10k rev limit

[theJeStEr1340]

QUOTE

Originally posted by cannondale27
Why does it seem that the more cylinders a bike motor has the higher the redline is?

Because the pistons for the bike get smaller and the vrank and such can handle the higher rpm's because of the smaller pistons and less weight in 1 place. the same reason my they do the same with high end cars, jaguar's and higher, they have small displacement (3.6 and such) V8's. They produce more HP then a 4.3l V6 would because of the 8 cylinders, an dit will rev out a lot faster because fo the less weight. Hope thsi helps.

[jacobw]

I know cannondales are suppose to be plagued with problems but my cannondale has been one of the most reliable machines I have ridden always start and runs good. if it drops a valve for gives up the ghost then I guess haydug will be playing with mine. I dont think cannondale engineers would have made a 11k rev limit if the motor wouldnt handle it but I think we are getting to touchy about this topic so everyone come over to my place and we will have some beers :drink: :drink:

[wistech]

Heres one for the experts . Why did one of my exhaust valves drop? The lobe on the cam driving it was half worn out. The intake lobe kitty corner from it was starting to wear. All valve springs load tested between 33 and 35 ft pounds.
I cant make any sense of it. Shouldnt the valve with the good lobe have stressed out and broke of first.
Why are cam lobes failing? Why do some wear out and some in the same head look like new. If it was from the rev limiter shouldnt all wear be the same?

[bombsquad54]

maybee wistec, thats the first valve to float? it wears out first, the rest dont have time to wear out before failure?if that valve floats the lobes will hit too some or too late on the valve bucket thus premuturely wearing ?

[Happyboy]

QUOTE

Originally posted by jacobw
I dont think cannondale engineers would have made a 11k rev limit if the motor wouldnt handle it

Beer good.


Now, as to the question of this all being tested. I used to work in a manufacturing area. I was in engineering and I saw this all the time.

Cannondale build a great 1st quad. What is the motor that everyone looks for? Early 02 late 01. Cast case, billet rod, good crank, yada yada yada.

Then what happened? Lets go cheaper!! They start working in cheaper replacement parts that they thought were just as good. Year later, this stuff blows up. And guess what? This happens all the time in the manufacturing world. I used to see it all the time.

Now, none of this was to say that lowering the rpms would fix the motor problems. Just as replacing hte crank bearing with a Z400 bearing won't fix an unbalanced crank, it will help it last longer by inproving the bearing. Lowering the rpms just a little won't keep the valve train from failing or wearing on the crank bearings, but it will help it last a little longer.

[Happyboy]

QUOTE

Originally posted by wistech
Heres one for the experts . Why did one of my exhaust valves drop? The lobe on the cam driving it was half worn out.   The intake lobe kitty corner from it was starting to wear.  All valve springs load tested between 33 and 35 ft pounds.
   I cant make any sense of it. Shouldnt the valve with the good lobe have stressed out and broke of first.  
   Why are cam lobes failing?  Why do some wear out and some in the same head look like new.   If it was from the rev limiter shouldnt all wear be the same?

Maybe.....

Your valve was floating/sticking whatever. Causeing that one side to slap and wear out faster. Then the violent motion of the slap just wearing on that valve to the point it finally just gives way.

[Cdale_racer_669]

just to add to this, my decompression mechanism failed, and i have stock cannibal mapping.

[Cdale_racer_669]

why not start a poll of failures and what map ppl were running?
custom
low rev limit
high rev limit

[cannondale27]

Well we all agree that better parts would help.Valves are on the way and decompression is also on its way.Cams can be fixed.Springs are all that is left.
I believe that our rate of failure is less or the same as the Yamaha,Honda,Suzuki motors that rev at equal RPM's.Even those can be improved with high quality parts.The trick is ensuring the replacement parts we put in are better than stock.

Some known facts of our valvetrain
Minuses
1)Some of the cams were made soft
2)Valvesprings vary in height and tension when new
3)Decompression has poor rivet design in some,powdered metal weight which wears and breaks
4)Most have a valve design which could be improved
5)Cam profile might be a contributer to wear and float
6)Cam chain guide mounts have broken

Plusses
1)Dont seem to fail anymore than other motors
2)Ballbearing cam bearings
3)Stainless valves(better wear for conditions)
4)Camchain and tensioner seem to be superior
5)Valve adjustment (wear)stays very consistent 100 hrs easy before any adjustment on vast majority.
6)Cam chain guides hold up great
7)Most have never had valvetrain failure at any RPM

[fig]

I have read that the factory bearing was rated to 10k. Not 11,600 or 11,800. That is my understanding as to why you drop the limiter to 10k.

Guy's be nice, don't hurt my feelings. Remember I'm the newbie here.

Arkie boys,

What part of the state are you from? I was born in the city of Ozark, but raised in Kalifornia. My Grandma still lives in the big town of Pettigrew.