ORIGIN OF THE LANCE GAMMA AIR FILTER AND JET KIT FOR RG5OO's

     In the summer of 1986, I was enjoying my last 4 stroke sportbike, an '83 Suzuki GS750E and in escrow for my first house.  I thought that I was happy.  Then I discovered the RG500.  Greg Lewis was advertising a Gamma for sale down in Ensenitas, as I recall, with the bike being stored for showing purposes at his friend, Steve Johnson's house where I first laid eyes on the type of bike I would be riding for the next decade and beyond; the RG500 Gamma.  Cool.  Two questions that I didn't have the nerve to ask Steve about the bike were; "If it is called a Gamma, why doesn't it say 'GAMMA' on it somewhere" and "What's up with the dopey looking 'R' on the tank?"

 I would like to think that I've learned a lot about the Gamma over the last 10 years both from talking to many (over 400 worldwide) owners beginning with Greg Lewis, as well as experience gained by owning 50 or so RGs and working extensively on well over 100 of them.  (By the way, Greg, in hindsight, I really should have figured out how to come up with the money to buy that bike from you.  Thanks a heap for bringing so many Gammas into this neck of the woods.  At a time when monsters like EMI and DPL Eurostyle roamed the earth, looking for anyone in need of a headache, you took care of people wanting RGs with integrity).  How I took delivery of my first RG in September of '86 is subject for another post.  Suffice to say that I should have listened to Greg.  My blue RG now has 106,000 kms. 

I hated it.  It would have to be faster than the space shuttle to justify the screwed up powerband as delivered.  It wasn't.  No bottom end.  No midrange.  Decent top end from 7.5 to 10k and all done.  To pass cars on the freeway, I had to downshift THREE gears just to get into the powerband.  It fouled plugs, smoked A LOT and delivered rotten gas and oil mileage.  I thought that I had made a mistake in buying it.  I had to find a way to improve it somehow or get rid of it

     My last experience with a 2 stroke was with my 1972 Kawasaki H2 which I purchased new while in high school.  I remember how restrictive the airbox was on that beast, designed to stifle a horrendous intake honk.  That it did, but in the process, it choked it to death.  When I went to individual K&Ns (without rejetting!!), that thing went wild!!  Where it used to fall flat at 7,000 rpm and quit, it now rocketed to 10,500 rpm and beyond!  Performance gains were in the range of 3-5 bikelengths PER GEAR! Evidently, the bike was jetted spot-on for the open air filters and then choked by the stock airbox to restrict rpm and performance, as well as noise.

     Needless to say, I wasted no time in removing the stock air filter in the RG. I was astonished to find that the motor fell flat on ifs face at 5000rpm and was pitifully lean above that point.  What gives?  The stupendously loud intake noise was back even louder than I remembered, but the jetting was way off.  The noise was SO BAD that I decided that if that was the price of performance, I'd take the GS750 back any day.  The Gamma was tuned to prefer a 110 or so mainjet with the stock airbox intact.  (I was later to find out that open carbs with free flowing filters require a 230-240 mainjet.  Oddly enough, with the 240, the stock needle position and stock pilot worked fine!)

     It appeared that the stock airbox and trunk arrangement was setting up an intense resonance in the open air filter cavity and the tank was acting as a speaker to broadcast this racket straight up my helmet. Very annoying!  I decided to revert back to what worked before; the K&N filters mounted directly to the carb bodies.  I paid a visit to K&N, (located in Riverside, CA, about 20 miles from home) where I discussed with them my problem.  All they could offer was a filter designed for a Rotax ultralight aircraft motor which had 2 flanges on one filter body with the spacing compatible with the carb spacing on the Gamma.  Great!  Still being a K&N fan, I thought that for sure, this was it!  One problem; the fairing side panels would not fit over the filters.  No way.  I proceeded to test the setup anyway, without the sides. Yippee!!  The noise level was much reduced!  No more resonance from the air ducting and tank area.  As I jetted up, the midrange grew stronger but even with 170 mains, I could not get the top end right.

     At this point, I knew that I was onto something good, but I wanted to pursue having K&N make custom filters so that my fairing side panels would fit again and I was concerned that the new filter design would alter jetting significantly.  K&N explained to me that their filter design was not conducive to solving the clearance problem on my RG without reducing the surface area to an unacceptable level for airflow.  They suggested that I go with some sort of filter arrangement in the stock airbox.  Nope.

     Enter Uni Filter.  I spoke with Tony at Uni Filter (Garden Grove, CA, 60 miles from home, but oh, well) about the need for a custom filter that would clear the fairing and not restrict air flow in any way. Uni agreed to keep the bike for 2 weeks in which time they would design and produce a new filter made just for the RG if I agreed to pay for the tooling charges and purchase 100 filters!  There was no turning back.  14 days later, I had 100 filters that fit fine and breathed as well as open carbs.

     When I passed 200 on the main, I encountered fuel starvation from inadequate delivery to the float bowls via the stock needle seat.  This part was also causing trouble with the carb overflow tubes spitting gas all over my belly pan as well as excessive gas level in the carbs from poor sealing at the needle seat. I had custom gas valves produced to fit the Gamma carbs which cured both problems.  When I arrived at 240 mains after trying every Mikuni jet made from 110 to 280, I was done and very pleased with the results.  Throttle response was much improved everywhere with excellent midrange passing power without any need for downshifting to pass anymore.  No more plug fouling due to unstable float levels.  As a bonus, without the intake trunking in place, I could change all four plugs in 5 min. without removing anything but the plugs.  The effective powerband width was doubled (6500 to 11000rpm) and the bike was much faster.

     In the summer of '88, I paid a professional call to Lee Chapin at Mikuni American in Simi Valley (almost 100 miles, but my employer was paying me this time).  While I was there, I asked him if he would advise me on availability of suitable needle options for the RG 28mm Mikuni carb, as well as the RZ500 Yamaha 26mm.  After personally checking every possible substitute, we determined that nothing else was in the ballpark.  Since I was getting fine results from the stock needle on the Gamma, we moved on to other topics.  Lee explained that the Gamma carb was designed not by Mikuni, but by Suzuki and was unique in many aspects.  When I showed him the stock intake trunks, he laughed out loud.  Lee explained that carb airbells, particularly those feeding 2 strokes, require airflow approaching the venturi from 360 degrees around for a smooth transition from the needle onto the main to occur.  He then proceeded to describe how the stock RG setup must have ran as if he had ridden it himself.

     After 9 years of personal use (exceeding 120,000 miles) and feedback from over 200 Gamma owners (with combined mileage using the carb kit approximately 2 million miles), I am convinced that it works as well as my description implies on any Gamma where it was properly installed and carbs tuned for optimum performance.  I have been approached several times in the past by people expressing interest in selling my filter kit as a dealer or distributor.  However, I prefer to make contact with the end user personally for as long as I can, and so I have only offered this product directly from me.  It is my hope that I can maintain direct contact with as many RG owners as possible as this is my most satisfying aspect of what I now do for a living (5 years full time business serving only RG500 Gamma owners).

Rick Lance    Lance Gamma