Bonneville America Forums Forums Technical Forums Performance Mods Thunderbike cams with Wiseco kit?

Just wordering has anyone tried the thunderbike performance cams with the Wiseco big bore??

I have the big bore waiting to install, but I was thinking of doing the cams at the same time..... any comment whether it is worth it or is the Wiseco kit enough?

Any comments welcome.....thanks.

might want to pm RCV on this site, he is our resident thunderbike guy and normally gets back pretty quickly

Frank

[Tim the Toolman voice]GRUNT GRUNT MORE POWER![/Tim the Toolman voice]
Cams = better breathing, and that is a good thing. If nothing else, because the effective compression is reduced a little at low speeds where detonation does the most damage, cams could save your engine if you ever find yourself having to use crap gas.

The Thunderbike cams that Brent sells are listed for the 865cc Speedmaster. If I understand correctly, the 865 has a little different cam profile than the the Americas and the older SMs. So the question is, would the Thunderbike cams help the 790cc engine? If not, does Thunderbike make a cam for the 790?

Cody

I can say for certainty that the Wiseco is enough, for now...
But I also have a set of MegaCycle cams I need to get around to installing soon. Definetly before the NH romp.
You can also save some big bucks by just buying another stock intake cam and putting that in the exhaust position. That supposedly works like a dream, and the Thruxton racers are all doing just that.

How much are those?

Remember that the 790 cams (intake and exhaust) have "better", i.e., bigger and longer, specs than the 835 cams. A pair of 790 intake cams, as ol' Dinq has suggested, is a decent way to go.

And those MegaCycle cams he has are the "bees' knees"! At slightly higher lift and longer duration than the 790 cams, they'll feed a big bore kit very well. What's really nice about those particular grinds is that they work with stock valve springs, though I'm sure one can get stronger springs, if he feels the need to "rev the snot" out of his new motor. (Since the Wiseco big bore kit has forged pistons, you have my blessing to wind 'er up!)

Technical note: Both the 790 and 835 cam sets have a slightly smaller ex. design as compared to the intake. This does 2 things: helps broaden the torque curve, especially at lower rpms, AND, helps reduce emissions output.

Special note to Runner0023: If your budget will allow the purchase of those Thunderbike cams, by all means, buy them. You'll be the happiest biker in all of New South Wales!

Thanks for the encouragement PapaDean,
I made contact with RCV about cams best suited to the Big Bore motors, and he has told me that Thunderbike powersports have been working on many different grinds to suit different New Bonneville motors. As mentioned before the 270'865cc cams are complete, and 360' cams have been tested successfully.

The best news for me is that the 270'904cc cams are expected to be installed in a fresh 904cc America for testing in the next few weeks. I am talking to RCV about getting one of the first sets to use when i install my big bore, hopefully I can be a test pilot to see how they really do go!

I wonder what the limit is for Thunderbike cams, as regards valve springs. As cams get "bigger" (i.e., higher lift and longer duration) the velocity of the follower/lifter/shim gets higher at a given rmp level.

In other words, the new cam lobe "throws" the lifter faster and harder than stock. A result could be that one might get valve float at an rpm level where he didn't have such with his stock cam.

NOTE: This faster lift rate is usually the case, though aftermarket cams can have mild lift rates. Dr. Harold Brookshire of Ultra-Dyne Cams has said that there are over a million different lobe profiles that can be drawn through a given set of 3 parameters, that is, the opening point, closing point, and total lift. Yipes.

Stock Triumph valves springs may handle this, I don't know. Hmm, those guys down in the southeast who flat track a Triumph might know, though. MegaCycle Cams might know, and as smart as the guys at Thunderbike seem, I doubt they will overlook something like this.

Does anyone know what the stock valve spring specs are? That would be, seat pressure at installed height and "over the nose" pressure at max lift.

It's possible that just a 10% increase in overall spring pressures would handle about any cam one would want to run on the street. The guys at a cam company should be able to easily come up with a proper spring. Hey, they do this for a living, after all. (Besides getting the right pressures and spring diameter, they need to avoid coil bind and select a good grade spring material for longevity.)

Another too-long post here. Since I'm getting older, it is more difficult to compose sentences and paragraphs that make sence. Then, I have to read, reread and read some more, to make sure my spelling and puntuation are correct, lest I come off as a "Hardley" rider. <chuckle> (I've got over 20 minutes in this post. Good thing I'm retired......)

A million? Wouldn't it be more like infinite? (in theory anyway)

I really don't know, Benny, as I was a business major (seriously!). That statement by Harold Brookshire is fairly old. By the way, I think he worked for Crane in the old days, then was one of the founders of Cometition Cams in the early '70's, and after that, moved south from Memphis into Mississippi to start his UltraDyne cam company.

I guess there would be theoreticaly infinite combinations cause in theory you can grind away infinitesmal amounts of material, but in reality it is probably more incrimental, like grinding .0001 at a time or something, therefore getting the million.

But whatever, point is there's LOTS of different grinds you can have

you guys are WAY deep!

Yeah really!! It would be nice to find cams that work with the 790 AND 904 motors. Not sure if that is possible... But like those Carbs pat is getting, if they would work on both, then one could install them now and then not worry about it when the big bore money train rolls in.

Good point, but I think to get the cams to work best they must be specific to the motor size.

The big bore is similar price (including machine work) to the cams being offered. So my thoughts are that big bore should be should be done first, then add cams when your decide wheelies are you thing!

Yeah that's a good point. Oh well, still gonna have to wait At least the carbs seem like a fairly inexpensive upgrade.