Author Topic: CB750 AHRMA Sportsman 750 Racer  (Read 175356 times)

0 Members and 5 Guests are viewing this topic.

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1025 on: January 14, 2020, 01:04:32 PM »

Very interesting. Makes me even more confident in the beehive spring being the better choice over the traditional double spring. When those fancy conical springs come the SOHC way, I may have to give them a try!!
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 MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,598
  • Big ideas....
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1026 on: January 14, 2020, 03:45:32 PM »

Very interesting. Makes me even more confident in the beehive spring being the better choice over the traditional double spring. When those fancy conical springs come the SOHC way, I may have to give them a try!!
Exactly Matt.
Owner of the "Million Dollar CB"

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,813
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1027 on: January 14, 2020, 06:59:10 PM »
Thanks for posting, Mike ;)............ I've been using the Ferrea version of conical springs along with their very small (light) Ti-retainers in my Salt-Flats motor with pleasing results. The answer for full-contribution to overall spring performance seems to be maximum cam-lift. 
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 Tracksnblades1

  • My Son was a collegiate competition Trap, Skeet, and sporting Clay
  • Master
  • *****
  • Posts: 1,926
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1028 on: January 14, 2020, 09:35:39 PM »
Feel your pain silk....😩

Did that drop at 10k...😳?
Was that a Serdi or a dead pilot..?

Thanks for the peek inside your cases..
Are those picture windows precision milled or precision die grinder cut..?

Hope you get'r sorted...


« Last Edit: January 14, 2020, 09:40:27 PM by Tracksnblades1 »
Age Quod Agis

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1029 on: January 15, 2020, 06:44:02 AM »
Feel your pain silk....😩

Did that drop at 10k...😳?
Was that a Serdi or a dead pilot..?

Thanks for the peek inside your cases..
Are those picture windows precision milled or precision die grinder cut..?

Hope you get'r sorted...

It went at about 8k rounding T2 at Barber, with me in 2nd place, 3 laps to go. Would have been nice to cap the season off with one more podium and not grenade the motor, since it was coming down for a look over at the end of that race, but I guess I learned my very valuable, and expensive, lesson.

I believe Mike does Serdi valve jobs.

The windows were hand cut with drills and a right angle head for my Dremel tool. Im not sure how much support the small bridge between sleeve holes in the upper case actually provides, but in the future, I may just put the top half in the mill and cut down through to make the windows for any future builds.
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 Ramrod_Racing

  • Full Member
  • *
  • Posts: 76
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1030 on: January 15, 2020, 09:45:30 AM »
Great to see your progress. No lie, Roebling is coming up FAST.

Offline Tracksnblades1

  • My Son was a collegiate competition Trap, Skeet, and sporting Clay
  • Master
  • *****
  • Posts: 1,926
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1031 on: January 15, 2020, 03:57:37 PM »
Silk,
Does your plans for next round include: CRF type pistons...?
                                                          Oil jet piston cooling?

Those bridges above your magic windows  disappear when boring for
JMR big block....and newer engines don't seem to utilize them any more....

What lift was your exhaust valve seeing?
Was you running a 410 cylinder head?

I like your magic windows and your pan-a-vac system......
Age Quod Agis

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1032 on: January 15, 2020, 05:32:08 PM »
Silk,
Does your plans for next round include: CRF type pistons...?
                                                          Oil jet piston cooling?

Those bridges above your magic windows  disappear when boring for
JMR big block....and newer engines don't seem to utilize them any more....

What lift was your exhaust valve seeing?
Was you running a 410 cylinder head?

I like your magic windows and your pan-a-vac system......

What are CRF pistons? Im already running 62mm 12:1 pistons that Kenny and I worked on, incorporating many of the best modern piston features.

I thought about some additional way to cool the piston but have not explored it further.

Good to know about the magic windows and the small bridge between holes in the upper case.

I was running three CX7 cam and will again this year on a 392 head. I do have a 410 head that I may use on my bigger bore superbike racer project though.

The venting system on the engine seems to work nicely. It can never fill up and the only oil issues I had were related to gaskets on side covers so I'd say it's doing its job.
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 Tracksnblades1

  • My Son was a collegiate competition Trap, Skeet, and sporting Clay
  • Master
  • *****
  • Posts: 1,926
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1033 on: January 15, 2020, 06:43:01 PM »
Silk,

Honda CRF/CBR pistons...The one below is 2 ring wiseco...

2012 Kawasaki Ninja 250R has 62mm standard 3 ring piston.i
(It will have a narrower wrist pin rod witdth than the stock .900 sohc little rod end width.)
With a compression height that would allow for higher rod/stroke ratio.
The 2 ring version would allow even more rod...Without any spacers...😎

« Last Edit: January 15, 2020, 07:37:29 PM by Tracksnblades1 »
Age Quod Agis

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,783
  • Bike almost back to the 70's 2015
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1034 on: February 16, 2020, 03:01:03 AM »
Sorry to remind you about the failure....
Did you find the root cause of the valve failure?
Cam caps/holder threads all OK?

I saw a similar head here last year. Also a 750 classic racer using 5mm stems (34/28mm), K head. Ex valve dish sat like a crashed UFO into the piston crown. JE pistons shaped after the chambers. I should have taken a photo since it looked very special with dish only vertically into piston crown

In that case a loose cam cap/holder that probably caused a huge valve lash,  lash cap flew off, engine sounded bad but not stopped direct, stem could have been bent and snapped off when rocker arm/adjuster screw aimed wrong....
That was only one valve. Head could be fixed by welding chamber, installing a new seat and final machining. A Carillo rod wasted and crank too if I remember correctly.

I use Kibblewhite 5mm stem valves 34/28 on my 1005cc street bike so the first dropped valve here got me to think, now this.
- I guess that an adjuster screw that loose the nut can end up in lost lash cap that make it possible to cause side forces to the valve, finally snapping it off.

The 5mm valve stem look really thin without lash cap that make the landing area for adjuster screw much wider.
The installed 5mm stem valves with springs feels rather flimsy when bending them a little by hand compared with stiffer 6.5mm stem and old style race springs.

I have had thoughts to replace the valve cover using one I have with bolts keeping cam holders down as an extra insurance. My cam caps/holder threads have all glued time-serts and all M6 bolts carefully tightened, not too much.

But you never know, one nut coming loose might be enough for for a really bad domino effect draining the wallet, money that could have been used for two, travel to a sunny warm place with cooling drinks.  8)

I'm sure you will have an even better engine for 2020! ;)
« Last Edit: February 16, 2020, 12:23:18 PM by PeWe »
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 bwaller

  • Really Old Timer ...
  • *******
  • Posts: 7,449
Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1035 on: February 16, 2020, 06:36:45 AM »

I'm sure you will have an even better engine for 2020! ;)

+1 PeWe.  Just a few days to go Matt, I hope it's coming together well.

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1036 on: February 25, 2020, 12:47:03 PM »
Well dudes and dudettes, Im back from round one of my 2020 season and it was a great one.

The bike came to life Sunday the 16th for the first time after a full motor build and ran like a champ. The bike has a bit of a new look this year with a new seat as well as some smaller details like plated/dimpled front brake rotor and modified breathing system for the oil tank, but it mostly unchanged. The new head has 6.5mm stems, oversized intakes and was ported by Mike Rieck to perform best with my current carbs (per the rules). Four new rods, four new pistons and a new trans later, and its like nothing ever happened!!

The Mrs. couldnt make the trip this time, so for the first time in my racing life, I was heading out solo. The 14hr drive was made more manageable by doing some on Wednesday and finishing up Thursday. I arrived at the track Thursday afternoon to rain and 40 degree temps, neither is conducive to unloading gear and setting up camp. Fortunately for me, my wife booked hotel accommodations for the entire trip, so I was able to enjoy warm, cozy sleep under a real roof all weekend.

Friday morning came nice and early and I was at the track by 7:30AM. The bike went through tech flawlessly (as always) and it was time for 4 rounds of practice.

I've been here once before but I always take the first practice to brush the rust off from not racing for a while and get to know the track again, and it was like 35 degrees outside at that time. Neither I or the bike had operated on a track in temps that cold, so I had no clue how the tires would warm up and when I would get good grip. Naturally, lap times we abysmal due to all of that.

After parking the bike in the pits, I noticed a bit of oil coming from under the stator plate/shift cover area. I went round and round fighting a few small oil leaks all day, eventually using thread sealant on each of the main stud nuts, as well as on the oil pan drain plug. My drain plug is from Joker Machine and has an aluminum "crush" washer. Problem is that the aluminum its made from is so hard, it doesnt really crush. Id had issues with this in the past and never took the time to remedy the issue with a proper soft copper crush washer, which WILL be done before next race. The nuts on the mains leaking is another thing that is really annoying to me. I get the benefit of the studs but the ability for oil to make its way between the case halves, down that stud and out the bottom of the motor is maddening. I was able to find some grade 10.9 acorn nuts from McMaster that I am going to try to replace the nuts. It seems that the tip of the stud is the biggest offender, as if oil is getting past the threads rather than out from under the nut flange. I thing with some copper crush washers as used on many other head nuts with higher torque, the 17.5ft lb these are torqued to should be no issue at all.

Friday after practice as the sun sets on a beautiful, cold day of practice:


Saturday, race day. I skip practice #1 for the day since it was still about 35 degrees out and riding around at 75% of pace is useless to me so I waited until the next round and went out. Lap times are still not stellar, and I think its mostly to trusting that the tires are warm enough to do the job. Coming off the track and checking pressures tells me they are heating up nicely as intended. I was race 13 on the schedule, last of the day. It sucks being last especially on Sunday as people peel out when they are done racing so it starts getting pretty sparse in the pits for a race that late. The benefit to being last was it was still the hottest (hottest being 58 on Saturday and about 65 on Sunday) part of the day so I had more confidence in tires coming up to temp quick for a strong race.

The hot bikes in my class this weekend were both Triumph twins, punched to 750, both with fast riders, one of which is who beat me pretty good last year on Saturday. The other guy was a front runner at Barber last year, so I knew there was work to do on my part to make a good race. I lined up with the guy from last year, and the other guy on the row behind. I had, without question the best start of my whole racing life. The front tire carried a few inches above the ground until torque fell off and the wheel touched down, just in time for 2nd gear. I see the guy from the second row pass me, but he was the only one. I was sure the other guys was hunting me all race, as I tried to catch the other fast Triumph. He pulled away without a ton of effort on his part and while I tried to keep up with him, he steadily pulled away. I knew then that I wasn't hunting 1st, but defending 2nd! I rode hard all 8 laps of the race, trying to keep steady and not beat myself to death before the finish, just knowing that the other rider was hunting, waiting for me to screw up and take advantage. The white flag came with me in 2nd and I said to myself as I always do "Don't f*ck this up, 1 more lap and you're locked in 2nd!" and so I rode that lap as strong as I could and never saw him even once, crossing the finish line in 2nd place.

I pulled into the pits and stripped off my gear to get ready for the awards ceremony and meet the guy that won. He reaches out to shake my hand and congratulate me on winning. Clearly I have no clue in hell what he's talking about and he explains that on lap 3 (far enough out of my sight that I didn't see him) he had a bad spark plug boot that came off and wouldn't go back on, forcing him off the track. I had won! No matter that it was by default, as my uncle always says "To finish first, first you must finish!" I was pretty thrilled to start the season off that way and was looking forward to another run at him tomorrow, now that his bike had fresh plug boots on both wires.

Getting that top box plaque:




Sunday's racing starts with one round of practice, which again, was colder than a witches titty, so I skipped in favor of warming up the bike with some scrub laps ahead of my race. Grids are redone to reflect points accumulated from Saturdays racing, so now I was lined up on one row with the two fast Triumphs, ready to drag race to turn 1. The green flag drops and I get a pretty good start again, but not as amazing as the day before, and of course the one Triumph pulls out ahead as I drag race the other into turn 1. I follow the fast guy (same guy from Saturday with the bad plug wire cap) and start pushing to close the gap he opened up. Again, after about 1 lap he had enough space in front of me and I was riding at my comfort limit, I settled in to stay in 2nd and not screw anything up. The Thruxton class started behind us again and a few of those guys made their way around me. Each time I heard a Triumph engine, I knew it was the other guy, back for redemption from yesterday, but each time it was a rider in the other class. I approached lapped traffic about half way through the race and used them as a chance to work on passing other riders as well as to create a buffer between me and the guy behind me. The last few laps were quiet for me, just keeping my head down and putting in the best laps I could, and this time, finishing in 2nd place for real.

After reviewing lap times from both days, it turns out that not only was my fast lap on Sunday 2.3 seconds faster than Saturday and 5.5 seconds faster than last year, all my Sunday lap times beat my best on Saturday! That means that Sunday was far faster and more consistent than any other time I had been on that track. The thing is that I know there is so much more in that bike, I just need to get it out of me.

A few action shots from the weekend:








Next up is racing in Kershaw, SC at Carolina Motorsports Park.

Leaving in 29 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 MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,598
  • Big ideas....
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1037 on: February 25, 2020, 01:51:44 PM »
 Great story Matt.....congrats sir!
  As for the leaking studs.....I have run into this before. Copper washers and acorns will seal it up and you can use orings that fit tightly around the stud and tightly in the case hole for the stud. Use a little Hylomar on those crush washers too.....that will seal them.
 I have to send you some stickers.....they have been sitting on one of my benches for weeks. Feel free to have it copied in silver to keep your graphics consistent. ;)
Owner of the "Million Dollar CB"

Offline Tintop

  • Old Timer
  • ******
  • Posts: 3,965
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1038 on: February 25, 2020, 02:06:45 PM »
+1, congrats on a successful season opener.  Did your clutch demons from last year go away with the rebuild?
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 Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,938
  • Bought her new 4/75
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1039 on: February 25, 2020, 04:53:36 PM »
Excellent
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline dragracer

  • Really Old Timer ...
  • *******
  • Posts: 5,145
  • CB750F Dragbike
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1040 on: February 25, 2020, 05:20:12 PM »
Great race report and congratulations on Saturdays  win. Cudos on the solid 2nd place finish on sunday and the stellar  lap times. What an excellent way to start off the season!!! So the next race is Kershaw? Hmmm, that's less than an hour away from me. If you're in need of a pit crew, I  can look at my schedule to see if I can make it up to give a hand.

Offline MessnerMoto

  • Hot Shot
  • ***
  • Posts: 708
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1041 on: February 25, 2020, 11:30:41 PM »
Congratulations Matt!

you still own me pictures of primary chain installation ;)

did you use cam tensioner ?


Offline bwaller

  • Really Old Timer ...
  • *******
  • Posts: 7,449
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1042 on: February 26, 2020, 05:10:18 AM »
Atta boy Matt. Starting off on the right foot!

Re the oil leak, did you apply case sealant around the stud bosses too?

Offline MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,598
  • Big ideas....
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1043 on: February 26, 2020, 05:17:00 AM »
Atta boy Matt. Starting off on the right foot!

Re the oil leak, did you apply case sealant around the stud bosses too?
That is key....just have to be careful with the application.
Owner of the "Million Dollar CB"

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1044 on: February 26, 2020, 08:54:07 AM »
Great story Matt.....congrats sir!
  As for the leaking studs.....I have run into this before. Copper washers and acorns will seal it up and you can use orings that fit tightly around the stud and tightly in the case hole for the stud. Use a little Hylomar on those crush washers too.....that will seal them.
 I have to send you some stickers.....they have been sitting on one of my benches for weeks. Feel free to have it copied in silver to keep your graphics consistent. ;)

Thanks Mike! I was thinking the same thing about figuring out how to incorporate and oring in there somehow. I'll get those nuts and washers ordered and set up before next race. Gotta keep the oil inside!!

+1, congrats on a successful season opener.  Did your clutch demons from last year go away with the rebuild?

My number one worry for this year TT and it did come up the first few times out and I had to make some pretty significant on the fly adjustments to the lever to get in a good place. That said, as the bike got more heat cycles in it, the issue seemed to almost disappear, to the point that I did not have any adjustments on Sunday. Seems like the parts all married up nicely and are not moving around as they did before. There is an all new transmission in the bike now that has not been beat to death by my former imprecise footwork. In fact, I did not have A SINGLE blown shift all weekend, either up or down!!! I'd call that success by any measure.

Great race report and congratulations on Saturdays  win. Cudos on the solid 2nd place finish on sunday and the stellar  lap times. What an excellent way to start off the season!!! So the next race is Kershaw? Hmmm, that's less than an hour away from me. If you're in need of a pit crew, I  can look at my schedule to see if I can make it up to give a hand.

That's right, coming back to your neck of the woods! Id love to meet you finally so come on down. All the action is Saturday/Sunday and we will have a garage with 3 other bikes, so plenty of room and shade for any visitors.

Congratulations Matt!

you still own me pictures of primary chain installation ;)

did you use cam tensioner ?

I don't think I have any pictures but need to look back. I did notice that with the chains having such large contact now compared to the old system, it makes a very pleasant WHIRRING noise from the bottom end now. Sounds very supercharger-ish. The oil in the tank is still a beautiful golden brown and I will take a closer look when I change it for any particulates from anything, be they aluminum, steel or from the tensioner feet. It took a bit of fettling to get installed just right, but overall I am really pleased with how easy it was.

Atta boy Matt. Starting off on the right foot!

Re the oil leak, did you apply case sealant around the stud bosses too?

You mean between the case halves around where the studs are? I did not, and would have thought that even that minute additional material would cause and issue with the bearing clearances to the crank. Correct me if I am mistaken though. Hopefully the acorn nuts and copper washers will cure all of the issues. All in all, if thats the only issue I had with a fresh build, Im pumped!

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 MessnerMoto

  • Hot Shot
  • ***
  • Posts: 708
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1045 on: February 26, 2020, 09:25:59 AM »
... one thing... leave 2-4mm of free play in primary tensioner...

you missed my question about my Cam tensioner. Did you use install it ?

Offline slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1046 on: February 26, 2020, 09:28:39 AM »
... one thing... leave 2-4mm of free play in primary tensioner...

you missed my question about my Cam tensioner. Did you use install it ?

I ended up not installing the added adjuster screw for the primary tensioner but may do so in the future.

I did not use the cam tensioner this time since I was not able to get the longer chain in time to get the motor all back together.
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

  • Really Old Timer ...
  • *******
  • Posts: 15,783
  • Bike almost back to the 70's 2015
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1047 on: February 26, 2020, 09:29:40 AM »
Congrats of a good start of 2020!! :)

About oil leak.
Maybe this kind of washer is an improvement? Dowty washers/ Bonded seals.
I have ordered for my engine build, viton sealed washer.
https://www.ebay.co.uk/itm/331894111515

I have M6 version somewhere I intend to use for valve cover with bolts to ensure cam holders in place.
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 slikwilli420

  • Master of Disaster
  • Master
  • *****
  • Posts: 2,357
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1048 on: February 26, 2020, 09:42:09 AM »
Congrats of a good start of 2020!! :)

About oil leak.
Maybe this kind of washer is an improvement? Dowty washers/ Bonded seals.
I have ordered for my engine build, viton sealed washer.
https://www.ebay.co.uk/itm/331894111515

I have M6 version somewhere I intend to use for valve cover with bolts to ensure cam holders in place.

Good solution. Seems like there are a number of ways to tackle this issue. I ordered the grade 10.9 acorn nuts and some 14mm OD copper crush washers, and will use a bit of sealant on both sides of the washer as well. Ordered copper washers for my drain plug as well to replace the hard aluminum one that came with the plug.

I did a cam tower hold down valve cover as well and my idea to seal that was to make a recess under the nut for a small, tight fitting oring so when the nut is tightened down, the oring squishes and fills all the little gaps, making for an oil tight install.
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

  • Really Old Timer ...
  • *******
  • Posts: 15,783
  • Bike almost back to the 70's 2015
Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1049 on: February 26, 2020, 11:50:35 AM »
I will have o-ring in mind when preparing the old valve cover. It has US bolts. Will install inserts to M6.
Minor oil mist is irritating.
Oil cover o-ring has been one on my K6 1005cc. I had thoughts about weeping block in need of open and reseal with Loctite 518. Happy to find the weeping filter cover.
Not all filters have good o-ring supplied. I ordered 50 pack of 89x4.5mm NBR 70 for not much that feels as good as Honda. I hoped to find a harder variant.
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