CCW Motor Improvement?
-
Deleted User
CCW Motor Improvement?
I have a '72 CCW 436cc motor of which I would like to improve in order to get the utmost power out of it. I will be racing it this next winter in a Hillcross venue and I feel in order to do well I need as much power as I can get. I have some Arctic Cats and Polaris's to beat. Any experience in doing improvements to this motor that could help me. Thanks for your help and keep doing the good job that you JD people are.
-
Rodimus Prime
- Posts: 738
- Joined: Sun Jul 24, 2005 12:00 am
CCW Motor Improvement?
that depends on what class you race in stock , stock modified( your allowed one modification), or modified.
you say its a 72 kec 436 motor.. what does the engine tag say 440 /2 , 440 /3 , 440 /5, 440 /21, 440 /22 if your not sure ie tag is unreadable, missing or has a generic housing. ie kec 440 ill explain how to identify it.
/2 engines have a square type intake. Short head fins. shroud sits above the intake but doesnt connect to it.
/3 engines have tall head fins, intake is more v shaped looking. shroud covers intake manifold but isnt bolted to it.
/5 engines have a bigger looking intake compared to the earlier ones but is more squarish looking and is bolted to engine housing. this engine has mediun height fins compared to a /3. intake port bolt are opposite each other instead of offset like earlier models. this engine also has 4 transfer ports instead of the 2 of /2 and /3.
/21 engines are reed valve engines and look the same as a /22 from the outside the difference of these engines is mostly the piston pin size. other small differences include the flange for reeds is closer on a /22 than a /21 reed. reed valve engine are easy to identify as carb intake is at bottom of engine.
improvments for all these engines are to knife the intake port ( intake ports have an I in middle of port puting a knife edge to it increases flow(note mostly /2 /3 /5 engines). exhaust port take manifold gasket and put against port increase port size with a dremel tool to match gasket opening. once that is done use the flap wheels for dremel tools 120 grit and polish the exhaust port to almost chrome like finish. on the /5 engine between the two transfer ports is a seperator knife this edge.
on intake and transfer ports a good idea after grinding is to stick a carboard tube down cylinder tape gasket surfaces with two layers of duct tape and sandblast the ports to a rough finish. it helps keep gas mixed properly with air. make sure that the cylinder edges on ports exhaust and transfer ports are not sharp in any way. Once the grinding/ machining is finished wash cylinders int a 5 gallon buck of hot water and laundry detergent to remove any remaining filings. Blow dry and oil cylinder.
the heads on a /2 are already quite close to piston so taking material off is a bad idea just make sure they are not warped. /2 heads also take a short sparkplug.
/3 and /5 heads can be shaved 10 - 20 thousands to increase compression.
/21 /22 heads can be shaved 10 thousand only otherwise head becomes to thin and is prone to cracking between bolts.
exhaust manifolds should be rebuilt with new pipe to match port diameter angled slightly downwards as well. where two connect you can increase the diameter of pipe to match both port openings added together . ie if pipe is say 1 and 1/4 at both ports add together so your joint should be a pipe diameter of 2 and 1/4( there is a bunch of math involved in circumference and back pressure involved) stock manifolds are 1 in with a 2 inch opening. rest of exhaust would also have to be changed accordingly the slide joint the ball opening tapered slowly to muffler. muffler exhaust tube can be increased by 1/4 diameter as well. when done this would still be a very stock looking engine.
stock modifed would allow use of the tuned pipe from the jdx8 75 800s or 295s sleds.
modified would allow twin pipes.
pistons and piston pins should be weighted and shaved to match each other withing .5 of a gram. sometimes just switching the pins from one piston to another will correct the wieght difference. for racing use the single l ring piston from a rotax 440 tnt f/a engine 0.020 over or if bored 0.020 over in cylinders use 0.040.(this piston is 0.020 less than a stock kec 440 piston port piston.) the same can be done to a reed engine pistons but instead a stock 440 rotax piston is bigger than a stock 440 kec reed piston.
crank conrods should be wieghted and matched to 0.5 of a gram. brand new high quality bearings should be installed on crank and crank should not have more than 0.0005 thousands runout. con rod side play should be less than 0.010 but more than 0.008.
spark plugs. the tang that goes over the electrode should be trimmed back to be in center of electrode. make sure spark plug is non resistor type. ie instead of br8es use b8es or rn2c use n2c.
Carbs.. now here is where it depends on class your running.
stock would be a walbro carb. improvements to it are to spiral bore the carb. also called rifling. some engines came with a small bore intake for a smaller walbro carb some came with the bigger bore wd31. go with bigger bore of course.
stock modified would allow use of a tillison carb instead of walbro carb use one from a 75 rotax everest engine as it has a tube up center for better gas mixture spiral bore this carb as well. some will allow use of a mikuni single carb but limited to 34 max. they can be spiral bored at end where flange meets intake mount boot. ufo kits and dial a jet would not be allowed in this class.
modfied class would allow the use of twin 38 powerjet carbs, ufo kits and dial a jet. this is a page or two to explain how to do that but im not gonna get into that.
electrical system.. stock is points use new points and condensors. make sure to time both points to 22 degress isntead of 23 degrees and use a gap of 0.014 you may have to switch point sets a few times to get this exact. use good stock coils with new solid core wires.
stock modified would allow the use of the presotlite cdi from the 75 - 77 ccw engines.
modified would allow the use of cdi from a kawasaki engine with the better after market cdi box. Or use stock cdi from 75-77 but iwth hewlitt box.
some people wouldnt understand half of what i stated but you did ask what could be done.
you say its a 72 kec 436 motor.. what does the engine tag say 440 /2 , 440 /3 , 440 /5, 440 /21, 440 /22 if your not sure ie tag is unreadable, missing or has a generic housing. ie kec 440 ill explain how to identify it.
/2 engines have a square type intake. Short head fins. shroud sits above the intake but doesnt connect to it.
/3 engines have tall head fins, intake is more v shaped looking. shroud covers intake manifold but isnt bolted to it.
/5 engines have a bigger looking intake compared to the earlier ones but is more squarish looking and is bolted to engine housing. this engine has mediun height fins compared to a /3. intake port bolt are opposite each other instead of offset like earlier models. this engine also has 4 transfer ports instead of the 2 of /2 and /3.
/21 engines are reed valve engines and look the same as a /22 from the outside the difference of these engines is mostly the piston pin size. other small differences include the flange for reeds is closer on a /22 than a /21 reed. reed valve engine are easy to identify as carb intake is at bottom of engine.
improvments for all these engines are to knife the intake port ( intake ports have an I in middle of port puting a knife edge to it increases flow(note mostly /2 /3 /5 engines). exhaust port take manifold gasket and put against port increase port size with a dremel tool to match gasket opening. once that is done use the flap wheels for dremel tools 120 grit and polish the exhaust port to almost chrome like finish. on the /5 engine between the two transfer ports is a seperator knife this edge.
on intake and transfer ports a good idea after grinding is to stick a carboard tube down cylinder tape gasket surfaces with two layers of duct tape and sandblast the ports to a rough finish. it helps keep gas mixed properly with air. make sure that the cylinder edges on ports exhaust and transfer ports are not sharp in any way. Once the grinding/ machining is finished wash cylinders int a 5 gallon buck of hot water and laundry detergent to remove any remaining filings. Blow dry and oil cylinder.
the heads on a /2 are already quite close to piston so taking material off is a bad idea just make sure they are not warped. /2 heads also take a short sparkplug.
/3 and /5 heads can be shaved 10 - 20 thousands to increase compression.
/21 /22 heads can be shaved 10 thousand only otherwise head becomes to thin and is prone to cracking between bolts.
exhaust manifolds should be rebuilt with new pipe to match port diameter angled slightly downwards as well. where two connect you can increase the diameter of pipe to match both port openings added together . ie if pipe is say 1 and 1/4 at both ports add together so your joint should be a pipe diameter of 2 and 1/4( there is a bunch of math involved in circumference and back pressure involved) stock manifolds are 1 in with a 2 inch opening. rest of exhaust would also have to be changed accordingly the slide joint the ball opening tapered slowly to muffler. muffler exhaust tube can be increased by 1/4 diameter as well. when done this would still be a very stock looking engine.
stock modifed would allow use of the tuned pipe from the jdx8 75 800s or 295s sleds.
modified would allow twin pipes.
pistons and piston pins should be weighted and shaved to match each other withing .5 of a gram. sometimes just switching the pins from one piston to another will correct the wieght difference. for racing use the single l ring piston from a rotax 440 tnt f/a engine 0.020 over or if bored 0.020 over in cylinders use 0.040.(this piston is 0.020 less than a stock kec 440 piston port piston.) the same can be done to a reed engine pistons but instead a stock 440 rotax piston is bigger than a stock 440 kec reed piston.
crank conrods should be wieghted and matched to 0.5 of a gram. brand new high quality bearings should be installed on crank and crank should not have more than 0.0005 thousands runout. con rod side play should be less than 0.010 but more than 0.008.
spark plugs. the tang that goes over the electrode should be trimmed back to be in center of electrode. make sure spark plug is non resistor type. ie instead of br8es use b8es or rn2c use n2c.
Carbs.. now here is where it depends on class your running.
stock would be a walbro carb. improvements to it are to spiral bore the carb. also called rifling. some engines came with a small bore intake for a smaller walbro carb some came with the bigger bore wd31. go with bigger bore of course.
stock modified would allow use of a tillison carb instead of walbro carb use one from a 75 rotax everest engine as it has a tube up center for better gas mixture spiral bore this carb as well. some will allow use of a mikuni single carb but limited to 34 max. they can be spiral bored at end where flange meets intake mount boot. ufo kits and dial a jet would not be allowed in this class.
modfied class would allow the use of twin 38 powerjet carbs, ufo kits and dial a jet. this is a page or two to explain how to do that but im not gonna get into that.
electrical system.. stock is points use new points and condensors. make sure to time both points to 22 degress isntead of 23 degrees and use a gap of 0.014 you may have to switch point sets a few times to get this exact. use good stock coils with new solid core wires.
stock modified would allow the use of the presotlite cdi from the 75 - 77 ccw engines.
modified would allow the use of cdi from a kawasaki engine with the better after market cdi box. Or use stock cdi from 75-77 but iwth hewlitt box.
some people wouldnt understand half of what i stated but you did ask what could be done.
-
Deleted User
CCW Motor Improvement?
My class rules explains that internal parts of motor can be modified along with the exhaust system. I'll check to see which motor I have and then my next question to Rodimus Prime is this: Are you interested in doing some engine work if need be? Where you located? I'll get my information and get back to you.
-
Rodimus Prime
- Posts: 738
- Joined: Sun Jul 24, 2005 12:00 am
CCW Motor Improvement?
I live in manitoba canada and my shop is quite full right now.