Topic: Another SOHC heavyweight superbike!

[Eddie747]

This year I got the itch BAD to go racing after quite a few track days. I picked up a low mileage, minty, dirt cheap 78 supersport and built it to run novice production and track days. While I was trying to keep it sane and simple in novice production, I was resisting the itch to just jump straight to the ultimate goal of heavyweight superbike. After reading through another superbike thread I finally made up my mind to just jump all the way in. This build will not be as exotic and trick as slikwilli's but it will be pretty budget friendly. I have access to a full machine shop and fab shop which includes a haas cnc mill and two waterjets. Here is my plan to start out with, and I am looking for tips and suggestions.

Chassis-

CBR 600 F3 forks and wheel. 41mm forks and 2 piston calipers, falls perfectly within the rules and very cheap, I also much prefer the 6 spoke wheels over 3 spokes. At a minumum this will have a billet top clamp to allow for superbike bars and possibly a lower to get the geometry where I want.

Chromoly swingarm and F2 wheel.  4.5x17 rim and easy to get good sticky rubber. I have 1x2x.065 wall tube that I plan on using along with bracing if I feel necessary once the arm is finished. This will most likely be hooked to racetech shocks. I am unsure of length until I can get the forks and wheels on. I will also use either a F2 or F3 rear brake system here.

As far as frame bracing goes I am not sure how much is necessary. Some people use tons of bracing and gussets and others do nothing. All unnecessary tabs will be removed, custom aluminum oil tank, and aluminum or chromoly brackets and tidbits wherever I possibly can.

Engine-

 I know it will be very costly to make it competitive with the DOHC bikes. I would like to keep this as budget friendly as possible and also reliable as I plan on still playing with this bike at track days. I am somewhat unsure what the best package would be, and will probably be calling cycle x in the near future to figure out some things and get a direction.

[slikwilli420]

Welcome to the club!I think if you focus on weight reduction the single cam cam hang with the dual cam bikes. I wish I had access the the cnc. My mind is racing with ideas!

I do think you will need to build a pretty stout engine to be competitive but it can be done. The 17 wheels is definitely a good idea but I may try to go with a period caliper which is opposed piston design. The 2 piston on the same side type seem to be less popular amongst racers based on what I've seen.

Really looking forward to seeing what you come up with.

[Captain]

 Just exactly what are the rules for this " Heavyweight Superbike" class ?  Where in the US is it run ?   Is anybody able to point me in the right direction so as I can read them and know what is needed to compete ?

 If anyone can help with this it would be appreciated.

 Captain
 

[seanbarney41]

Just Google ahrma...  captain, from what I have seen of your stuff, you will find find the rules pretty restrictive.  Would love to see one of your bikes racing in the states though!

[Eddie747]

https://www.ahrma.org/ahrma_pdfs/Z-2018/Forms/18_Handbook_web.pdf

This is the link to the rule book

[bwaller]

Brent scroll down to section 10.8.

[Eddie747]

Has anybody played around with microblue coating on engine internals? Not our 750's, just any high performace applications? It sounds like it could help free up some horsepower and help longevity in high performance, high stress engines and even transmissions. I know a couple guys that use it in the snowmobile world but they won't admit to it due to the rules. From racing against them, it seems like it works fairly well, though that is also probably a result of other work done. I couldn't really find anything for costs except for a trans starts at $500. I am very interested in this process, and from what they say, it can be applied to anything that moves. I just can't seem to find much real world reviews other than the sales pitch.

[Captain]

Has anybody played around with microblue coating on engine internals? Not our 750's, just any high performace applications? It sounds like it could help free up some horsepower and help longevity in high performance, high stress engines and even transmissions. I know a couple guys that use it in the snowmobile world but they won't admit to it due to the rules. From racing against them, it seems like it works fairly well, though that is also probably a result of other work done. I couldn't really find anything for costs except for a trans starts at $500. I am very interested in this process, and from what they say, it can be applied to anything that moves. I just can't seem to find much real world reviews other than the sales pitch.

 I think you might be interested in what I think is called Micro Blue.  I cannot be sure but in reading about it and it's appearance then it certainly seems to be Tungsten Disulphide and is the same as I use.

 This material is a step beyond all else.............. (No sales pitch or marketing hype)...............Look it up.        I won't bore you with the operating range details other than say it's well beyond anything experienced inside an engine/gearbox in chemical, heat and pressure.

 This process is the high water mark of surface treatments for durability and low friction.  Just to give you an idea of just how low this is.......It's 50% that of Teflon.

 There is just nothing else out there that comes close.

 Captain
   

[Eddie747]

Thanks, that is great to hear. I was reading about it on their website this morning and it is very interesting. I can see it being pretty beneficial in our application depending on the cost. Especially with the ability to treat just about everything internally

[Captain]

Brent scroll down to section 10.8.

 Hmmmm looks like the closest would be 10.9  (next Gen Superbike)   However it lists a lot of specific bikes and not the CB1100F so does anyone know if it's acceptable to run a DOHC CB in this. Has it been done before ?

 I realise that this forum is all about the SOHC (and I have one) but I race a DOHC and this forum has many who are road racers that are more experienced than I am about what the standards and conditions are in the US and Canada.

 Captain

[bwaller]

Will check later but we raced in Formula Vintage last fall against Katana's, KZ1000's, and a CBX1000. You should fit in it I expect.

I thought it might have been Formula Unlimited (doesn't seem to exist), then Formula Vintage, but it doesn't list many of the bikes that were in the class. I'll find out tomorrow.

[slikwilli420]

Totally different class of bikes in next gen.That covers later 80's bikes as opposed to superbike which is more about the first era of superbike racing where the earlier DOHC bikes competed. In current configuration Brent's DOHC bike would need a number of changes to become legal for the class.

[Bill/BentON Racing]

Talk to Kenny at CycleX,  hes used the process on internal engine/ trans bearings for sure, probably some other things but not sure. Bill

[westfieldandy]

Interesting to see your idea's

I ran a cb750 in under f750 pre 73 rules over here, and the machine was developed into a real winner by my rider and myself.  But we learnt that the engine is fragile at the level of power we needed, and it was difficult to get the weight of the machine down to a reasonable level. Having a good rider also helped us beat everyone in the end including the twin cam heavyweights,  we won open 1300 class too.

try and get rid of as much weight as possible.  and find some decent brakes.

If your class is post classic then you will have a hard time against the big superbikes.

andy

[slikwilli420]

Interesting to see your idea's

I ran a cb750 in under f750 pre 73 rules over here, and the machine was developed into a real winner by my rider and myself.  But we learnt that the engine is fragile at the level of power we needed, and it was difficult to get the weight of the machine down to a reasonable level. Having a good rider also helped us beat everyone in the end including the twin cam heavyweights,  we won open 1300 class too.

try and get rid of as much weight as possible.  and find some decent brakes.

If your class is post classic then you will have a hard time against the big superbikes.

andy

Not sure where the fragile engine comments are coming from as that doesn't seem to be the case at all with the SOHC when properly built. My other bike in a 750 class is around 356lb wet and likely making low-mid 80's power at the wheel. I have no reason to assume reliability will be an issue.

For this class on the other hand, weight will be harder to drop given the restrictions on bodywork and the need to have certain parts to keep it looking like a street bike. Even with that, an SOHC honda should be able to get a good bit under 400lbs wet and make over 100hp at the rear wheel. A bike like that would really shine on shorter tracks where handling would be the great equalizer vs a place like Road America, where long straightaways might make the SOHC stand out in a bad way compared to the bigger bikes. The larger displacement bikes in class also need to run 29mm carbs, where as SOHC Honda can run whatever they want. I chose 31mm CR's for mine, but a motor built really well may work fine on some 33's as well.

[westfieldandy]

I can assure you the engines were properly built, and speak from experience.

I did say it was fragile at the level of power we needed,   so things start showing up once we passed the 80bhp mark. we learnt a lot.

[slikwilli420]

I can assure you the engines were properly built, and speak from experience.

I did say it was fragile at the level of power we needed,   so things start showing up once we passed the 80bhp mark. we learnt a lot.

Care to share specifics? Plenty of guys getting over 80hp on these with no reliability issues.

[westfieldandy]

Most of the racers I have had contact with during our racing, were mainly based in usa & europe, had encountered all the same issues that I also discovered,

rods break
cranks break
chains break
primary rubbers disintegrate.

Learnt a lot,  but I discovered afterwards that it is not uncommon,  spoke with a lot of sidecar racers and motorcycle racers all of whom experienced similar issues,  just sharing my experiences. and I am talking top level racing not fast road / occasional track use.

[slikwilli420]

Most of the racers I have had contact with during our racing, were mainly based in usa & europe, had encountered all the same issues that I also discovered,

rods break
cranks break
chains break
primary rubbers disintegrate.

Learnt a lot,  but I discovered afterwards that it is not uncommon,  spoke with a lot of sidecar racers and motorcycle racers all of whom experienced similar issues,  just sharing my experiences. and I am talking top level racing not fast road / occasional track use.

Aside from cranks, which I understood to be quite strong, very good solutions for all the other things mentioned exist here in the states. There are a number of rods well up to the task, as are options for primary chains that are far better than stock, and cryo treated if you like. Primary rubbers are also easily addressed, either by ones self or sending them off to have rebuilt.

[westfieldandy]

Think we are across purposes here,

if I have confused anybody on here I apologise.

I stated the engine is fragile, because it is.   

But if you are looking for decent power, and build the engine with a load of special parts readily available you can build out some of the fragility

Cost wise it makes an expensive engine, but will give you a stronger engine less likely to fail under race conditions.

regards

[Bill/BentON Racing]

Please continue with your input. You are quite correct.  Slikwilli is right about 80-100hp. After that all the things you said especially primary problems. Dont you go away... 1300cc methanol Honda's break things and I want to know! Tell us more about your big builds....very interested,  thanks and Good Luck to you and Slikwilli who's building a really nice roadracer, Bill

[westfieldandy]

Thanks Bill,

We have retired the bike now, after some real amazing racing with My rider Rob Wittey, taking 1300 and 750 championships  we achieved some really amazing results against some very competive machinery, rob north framed triumph triples our main adversary, I had some help from Mark at M3 racing with special cam profile and headwork, and ken at cycle x with some of the parts. But we got through quite a few engines getting there.   a truly great experience I will always remember for the rest of my years

[bwaller]

No argument Andy, when Honda developed these engines  mid 60's horsepower was adequate. There are many weak links. I think through this forum though some very good ideas and parts have been hatched to make them race reliable to a certain extent. Brian in Au did much development on his sidecar engine and broke a lot of stuff too. I feel there is a displacement limit and above that we're "stretching it" !

Back in the day my boss was a successful roadracer and he felt his 810 was the best engine, above that #$%* broke. Mind this was before better rods etc so "just saying" . A well ridden smaller displacement motorcycle can surprise....

[Bill/BentON Racing]

Here's some interesting pics, 17mm pins Golden rods and pistons

[Jerry Rxman Griffin aka MuthaF'er]

Bill, what are you taking apart now?