Don Eilenberger's K75 Dyno Runs

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This all started because Allen Clarkson couldn't keep up with Ute.

Allen rides a '92 K75, Ute rides a '95 R100 Mystic.

Allen's K75 had been modified with the 'go-fast' options of a K&N Filter-Charger airfilter, a high-pressure fuel-regulator (FPR) and a StainTune exhaust. In desperation, he'd asked the assistance of myself and Brian Curry in figuring out what was wrong with his K75.

Allen came to Sun Cycle (Mansquan NJ) where the owner, Frank Armadruto offered us the use of his dyno, and his expert help in doing the dyno runs.

We tried several things - we had 2 spare FI computers, we swapped them - no change. We had 2 spare Air-Flow-Meters, we swapped them - no change. We had stock and K&N filters, we swapped them - no change. We did the usual K bike free-power trick of advancing the ignition timing to 33 degrees (see the K-tech-FAQs at http:/

Finally in desperation we swapped the StainTune exhaust for a stock K75 system. The results were dramatic:

payer.jpg (58941 bytes)

Stock Exhaust vs StainTune - 1992 K75 - 4th gear 'roll-on'

At this point - Allen was happy, and we ran out of dyno time, so Allen went home with the stock exhaust, and the advanced timing, a stock air-filter and the high-pressure-fuel-regulator still installed.

Brian and I thought this must be a fluke - a defective exhaust, and we wouldn't publish this info until we could confirm it.

We got the confirmation recently. Sun Cycle's owner had another K75 in for service - it had a StainTune system on it that the previous owner of the bike had installed. Luckily - the previous owner gave the new owner the stock system.

Frank decided while he had the bike in - to give the owner some free dyno time - and try swapping the exhausts. Once again, the results are dramatic:clarkson.jpg (45159 bytes)

Stock Exhaust vs StainTune - 1992 K75 - 4th gear 'roll-on'

Different bike, different StainTune exhaust system, different owner - but the same results.

We'll let the facts speak for themselves. The StainTune is prettier than the stock system and is probably lighter (we didn't weigh them).


Don Eilenberger, Brian Curry

FOOTNOTE: We also did a test of a stock air-filter with 50% of the filter area blocked by SaranWrap[tm] - it was a used stock paper filter. 50% blockage had no effect on the power the engine produced. We also ran tests of the K&N vs stock and the K&N vs no filter at all. Power remained the same. Any claims K&N make as to improving power must not apply to K bikes (the same results were found on K100 tests).


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