KTM 990 Cam Timing Specs

[BillyD]

Originally Posted by tahoeacr

My current cam intake lift .409 Ex lift .376 stock pistons so
no worries on swapping out those little cams you guys are using.

Are these the SD cams or those mystery cams from the European Supermoto team?

What are the timing specs for these cams @ either .040" or .050" lift?

BTW, just in case some of you are still wondering why cam timing might be important, here's a dyno chart for a Ducati Testastretta motor comparing stock cam settings (Red) vs 109 degree lobe centers (Blue). Same cams, different timing and adjusted fuel/ignition map. 7 Hp and 7 N-M improvement at 8 000 RPM.



In other words, it ain't just about cam profiles, but also how you set them up. This is why it is so aggravating that KTM doesn't publish specs nor provide any means of cam timing adjustment.

Take a look at most modern sport bikes, for instance, and they have some means of adjusting cam timing, either individually or as a pair (intake & exhaust). In the case of the 990 and its use of the balance shaft as part of the cam drive system, there are as many as 14 sources of cam timing error that could tolerance stack. Yet, KTM provides no mechanism to compensate for production tolerance variations let alone for performance tuning purposes.

Short of modifying the cams themselves to incorporate some level of adjustability, offset keys might be a way to adjust each intake/exhaust pair a couple of degrees one way or the other.

I also wonder how effectively the oil pressure assisted cam chain tensioners really do their job.

[uk_mouse]

Originally Posted by BillyD

Hmmm. Sounds like I might have a math error by forgetting to add the .040" check clearance to my maximum lift measurement on the 950 intakes. I flagged the possible error in my earlier post with "???"

Not sure what you mean by the "check clearance", sorry. I'm a noob, so I was just measuring the two dimensions of the cams (ie perpendicular to the lobe and parallel to it), and calculating the difference between the two dimensions.

One thing is certain, however, I've been using the 950 cams in my 990 for a couple of months now and love how the bike is working.

This, coupled with Tahoeacre's comment, suggests you should have no clearance issues.

Thanks to both of you for the reassurance, when I get time I'll pop those cams in and let you all know how it goes :)

[BillyD]

Originally Posted by uk_mouse

...so I was just measuring the two dimensions of the cams (ie perpendicular to the lobe and parallel to it), and calculating the difference between the two dimensions.

A potential problem with this approach is the assumption that the perpendicular measurement is actually on the base circle of the cam.

Probably a good assumption, but perhaps not.

The ideal way to measure total maximum lift would be to set valve clearance at zero (of even a little negative) and then measure lift with a dial indicator.

I cheated by setting clearance to .040" and then measured lift, but maybe I forgot to add .040" to the lift indicated on the dial indicator.

[Willis]

I have some 950 cams for sale in the flea market if anyone is interested.

[uk_mouse]

Well, I finally got time to do some fettling. Popped the 950 cams in last night. Turned the engine over by hand a few times just to check no clearance issues, then fired it up. Everything seems OK so far, but I'm waiting on rear brake parts before I can actually ride the thing!

I couldn't find any scales to weigh them, but the 950 cams are noticably heavier than the 990 ones.

[StevenD]

Who needs brakes? skip that and go test ride!!! I want to know how this worked out!

[uk_mouse]

Yeah well, I did ride it a bit without a working rear brake but that wasn't very nice :)

Got the brake fixed and did a nice long trip over the weekend - down to SW England to see various flying machines at the Royal Air Tattoo. I got to stand under the bomb bay of the worlds only flying Vulcan, while 5 Hawks and a Rafale B taxied past about 10 metres away. Could hear a bloody thing, excellent

Anyway ... my experiences of the 950 cams.

Subjective - I think the engine feels nicer at low rpms. It seems to pull more smoothly and makes a slightly different noise - deeper though not louder. No real difference in vibration levels although I haven't yet balanced the carbs. Hasn't cured the annoying "fluffy" response coming off a closed throttle.

Whether the top end power has changed I couldn't say, it goes like stink, and I suspect a before and after dyno run would be required to see any difference.

Objective - no change in fuel economy :( With 990 cams I was getting 40 mpg (UK gallons, that's 32 mpg US). After doing about 400 miles over the weekend I can say with certainty this hasn't changed one iota. I filled up three times, every time the reserve light came on at 160 miles and every fill up equated to exactly 40mpg.

So - given that I had the cams anyway, it was worthwhile just for the nicer response. I'm disappointed about the unchanged mpg though. Nothing I've done to this bike has improved its economy significantly, I must have spent hours tweaking the jetting, it runs really nicely (apart from a bit of hesitation coming off closed throttle) but I can't get the economy that some have managed!

[Kenbike]

Reading this confirms a few have had good luck installing Super Duke Cams in a 2007 990 adventure. I will proceed with gettting a set on order and contacting Web cam for their inhouse cams.

[BillyD]

I continue to run the wheels off my 970 (990 converted to 950 CV carbs with cams) and absolutely loving it.

I consistently get 33 mpg (US) on my commute roads. I run it hard (i.e. 1700 miles out of a rear tire).

When I slabbed it with my pokey BMW buddies to the MotoGP in Laguna cruising 70-75 mph, I got 40 mpg and they 45 mpg. That's good enough for me, especially if it means I don't have to ride a GS.

If I had a set of SD cams, I would drop them in without hesitation just to see what they do.

I am still chagrin that KTM doesn't provide some means of adjusting cam timing (or offer a 690 Adventure for that matter).

[Kenbike]

Thanks for the update Billy, i am getting price on SD cams and looking for aftermarket cams but have not found any at this time. I agree KTM needs to provide a cam indexing method but it looks as if we are out of luck.

[ktmr32]

hi guys i am going to bite the bullet and go to the dynoroad with my 950 i am currenlty running fcrs 41 and akrapovic cans,so i have got a set of 07 superduke cams which i havent install them in my motorcycle and my plan is to first go to the dyno with my motorcycle as it is! and then go with the cams installed! Lets see i hope to solve the mistery for those cams!

thanks

[Kenbike]

I just installed the super duke cams in my 2007 adventure and picked up around 8 hp with a good mid range improvement. The bike pulls better and still has good low speed manners. You will enjoy the new cams!

[mousitsas]

Originally Posted by Kenbike

I just installed the super duke cams in my 2007 adventure and picked up around 8 hp with a good mid range improvement. The bike pulls better and still has good low speed manners. You will enjoy the new cams!

did you have to alter the fueling?

[Kenbike]

My bike was scheduled for a dyno tune session with PowerTripp so I had them drop in the cams first. I would think you will need to map it for the new cams.

[gefr]

Did you get your bike back from mapping it with the 950 cams? What are the first impressions?