Cam sprockets

[SyntheticReality]

What would installing Muzzys adjustable cam sprockets do? Increase hp? if so, how much?

[ZX7ROU812]

Originally Posted by SyntheticReality

What would installing Muzzys adjustable cam sprockets do? Increase hp? if so, how much?

What they would do is give you a better ability to adjust the timing of the cams. Increase horsepower? Depending on the state of tune your bike is in, you MAY gain about 2 horsepower.

BTW : Go here... www.redmonkey.com/7r

Search around and read the "Performance" section. Lots more info there then just asking minor questions concerning miniscule possible gains in horsepower by slapping on this and that part. You want REAL power from her? Either install a 94 to 97 ZX-9R engine, get the crank and rods from a 93-95 ZX-7R engine and stroke it out (like I did), install N2O (like I may ), or get a different bike. May not be the answer you are looking for, but the facts are the facts. We ride antiquated, under-powered, heavy-ass bikes.

What year ZX-7R do you own anyway? You have no info listed for it.

[SyntheticReality]

It's a '99 Why would a '97 engine with a 95 crank be more powerful? How much HP do you push? And I really don't know what it means to stroke it out. Wasn't the engine the same from 96-03?

[SqDancerLynn1]

Some times due to factory tolerences the cams could be off 2-3 degrees. Did you ever wonder why one bike may run harder than yours. Degreeing the cams will allow you to
adjust them to the exact factory specs OR you can move the torque curve up or down in the rpm range by retarding or advancing the cam timing. If you have done any machine work--- RE: surfacing block or the head surface it should degreeded

[ZX7ROU812]

Originally Posted by SyntheticReality

It's a '99 Why would a '97 engine with a 95 crank be more powerful? How much HP do you push? And I really don't know what it means to stroke it out. Wasn't the engine the same from 96-03?

OK, here we go. Ready ?

Adding the connecting rods and crankshaft from the 93 to 95 ZX-7R's to a 96 to 2003 ZX-7's engine would increase the displacement of that engine to 850 cc's. The reason ? The engines from 93-95 were still 749 cc's, BUT the architecture of their design was that the pistons (bore) was smaller in relation to the length of the connecting rods. So it was a considered a "Long Stroke" engine.

For the 96-03 engines, Kwak changed them to a "Short Stroke" setup to gain higher RPM horsepower, and to try to catch up with Suzuki (which they failed miserably at, I may add). The pistons (bore) was bigger than the 93-95, yet the connecting rods were shorter, still yielding 749 cc's of displacement.

Now savvy racer types soon realized that most Kwak parts (and most other manufacturer's as well) are modular. Meaning that footpegs that fit the 95 ZX-6R's also fit the 03 ZX-7R's and 98 ZX-9R's. Sooooooooooo...Adding those parts to the newer engine worked out lovely.

It's a bolt in affair that yields about 138 to 145 Rear Wheel Horsepower, and 85 ft #'s of torque, depending on camshaft and tuning.

[toddman35]

How does the stroker kit effect the top end on the bike? I would imagine that you couldn't rev it up as high, but would like to know for sure.

[ZX7ROU812]

Originally Posted by toddman35

How does the stroker kit effect the top end on the bike? I would imagine that you couldn't rev it up as high, but would like to know for sure.

Top end powerband is reduced to approximately 11,500 RPM. That's 1,000 RPM less than it was before it was stroked. So the power gained DEFINATELY offsets the negligable loss in "Top end."

[toddman35]

Thats not bad at all. As long as we're off topic still, what kind of rwhp numbers are stock bikes putting down? I believe they are rated at ~106 crank hp, but I have no idea what kind of drivetrain losses bikes have.

[SyntheticReality]

So all you have to do is bolt in the lower end from the older model and you have a stroker? no other work required? I'd like a detailed explaination of what has to be done. I am very interested in doing it.

[ZX7ROU812]

Originally Posted by toddman35

Thats not bad at all. As long as we're off topic still, what kind of rwhp numbers are stock bikes putting down? I believe they are rated at ~106 crank hp, but I have no idea what kind of drivetrain losses bikes have.

Actually Todd, the ZX-7R's are rated at 125 crankshaft HP. The result is about 106 to 110 rear wheel. If the bikes made @ 106 at the crank, we'd put down about 85 to the rear...YIKES !!!

[toddman35]

Originally Posted by ZX7ROU812

Actually Todd, the ZX-7R's are rated at 125 crankshaft HP. The result is about 106 to 110 rear wheel. If the bikes made @ 106 at the crank, we'd put down about 85 to the rear...YIKES !!!

Ahh, as you can see I'm new to the 7r scene. Is there a common drivetrain loss % for these bikes? It seems like 15% is fairly accurate.

[toddman35]

Now I know where I was misled. I was looking at the redmonkey site and under the specs they've got the following listed...

Claimed Power (Crank) 123 bhp @11,500rpm
Claimed Power (Rear Wheel) 109 bhp @11,500rpm

I was under the assumption that bhp was always brake hp, IE at the crank. I must have misread it.

[SyntheticReality]

you silly goose

[Zippy]

The stroker kit sounds interesting, however, do the stock 38mm carbs bottleneck the larger engine, and have you dynoed your bike yet?

[toddman35]

Originally Posted by SyntheticReality

you silly goose

Yeah, but Bhp is at the crank correct? At least I've got a some what reasonable excuse - I think.