Fine-tuning a 1992 ZX1100 C3


zx 92
By: Ross Bartick, January 1996

I thought you might be interested in my experiences with my 1992 ZX1100 C3. I have made over 20 dyno runs with this bike trying different things.
My results follow:
6000 miles - Bike bone stock
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120 rear wheel HP @ 9500 Rpm. The curve was very smooth.

I then added a K&N filter, Dynojet Stage I kit (using DJ 136 main), a Factory ignition advance, and a 16 tooth front sprocket.
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125 rear wheel HP @ 9500 Rpm. The curve was still very smooth. I also gained a little midrange HP and the powerband looked slightly wider. The gearing change shifted the whole curve slightly to the left. What that means is that more HP is available to the rear wheel at the same road speeds, or the same HP is available 5 MPH sooner, compared to the stock gearing. I lost about 5 MPH in speed at redline from the gearing change. All of this is due to the fact that the motor now spins slightly faster due to the gearing change. The gearing change WAS NOT responsible for the change in peak HP.

I still wanted more power so I figured that an aftermarket 4-1 pipe was the way to go. I looked at all pipes on the market and then went with the V&H SS2R. I went with this pipe for a few reasons. Number one was noise level. This seems to be the quietest 'performance' pipe on the market. I also liked the nickel plated finish and I feel this is the best looking pipe available. I was also considering the Muzzy pipe and was told by various tuners that it might be worth a few more ponies over the SS2R but I was willing to sacrifice 2 or 3 HP for a quieter system. I assumed that the new pipe was going to make the motor run lean up top so I opted to use the DJ140 main rather than the DJ136. My results follow.
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136 rear wheel HP @ 10500 RPM. The curve now had a double dip between 5500 - 7500 Rpm.

The SS2R added a lot of high rpm horsepower. Not only did I gain 10 peak HP over the stock pipe, the SS2R carries its power peak right up into the rev limiter. The powerband looks much wider on the dyno sheet. The bike no longer runs out of steam after 10000 Rpm, it SLAMS right into the rev limiter (this can be a little dangerous when riding a wheelie at 65 mph). The motor now carries over 128 Hp from about 8500 Rpm to redline. At some points in the dyno chart the SS2R produces over 15 more high Rpm HP then the stock pipe. A race pipe, like the Muzzy, with an open baffle would probably produce more peak HP. Remember that these dyno runs are not using the benefits of the Ram Air system.

I tried almost everything to eliminate the double dip between 5500-7500. I tried going leaner and richer on both the main jet and the needle jet but I was not able to eliminate the problem. But I was able to establish that the DJ140 was the main jet that the motor liked best (and this was without the benefit of Ram Air). I have the needle currently set on groove 4. Please note the needle jet has absolutely ZERO affect on a dyno run. It seems that the carbs get on the mains very quickly and the needle has basically no affect on a dyno run. The needle will affect part throttle cruising jetting which is not seen on the dyno. The double dip caused by the SS2R never drops more than 2 HP below the stock pipes smooth curve and by 8000 Rpm there is no contest between pipes. I spoke to Dynojet tech services and they told me that I would never be able to eliminate this double dip in the dyno curve. The technicians said that the ZX11 has a lot of cam overlap and needs backpressure to make good HP at low RPM. They said to eliminate the double dip I would have to reinstall the stock pipe. I was curious to see if they were right so I reinstalled the stock system and DJ136's and found out they were right. A couple of tuners said that I could eliminate the double dip caused by the SS2R by playing with the cam timing. I choose not to try this because I was afraid of what would happen to my part throttle driveability which is fine as is. I also tried to vary the valve clearance to see how it would affect the dyno curve. This did have a very small effect on the double dip but not enough to eliminate it. It did not seem to have much affect on peak HP or the powerband width. In the end, I left my clearance within specs, but towards the looser side, and reinstalled the SS2R and DJ140's.

I spoke with Vance and Hines tech support and found them to be of absolutely no use. I faxed them my dyno printouts and they promised me that they would work with me to eliminate my double dip. The promise was never fulfilled. I would not recommend dealing with these people unless you like to be told lies and don't mind people promising you return calls which never come.

On the street the SS2R and DJ140 does not feel any stronger than the stock pipe and DJ136 below about 7500 RPM. When I reinstalled the stock pipe and DJ136's(as per Dynojet's suggestion) and road tested it I think that the Stock Pipe and DJ136 DID feel a little bit stronger down low than the SS2R and DJ140. I don't remember how the stock pipe and stock Keihin jetting felt so I can't compare the SS2R to that down low. But after 7500 it is absolutely no contest. The SS2R explodes with the front wheel flying high every time. First gear power wheelies come totally unexpected. No clutching or throttle whacking is required. You can just sit back and hold the throttle open and when it hits about 8000 the front wheel comes way off the ground on its own and doesn't fall until you smack into the rev limiter. I also feel that even with the shorter gearing the bike is capable of a slightly higher top speed than it was when stock. When the mags tested the top speed of the ZX11 it reached 175 MPH at about 10,700 RPM. I don't think my bike would have a problem pulling redline in top gear.

When riding at normal speeds the SS2R is a very quiet pipe. On the highway you can't even hear it. This pipe stays quiet until you hit the powerband at full throttle. Then its considerably louder than stock but still quieter than the race pipes I have heard.

I recently raced a stock 1995 ZX1100 D and it wasn't even close. We first raced from a first gear 10 MPH roll. The '95 D model took off first, then I whacked the throttle wide open (no clutching and at low RPM). I took off with the front wheel about 60 degrees off the ground and blew by him and kept pulling away. I actually thought that he would beat me right off the line with his stock pipe and jetting. I guess my gearing change and the fact that he was running the stock Keihin jetting and air cleaner hurt him. We also did a few high speed passes which always ending with me easily pulling away. During these high speed runs I reached speeds of about 173 MPH as indicated on the speedometer.

As to whether these modifications are worth it is up to you. I would definitely recommend at least the Stage I jet kit, K&N air filter and the ignition advancer. This will keep your bike as quiet as stock while adding at least 5 peak Hp and widening the powerband. The gearing change will also add a little pep while only taking away about 5 seldom used MPH in top speed. If you are the type of rider who seldom sees redline and just cruises around town this would be the perfect setup. If you are like me and trips to the redline are a daily occurrence then I would recommend a 4-1 pipe. You may lose a little (very little) down low but the rewards in the upper RPM are worth it.

 
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Go to Ross's site:
ross@rbartick.com