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93'RMX CDI conundrum

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I am in need of a CDI for a 93' RMX250.  I tested the original with an ohmmeter according to the shop manual, and it has a 

number of opens. The bike runs good, but nearly impossible to start. I have investigated a number of the usual channels,

and firstly, I,m not going to pay around $400 for one from Suzuki, "The price, increase, on average, from the OEM online suppliers, was about $50 

last week. No how, No FN, way is that going to happen. Either is a non-returnable 20-30 year old unit from fleabay.  Another option, I may go for is  

to have mine rebuilt, or custom made, this would be about $200, and am considering this.  Last, but not least,  because I can find my way around a

wiring diagram, there exists a world of alternatives for non-specific, (to RMX) choices. 

My question is: If the unit I use matches the alternator configuration, and voltage, and comes from another 250cc two-stroke, that likely has a

similar ignition curve, can I adapt?  There are new aftermarket CDI's for a lot of bikes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited by ventabular
typos

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Sounds pretty similar to my ignition problems I had on my 1998 RMX. Mine has the compression ratio bumped up, and was always a bastard to start when cold. Tried new CDI, stator, and coil, even though everything was to "spec". Nothing helped. I believe the weak spark is due to the small magneto used on the RMX. 

I looked for alternatives to swap, and contacted a few aftermarket companies. Only one that was helpful was Zeeltronic.

Ended up chopping out the magneto and went with a programmable DC-CDI from Zeeltronic. No more startup problems and producing a lot more power than it ever has before. Couldn't be happier.

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I read your write up and am impressed. You are a real troubleshooter, in a sea of parts changers.

 I also read what seems like a hundred posts about an RMX that  is hard to start.

Seems that enough people like the RMX, that fixing one of its major flaws, and making it common knowledge would be worthwhile.  

I'm not at your level, electrically, but have taught myself other things pertaining to motorcycles.

Will share what I know, when I figure this out. Thanks for the post.

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Jeremy, have you converted a stock stator to DC?  What parts do I need from Zeeltronic? I assume, that I need a 12v battery pack for this conversion. Also own an IT490 that I think could benefit from this.

 

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I'll admit, I did get a bit carried away with the modern carb/ignition mods. lol. The wiring is really not as complicated as it may seem, and certainly be wired a lot simpler than what I did. All it really needs to replace stock CDI and work is 6 wires. 12VDC, magnetic pickup, coil output, and kill switch.

The DC-CDI will need somewhat of a clean 12vdc. You'll need to modify the stator for full wave rectification, which is also useful if you plan to run LED lighting. The battery is really just to clean up some of the noise from the 12v output of the rectifier.  Baja Designs used to have a tech article on how to do the floating ground mod, but looks like they have the link messed up... Took me to a KDX floating ground mod page instead...

Luckily I have the stator from my 96 here on the bench.

The RMX ground mod is done basically the same as KDX. The lighting coils are the 3 large windings on top of stator. One end of the coils goes to a grey wire, the other to a black/white stripe wire to ground.

IMG_2060.JPG.ffbd07e9457bb722cdaae9f34e5afd24.JPG

Remove the ground screw, chop eye terminal from B/W wire on stator side and remove protective cover to expose soldier connection. Heat wire side and pull wire from ferrule.

IMG_2061.JPG.ba1d517c163336808233929b5974bcd5.JPG

Then you'll chop eyelet from harness side Black/White wire as close to eyelet as possible, slide a short piece of heat shrink over wire, strip, insert into ferrule, and resolder. I took the old abrasion cover, slit down the side, and covered the heat shrink for a little more protection.

Since magneto is gone, I used the wires from it to replace the B/W ground wire.

IMG_1541.thumb.JPG.ffcba019fe3df2c0294ed12892a5b7b1.JPG

 

For Reg/Rec just look for one that's "full wave". I went with the Trail Tech 7004-RR150 since it was advertised to not switch lights on until engine is running. Unfortunately that was not the case and lights were switching on (and staying on for a couple seconds) as soon as kick start starts to move. So, I ended up having to use a relay to do what the TT R/R should have done in the first place. 

My newly acquired 96 RMX I'm rebuilding now will be getting the same MX11T CDI as my 98, but will be wired a bit different. (No TPS or PJ) I'm thinking the Baja Designs battery on my 98 will be the weak link so I'll set the 96 up for a battery eliminator instead. (Basically about 30000uf of 25v polarized capacitors in place of the battery). Then I can eliminate the ignition switch too...

 

All you'll really need is, full wave R/R, either battery and ignition switch or battery eliminator, the MX11T, and handheld programmer.

If you plan to run lights, you most likely will need a relay controlled by RPM switch (GPO 1 or 2), or handlebar switch to keep the lights from robbing power from the CDI while starting.

Programming is definitely easier with the Zeelprog PC software, but since you'd just be running a 2D curve, it still should be relatively simple even with handheld programmer. I went ahead and bought both since they're not all that expensive. Also bought his high output coil since mine's 20 years old. The stock timing curve can be replicated by as little as programming 4 ignition points. Most all the programming info you'll need to get running is in my instal post. Just don't forget to connect the green to red, and red to green for the mag pickup wires. lol:thumbsup:

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So from Zeeltronic, I need the CDI unit, and the programmer, (can I use a laptop?) . Where does the 12v magnetic pickup come from? Looked at a few battery eliminators. Looks like the 30,000uf unit is a fairly large one. I,m a fairly computer illiterate old geezer, but smart enough to see a problem trend with the RMX, and see the futility of conventional parts replacement. Thanks again for the help.

Edited by ventabular

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CDI will work with laptop if you get the USB-Prog adapter. PC Software for MX11T is not up on his website yet, but he'll send it if you go that route. IMG_1525.JPG.753fa97fea140ab85f7f04bcc5664afb.JPG

 

Or you could go handheld, convenient for fine tuning timing tweaks on the trail.IMG_1620.JPG.aea61119d5f100ca3eebc14ca7d37f4a.JPG

 

Magnetic pickup is the coil located outside of flywheel. It's important that the polarity to the CDI is correct so it receives the + voltage signal before the - signal, or timing will be off. To get the + signal first on the RMX the Green wire from pickup goes to Red/White on CDI, and Red from pickup to CDI Green/White.

I'm looking into the battery eliminators. I've read some guys running as little as 4700uf. I sent Borut (Zeeltronics) a message this morning. Might not be till Monday or Tuesday (he usually takes weekends off), but I'll let you know what I find out. 

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