Gut feeling or "60 horses and a duplex front brake"

[StephenB]

This isn't one of those "just because I can" disucssions (or maybe it is!):

So, here I am with an empy engine case with the # that matches my frame ( thanks to Ken C. in Chilliwack, BC - long story). Task at hand is to move the inerts of the currently installed engine to the "new" engine case to make this a matching numbers R60/5.

Now as with all things, you think about improvements: the 750cc piston/barrels/head are a given as they are there. Consider that a reasonable upgrade that won't even offend the collector.

Now, there is the 336 sport cam that was originally developed for exactly this 750cc engine and there are 900cc barrels/pistons/heads that you can make fit.

I am looking at four scenarios/variations:

Option 1: do a 1-to-1 swap and be done with it (min $$$)

Option 2: add a 336 cam to the 750cc engine (since the cam has the flat asymmetric keyed interface that also requires the use the later timing cover, points-in-beancan, 107mm alternator etc) (option 1 + 336 cam)

Option 3: add 900cc barrels/pistons/heads and use everyhting else as is (option 1 + 900cc)

Option 4: option 3 + 336 cam (max $$$)


I am torn between the two extremes (as-is or 900cc with 336 cam) but the problem I really see is the following: if I have a 900cc engine, it will accelerate faster and I will get into situations far more easily where good brakes save lives. Is a well adjusted and maintained /5 front duplex front brake up for the job? I have heard it beats the single ATE but have no first hand experience myself.

Is the 750cc engine with the 336 cam a worthwhile (as in noticeable) improvement? Also, does a 1979 timing cover with single chain fit the /5 housing, does the later flat keyed cam (1979-on) fit the engine case when used with the correct inner rotor?

It being a R60/5, would the options 3 and 4 be considered over the top upgrades by collectors (not that I intend to sell it ever but you never know there might be situations where an emergency sale has to be considered)? In other words, will the value be affected? The color is Monza Blue Metallic #538 which is correct for a 1972 R60/5, but the original painted parts I used were a contribution from my Dad, and were not on the bike originally.



I will install the matching engine case into the frame, that's for sure! In the process and since the case is empty, I will learn about installing camshafts and crankshafts and by that complete my apprenticeship on Airhead engines by reaching the final frontier, a rebuilt engine from an empty case to full completion.

Would like to hear about your views/opinions/lessons learned etc., technically and philosophically!

Thanks, Stephen

[gspd]

This isn't one of those "just because I can" disucssions (or maybe it is!!)

I concur :>)

[Ken in Oklahoma]

I won't be of any help technically, but I do have a philosophical idea or two.

To over simplify what I got from your post I read that you really want the performance, you very much enjoy the toaster look, and you don't want to compromise the collectability value of the bike.

Taking the last first, it strikes me that there are two types of collectors, those who want the bike dead original or at least period correct. And then there would be the collector wants the essential look and feel of a toaster or /5, but want to be able to ride and enjoy the thing. A major question, for which I sure don't have the answer, would be how many of the first type of collectors are likely to show up on your doorstep compared to the second type of collector.

Here's my thought: If you kept yourself in a position where you could offer the buyer a box with the parts needed to "de-modify" the bike, that should be very appealing and capture the "purist" collector as well.

Now to address your desire to "hot rod" the bike or not: A lot would depend on the number of airheads you have or intend to have. If your only other airhead will be your gs then I think you will need to feel the performance of your /5. If, on the other hand you intend to acquire a "road" bike such as an RS or S or even RT, then I'm guessing you will be quite content with the lesser performance of your 750cc mildly performing /5--maybe to the point of even preferring the contrast.

Changing subjects again: If you "hot rod" the bike, aren't you going to need to fit the bike with a taller final drive? I'm guessing it's going to feel a bit too buzzy for your taste.

I've never ridden a drum front braked airhead, so I can't attest to how adequate it might be. I've always been a bit puzzled about the notion of greater brake performance being needed for bikes with more performance potential. I view your riding as considered and controlled. I'm guessing that you would ride the hot rodded /5 the same as the lower performance /5 except for the occassional burst of speed or twistie that you can't resist. Since I see you as being a thoughtful rider, I also see you as always having the performance of your brakes in the front of your mind, even during a bit of exhuberance.

I presume that to swap on a dual disk ATE fork with the attendant master cylinder would be way off the mark for you to still get off on the "classical" ride. It would me, but I wanted to throw it out there.

The thing that strikes me the most from your post is that you intend to enjoy your bike, while keeping a prudent eye on it's marketability should the desire or need to sell it ever come up. I think that if you keep the parts you took off, and include the 750cc setup, and also include the mild R60 camshaft, then most collectors will be just fine with the bike. Plus I'm betting they would never put the lower performing parts back in the bike either. It the psychological knowledge that he could that will make him open his wallet and blow the dust out.

As an aside, aren't you going to need a toaster tank or toaster panels for a tank to make the bike look right? And if it's a regular /5 look you're after, won't you need to take the side covers off?

My personal advice is probably the same advice you might give somebody else. It's your bike. Make it the way you want it. And when the time comes to let it go, I'm guessing that there will be buyers who are really turned on by what you're offering for sale. Just don't trade away any of the parts you take off.


Ken

[StephenB]

Interesting point of view, Ken. I don't have the toaster tank (I have side panels and the big 24l tank, a period upgrade!), nor do I have the R60 internals, so that "psychological advantage" is gone already. I also would need to sell the 750 engine to make money for the improvements. Those parts wouldn't count anyways for a R60/5 becausde those themselves are already period upgrades!

I don't think I'd call it hotrod'ing, but since it is a "sports" cam the term isn't that far fetched. Your last paragraph mirrors my train of thoughts exactly.

It is quite possible that the /5 will be my only Airhead in future, in fact, it could be my only bike as my interests will be shifting towards something else (think RV'ing around NA with a 250cc dirt bike and the /5 in the back). My wife and I are planning to be much more mobile which in turn has me show up in BC, OK more often, esp. in May and October! Hence the thought of making the bike a little bit more powerful for the odd cross country trip.



No, in fact, I really don't care about collectability ...

[Deleted User 287]

It sounds like someone is gearing up for retirement?

[StephenB]

Way too young to retire, unfortunately. But we have big plans that require some money so now is as good as any time to start planning.

[Chuey]

I don't get the importance of matching numbers. I kind of get it for collector bikes but not for riding. I know that my R90S, which has an actual "S" case but not an "S" frame number, won't bring as much when it is time to sell, as would a matching number bike, but I want to ride it, and I can't read the numbers when I'm doing 80.

If some wise acre at a stop light ever says anything about my numbers not matching, I will act as if I can't hear him.

Chuey

[StephenB]

Back to the technical part of the question about upgrading a R60/5 (that currently IS a R75/5):

I am looking at four scenarios/variations:

Option 1: do a 1-to-1 swap and be done with it (min $$$)

Option 2: add a 336 cam to the 750cc engine (since the cam has the flat asymmetric keyed interface that also requires the use the later timing cover, points-in-beancan, 107mm alternator etc) (option 1 + 336 cam)

Option 3: add 900cc barrels/pistons/heads and use everyhting else as is (option 1 + 900cc)

Option 4: option 3 + 336 cam (max $$$)


I am torn between the two extremes (as-is or 900cc with 336 cam) but the problem I really see is the following: if I have a 900cc engine, it will accelerate faster and I will get into situations far more easily where good brakes save lives. Is a well adjusted and maintained /5 front duplex front brake up for the job? I have heard it beats the single ATE but have no first hand experience myself.

Is the 750cc engine with the 336 cam a worthwhile (as in noticeable) improvement? Also, does a 1979 timing cover with single chain fit the /5 housing, does the later flat keyed cam (1979-on) fit the engine case when used with the correct inner rotor?

So, can the following be assembled to work together:

/5 engine case
1979-1980 (single row timing chain) timing cover
/5 engine cover
single row timing chain
hydraulic timing chain tensioner
336 cam for Airheads from 1979 with oilpump inner rotor with flats (not woodruff key)
points-in-beancan
add 900cc barrels, pistons and heads

Stephen

[Ken in Oklahoma]

I don't get the importance of matching numbers . . .

I kind of get it Chuey, or at least I think I do. My take is that Stephen is not enamored with matching numbers. However he is enamored with getting maximum money when he goes to sell the bike. I suspect that many "collector bike" buyers are like me. When I'm looking at a bike I have this tendency to see the potential rather than what the bike actually is as presented. Show me a basket case with matching R90S frame and engine casting, a few "signature" R90S pieces such as the black painted cylinders and the unique handlebar clamps, and I will be seeing the finished R90S bike in my shop, Daytona Orange paint job marred only by my slobbers, and those lovely Dellorto carbs.

I would need a friend with me who would (figuratively) kick me in the ass, reminding me to really look at what I was actually buying, most of an airhead with some unique R90S parts in the pile.

Stephen is thinking about what it takes to attract a buyer like me!

Ken

[Max Headroom]

FWIW Stephen, since you've asked for suggestions I'd go for either the 750 or 900 top end, but with the 308 cam instead of the 336. The 336 works best when the compression is bumped right up, but offers little in return on standard compression unless you're keen to rev the crap out of the bike to find some power. If some of your riding will involve a pillion, you'll want torque which the capacity upgrade will offer but the 336 will conversely rob. IMHO, the TLS front drum won't have a problem coping with either the 750 or 900 capacities if, as you say, it's set up correctly.

The single row cam is less attractive for me, partly due to the necessity to use the later front engine cover. The early front cover isn't a comfortable fit on the later timing chest 'cos it won't clear the beancan.

I can understand the attraction for matching numbers. All of my bikes have matching numbers, even the basket cases, and there are a few reasons for that appeal to me. Firstly the bike's identity can be clearly identified regardless of subsequent mods, and secondly, we are at best only temporary custodians of our possessions. If anything were to suddenly cause my demise, my surviving wife or family would have no problems when selling my bikes by unintentionally misleading potential buyers with a misrepresented machine. I was originally headed down the same path as Chuey by building an R90S replica out of an R90/6, but chose to substitute a genuine R90S frame and its matching numbers crankcase just before assembly began. The only exception in my fleet is a frankenbike I'm about to start building soon, which will be a complete bitza and good luck to anyone in years to come trying to identify which bits were used in its construction!

YMMV etc