Adjustable Camshaft gears

[JRMarchand]

I am aware that adjustable camshaft gears/camshaft sprocket tampering is illegal in FB unless its factory stock original, but why? Once these engines are opened and worked on, it is very difficult to get the correct camshaft timing. More than likely the camshaft will never go back in the same "spec" that it came from the factory. How likely is it that a rule change will be made in this area in the future. I'll be watching what the new committee does with some of the rules This rule seems a little extreme considering that all sorts of electronic interfaces can be used to manipulate the factory engine management outputs. When I set cams on moto engine with adjustable sprockets, I go to extremes to make sure all my degree-ables are covered.

ps. i know my K5 Gixxer motor has a few extra ponies in there somewhere, cam sprockets might be the answer, freecamsprockets!!!

Marchand Juan

[Jnovak]

I am aware that adjustable camshaft gears/camshaft sprocket tampering is illegal in FB unless its factory stock original, but why? Once these engines are opened and worked on, it is very difficult to get the correct camshaft timing. More than likely the camshaft will never go back in the same "spec" that it came from the factory. How likely is it that a rule change will be made in this area in the future. I'll be watching what the new committee does with some of the rules This rule seems a little extreme considering that all sorts of electronic interfaces can be used to manipulate the factory engine management outputs. When I set cams on moto engine with adjustable sprockets, I go to extremes to make sure all my degree-ables are covered.

ps. i know my K5 Gixxer motor has a few extra ponies in there somewhere, cam sprockets might be the answer, freecamsprockets!!!

Marchand Juan

Juan, if you want a rules change send a letter to the CRB. It is the only way to change the system. Right now adjustable cam gears are not legal.

[Northwind]

Juan,

It has been my experience that following the factory manual for engine rebuild will bring the motor back to as reasonably possible to initial factory specs. There is inspection criteria for measuring cam chain length and wear. If the cam chain does not meet the specs you could see some variability in valve timing. Another potential for valve timing variation would be head deck height. If this were to happen the head is probably not in spec. The factory manual reccomends replacement of components to new spec to maintain initial factory specifications. Refering to these factory component specs also may indicate and prevent engine failure before it happens.

[JRMarchand]

Jay, I am not trying to change the rules(although it maybe), but more of wondering why can't camshafts be dialed in properly using adjustable sprockets. Why was this a rule in the first place, to restrict the woes associated with degreeing a cam? Yes degreeing a cam can be a pain but it is more reassuring than matching up some dots or casting lines and then checking centerlines, I just think its a bit crude for our specific use, we dont use much low or midrange so the cams could have more life if dialed for our specific use. Wondering if allowing some engines to have adjustable sprockets would make them just "too powerful", I dont know, welcome any comments, thanks Dan

Cam Sprockets are not a big expense, usually like $140 plus labor, i dont think they are cost prohibitive, once on the engine and degreed/dyno maybe $400.

[Jnovak]

Juan, we have never degreed or have had our cams degreed and we have been right at the front all the time. I also know that Brandon Dixon (the fastest guy in the country) also never degreed the cams. The rules are essentially bone stock internals and that is the way it should stay IMO.

Yes, degreeing the cams might produce more HP with adjustable cam gears but then everyone would have to do it adding significantly to the total cost of building an engine.

My vote it to leave well enough alone.

[proutyc]

Sorry to play devils advocate.

But how do the rules stop someone dynoing an engine to optimise the cam timing with adjustable. then repress on the standard sprocket at the new timing pisitions?

I agree its a great rule but would suggest its already exploited

[Jnovak]

Sorry to play devils advocate.

But how do the rules stop someone dynoing an engine to optimise the cam timing with adjustable. then repress on the standard sprocket at the new timing pisitions?

I agree its a great rule but would suggest its already exploited

Nothing. Do you know that this is happening?

[proutyc]

No sorry I dont.

Its not difficult and just wanted to put it out there as its very hard to police as what would be defined as stock?? It's really a matter of the wording and the integrity of the racers/owners

[JakeL]

Nothing. Do you know that this is happening?

Certainly been around the rumor mill for a few years now.

-Jake

[JRMarchand]

Jay

I've heard stories of rewelding cams in stock classes back from the Neon Challenge days, its hard to police like our friend from NZ mentions.

"Camshafts and camshaft drive mechanisms may not be modified or
adjusted in any way unless specifically authorized in these rule" this is from the F600 class rules, F1000 engine rules are similar in many cases except where specifically authorized like the allowance of aftermarket rod bolts in F600 and not in F1000, bolts are internal and the upgrade to better internal bolts is to keep it that way and not have bolts and pieces in the exterior.

I still think its kinda of a hack job to not degree a race engine, Smokey Yunick would agree. It would not be much of a spending, APE sells cam gears for next to nothing. Most engine builders would opt to properly setup and degree an engine. The cams in most of these bikes were degreed for street/sport riding not for formula cars.

If I was sending my engines to someone then I trust that the camshafts are in optimum placement. How is this accomplished, by lining up scratch marks on the cams and head casting and counting chain links??, wow great!!! sorry but can't fathom as to why the camshafts are not properly setup for the conditions the cars are used in.

[Northwind]

Stock cams are the conditions the cars are used in.

I didn't know there are people upset with the performance as is.

[Jnovak]

Send in a letter Juan.

[JRMarchand]

Sorry it is probably just me, I'm not satisfied with the way the cams are installed "lining up marks" feels like i'm putting together a small block for a plow truck hahahah.

i didnt say anything about poor performance or anyone upset, if anything its the opposite, everyone is happy and eager to go racing some more.

Jay thanks, but assume my letter for review of rule denied.

[proutyc]

Juan send letter but I'd suggest more the why it should be done and not directly performance related and I think you'd have more chance. If I was building for these rules you could still do it without breaking the cam rules mentioned above. If the 08 1000(which seems popular) has a separate cam sprocket at the bottom. These may be able to be clicked somewhat allowing a change in cam timing. Not perfect but a change