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Looking for Cox .049 mods?

Old 12-03-2008, 05:06 PM
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Duane-RCU
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Default Looking for Cox .049 mods?

I know I did a search, but can't seem to find the info. Maybe it wasn't here, but I thought I remember product and regular tanked reed hop-ups somewhere. The sticky with 5 pages (lots of off topic stuff!) didn't help. Somewhere around here I have an article "How to prepare a Cox for mouse racing" or something like that. I'll see if I can find it.
Old 12-03-2008, 05:17 PM
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Default RE: Looking for Cox .049 mods?

Go here. It is from Paul Gibeault, a Canadian mouse racing champ.

http://www.balsabeavers.ca/images/Mo...le%20three.doc
Old 12-03-2008, 06:48 PM
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Default RE: Looking for Cox .049 mods?

Linky No Worky,......
Old 12-03-2008, 06:58 PM
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Default RE: Looking for Cox .049 mods?

Just now worked for me -6:00 CST. It's a .doc file, so you'll need MS Office, Open Office or Wordpad to open it.
Old 12-03-2008, 08:54 PM
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Default RE: Looking for Cox .049 mods?

The Gibeault Mouse Race Program

By Paul Gibeault
Submitted by Les Akre

Class 1 Mouse Race has always been a favorite of mine. It is cheap to fly, but oddly enough, cubic dollars have little to do with how you place in competition. Although deceptively simple looking, when taken to the limits, Cox .049 engines and their subsequent rework can be very involved, and sometimes frustrating. The following article represents much of what I have learned in my 20+ years of competition in this event, and it is my hope that those wanting to fly Mouse Race will find it useful.
The first part of this article will deal with setting up the engine for Mouse Race duty. The second part will cover the airframe and race equipment, and the last part will cover tips and suggestions for success.

Engine

1. Crankshaft/Crankcase Assy.

Problem: Cox .049’s are prone to breaking the crankshaft, when pushed really hard – usually the crank pin parts company with the crank throw web.
Solutions: The use of the “race car” crankcase assembly reduces this problem as the crank throw web is noticeably thicker on these variants. Having personally blown up both crankshaft types, I have found that the assemblies from very old engines seem to last longer than the newer ones. Years ago, Kustom Kraftsmanship offered crankcases with an “Oilite” bronze sleeve bearing, but I have never used one. They also offered a tempered crankshaft, but there’s no guarantee it won’t break either, as I have seen them fail also. The best bet is to use Cox “Killer Bee” cranks, or Davis Diesel cranks for greatest longevity. I’ve had my crankshaft shear in half during the Nat’s final, (as have others) but there is little you can do about it, but replace it and carry on. It’s all part of the fun of Mouse Racing!
It’s a good idea to lay some 400 wet/dry sandpaper over a piece of glass, and with the addition of some WD-40, sand
the back of the crankcase. This will remove any burrs that might otherwise prevent a perfect seal with the fuel tank.

It is very useful to disassemble the crankcase assy, thoroughly clean everything, and then polish up the crank with 400-600 fine sandpaper to remove any nicks & scratches that may be present. For re-assembly, use a 5-40 socket head cap screw & old prop to draw the crank squarely into the drive plate. When re-assembled clean & dry, give it a spin. It should be really free with no binding whatsoever. On the best examples, the crank throw will even rock back to the bottom.





2. Integral Fuel Tanks

Problems: The stock fuel tanks are slow and sometimes short on range. They also may have trouble holding a consistent needle valve setting. They are also prone to “reed float” above 17,000 rpm.
Solutions: Modify the needle valve assembly as follows,
as the stock needle leaks air. Remove needle valve, discard the spring, install a #4 flat washer, and then add a piece of ¼” silicone fuel tubing. Re-install the needle valve and you now have one cheap, but airtight needle valve assembly. With the tank and tank back together, remove the screen and drill out the tank and tank back inlet venturi to .082”, (this is what the record holding engine used). This produces a gain of about 500 rpm, but at the expense of less fuel economy. Use one of the larger 8cc tanks for the greatest range. These are commonly found on Golden Bee, Super Bee, & Black Widow engines. The Venom uses this as well, but the venturi hole is already at .082” ID. Next sand the tank back flat over glass (again with the 400 paper), as many tank backs are warped and do not sit flat when bolted to the firewall. While you’re at it, use your dremel tool to grind away the screen holder from the venturi area of the tank back. Do a good job of blending in this area. The fuel pickup must be located at the outboard corner, and then held in place. Using a pin drill, drill a tiny hole through the “fence” where the tank back joins the tank, and wire the neoprene tube in place with some .020” stainless steel wire, (S/S is non- corroding). If you have a tank back with no “fence” you can also get the neoprene pickup tube to stay in place by inserting a small piece of 1/16 brass or alum tubing, about ¼” long. The net effect will be that the tank front will now hold the pickup in place. Or, bend a piece of soft aluminum tubing & make the pick-up one solid piece. Attach it to the tank back with a short piece of silicone tubing.
The next step is to prevent the integral tank from leaking.
This is a MUST if you wish to hold a consistent needle
setting, and have the engine shutdown consistently. This is
done by wrapping a piece of 1/2A dacron line around the
entire peripheral groove of the tank. Hold the dacron thread
in place with saliva (crude but effective) or oil for final assembly. If you want, it may help to lap the metal tank & tank back joint, but it’s not required if you’re using one of
the newer nylon tank backs.

Mega-Power: In a reed valve engine, top performance is only attainable by using the mylar reed! Either shape, cross
or rectangular, is acceptable. The copper/beryllium reeds
have just got to go. This last production change allows reed engines to be on par with “TeeDee’s” in performance! My
test bench results indicate that 24,000+ rpm is achievable for steady-state running with such reeds. That being said, Larry Renger prefers the Cox stainless steel reed over the mylar
reed & Bob Davis prefers his teflon reed. I have no contest experience with these other reed materials, but they are certainly worth trying out.



Final Assembly: Since all Cox engine components are notorious for coming loose, clean the 2-56 engine to tank screws with thinner, then final assembly is done using blue Loctite threadlocker. Every time you tear down the engine, replace both the paper tank gasket and the venturi o-ring. This may seem like a waste, but $2.00 worth of new gaskets is worth $100.00 worth of reliability in the racing circle!
Apply a layer of mylar tape to the entire tank back to provide
a final barrier seal against fuel leakage, and you’re done.

3. Piston/Cylinder Liner Assembly:

Problem: Not enough power!
Solution: Any type of piston/cylinder liner assembly made by Cox can produce good results. However, a superior “fit” will overcome nearly any porting deficiency. This means that a well fitted “Babe Bee” P/L is better than a bad “TeeDee” P/L. I recommend a flying test for all P/L assemblies in your possession, as certain assemblies will occasionally defy all rules of performance. Having said this; I find that excellent fitting “TeeDee” #4 P/L’s to be the best. Most all of the really fast engines use these. “Killer Bee” P/L’s are a good choice as well. It is worth noting that new Cox pistons often come with the ball socket joint set too loose. Therefore it is a good idea to re-set the fit with a Cox factory tool (or equivalent) to .002” slop, or less. Using the piston holding fixture usually results in a mushroomed head piston (totally ruined), so I don’t use it. Clean the socket area with acetone or brake cleaner first to remove the oil. For best results, lay the piston on a heavy piece of ½” plate glass or flat thick piece of steel (something quite dense). Then with the tool in place, tap with a hammer, rotate a bit, tap again and continue, checking often until all excess play is removed. It is necessary to check and adjust this joint after every contest. At normally low rpm’s this isn’t critical. However, at racing rpm’s (20,000+) a loose ball/socket joint reduces piston life to a few minutes.
Optimum piston/cylinder fit is to be checked with parts
being absolutely clean and dry. To check the fit, slide the piston up the cylinder bore (with no finger prints!) until it sticks. Ideally, it should stick flush with the glow plug land,
or even slightly higher. Now, with a slight tap, the piston should fall right out of the cylinder. If the fit is slightly looser, this may be OK too, unless power and starting consistency deteriorates. In this case, the P/L assembly is worn too far for that particular cylinder. Keep it to try in other slightly smaller cylinder liners later on.
Please note that a new TeeDee P/L assembly is usually fit too tight. Those of you with an excellent feel can go ahead and
lap the piston to fit. However Dale Kirn’s easier way to do
this is by just running in the engine. Start by cutting down a 5x3 prop until it turns up to 24,000 rpm rich. Run up to 2 dozen tanks of fuel through the engine, but for no more than 2 minutes at a time, to allow for cooling in between runs. It is better to use a TeeDee crankcase for this purpose, and
transfer the P/L assembly to the reed valve crankcase when it is run in. The reason being, that at 24,000+ rpm, the reed
valve crankcase will wear out quickly, sometimes in only a half dozen runs!

Lastly, it is VERY IMPORTANT to keep carbon varnish off the piston and especially the cylinder walls. #000 steel wool or medium grade Scotchbrite wrapped around a small dowel wet with WD-40 or thinner easily removes all the carbon. This procedure takes only a minute, but really MUST be done before every contest to ensure peak performance.

4. Glow Plug

Running 40 to 60 percent nitro requires the use of 5 head gaskets. Yes five! Low compression is the only way to run consistently (first 5 laps to last 5 laps) on highly nitrated fuels, whilst retaining acceptable plug life. I never use less than 4 or more than 6. I use only p/n 1702 Cox high compression glow heads for maximum power and reliability. I have not found the 1/2A Glow-Bee plugs to be reliable enough for mouse racing, (they are also no longer in production). Some of the newer heads manufactured by Doug Galbreath ([email protected] ) and others, use standard Nelson plugs which offer good performance at less than half the cost. These are certainly worth experimenting with, given the relatively high cost of the Cox glow heads. After removing a new Cox plug from it’s package, carefully sand the seal band on a plate of glass with 400 paper and oil. This will ensure the plug seal area is flat, and will seal properly when tightened. Now examine the plug element, and with a T-pin, make sure it is centered. Finally with a T-pin, very gently pry at the element where it is welded to the plug. It should be a firm weld. If it breaks loose, kiss your money goodbye, and start with a new plug. Console yourself a bit by knowing that you’ve just prevented yourself from using a plug that would have prematurely failed. (Most likely during a Nat’s final). After a while you may notice your glow plug constantly keeps coming loose. This is due to the copper head gaskets becoming old and hardened due to the constant heat cycling. Since the Cox engines use an annealed copper gasket, replacing the head gaskets with new ones will solve the problem.

5. Assembly & Miscellaneous Problems
Problem: Engine comes loose in flight, prop falls off, glow plug comes loose in flight.
Solutions: 1. Check and tighten the mounting bolts before every race. 2. Tighten the glow plug vigorously before every race. 3. Replace the stock prop screw with a 5-40 x 1 inch hardened socket head cap screw, and check tighten before every race. 4. If field disassembly can’t be avoided, use Loc-Quik super primer T accelerator, with blue Loctite thread locker upon re-assembly.

Airframe & Race Equipment

Airplane: In my opinion, there is no better design to start with than the record holding Streaker Mk V. Plans are available from: [email protected] . Laser cut kits are available from Melvin Schuette that can be built in a day.
Contact: [email protected]


Prop: You must have 4” of pitch to get rolling! Any 1/2A prop made by Cox, Tornado, or Top Flite is OK. However,
cut down props (less than 5” diameter) go faster than stock. Only test flying will determine which prop(s) ultimately work best for a given combination. A Tornado black 5x4 cut to
4 ¾” has won the Nat’s final, so you could start there. The APC 4.75Dx 4P is also great, and holds the current records. The APC 4.5D X 4P is also an excellent choice.

Fuel: A minimum of 40% nitro is required to get with the program. A 60% mixture, or more, yields faster times, but only if everything else is correct, i.e. You have fabulous reliability on the 40% mix, and are practiced and know what you are doing! (Be prepared to buy lots of expensive glow plugs as well!) A most important note about mouse fuel: A minimum of 5%, & preferably 10% of the oil mix must be castor oil. Should you decide to race your Cox .049 on a castor oil deficient fuel, your engine will commence a course of self destruction, and you will find out first hand why many have sworn off flying Mouse Race for good! YOU HAVE BEEN WARNED! For those of you able to blend your own fuel, I have developed a truly good mix for class 1 Mouse consisting of the following:

5% Klotz “Benol” (or pure AA castor oil)
15% Klotz KL 200 (or K&B x2c) synthetic oil
40% Methanol
40% Nitro methane

Pre-Race Start & Warm-Up

1. Before the first run, always prime the crankshaft
with oil or raw fuel for additional lubrication at this critical time.
2. Fill tank, prime exhaust, and wind up the spring starter 1 ¼ turns to start, anything less than 1 ¼ turns will allow your engine to start backwards. 1 ¼ turns ensures a correct start first time every time.
3. Most Cox .049 engines do not take a really good needle setting until warmed up. Therefore don’t be surprised if the ground and air settings differ, sometimes as much as ½ a turn! The best time to fine tune the needle valve is immediately after a flight. Important note: If your needle valve setting changes by more than a ½ turn, you have a fault! Clean or flush out the dirt, or fix the leaking tank, or loose glow plug, but stop perpetually messing with the needle valve.
4. To stop a running engine on the ground, squeeze your thumb and index finger over the tank vents. If using a uniflow tank, then just covering the uniflow vent will suffice. This will verify your tank seal. If the engine doesn’t stop, but continues running, then you have a sizeable leak somewhere that must be fixed!
5. I have mentioned earlier that Cox crankshafts may have a fatigue problem when run really hard on high nitro fuel. You can accelerate all kinds of shaft and case problems by stopping a running engine by it’s prop nut. DON’T DO THIS!
Stop the engine by blocking the vents or pointing the model’s nose down, & pick-up to the top. You will increase the life of these parts considerably, as well as save yourself some grief.
6. Always monitor the color of the engine exhaust oil. Usually a good running engine will alert you in advance of an impending failure by “making metal”. This usually means tiny aluminum particles are being rubbed off and are visible in the exhaust oil, if you look closely. This is usually accompanied by frequent plug failures. At this point, it’s best to find the trouble spot and fix it. The same holds true if your crankcase ever makes a squeaking noise on start up, or shutdown. When this happens, I replace the whole crankcase assembly, because the crankpin has worn (tapered) causing the rod to slide off the crankpin and rub away at the tank. If you are able, use the newer type tank that incorporates the nylon reed retainer. A steel crankpin rubbing on nylon is much preferable to one rubbing on aluminum.
7. Always keep your engine scrupulously clean and always protected from the elements with a plastic bag or rag. Always filter your fuel, especially when changing containers. Ensure your fuel bulb is in good shape and not cracked, hardened, or flaking rubber. Better yet, replace it yearly and don’t worry about it. When everything checks out ok, and your engine still hics and coughs, it’s very possible that dirt in the fuel
system somewhere is causing the problem. It doesn’t take much dirt to raise havoc with a reed engine so remember, “Cleanliness is next to Mouseliness”


Tips and Suggestions

“The Engine”

I assume that if you followed my engine set-up tips, you should have a very decent running engine. I do like the later “Killer Bee” type crankcase ass’y and would recommend
them over the older type if you are experiencing crankcase
or crankshaft problems. The later Cox “Venom” engine
makes you competitive quicker, but I strongly recommend
one change. In production, they varied from designer Larry Rengers’ original drawing & made the piston too light at the top. This caused the piston top to separate in as little as a half dozen runs. My cure has been to fit up a TeeDee piston to the Venom liner (as described earlier) & then you have one great running set up with no more piston failures. A “Venom” will not necessarily make you an instant winner. You still need to keep in mind all of the maintenance tips mentioned earlier. Besides, both AMA records (2:18:6 & 4:34:0) have been held with a much older engine, (converted Golden Bee) so don’t go throwing out “ole reliable” just yet.





“The Model”

I assume that you have built the Streaker Mk V with 2 ounce fiberglass cloth all over & 1/4 -1/3oz. tip weight, for a total model weight of 6 ¾ oz. In this event only, heavier is better.
You will notice this advantage in windy conditions (and when isn’t it windy when flying Mouse!) Unlike many designs, the heavily tip weighted Streaker can darn near fly in a storm if need be. After all, anybody can fly in calm…..but successfully flying in wind separates the men from the boys!
However, if you have ignored the instructions and built your Streaker too light, and without enough tip weight, then you will find out two things. 1) That it doesn’t whip well flying high and falls out of the sky downwind, cart wheeling upon landing. 2) It builds momentum slowly and won’t keep its speed up with a dead engine, and you end up crashing in a line tangle anyway.
When flying in rainy conditions it is the pilots’ job to wipe the lines with a soft cloth moistened with acetone. Do this often, and always prior to every race. Much of the sticky film buildup is caused by the oily exhaust residue produced during flight. If not cleaned often, the lines can stick together causing a loss of control, almost always with disastrous results. I have lost races neglecting this!
You need to use a good quality nose wheel, and solder it on with Sta-Brite silver bearing solder. I have lost face (and races) when my wheel fell off during a race. Regular solder just doesn’t cut it.

“Piloting”

An otherwise great airplane/engine combination is obviously disadvantaged by poor piloting. Here are a few suggestions you might find advantageous. Since Mouse races often involve line tangles, (surprise, surprise!) choose a pilot with combat experience. This type of individual often has a “never say die” attitude when lines from other (often crashed) models have him wrapped up like a fly in a spiders web. He just keeps on flying, no matter what. A good pilot when suddenly caught in a line tangle will calmly change hands if necessary to get out of it. I can fly with either hand and this ability has paid off many times. The lesson here is that not all line tangles will bring you down if you keep a cool head about you. A great pilot must train himself to not look at his own model; but watch his opponents and his own pitman for signals. This allows you the important split second to see and avoid accidents just as they happen and fly accordingly. Cox .049 reed valve engines do not have shutoffs (although some homebuilt engines do.) This lack of a shutoff, often causes a fatal mistake as seen in the following scenario: You are flying along, just overtaking a slower model and your engine quits! You quickly lose airspeed and sink into the model you just overtook, bringing both models down in a line tangle. Happens every contest it seems, but consider this:
A great mouse pilot must:
Count and be aware of his laps at all times, i.e. Know what
lap his model is on, and how many laps his model is capable
of flying in traffic. (for this example 30 laps per tank)

At maximum laps, less five (per example, 25 laps), assume that your engine will quit if you overtake. If you are approaching a passing situation at this critical stage then: If you are ahead, flap your elevator (up & down) and do not pass since it is only a few laps until you will run out of fuel.
If you are not ahead, as you approach to overtake, quickly whip hard with just enough height to get by safely. Do not climb any higher than absolutely necessary or your engine surely will quit! As soon as you have gotten by, stop whipping. You shouldn’t have to whip for more than two seconds to accomplish this correctly! You may be warned for whipping, but better a warning than a crash. Should your Streakers’ engine quit while passing, the whip momentum will allow you to complete the pass even with a dead engine! Such is the beauty of a properly weighted Streaker Mk V.

“Pitting”
An otherwise good pitman can cost you the race by launching your model without first looking for traffic! Sometimes you will be taking off just as another pilot is landing. A launch at this critical time involves you in an instant line tangle/crash, and disqualification from that race. The solution is “heads up” pitting. A great pitman will grit his teeth and hang on a second or two until it’s safe and clear to release. You must remember to always yield to the landing model. Seldom is a mouse race lost by 2 or 3 seconds, but it’s always lost on a pitting accident that results in disqualification.

“Conclusion”

TEAMWORK: Where the sum of the whole (working together in harmony as one) is greater than the sum of the individual parts working separately. A winning Mouse race effort can basically be put down to the right amount of teamwork. That is to say the ability of a good team working together in a nice flowing manner, carefully avoiding accidents, yields better results than a team with a killer model, but lack of team work and practice. I have been most fortunate to fly with my buddies, Roy Andrassy, Les Akre and Todd Ryan. Their superior piloting and pitting abilities have guided us to many victories. Thanks for all the great work guys, I enjoyed every minute of it! Thanks also to John McCollum, Dale Kirn, Joe Klause, & Larry Renger whose knowledge and expertise has helped me on many occasions.
I wish to thank the rest of you fellow Mouse Racers out there for coming out to race with us. If it wasn’t for all of you, Mouse Race wouldn’t be the one of the more popular Nat’s events that is today. I wish all of you the best of luck and most importantly, take it easy on my delicate ego when you beat me!
…………Mr. Open Mouse


This work is dedicated to the late Wayne Trivin of Tampa, Florida. He was an AMA Nationals Mouse Race champion,
and Sportsman of the highest caliber.


Old 12-03-2008, 09:33 PM
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Default RE: Looking for Cox .049 mods?

Besides detailing the crank fit and opening up the airway, the most important mod of all is to thin the piston walls to paper thin and to raise the skirt to obtain .010" of SPI. The ball socket should have zero slop. Beyond that, going with a 128 tooth NVA is mandatory.
The easiest way for anybody who wants to see how to make a Cox .049 run would be to examine a KillerBee and do your best to copy what that engine has had done to it.
Old 12-03-2008, 11:29 PM
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Duane-RCU
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Default RE: Looking for Cox .049 mods?

That's the article I was looking for. I'm also looking for mods to the product (plastic backed) engines, and sure starts. Thanks for the help, I don't have anything in particular to put one on, I just wanted to do something with this big can of parts I've collected. I have MANY pistons/cylinders, but they seem pretty worn, due to my lack of knowledge (castor) and lean runs more than 30 years ago!
Old 12-04-2008, 08:40 AM
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Default RE: Looking for Cox .049 mods?

You should send an email to paul, and build his streaker V of course.

Mine rips around the circle with my paul'd cox.

ps-dont put the cylender sideways like that. paul runs them strait up and I broke my needle once like that. ha!

pps- pauls [link=http://www.balsabeavers.ca/Mouse_4.jpg]streaker[/link]
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Old 12-04-2008, 11:20 AM
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Default RE: Looking for Cox .049 mods?


ORIGINAL: forsakenrider

You should send an email to paul, and build his streaker V of course.

Mine rips around the circle with my paul'd cox.

ps-dont put the cylender sideways like that. paul runs them strait up and I broke my needle once like that. ha!

pps- pauls [link=http://www.balsabeavers.ca/Mouse_4.jpg]streaker[/link]
I use the Streaker 4 as well, It is a Zoomer. I met Paul at a MAAC Zone meeting in Halifax in the early '80's and he stated that when the cylinder was mounted sideways, it actuall reduced the RPM at high speeds.
Old 12-04-2008, 01:36 PM
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Default RE: Looking for Cox .049 mods?

Back in the early 70s my father converted a Cox Baby-Bee to rear rotary valve. I ran like it was on steroids but the little parts and lack of metallurgy made for the small parts to wear out quickly. It was originally in a plane he built for club mouse racing called the Loud Mouse. It had snap full up & down mechanical retracting landing gear & fuel shut off. It did most of its flying with a Cox DT 049. It still sits in my desk/building bench. Cox made allot of different barrels for the Baby-Bee, if I remember right the #2 was the hottest.
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Old 12-05-2008, 12:49 PM
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Default RE: Looking for Cox .049 mods?

Is Kustom Kraftsmanship, or its successor, still in business? They supplied many mod parts for TD and BW. One item I remember were cylinder shims so you could adjust port timing of the cylinder. But I can't remember what the instructions were. I noticed that Gibeault made no mention of this procedure. Maybe that was the secret to his success. What would be the best setup now on a BW for Mouse?
Old 12-05-2008, 01:16 PM
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Default RE: Looking for Cox .049 mods?

The shims are good for orientation of the liner ports. Having the bypass ports in line with the rotating parts is desirable.
The guy who took over KK's stock might still be around, Darren Albert. I haven't heard his name mentioned recently.
Old 12-05-2008, 01:43 PM
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Default RE: Looking for Cox .049 mods?

Try [link=http://www.texastimers.com]Texas Times[/link] - they carry some hop up mods including fine thread needle valves.
Old 12-05-2008, 02:23 PM
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Default RE: Looking for Cox .049 mods?


ORIGINAL: tigrejohn

Is Kustom Kraftsmanship, or its successor, still in business? They supplied many mod parts for TD and BW. One item I remember were cylinder shims so you could adjust port timing of the cylinder. But I can't remember what the instructions were. I noticed that Gibeault made no mention of this procedure. Maybe that was the secret to his success. What would be the best setup now on a BW for Mouse?
Solutions: Modify the needle valve assembly as follows,
as the stock needle leaks air. Remove needle valve, discard the spring, install a #4 flat washer, and then add a piece of ¼” silicone fuel tubing. Re-install the needle valve and you now have one cheap, but airtight needle valve assembly. With the tank and tank back together, remove the screen and drill out the tank and tank back inlet venturi to .082”, (this is what the record holding engine used). This produces a gain of about 500 rpm, but at the expense of less fuel economy. Use one of the larger 8cc tanks for the greatest range. These are commonly found on Golden Bee, Super Bee, & Black Widow engines. The Venom uses this as well, but the venturi hole is already at .082” ID. Next sand the tank back flat over glass (again with the 400 paper), as many tank backs are warped and do not sit flat when bolted to the firewall. While you’re at it, use your dremel tool to grind away the screen holder from the venturi area of the tank back. Do a good job of blending in this area. The fuel pickup must be located at the outboard corner, and then held in place. Using a pin drill, drill a tiny hole through the “fence” where the tank back joins the tank, and wire the neoprene tube in place with some .020” stainless steel wire, (S/S is non- corroding). If you have a tank back with no “fence” you can also get the neoprene pickup tube to stay in place by inserting a small piece of 1/16 brass or alum tubing, about ¼” long. The net effect will be that the tank front will now hold the pickup in place. Or, bend a piece of soft aluminum tubing & make the pick-up one solid piece. Attach it to the tank back with a short piece of silicone tubing. This works well on the BW. I have tried various positioning of the transfer ports and I found it made no difference in the RPM. The shims do make a difference in exhaust duration though.

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