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  • What do you want to know about set up or what question do you have on how your motorcycle works?

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What would be the potential drawbacks of running a single, large throttle body ahead of the plenum ( injectors at the ports, as per normal) , as opposed to 4 conventionally located ones ?


I could see it being a little lazier in on/off/on boost situations , which we don't have, and would require any idle/balance adjustments be done through fuelling.


Thanks, and Merry Christmas,

Dan Rockey



Hi Dan, 
         I have tried the combination you are referring to a couple of times, I have never had any real success.


         Yes, it did work, NO it did not work well.


         The problem as I see it with mechanical or electronic injection is placement of the throttle plates or plate and injectors, with one single throttle body you need to place the nozzles directly into the plenum and point into the port, or have the nozzles in the port casting. 


          When you have with the nozzles in the plenum they are in a lowest velocity area of the system, hence the fuel is not get proper atomization and you must run more fuel pressure (overly rich) to deliver the fuel to the cylinder. 


          With the individual throttle bodies the nozzle is directly at the throttle plate, the highest point of velocity in the system this placement insures proper atomization and fuel delivery to the cylinder while using the proper air to fuel ratio. Idle characteristics, transition to boost, drivability etc... are all effected by that placement.  

           If you ever have the chance to listen to the two systems, you will notice how much smoother and responsive the individual throttle bodied motors run. 

           I wont attempt to do it again. 


           If you need any assistance I will be more than happy to help.

Subject: Q's about turbo funnybike.

   I've recently purchased an older funnybike with a Sam Wills 88" (measures closer to 86") wheelbase, a 1400(?) Kawi KZ with GPZ head, 8.5:1 comp., Falicon Top Fuel Crank, with steel crank girdles, Orient Express 3-speed, Rajay 370 F40
The best combination for what you are doing maybe an EF60 

MR Turbo Super B draw through, Cam Motion turbo cams (don't have the specs),

I would run a camshaft with at least .380" lift and 240 duration @.050, but no more than .425"

HMP magneto ignition,
I prefer the Dyna 4000

(thinking HARD about the MSD MC-4!), two stages of NO2 on a 2.5lb bottle, (also thinking HARD about a single variable nitrous controller!), and a Goodyear 11.5 x 30.

The 11.5 x 30" tall tire is mostly used on cars, you might run into a problem with tire shake on a tire that tall.  What what you will find on the bikes is either a 11 x 29 or the 12 x 29, if you have the room I would recommend the 12" tire.

When wicking it up, trying to see some boost, I'm getting no indication at the boost gauge, and don't hear the turbo spooling, nor do I hear the waste gate popping off when closing the throttle quickly after wicking it. 

With as low a compression as you are running I doubt that you will see much if any at all.  I would also CC the motor to verify the compression ratio, since  the GPZ head a larger combustion chamber than a KZ. You might actually have 7:1, you could get away with as high as 10:1 if you are careful with your tune-up.

Took off the exhaust pipe, gently turned turbine with finger.  The shaft exhibits no side or end play, it feels rather stiff to me (just the seals?) but very smooth turning.  With throttle open, found compressor wheel in good condition, (read: no obvious defects). 

Get familiar with how the Ray Jay goes together and what to look for, seizure, too much end play and up and down, also how to check it. Taking the turbo apart for inspection is basic between race maintenance.

You might not be able to feel a problem with the impeller shaft or see any damage on the wheels without disassembly.

My next step, I think, is to check the waste gate for proper seating.  It doesn't sound like its holding open, but it might not be sealing up enough to build any boost under such intermittent throttle shots. 

Waste gate technology has vastly improved over the last couple of years, it maybe worth your while to look at some of the new diaphragm type of waste gates that available today.

 Also, I don't believe the header is leaking, at least I don't hear anything. 

Any exhaust leak will hinder how the turbo performs

My questions are:  1)  Am I on the right track?  2)  If not, what else should I look for?  3)  I'm looking to get deep into the 7's (7.10's). 

If you are planning to run these kinds of times be prepared to be a mechanic, make friends with a machine shop, learn how the different systems work together. But, mostly DON'T TAKE ANYTHING FOR GRANTED, verify, verify verify. When you are working on the bike trust only yourself.

 I would like to eventually run FunnyBike, and be one of the buys that make the Big Guns sweat, because they KNOW I'm going to the other end EVERY time!  Even though I won't be the fastest.  At least, that's the plan!  What would be your recommendations for my combo?  Thank you in advance, for your answers!  I'm very appreciative of any help you would give me.  Also, what products/services do you offer that I might make use of?

I would suggest that you look at the Head Gasket Saver, and Receiver grooves service that I have for the KZ. http://stevericeracing.com/gasket_saver.htm   I am sure that there is more help I can be also, you need to make the motor sound first; then you can start making laps. 



    I was given your name from a friend and co-worker in Clearwater Fl. he said you might still have a 1976 BMW R90/6 in your garage. I have a 1975 R90/6 I'm having some problems with the carbs. I rebuilt them a couple of weekends ago because I don't think that they have ever been taken apart, and the bike wouldn't idle it would die every time I stopped at a light or stop sign. After the rebuild the bike still wouldn't idle, I checked the timing and the points, I regapped the points and the timing looked fine although I might retard it a bit since the bike pings a little. I finally got it to idle but only after adjusting the jet on the bottom of the carb and the idle screw. It still doesn't seem to run right though it almost sounds like its only hitting on one cylinder but it smoothes out when you ride it (runs smooth at ~1500 rpm). Any thoughts or suggestions would be greatly appreciated.


Hi Chris,

Actually, my street bike is a 77 R100/S, (some asshole stole my R90/6) I just put a new battery in it and had to clean one of the carburetors because of a running condition exactly like what you are describing. 

What you describe may be a problem with pilot fuel and /or air circuit being blocked. This would be the pilot jet, low speed mixture screw and passages in the carburetors themselves.

Since there are two of everything carburetors, cables and screws -  making the bike run evenly is a challenge that requires good balancing and synchronization between the throttle cables and idle screws. But, it sounds to me like just a good cleaning and synchronization should fix your low throttle position running problem.

You can determine which carburetor it is by pulling the plug cap off of the spark plugs one at a time to see if it will run or not, The cylinder that doesn't run is the one you need to look at.

Hope that helps, if you have any other questions or if I can be of assistance feel free.

Steve Rice



       Have a 1991 ZX-11c 12000miles. this bike is now used drag race only (top eliminator once). Going down strip it is fine - on the return road after getting time slip in first & second gear with slow smooth throttle the drive train gets jumpy like skipping a gear or tooth engagement is bouncing in and out. Engine oil is perfectly clean with no metal on the magnetic drain plug. Going down strip it is fine when shifted hard. Any thoughts that might lead me to solution?


Hi Robert,

Sounds to me like you have rounded engaging dogs on second and the gear that engages it.
Most likely you will need to replace second, the mating gear, shift forks and drum.

Be sure to use parts from the later ZX1100-D2 or later, they have been updated.



 Enjoy your web site keep up the great work.
 Question: I am run 1973 Kawasaki in Pro Street, It is turbo charged with fuel
 injection, the motor is a J model with a Gpz head stock. The problem is the
 cam cap bolts stripping out and then you have to heli coil new threads. Well
 even the heli coil will strip out at some point. The head goes through so much
 with hot/cold cycles. What I would like to know is there a better way to
 resolve this problem? or are there any steel incerts on the market that can be
 drilled over size to use the stock 6mm bolt or do you go to over size bolts and
 make new cam cap sleeves to fit the over size bolts?
 Thanks Pat


Hi Pat,

Usually what you run into is the threads failing from the springs running into coil bind, the caps being over torqued, and just the constant in and out of the bolts stressing the aluminum in the cylinder head.

Of course its always better to start with fresh parts, ie. a new head, but that is not always feasible. Plus a used head is seated in well and will hold a valve job longer than a new head will.

If you have damaged Heli-Coils in your head now, your only recourse may be to install a larger diameter bolt, this can get tricky (read expensive) since you don't want to get the caps out of alignment.

When I have ran into this problem I do not use Heli-Coils, I prefer to use Time-Serts they are a one piece steel insert that goes into damaged threads. They usually provide a lasting repair for the damaged part. I use them any place in aluminum where the hardware is taken in and out allot. Clutch cover, inner clutch hub. etc...

But the best way to keep from damaging the threads is not to over torque the bolts which will pull the threads from the head. The 6mm bolts are a special hardened bolt that is adequate for your application. It is important to follow the manufacturers tightening sequence and use the specific torque number (I have 1/4" drive torque wrench that is dedicated to cam caps).

To keep unnecessary stress on the treads and to prevent galling of the threads in the head to the bolt use a good assembly lube on the threads and under the head of the bolt.

Hope this is helps.

Steve Rice


Hello Steve :o)
You have a verry good websight. :-) 
I am a man from norway and im rideing a old kawa gpz funny bike with a zxr 750 engine in it.  
The last jear i have run the zxr 750 engine for funn and learning the game. and my dream is to find a zx12r engine to use in the bike. 
But thru the jear i got the desire to se how fast i can get the 750 engine to run with a low budget. With al original engine i run 11.47 on 1/4 at 187 km.h and 6.97 on 1/8 at 167km.h  
I have thru the winter started to fit a garret T3 turbo on it. to se wat it can do.
Maby you have som tec tips for me? Methanol, whater injektion maby. My goal is to beat the hell out off the engine to learn and praktice to leather projekts. 
I hope to heare from you.
Venlig Hilsen
Stig Stene
Web side



Hi Venlig,

Thank you for the compliment on my web-site, I looked at yours I think it is much better than mine.

I think with the addition of a turbo charger your 750 will be quite fast.

Are you going to blow through the carburetor that are on the bike now, or are you going to do a draw through?

Blowing through the carburetor will be a bigger challenge to get figured out, however when its done you will have a better running bike than a draw through system.

With methanol you will want to be 60% richer than gasoline or have a A/F ratio of about 6.5:1, gasoline will be near 13 or 14:1:1, if by chance you decide to try ethanol you will be looking for 9:1 A/F ratio.

With the b/t carburetor it maybe hard to get the jetting big enough for methanol, draw through with an S and S wont be a problem.

Ethanol would be easier the get the correct jet sizes, even more so with gasoline.

If you decide to run gas then I would use some kind of methanol or water injection system.

Waste gate selection will be a factor on how well the bike responds also. I have had best luck with a diaphragm type of waste gate, you can find those at several places or I can supply one.

I hope this information helps and if there is more I can do please let me know.

Steve Rice



Hey there Steve I have a question I have been drag racing a KZ 1000 turbo charged a few years now and have experienced good luck with the motor combo. But recently i have built a new motor the new motor is 1200 cc with the same turbo that i had freshened up buy Turbonetics. My question to you is I have considered running alcohol but the static compression is 8 to 1 and I have no experience with running alcohol I previously ran 118 octane fuel. Do you think there would be an advantage to running alcohol verses race fuel and could I run alcohol with that low of static compression?  

Thank you


Hi Dave,

Thanks for the question.

1200cc is a good size for a turbo application, especially if you are going to run alcohol. I am concerned though about your static compression ratio.

Alcohol in itself does not make horse power, what you get with alcohol is a very high octane rating, in the area of 130. What this does is burn colder than gasoline or ethanol for that matter.

Because of the higher octane rating you can run (and must) more of everything, static compression, ignition timing, boost and amount of fuel. When you do this you will experience a significant increase in horse power with fewer detonation problems.

Alcohol requires that you use 60% more fuel by volume than gasoline (14:1 vs. 6:1), if you are using a draw through equal fuel distribution becomes a problem when fuel begins to puddle in the manifold. End result being cylinders running rich and others lean, injection really is the best way to go with alcohol.

But back to your original question, is 8:1 sufficient static to run alcohol?

For optimum performance no.

After the motor starts making boost it would be ok, initially you will be lacking sufficient combustion chamber pressure to build heat and the motor will be quite lazy.

Ideally you want to get more than 10:1, 10.5:1 to 11:1 would be best.

I hope this helps and if I can be of assistance please let me know.

Steve Rice



 I drag race a street legal turbo ZRX1100, and have had some problems with rod bearings. The cranks have been blueprinted by Falicon, and I run Carrillo rods. Also I'm using a Muzzy dry sump pan, and oil starvation is not the problem. I have been setting the clearance using the specs from the manual - .042-.070mm, but I just ran across an old post of yours where you listed your clearance a bit bigger than this. Can you offer any advice?

Thanks very much,
Dean Sabatinelli


Rod bearing seizure is always a lack of lubrication at the failed bearing.

First thing you want to look at is the main bearings and how they are living. If your main bearings are in good shape and the rod bearing have damage, then it would be safe to say that oil does make as far as the mains but for some reason it isn't getting to the rods.

If your failure is at both the main and rod bearings there has been no oil at either.

In the first instance of rod bearing and not main bearing failure the reason can usually be tracked down to oil not making it into the rod journal this is usually from excessive engine rpm. As the crankshaft turns at a high speed the oil hole can actually travel fast enough not to allow the get in the journal. The high surface speed of the oil hole will cause the oil to begin to cavitate over the opening and only air and frothed up oil will get to the rod. Then you have a metal to metal contact, the bearing will soon fail.

The remedy for this is not running as high of engine rpm in excess of engine red-line, you can raise that RPM by modifying the main bearing holes to pick- up more oil as the crank is spinning.

If your failure is of the second type where both main and rod bearings have failed you need to check your oiling system for blockage or internal leakage. Also this will happen when a motor is revved high while the oil is cold and doesn't freely flow throughout the motor. A liberal warm-up time is recommended to help avoid this kind of failure. Also use only a Kawasaki brand oil filter some time other brands don't have the same flow rate as the OE filter. However I use a external filter with a 50 micron screen on the ZX11 Funnybike.

I recommend running your clearances near .003" you should also shim your bypass valve to raise oil pressure, also for race use you can significantly raise oil pressure to the crankshaft by restricting the oil pressure to the cylinder head by modifying the banjo bolt that feeds the head and cams. I also use Mobil 1 15w50, when its cold I will go with a lighter weight oil.

I also use only new crankshafts, re-welds have proven not to have the reliability as the new stock parts.

There are allot of small things you can do for you oiling system, being sure that oil is able to flow as freely and un-restricted as possible is the most important.