Topic: CB750 AHRMA Superbike Heavyweight Racer

[johno]

George,
Ya getting there mate 
just curious, did you anneal the capper gasket ? at .040 thick they are pretty damn hard and unforgiving. At that thickness I would anneal it then use sealant wisely as well.
ciao

[slikwilli420]

I did not anneal the base gasket as I was under the impression they were dead soft copper already. George enlarged the holes for the larger sleeves and I carefully deburred all the edges and applied copper coat to both sides. Viton coated steel gaskets only come up to 0.020", and I am not sure if those can be doubled up but I have not had a single issue with them on my S750 bike. We needed to go thick on the base as quite a bit of material needed to be removed from the cylinder to account for a couple sleeves that had sunk after being run last.

I did find that after retorquing the head 24 hours after initial torque but without heat cycles that I was able to get another 10-15 degrees of rotation out of the head nuts. I was able to get to the two outside nuts after a few heat cycles and they turned an additional 10-15 degrees after that torque. With the frame kit I will be able to pull the valve cover and use a crow foot to get to all the nuts again, loosening and retorquing one at a time. I really hope this is enough to stop the oil from the base gasket. Of course the MLS head gasket is totally leak free.

[MRieck]

 Cometic does not recommend annealing the head gaskets. I have copper base and head gasket on my 750 with the billet block.....no leaks at all.

[PeWe]

Cometic does not recommend annealing the head gaskets. I have copper base and head gasket on my 750 with the billet block.....no leaks at all.

Hi Mike,
Only copper gaskets, no additional sealer like copper spray..... ?
Possible to reuse these if head and ev cyl block is lifted?

I heard that copper gaskets can be heated and reused. Another thing how long that will work.

[bwaller]

Wow Mike, that surprises the hell outta me. I always anneal new gaskets and seriously they are much softer afterwards.

Regardless, whatever works. Everyone has a favorite, and I've tried several, but found Gasgacinch was the best sealant for copper.

Also, and for what it's worth, I often stack mls base gaskets if needed.

[johno]

I feel Cometic recommend not to anneal their gaskets as if its not done well it can distort the gasket causing problems, also commercially they sell more 
The first time I used one was on a nascar engine and it had water pissing out everywhere on the dyno, since that time I have installed maybe hundreds, both water cooled and air cooled engines along with some sort of sealant and never had a failure or leakage.
Once you have a oil weep and retention it may minimise the weep to an acceptable level but it rarely stops a weep due to capillary action of the oil.
The key is how you anneal the gasket, even temp on a flat surface does the job, holding the gasket vertical with a piece of wire through a hole & using a flame thrower will guarantee distortion. etc also I only quench sometimes when reusing the gskt as that also can distort gskt if not done correctly.
Thin copper gaskets say up to .020 thou I don't anneal but once your around .040 or 1mm or more I always remember that pain in the ass day about 45 years ago 

[slikwilli420]

I'm going to try and retorque the head nuts with the engine in and cam towers installed. I have the cover off and access to the nuts. What tools are guys using to accomplish this task? There is very little room to maneuver around the cam towers. I bought a crow foot but it won't work on the studs close to each other on 1/2 and 3/4.

[gschuld]

FWIW, Matt is referring to these.

George

[scottly]

I have, on occasion, resorted to modifying a box-end wrench for such situations, by bending and grinding clearance, as well as welding a socket on for the torque wrench. You will have to calculate how much the offset will affect the torque reading. 

[johno]

As old as I am I have never retensioned after hot set. On the initial build I always rention a few times or until the nut doesn't turn anymore, sometimes it takes a few days.  I persist with that because the hot set method is a real PIA  But you know Matt that's a great idea, similar to what scotty said but if you modify a crows foot to fit you won't need to do any calculations etc, which will likely entail grinding the cam tower base as well to fit the crows foot on.  You could be brutal grinding the crows foot cos the tensions not much so just need enough to hold the shape, might get lucky if you can make the crows foot thin and low, if not you'll only have to grind out the cam towers once

Yeh good idea guys, thanks,  Im heading out to my shed now to grind the absolute crap out of my crows foot

[PeWe]

Easier to remove the cam towers. Tighten each nut a certain degree might be difficult when the nuts sit tight.

Mark sprocket and cam so it can be reassambled without timing. Crank at TDC 1:4 as a reference.
Remove towers and retighten all nuts to correct torque value.
Important to ensure chain slack on right side so chain is not 1 tooth wrong.

I had a cam and sprocket marked like that from the shop that assembled it first time in the 80's. Cam was a K/H SS-1, a moderate cam.

[johno]

Thats right Pewe,
 to retention head bolts or nuts they must be backed of first then brought up to tension otherwise the friction to overcome the the tension will give you a false reading.

[slikwilli420]

I was able to get about half of the nuts to break loose and then torque back up but the rest were too covered to make any real headway. Ive learned a couple lessons here. No more copper gaskets. The first one I ever used leaked, while I have had trouble-free performance from steel coated Viton gaskets. Let's hope this one holds for now after a retorque and a smear of RTV on the perimeter of the cylinder/case. Not the way I wanted to go about it but based on where the oil was heaviest, it looks like it was coming from the return between 2 and 3. All I needed to do was stop the leak and I can address it more permanently later.

The second is to make sure I use the taller HD nuts for the studs next time. I had these nuts on hand from when the engine was broken down and figured if they had been used with the HD studs already, they were good. Of course they all torqued up find, but they are so short that getting on them from the side with a crow foot just doesn't give enough bite to be able to torque them all. With the taller HD nuts, they have a wider flat that will be better for the crow foot.

The last hurdle was the rear wheel. If you remember, I had initially thought it was bent. Fortunately, mere weeks before I had picked up a 4.5" rear wheel with extra hubs. Those hubs are interchangeable between wheels and had the same spacing on the drive side so it was only a matter of a few spacers to line the chain up and center the wheel. Now it spins true and I am confident that is the end of that mess. Fingers crossed the teething BS is done and now I can focus on tuning and learning the bike.

Next weekend is Vintage Motorcycle Days at Mid Ohio. It's my yearly pilgrimage (cancelled last year  ) to spend money I don't have on parts I don't need. I always find a deal on something awesome. I have pulled more special stuff for pennies on the dollar from there than anywhere else. It's a rare weekend to be a spectator rather than a racer but I always run into a few forum buddies and AHRMA racers as I make my way through the paddock. Best of luck to them!

The two weekends after are the double header of races that is Gingerman (home track) and Blackhawk Farms about 4 hours away. Gingerman is special because it's where I took the class to get my race license, its where I finally beat my uncle last year in Sportsman 750, and it's where I get to have more family come out to support my efforts. I should be a good couple of weekends filled with racing, and a LOT less driving than what is normally required.

[bwaller]

Just so I've spilled all my beans....I like a copper head gasket, but the sleeve flanges need to be o-ringed with SS or other metal wire. Copper dead soft and Gasgacinch sealant.

Now you can do whatever turns your crank! LOL

[paul_cb836]

Our 915 methanol CB has been rebuilt several times with the same copper head gasket. Can’t remember the brand but came from Dynoman. It came with instructions about annealing and has been annealed every time, including from new. We use Three Bond (white) painted on with a brush. It has never leaked a drop - in fact it is the most oil tight of the several CBs I own😀.

[gschuld]

FWIW, the Superbike engine has an MLS head gasket and copper BASE gasket.

It’s the copper base gasket that is leaking some.

George

[MRieck]

FWIW, the Superbike engine has an MLS head gasket and copper BASE gasket.

It’s the copper base gasket that is leaking some.

George

Like Brent said Gasgacinch or spray Copper Spray a Gasket from Permatex.

[paul_cb836]

George, we don’t use a base gasket so don’t have to worry😀😀

[johno]

Hi Matt,
Just curious, what fuel is allowed in your heavy class and what comp ratio are you running ?
cheers Johno

[slikwilli420]

Hi Matt,
Just curious, what fuel is allowed in your heavy class and what comp ratio are you running ?
cheers Johno

We can use up to 112 octane I believe. I run 110LL that I get locally. My other bike runs 12:1, while this one is more like 10.5:1.

[johno]

Thanks Matt,
In Oz we have had our compression world turned upside down with the banning last year of leaded racing fuels in gas classes so if your running hi comp you need to run in fuel classes ( methanol & racing unleaded) or reduce the comp and run pump gas, which sucks. A few of the race gas companies put out racing unleaded gas but it contains additives that makes it non compliant in our gas classes & is expensive at over $200 per 5 gall container.  Makes it hard to chase current records when changing the rules requiring less comp.  Kind of mulling over what to do, smart man would fly the white flag and run in the classic class which has a soft record but not much challenge in that,  so thinking for me,  forget the class thingy and focus on getting the 750 to run 150mph just for the sake of it. I'm finding that goal difficult enough as it is. Racing rule changes are happening more often than an old man can get his head around.

[slikwilli420]

I just realized it has been a long time since I posted on this one, so here we go. The remainder of this season was fraught with testing and tuning, not only of the engine, but the chassis. With some much needed help I was able to test a few different sets of shock setup with different springs and preload settings, but nothing really stuck. Tally was a month before Barber and while I was able to get out on track and keep the oil inside the engine, it just didn't handle right. Race Tech shocks were on order and promised right before Barber in early October so at least I had that going for me.

Fast forward to Barber weekend, no shocks. Race Tech makes a great product but it's very frustrating when they say one thing and do another. At this point I had the same shocks from Tally, with stiffer springs and with this being the last race of the year I had to send it! Friday practice as filled with the standard wallowing feeling in the rear end. I started conversations with many people that day and one thing started to surface, the tires. I was running the Metzeler RaceTech RR and people had more than once said, unprompted that they felt a very loose, wallowing sensation on those tires. Well sh*t, there you have it. Lucky for me, a Continental dealer was there and had fresh set of Conti 3CR tires ready to, of course I wanted another backup set for my Sportsman bike, so $880 later I was on the move. I had the wheels off the bike and dropped off at a vendor who does tires for races at all the rounds and was hopeful that this would be the right move. Even if it wasn't, I'd have another set for my S750 bike. Since there is no practice on Sat/Sun at Barber I had the time to get the bike put back together, but no time for practice, so I set up the pressures on those tires just like I did on my S750 bike and lined up on the grid.

Im happy to report that that uneasy feeling had subsided and I was able to finally ride the bike without that looming. Times weren't great but I finally got a feeling for the bike. The new Race Tech shocks are now on the bike and the offseason preparations are well under way.

The tweaks to the bike are few this time around which is nice. I will pull the engine and split the cases so I can replace the rivets in the primary tensioner both top and bottom, as I broke a number of them on my other bike and want to make sure that doesn't happen here.

I am gathering parts for a new engine build right now. Cases, auto crank and Carillo rods are off to Kenny at Cycle X for all the works. Upper case boring, crank bore line lapping and bearing fitment, crank lightening/balancing, and rod installation with fresh bearings. The Pro Cut trans is sitting in the basement and with that, the bottom end is nearly wrapped up.

Sorry for the lack of pictures on this one, but there should be plenty of eye candy coming soon, as I prep for the first race of the year, as AHRMA returns to the high banks of Daytona on January 7-9. If you have any way possible to make this weekend and catch some ARHMA racing, this is the one. It will be a full Classic Moto Fest with multiple disciplines of racing and tons of stuff going on all weekend. This is also the kickoff of Vintage Superbike Heavyweight as the Vintage Cup class, making the first round at Daytona even more special in so many ways.

44 days until I'm Daytona bound!

[dragracer]

Thank you for the report Matt. I may take you up on the offer to come watch you in Daytona.  By tbe way, per our mutual friend,  I owe you a phone call to discuss a little about road racing.

[bwaller]

Too bad about the Metzelers. Probably a good dry tire option, but were you planning to ride those in the rain too? I was/am hopeful Bridgestone and the others would offer up a better all round vintage race tire choice in sizes we can use. The Pirelli Phantom RS are supposedly reasonable tires both dry & wet.

Would you do me a favor and measure circumference of a mounted Conti 3CR please? I need to replace rear shocks & I hope to get a pair I can shorten to compensate for the Continental sidewall height. Unmounted they are way taller than Avon, enough to affect gearing and probably trail!

I thought about going to Daytona, but we only get back from the west on the 6th, and that just makes for too much craziness.

Good luck with preparations and have fun in Daytona.

[slikwilli420]

Too bad about the Metzelers. Probably a good dry tire option, but were you planning to ride those in the rain too? I was/am hopeful Bridgestone and the others would offer up a better all round vintage race tire choice in sizes we can use. The Pirelli Phantom RS are supposedly reasonable tires both dry & wet.

Would you do me a favor and measure circumference of a mounted Conti 3CR please? I need to replace rear shocks & I hope to get a pair I can shorten to compensate for the Continental sidewall height. Unmounted they are way taller than Avon, enough to affect gearing and probably trail!

I thought about going to Daytona, but we only get back from the west on the 6th, and that just makes for too much craziness.

Good luck with preparations and have fun in Daytona.

The metzelers are so much softer than the conti's when you flex the sidewall by hand. Conti's are good all weather tires as well so that eliminates the need for two wheel sets. Conti's are 26" tall mounted and inflated.

Daytona should be a wild ride, too bad we'll miss you down there. I'll get George to drink a pint with me in your absence!