A question for those who have Degree'd the cams...

[beondwacko]

For those who have dove into the XX's engine headlong and degree'd the cams, what were your findings from the factory spec's? How far off were your #'s, where did you decide to set them to if you installed adjustable sprockets, and what gains were recieved from your work?

The reason I'm asking is because I'm thinking about going the adjustable sprocket route for a little more top end power (retarding the timing). But , if it is the norm for the factory specs to be out of whack, then I may just set the timing to factory specs.

Chime in please. I'm curious to hear the results of what had been discovered.

[Pete in PA]

For starters.. you want higher lobe center numbers for higher peak HP.

I did it to my V65 Sabre and didn't really notice an improvement. I was looking for more mid range power, I backed my lobe center #'s down to 104 degrees. I believe the factory #'s were at 106 degrees.

[R1000]

For those who have dove into the XX's engine headlong and degree'd the cams, what were your findings from the factory spec's? How far off were your #'s, where did you decide to set them to if you installed adjustable sprockets, and what gains were recieved from your work?

The reason I'm asking is because I'm thinking about going the adjustable sprocket route for a little more top end power (retarding the timing). But , if it is the norm for the factory specs to be out of whack, then I may just set the timing to factory specs.

Chime in please. I'm curious to hear the results of what had been discovered.

As my rule of thumb, I translate one degree to shift the torque about 100 rmp only. I know this is a coarse assumption but is shows the actual territory, and you cannot expect a lot by going from the factory recommendations. Changing a few degrees is hardly noticeable and you can come into clearance problems if changing more than a very limited number. You don't even have to compensate for chain slack since this improves top en power, minimal though.

http://www.sporthoj.com/forum/showthread.p...elinst%E4llning

[shovelstrokeed]

Adam,

There is a whole bunch to this. Individual cam lobe centers plus spread between them can all have different effects depending on where/when. In general, tighter lobe centers (relative to intake and exhaust) will give a bit more overlap, providing more top end at the expense of mid-range torque. Within that, differential timing of the intake and exhaust can favor exhaust or intake tuned lengths to get better cylinder filling.

Step one is to find out where you are with the stock setup. The measurement is not all that difficult, requiring a degree wheel, a piston stop and a dial indicator with some form of mounting arrangement. Probably the most difficult thing is access to the components with the motor in the frame.

Another factor to consider here is that the XX uses a camshaft to drive the ignition pulse generator so, if you move that cam, you are gonna change your iginition timing and might wind up pissing off your knock sensor.

As in all things when seeking HP improvement, there are 3 stumbling blocks to every step in the ladder.

Given your bike's street mileage and the number of drag strip passes you have done, you might just want to consider a set of valve springs.

[beondwacko]

Adam,

There is a whole bunch to this. Individual cam lobe centers plus spread between them can all have different effects depending on where/when. In general, tighter lobe centers (relative to intake and exhaust) will give a bit more overlap, providing more top end at the expense of mid-range torque. Within that, differential timing of the intake and exhaust can favor exhaust or intake tuned lengths to get better cylinder filling.

Step one is to find out where you are with the stock setup. The measurement is not all that difficult, requiring a degree wheel, a piston stop and a dial indicator with some form of mounting arrangement. Probably the most difficult thing is access to the components with the motor in the frame.

Another factor to consider here is that the XX uses a camshaft to drive the ignition pulse generator so, if you move that cam, you are gonna change your iginition timing and might wind up pissing off your knock sensor.

As in all things when seeking HP improvement, there are 3 stumbling blocks to every step in the ladder.

Given your bike's street mileage and the number of drag strip passes you have done, you might just want to consider a set of valve springs.

Hi Ed !

Well the mileage I don't think should be an issue overall RE the valvesprings. It's now got 19K on the clock and ( I know I didn't like measure seat pressure or anything such as that though ) but I can't see the stock springs getting tired yet. The engine is operated in it's normal RPM envelope, and not for extended periods of time at high ( over 6K rpm ) speeds. I understand the fatigue issue.

I thougt the ignition was driven off the crank on the XX not the cam's.?

Where my curiosity is at is that there are variences(sp?) from the factory and I have heard of instances where the timing can be off as much as 4 degrees +/- from factory specs. I was especially curious about who's seen what on the XX's and if they changed or degreed the cams what the results were before I decide to open my engine up.

[shovelstrokeed]

My bad, actually 2 bads. Ignition pulse generator is on the crankshaft. There is a pulse generator on the exhaust cam that probably controls the firing of the fuel injectors or defines TDC compression on the #1 cylinder for whatever reason.

I'm pretty sure I got myself backward on the lobe center thing as well. Tighter lobe centers will give less overlap, not more.

I had pretty good luck on both my turbo K100 and nitrous Suzuki, both of which had mild street cams in them with 108 intake, 113 exhaust but both engines were carefully checked for valve to piston and valve to valve interference. That might be a bit extreme. The K motor probably doesn't count as it was a 2 valve engine with a hair dryer on it. The Zuke was an early 4 valve design though and would run low 9's all day on 8:1 turbo pistons with no squeeze. 1425cc and a 74" wheelbase with a 10" car tire probably had a bit to do with it as well.

As to the valve springs, well, I would be surprised if they meet seat pressure and overall length specs at 20K miles. Revs have very little to do with it, just number of cycles, so long as you are not getting into coil bind or floating the valves.

If I were going to go so far as to pull the engine, or even just drop the thing far enough to check the cam timing, I'd probably go ahead and pull the head, send it off for a good multi-angle valve job, replace the springs and put some mild cams in there. A little light porting and chamber work would do wonders as well. Of course, your looking at a grand or so there, maybe 2.

[tomek]

There is some info here http://www.cbr1100xx.org/forums/index.php?showtopic=43548

And here are some pics

http://www.cbr1100xx.org/forums/gallery/11...7_507_23121.jpg

http://www.cbr1100xx.org/forums/gallery/11...7_507_32806.jpg

http://www.cbr1100xx.org/forums/gallery/11...7_507_19798.jpg

http://www.cbr1100xx.org/forums/gallery/11...7_507_47463.jpg

I don`t like magnetic attachments for dial,they are pretty much useless on motorcycles as almost everything is aluminium.

That set up on my pics is a breeze,takes 30 seconds to get dial in place .

It is important to clean treads and locktite them,otherwise cams may move,,,,,,,,,do it one at the time so your timing won`t move.

Don`t get dials,etc from Harbour Freight,it is utter,useless cheap fucking junk,,,,,,,,

I got mine from http://www.jlindustrial.com/, even their least expensive tools are 20 times better then Harbour Freight.

[tomek]

BTW,I was gonna flame (ign trigger ) shovelstroke,but he corrected himself.

Lower numbers ( lets say 100/100 )- more overlap.

Higher numbers (105/105) -less overlap.

[shovelstrokeed]

After I opened my mouth, I decided to do a bit more research/reading on the topic.

Thank you for your restraint.

BTW, just what the hell is the cam pulse generator used for?

Silly thing has two teeth on it. I figured one of them tells the injectors when to fire and the other is used to keep the fuel pump running. Anybody know for sure? I'm helping a guy with a wonky fuel pump circuit on the other board and would prefer to go with actual knowledge rather than speculation.