1981 CR 430 running rich ?

[Mike 1]

My restored CR430 is running rich on top. I have replaced needle jet and needle, reduced main jet significantly, set float height, checked timing, but still runs rich. Could read valve be the problem ? I have checked needle and seat and work fine. I rebuilt the motor totally and has new seals, rod kit psiton kit etc. Bike starts easy but just sems very rich. The plug is wet when I do a plug chop, but the jetting is lean. I also have installed an electrex works ignition from UK as part of the rebuild.Spark seems fine thought week spark may make motor run rich.

The only item with regards to ignition is that the new rotor has two keyways. The first allows me to set ignition withTDC as per manual, the other is about 25-30mm further. Maybe not getting good timing at higher RPM.

Any advice

 

[GaryM]

My restored CR430 is running rich on top. I have replaced needle jet and needle, reduced main jet significantly, set float height, checked timing, but still runs rich. Could read valve be the problem ? I have checked needle and seat and work fine. I rebuilt the motor totally and has new seals, rod kit psiton kit etc. Bike starts easy but just sems very rich. The plug is wet when I do a plug chop, but the jetting is lean. I also have installed an electrex works ignition from UK as part of the rebuild.Spark seems fine thought week spark may make motor run rich.

The only item with regards to ignition is that the new rotor has two keyways. The first allows me to set ignition withTDC as per manual, the other is about 25-30mm further. Maybe not getting good timing at higher RPM.

Any advice

Please share what jetting you have installed

 

[390Dave]

Mike,stock jetting for a 430 38mm Mikuni: 2.0 slide,45 pilot jet,6DH3 needle middle clip,R-0 needle jet,440 main.The stock jetting is too rich at low speed,too lean up top.A good starting point would be:2.5 slide,40 pilot,480 main with your existing R-0 needle jet and 6DH3 needle in the middle clip.You can also run a 3.0 slide with a 30 or 35 pilot.Make sure the U-shaped wire clip is around your new inlet needle and seat,without it the needle will bind and stick open.Doesnt sound like you have a problem with your reeds,you can disassemble the intake manifold and make sure all of them are sealing against the holder.Make sure there is no paint,powder coating,etc.between any of the motor mounts,the cases and frame around the swingarm pivot bolt,and underneath the baseplate and coil of your new ignition system.Base timing should be 2mm btdc.Follow the manufacturers' recommended spark plug type and gap settings.

 

[Mike 1]

Mike,stock jetting for a 430 38mm Mikuni: 2.0 slide,45 pilot jet,6DH3 needle middle clip,R-0 needle jet,440 main.The stock jetting is too rich at low speed,too lean up top.A good starting point would be:2.5 slide,40 pilot,480 main with your existing R-0 needle jet and 6DH3 needle in the middle clip.You can also run a 3.0 slide with a 30 or 35 pilot.Make sure the U-shaped wire clip is around your new inlet needle and seat,without it the needle will bind and stick open.Doesnt sound like you have a problem with your reeds,you can disassemble the intake manifold and make sure all of them are sealing against the holder.Make sure there is no paint,powder coating,etc.between any of the motor mounts,the cases and frame around the swingarm pivot bolt,and underneath the baseplate and coil of your new ignition system.Base timing should be 2mm btdc.Follow the manufacturers' recommended spark plug type and gap settings.

Thanks for the info. I have added a separate earth from motor to frame just to test the grounding / earthing.I use the plug as listede on tech data sheet I use clock guage mounted in plug hole to set ignition, so I know that is accurate. My current jetting is 380 main as I live at higher altitude ( 5800 ft above sea level) 40 pilot ,6DH3 needle clip in middle, 2.0 slide the only difference that I can see is that I have a R4 needle jet. This is what was in the bike when I bought it, and what my tech data says it should be. I will try the RO and see what happens. As mentioned bike starts easy and runs smoth and crisp of the bottom, it just doesnt seem to clear its throat at high rpm.

 

[Mike 1]

Please share what jetting you have installed

Hi GaryM
I run a 380 mian, 40 ppilot, R4 needle jet ,6dh3 needle and 2.0 slide. All jets are new even needle and needle jet. I run leaner main and pilot as I live at 5700 ft above sea level, and stock jetting is normally sea level.

 

[390Dave]

Mike,I would still take the 2.0 slide out and go with a 2.5 or 3.0 and a smaller pilot,despite you are over a mile above sea level! 2 strokes are not affected as dramatically as 4 strokes at higher altitudes because of the expansion chamber{pipe},but I am no authority on the subject. I would also re install the orig main jet{or a 480} when changing the slide and the pilot,if for no other reason than protecting it from seizure until you get it dialed in.The air screw should be 1.5 turns out,fuel mix between 32-40:1.Something else I thought of,what are you using for a silencer/muffler,the oily and/or dried and broken up packing inside an old or unserviced silencer can block the exhaust system. Dave

 

[Mike 1]

Mike,I would still take the 2.0 slide out and go with a 2.5 or 3.0 and a smaller pilot,despite you are over a mile above sea level! 2 strokes are not affected as dramatically as 4 strokes at higher altitudes because of the expansion chamber{pipe},but I am no authority on the subject. I would also re install the orig main jet{or a 480} when changing the slide and the pilot,if for no other reason than protecting it from seizure until you get it dialed in.The air screw should be 1.5 turns out,fuel mix between 32-40:1.Something else I thought of,what are you using for a silencer/muffler,the oily and/or dried and broken up packing inside an old or unserviced silencer can block the exhaust system. Dave

Hi Dave
I have a brand new silencer from HVA parts in the UK, and the pipe is a unit I purchased from vintage iorn in the USA. ( I am based in South Africa) so must buy most parts from around the world. I will go back to standard and try different slides.

Regards

 

[390Dave]

Mike,is your Electrex system the internal or external rotor type?After reading the installation instructions online,it seems you set the base timing at 2mm btdc,then advance the baseplate to full advance,while holding the rotor from moving while you line up the timing marks,then tighten the baseplate mounting screws.Yours seems to have a different means of accomplishing the same thing with the 2 keyways,using the furthest clockwise keyway to set base timing,tighten the baseplate screws,then pull the rotor back off and re-install it on the other keyway at full advance.If you still have your rotor set at 2mm and its a fixed time system,that will most certainly prevent the engine from reaching its' full potential.I am not that familiar with the Electrex systems,I hope there is some type of starting retard built into the electronics,or at least it holds the base timing setting to about @2500-3000 rpm before it lets all the advance out.

 

[Mike 1]

Mike,is your Electrex system the internal or external rotor type?After reading the installation instructions online,it seems you set the base timing at 2mm btdc,then advance the baseplate to full advance,while holding the rotor from moving while you line up the timing marks,then tighten the baseplate mounting screws.Yours seems to have a different means of accomplishing the same thing with the 2 keyways,using the furthest clockwise keyway to set base timing,tighten the baseplate screws,then pull the rotor back off and re-install it on the other keyway at full advance.If you still have your rotor set at 2mm and its a fixed time system,that will most certainly prevent the engine from reaching its' full potential.I am not that familiar with the Electrex systems,I hope there is some type of starting retard built into the electronics,or at least it holds the base timing setting to about @2500-3000 rpm before it lets all the advance out.

Hi Dave . Thanks for the help. It is the external type. And according to the specs at has an auto advance system built in to the electronics. They have done this to have some retardation built in for easy starting. So what you are saying makes sense. My instructions that I recieved with the unit just explain how to install as if it were a fixed system, and make no mention of the second key way. I will give it a try. Bikes starts easy runs smooth all the way, just seems to come short at higher RPM. No missing etc. So I agree with what you are saying , ignition is not advancing enough to cope with higher RPM range . Hence the unburnt fuel and perception that it is running rich. Thanks again for the advice. Will definatley drop you a note of how it went. Will be a good learning curve.

 

[390Dave]

Mike,I would suggest checking for advance first with an automotive type strobe light ,before repositioning the rotor at full advance.I used to time some of the older bikes this way,by scribing a line across the rotor,then making a pointer out of solid wire,wound around one of the mag cover screws.As far as timing lights go,the less sophisticated,the more accurate they usually are,here in the USA one of the popular auto magazines{Hot Rod} did a test on inductive pickup-type timing lights back in the mid 80's,the only accurate one was the cheapest and simplest ,because it had no electronic circuits for the dial-back to zero feature,or a digital display!I use an old Matco brand model TL82,that I bought used at a swap meet for $2! brought it home,cut the inductive pickup off and replaced it with an alligator clip,then I use a piece of brass tubing {split lengthwise like a roll pin}in between the plug and boot,then clip the light to that,works every time!

 

[Mike 1]

Mike,I would suggest checking for advance first with an automotive type strobe light ,before repositioning the rotor at full advance.I used to time some of the older bikes this way,by scribing a line across the rotor,then making a pointer out of solid wire,wound around one of the mag cover screws.As far as timing lights go,the less sophisticated,the more accurate they usually are,here in the USA one of the popular auto magazines{Hot Rod} did a test on inductive pickup-type timing lights back in the mid 80's,the only accurate one was the cheapest and simplest ,because it had no electronic circuits for the dial-back to zero feature,or a digital display!I use an old Matco brand model TL82,that I bought used at a swap meet for $2! brought it home,cut the inductive pickup off and replaced it with an alligator clip,then I use a piece of brass tubing {split lengthwise like a roll pin}in between the plug and boot,then clip the light to that,works every time!

Thanks Dave. have an old unit that is dependaple, will run motor and test to see what happens.