Rotax Camshafts?

[comanche91]

Since I'm constantly looking for a few more engine ponies, has anyone ever swapped out our "lawn and garden" mild camshaft for a more aggressive one? Here are some examples:

660 cam, 7.9mm lift/225 degree duration. Our stock"lawn and garden" cam.
670 cam, 8.9mm lift/261 degree duration.
675 cam 9.65mm lift/297 degree duration (Intake), 9.56mm lift/285 degree duration (Exhaust)
805 cam 9.60mm lift/248 degree duration.
860 cam 10.55mm lift/292 degree duration.

[Nozz]

I'd give Ron Wood's shop a call. They made several cams for these. I have one for my "rebuild project" motor from their stage one kit, along with the dellorto 40. I bet they can get you a cam that will bring it up a notch or two.

[comanche91]

Thanks, I have been talking to them Nozz. Just looking for "real world" yea or nay results if anyone has actually ran a non-stock cam on a street Rotax machine.

[hmmmnz]

i ran the 675 cam in my ktm 500, along with what ever the standard carb was, it was considerably more powerful bike than the mz is, the only problem is, when the cam belt breaks.. it never happened to me, but piston hitting valves is never fun
if you have a bit of cash, id say go for the cams, they make a huge difference, coupled with a bigger bore and carb you can get somne stupid power of of a otherwise stock rotax lump

[comanche91]

A higher lift/duration racing cam has no more affect on breaking belts than the stock cam would except for the increased power? This is what you mean, right?

A lot of the Germans run the 805 cams on the street w. dramatic results, except they don't idle that well. Most of their bikes MZs are equipped w. the Dellorto carb though........

[lcrken]

I'm running the 860 cam in my Saxon Tour, along with a Ron Wood big bore kit, Axtell head, and 45 mm Mikuni. It's a blast, but only if you keep the rpm up. It refuses to carburete well at low speeds and small throttle opening. I wouldn't recommend it for anything except a hooligan bike (or a race bike). I used it because I already had all the parts laying around from my race bike, and thought it would be fun to do an over-the-top engine for the street.

Ken

[comanche91]

I'm running the 860 cam in my Saxon Tour, along with a Ron Wood big bore kit, Axtell head, and 45 mm Mikuni. It's a blast, but only if you keep the rpm up. It refuses to carburete well at low speeds and small throttle opening. I wouldn't recommend it for anything except a hooligan bike (or a race bike). I used it because I already had all the parts laying around from my race bike, and thought it would be fun to do an over-the-top engine for the street.

Ken

Yeah the 860 is over the top, along with the big bore and 45mm Mikuni. But that sucker must fly at high RPM. Not looking for anything that radical, maybe the 605 or the 805 cam that I think the versatile Bing 36mm could handle with proper jetting and still retain decent street manners. I'm basically looking for a little more low end grunt. Thanks for the reply Ken; your Tour must be hell to ride in traffic. Ever had it dynoed?

[Nozz]

I thought HMMNZ may be referring to the extra lift causing interference if a belt broke with a valve open. That sounds like another ron wood question.

[comanche91]

I thought HMMNZ may be referring to the extra lift causing interference if a belt broke with a valve open. That sounds like another ron wood question.

Hmmm. Yes, it does.

[hmmmnz]

yea it doesnt put an more stress on the valve train or belt. its just if the cam belt does break,
well evil piston into valves can occur
not likely to happen if you change and tension your belt regularly,
and its only a few cams the allow the valves to hit at all,

[comanche91]

I do have a new 865 cam now and will install soon along with a new Ron Woods muffler. Stock Bing carb and cylinder/valves will remain - for now.

[Nozz]

I just checked my cam for my rebuild; it's an 865. Did you get yours put in??

[comanche91]

Not yet Nozz. Over on the CCM forum in the Tech section they list the specs of all the Ron Wood performance cams that were made, and this is the last paragraph:

"The Rotax engine is non interference so cannot be over-revved with the exception of the following camshafts - 675, 860 & 865."

So I'm thinking I'll look for a bit milder grind cam.

[DAVID THOMPSON]

trust me bent valves are no fun if you loose a belt 500 miles from home
doing the belt on the road is a pain
hauling one home in a rental truck because you bent a valve
is a big pain in the pocket book
dave

[comanche91]

trust me bent valves are no fun if you loose a belt 500 miles from home doing the belt on the road is a pain
hauling one home in a rental truck because you bent a valve is a big pain in the pocket book
dave

Yep I hear you Dave. If you ride a lot, you WILL have a breakdown sooner or later, I sure have, so there's no use adding another possible reason to cause one.