Lobe Centers

[Anonymous]

I was just wasting some company time here and ran the lobe center numbers for the stock cams on my 82 1100E. The raw specs are (from my factory manual):

Intake - opens 30deg BTDC, closes 70deg ABDC
Exhaust - opens 63deg BBDC, closes 25deg ATDC

These numbers give an intake lobe ceter of 110deg and an exhaust lobe center of 109deg. Since many people seem to like 108/108 or even 106/106 for more midrange power, it would seem Suzuki intended to tune for higher RPM power. Does anybody have any dyno charts or other info showing what to expect from my 1100 if I simply degree my cams accurately to the factory specs? I am running a single K&N filter with no back airbox and a Kerker 4-1 exhaust. The bike currently makes 102rwhp @ 8500rpm and 69ft-lb @ 6500rpm. There is a smallish hole in the torque curve between 3500-4500rpm, but even at that it makes over 60ft-lb from 3500-9000rpm. If the hole was filled in, it would make over 65ft-lb from 4000-8250rpm. Perhaps cams will help with a bit of this?

Mark

[pano]

I have a factory manual and cannot find that info anywhere. What section is it in? Thanks

[gtsg01]

I have an 81 manual, and it is under Top End Inspection, page 7-23.

[pano]

Ok...from the diagram...thanks

[massakins]

Mark, other than pure horsepower contests (i.e. dragracing or dynos) it seems cam timing has more to do with seat of the pants feel. If you degree the cams on your bike you may very well notice an improvement. But bear in mind, they might be in the optimum position now.

There is really no formula to determine if its right for you or not. Those that committed the funds to install aftermarket cams value the performance and degree the cams to get it. Many of them repeat the process several times until this trial and error identifies the best combination for their setup.

Expensive if you're paying; time consuming if you do it yourself. But this is the price of excellence.

[Anonymous]

There is really no formula to determine if its right for you or not.

That's the problem, all right. I was just wondering if anybody had any dyno charts showing 106/106, 108/108 and 110/110 centres and how it affected the power curve. When I get my slotted sprockets I am first going to measure where the cams are now, as delivered by Suzuki. Assuming they are not really close to the factory specs (and from all I have seen, they won't be close at all), I will reset them to the 110/109 specs from the manual. If I like what that does, I will leave it alone for a while and ride it. Then maybe try 108/108 to see what that does.

Expensive if you're paying; time consuming if you do it yourself. But this is the price of excellence.

Since it is my time, I can fart around endlessly if the mood strikes me. It is definitely time consuming to get it all right.

Thanks,
Mark

[massakins]

Mark, one other thought for you. Before embarking on this work, make sure the engine is "right". All cylinders should be very close on compression and better yet, show very similar leakdown from that type of evaluation. If this is good, valve clearance is good, carbs are clean and evenly adjusted and ignition is good, then your efforts will be rewarded. If any od these are sub-par you may get confusing and conflicting results. Good luck and let us help you out if we can.