: September 04, 2018, 06:43:47 AM »
Back at it on this one. Had a track day last Friday and had a bit of a get off while on a heater of a lap. I know I shouldn't have been pushing it that hard, but after the first session, I was really feeling good on the bike. Things were going really well, and the lap before I took 5 seconds off my personal best at this track. That put me in class-leader lap time territory, but then again, they don't count in practice and really don't count when you dont FINISH the lap!!

The carnage:






At first glance it was far worse that it actually ended up being. I bent a bar that I have an extra of, and broke the clamp on the front brake master, but found a spare from another master that will work for now. The pipe took a bit of a beating and was full of dirt, but after a quick cleaning, its back to functioning. The tach mount was bent but was easily straightened, and the front number plate mount twisted, but was easy to fix. The rear number plate mount took a beating but is simple 3/4" aluminum strap, so again, was easily bent back to shape. The only piece I am now waiting on is the rear exhaust hanger, as it broke off clean at the weld. Once that is welded up, I will be ready to load up for Talladega GP Raceway down in Alabama this weekend.

I had not initially planned on racing this weekend, but after a high at Road America, I didn't want to wait all summer until Barber in October, so I slotted this one in as well. Its a small track that requires good corner entry/exit to make good time. There is only one other guy in my class, but this is about practicing technique during a race so I need to focus on that for the weekend. With such a short track I will get in tons of laps this weekend, even the races are 10 instead of the usual 8 laps.
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

  • Old Timer
  • ******
  • Posts: 3,970
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #786 on: September 04, 2018, 06:57:08 AM »
Keep an eye on that tach mount that you straightened.  It will now be weak where it bent, and will fracture with vibration.
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #787 on: September 04, 2018, 07:08:20 AM »
Keep an eye on that tach mount that you straightened.  It will now be weak where it bent, and will fracture with vibration.

I thought about that since it was bent then to begin with to get the right angle for the tach. Ill keep an eye on it this weekend. I may have a spare I can bring along too.
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

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #788 on: September 04, 2018, 07:46:55 AM »
If it cracks, weld it. Or, heat it up fully, then let it re-anneal. Should be fine (assuming it's ally?)

Not sure what grade, but yes aluminum. Just basic 1/8" sheet. Ill look it over but it seemed good when I bent it back, as in it didnt bend back really easily like it was about to break.
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

  • Old Timer
  • ******
  • Posts: 3,970
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #789 on: September 05, 2018, 06:20:35 AM »
I would put a bead of weld on that bend, it will definitely be weak now.  Last thing you want is for the bend to break & the tach to start flopping all over.
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #790 on: September 11, 2018, 08:44:46 AM »
Well, it was a long road to Little Tally down in Munford, AL but my dad and I made it and it was well worth it. Im happy to report I pulled out 2 wins this weekend!

Our 12 hour drive from Michigan started at about 6:15am on Thursday, only to find that the trailer running lights weren't working on my dad's truck. I was really hoping this wasn't going to set the tone for the whole weekend. We got on the road around 8 (still no running lights) and headed south. Usual stops along the way for food and gas were supplanted by a stomach bug I was trying to beat all week and just wouldn't leave me be. The whole trip was littered with construction slowdowns and pockets of rain. We pulled into the campground at around 8:30pm CST and got set up right next to another guy I race with. All set up about an hour later, it was bed time.

7am came real early Friday morning after the long drive and the stomach bug, but I was ready for action. I had gone through all the maintenance items on the bike and was ready to make some laps on the track. Friday was hotter than hell (92* and high 90's for humidity) but the bike ran really well. I always have certain expectations of where I will settle on lap times relative to the class winning guys. Hot laps were running 1:09 to 1:10, so I figured I would be in that 1:15-1:18 range just getting out and work down from there. My transponder wasnt working for the first half of the day but based on keeping up with a guy in my class, I was running around 1:18.

I called MyLaps and got my transponder figured out and I was ready for the afternoon practices. This track is hard on tires so I was monitoring my pressures closely as well as the wear. The track is all left handers and one 180* right hander, so the left sides were getting lots of use. More rubber boogers on my front tire after this weekend than after almost 2 seasons of racing other tracks. I knew they would got the weekend but new rubber would be on order before Barber in October.

Lap times for the 3rd session of the day settled into the 1:16 range and I was starting to feel good on the track. It seems like its an easy track but its so tight that mistakes cost you huge amounts of time to fix. Someone said it was easy to learn, but very hard to master. I totally agree. The last session of the day had me under 1:16 and there was still practice before racing Saturday.

I only did one practice Saturday morning to save the tires, but times were in the 1:14-1:15 range now and I was ready to race. After all the last minute checks race 7 was ready to go.

I got an OK launch but with the larger rear sprocket (48 tooth) I lifted the front tire and had to back out of it a bit to correct. The one other guy there from my class got out in front and I began chasing. I tried to calm myself after my bad launch and get in the game. A couple corners later coming into the only right hander I hit a false neutral just as was downshifting. That put me off race line as I got back in gear and completed the turn. Now I was a bit further back but fortunately that was a slower part of the track for him and I was able to make up some ground. I have the whole race on the Go Pro and just need to get it put on my PC so I can post it.

I don't remember exactly but I do know that I was able to take the lead from him that first lap and I lead him for each of the first 5 laps. He passed me coming out of the little left-right-left just before the front straight and beat me to the start/finish by about 2 tenths. I promptly dove deeper into 1 than him and regained the lead, carrying that through most of the race.

On the 8th and final lap, he passed me just coming out of the last long sweeping left hander, which was a slow portion of the track for my anyway so Im sure he was just waiting for me to tire out a bit. Well I was on his rear tire all the way down that straight before the left-right-left leading to the checker, and I started braking just after him and was able to dive to the inside as we started the turn and he goes wide but keeps it on the track. I crossed the finish less than 1.8 seconds before him, turning a 1:12.759 in the process, which was my personal best for the weekend.

It turned out that he had picked up some nasty brake fade in that last corner and he had to pump his lever just to keep on the track. So far with my cast iron disc that has not been an issue at all. Most of these guys run a thinner disc and it works fine, while it works. Too many stories of warping rotors out on the track. The thicker cast iron on my bike seems to be holding up really well.

Sunday came and I wanted a quick practice just to make sure everything was working correctly after the race on Saturday. It was and I looked over the bike again to get ready for the race in the afternoon.

Sunday's race went quite differently. I knew he was out to get the win for the day and was prepared to give my all. My launch was far better today and I was able to stay closer to him throughout the first half of lap one. My plan was to watch him and keep pace, waiting for my chance. I had planned on another barn burner of a race just like yesterday but as he led me coming out of the last big left hand sweep on the track (where he passed me going for a win on Saturday) his rear tire breaks loose and he and the bike slide off the track right in front of me. Fortunately it was the exit of the corner and I was able to stand the bike up and stand on the pegs, preparing to hit either him, the bike, or both. Well he slide right and I veered left and missed him by about 2-3 feet. The red flag came right out and I went back to hot pit.

Having had to bump start in the pits once this weekend already and knowing it was easy to do with a hot bike, I killed the engine and sat. Once the crew helped get the other guy off the track, we had 6 laps left to race. I lined up again, just me in my class, and tried to get another good launch. Of course this was the best of the weekend, but all I had to do was stay upright to get the win. The rest of the race was pretty uneventful, not pushing the tire or lap times to the extreme. I finished upright and collected my second win. Gotta be there to finish. Gotta finish to win. I did both and came out on top.

Happy guy


The spoils


Action on track


And now there are 23 days left until the big show at Barber, and the list grows:

New tires front/rear
Oil change
Get leathers fixed (from my boo boo at a track day the week before)
All other items checked on the bike
Adjust valves
Cam chain adjustment
Etc.
Etc.
Etc.

23 days...
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 Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,815
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #791 on: September 11, 2018, 09:08:22 AM »
Good on You :) :)

Take it easy on the new tires..........for a few feet ;)

Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2020 ROYAL ENFIELD Himalayan

Offline MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,757
  • Big ideas....
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #792 on: September 11, 2018, 09:34:24 AM »
Congratulations Matt. You look pretty happy in that pic. ;)
Owner of the "Million Dollar CB"

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,046
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #793 on: September 11, 2018, 09:47:44 AM »
 Lucky for you, I told you about quick change wheels.
 So run equal spacers both sides of wheel. Then before the racing starts, flip wheel around, use other side of tire.
 Works on the dirt.   not sure with slicks, The directional thing may bite you on this.

On the launch, don't let go of clutch lever so soon, or learn to slip it, as it starts to wheelie, you can control with clutch and throttle... and get a better launch.. backing off always costs time.. ( laymens terms, you lose the holeshot).
« Last Edit: September 11, 2018, 09:53:20 AM by 754 »
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 slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #794 on: September 11, 2018, 09:59:50 AM »
Good on You :) :)

Take it easy on the new tires..........for a few feet ;)

Good call! Thank god for practice sessions and scrub laps.

Congratulations Matt. You look pretty happy in that pic. ;)

That I am!!

Lucky for you, I told you about quick change wheels.
 So run equal spacers both sides of wheel. Then before the racing starts, flip wheel around, use other side of tire.
 Works on the dirt.   not sure with slicks, The directional thing may bite you on this.

On the launch, don't let go of clutch lever so soon, or learn to slip it, as it starts to wheelie, you can control with clutch and throttle... and get a better launch.. backing off always costs time.. ( laymens terms, you lose the holeshot).

Tires are not bidirectional otherwise that would be an option.

I really need to hang with some drag race guys and learn how to get those awesome holeshots.
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

  • Really Old Timer ...
  • *******
  • Posts: 29,046
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #795 on: September 11, 2018, 11:44:00 AM »
 Basically, if you are still holding the clutch lever, you still have a chance to control it without backing right off.
I was wheeling my XL 350 off the line at the flat track . With a street tire.. sometimes I had to clutch and trim throttle to bring it down a bit.,
« Last Edit: September 11, 2018, 11:48:07 AM by 754 »
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 MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,757
  • Big ideas....
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #796 on: September 11, 2018, 11:59:34 AM »

I really need to hang with some drag race guys and learn how to get those awesome holeshots.
Rev the crap out of it and slip the clutch. ;D
Owner of the "Million Dollar CB"

Offline bwaller

  • Really Old Timer ...
  • *******
  • Posts: 7,449
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #797 on: September 11, 2018, 07:15:17 PM »
Good news Matt, congratulations.

Who is that skinny smiling guy though? Just a shadow of your former self I met a year ago at Barber!  8) 

Offline scottly

  • Global Moderator
  • Really Old Timer ...
  • *****
  • Posts: 17,466
  • Humboldt, AZ
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #798 on: September 11, 2018, 08:59:51 PM »
Well done, Matt. 8)
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline RAFster122s

  • I feel like a really really
  • Really Old Timer ...
  • *******
  • Posts: 12,569
  • SOHC4 member # 2605
Re: CB750 AHRMA Sportsman 750 Racer - Race Weekend Update!
« Reply #799 on: September 11, 2018, 10:34:03 PM »
Congrats!
David- back in the desert SW!