Triumphrat

TriumphJohnny · 11-17-2009, 05:28 PM

Hello:

I have been thinking about putting in a new cam in my 07 SM. After seeing that some of the Hypo Cams run anywhere from $700 to $900 bucks I thought......man, back in the days we use to take the original Cam and have it machined to our specs. So.........anybody ever use their original SM Cam, have it machined to specs as to the mod cams? If so I would appreciate it if you would share your thoughts and possibly where you had it done...........and of course the cost. Thanks.

Overkill0084 · 11-17-2009, 08:07 PM

It's been my observation that go-fast stuff on most bikes is pricey (quality stuff anyway).
If I'm not mistaken, (can't rule it out) the TPUSA cams are essentially stock cams that have been upgraded/remanufactured to the improved spec. Similar in concept to what you described. Not a knock in any way, TPUSA stuff has a really good rep, but I am fairly certain that's why they do the core/exchange thing.
There are a lot of opinions regarding cams, I've read that Thunderbike cams are underwhelming and that they aren't any better than the older stock cams, others say the are wonderful. Can't say myself.
I somehow doubt that custom ground cams will save any money. Time for some reading.
One of the knocks I've noticed is that published info on lift, duration overlap etc just isn't out there. It's all very closely held by the makers, which complicates things for the consumer. You are forced to go on faith that they are what the maker/vendor says.
Enjoy the hunt.

TriumphJohnny · 11-17-2009, 08:11 PM

I agree. I was at a Hold'm Tournament Sunday evening, sitting and talking with a Motorcycle mechanic / racer, matter of fact he was the one who actually put my SM together when it was delivered in the crate at the shop............anyway I was talking about or considering changing the cam. He is the one that mentioned it would be cheaper just to take the original to a machine shop and have it spec'd out. We never did talk specs....and the shop I bought my bike at closed down. I am going to have to contact him and see what he can do or what direction he can point me.

'08 T100 · 11-17-2009, 08:20 PM

Quote:

Originally Posted by TriumphJohnny

I agree. I was at a Hold'm Tournament Sunday evening, sitting and talking with a Motorcycle mechanic / racer, matter of fact he was the one who actually put my SM together when it was delivered in the crate at the shop............anyway I was talking about or considering changing the cam. He is the one that mentioned it would be cheaper just to take the original to a machine shop and have it spec'd out. We never did talk specs....and the shop I bought my bike at closed down. I am going to have to contact him and see what he can do or what direction he can point me.

I am under the impression that first, you have to weld more material onto the lobes and THEN, reprofile/machine them to get the desired gain in lift & duration.

sweatmachine · 11-17-2009, 08:56 PM

TPUSA does weld/regrind stock cams to their specs. You could certainly have this done yourself, but you (nor the machinist making the cams) don't know what profile works best. You could weld and grind cams for weeks and months and blow tons of money, maybe only to be disappointed with the results. Or, you could pay TPUSA to do your thinking for you and go for what they know works. You pays your money and you takes your chances.

mikeinva · 11-17-2009, 09:42 PM

first there are not many people that grind cams and 2nd hardly any are set up to grind your cams.3rd you dont know what spec to grind them to.bite the bullet send your cams to tpusa and be done with it.If you want to hot rod these bikes you better be ready to spend money there not cheap to do.

TriumphJohnny · 11-17-2009, 10:41 PM

Both of you make some good comments, but...and not just to save a buck, but.....I have a number of buds, and including myself that have worked on both bikes and old hot rods for years. I consider myself a "back yard" mechanic to some of my friends who have built some nice rides. Another close friend of mine rebuilds vintage Trumps and I have been kicking this around with him. I know that Tpusa has done all the home work and know what is needed to be done, but come on...their staff has two arms, two hands just like you and I. It isn't some type of magic or unknown.....if they figured out, or know the specs I am sure that someone else has or can figure them out.

mag10 · 11-18-2009, 09:21 AM

I have a spare set of stock 865 -270 cams that I would be willing to let go at a reasonable price if you want to play with cam development.

If TP or thunderbike could do it there is no reason that you can't come up with something as well (maybe something even better). Might take a lot of time, effort and expense. but it certainly could be done. Or you could hit it first try.

If you just increase the lift on the 865 cams by a millimeter it would be a noticable improvement with very little risk. the stock pistons have enough clearenec for it.

Thruxboy · 11-18-2009, 10:54 AM

In the spirit of not divulging any vendor cam spec's but discussing the difference in firing order between the Speedy and Bonny, does anybody know if the cam spec's for the stock 270 deg cam profiles...Speedy right cylinder comprising two intake and two exhaust valves is purely a 90 degree retardation (or advancement) in anglular inlet and exhaust lobe position compared to the left hand cylinder to match 270 deg. offset cylinder firing?

Thanks.

PS: The stock 360 deg. 865 cam specs have been posted on here before:

3rd Generation New Bonneville (865cc, 360 degree engine)
Valve Lift: 374/1000ths
Inlet open BTDC: 0 degrees
Inlet close ABDC: 24 degrees
Inlet Duration: 204 degrees
Exhaust open BBDC: 39 degrees
Exhaust Close ATDC: 7 degrees
Exhaust Duration: 212 degrees
Intake overlap: 7 degrees

mikeinva · 11-18-2009, 01:19 PM

Go ahead design your own cam you might get one that works in 5 years or so at a cost of $5,000 to $10,000 After you figure all the grinds you will go through 100s of dyno runs and blow up a few motors.By the way for get what you know about old 2 valve bikes wont work with 4 valve heads.I hope if you copy someones cam they find out and sue you as they should.You will pay one way or the other,if your to cheap to pay maybe you should leave the bike alone.With your attitude you wont get much help from those that know much here.