Author Topic: Dynatek CDI Issues (Read 5829 times)

Bio86 · « **on:** August 14, 2014, 09:37:24 AM »

Anyone ever messed around with these? Stock ignition bike with no lights hooked up yet. CDI was bad when I picked it up, got a buddies oem cdi - fires up and runs great. Looking around to buy one and always wondered about the Dynatek so figured I'd just try the one out. It won't let me rev past 2/3 throttle, acts like a rev limiter. Wondering if my stator is weak and not giving it enough juice? I've played with plug gaps all over the place and my jetting is very close. I pulled my hair out messing with the carburetor thinking it was the issue at first.

Is there a good way to test it with the bike running or is ohm testing the best way?

Any thoughts are appreciated. I know OEM is the way to go but I already wasted money so just trying to get it working.

Trusty2stroke · « **Reply #1 on:** August 14, 2014, 10:02:37 AM »

Ran into the same issue with my bike when I purchased it. The only way to fix the problem is to get an oem cdi.

Jerry Hall · « **Reply #2 on:** August 14, 2014, 11:35:40 AM »

I have a lot of customers that bring me 250Rs to tune the carburetors. They bring me their bikes because they cannot get rid of the the high RPM miss-fire.

This is the process that most guys go through.

1. The engine has a high RPM miss-fire

2. Jets are changed, richer then leaner....engine does not respond to leaner jetting.

3. Stator, pickup and ignition coil are checked and are within specification.

4. Since there is not a good bench test procedure for CDI boxes, the customer has to assume that the CDI box is bad because all other electrical components have been checked.

5. The customer does not know anyone that he can borrow a good OEM box for testing.

6. The customer does his research ( Googles 250R CDI box)

7. Dynatech pops up at the top of the list and has a lot of good sounding features like different timing curves .............and...........MORE VOLTAGE OR ENERGY delivered to the spark plug. The price is competitive with the price of a new OEM CDI so he puts one in his shopping cart and one shows up at his house a week later.

8. He installs the new Dynatech and the bike still has a high speed miss-fire.

9. He decides to get professional help.

10. I strap it down on the dyno and do some test runs to verify and experience the problem first hand. The engine has symptoms that the main jet is too rich. I look at my data base to see what jets I have found to work best on similar engines. I remove the carb and go through it to make sure the customer did not miss anything in the fuel system. I install those jets and the problem remains. I lean it down a few more main jet sizes and the problem remains. I have to retrace the electrical testing procedures the customer has gone through plus a few more that he may have omitted.

11. I install a new OEM CDI or I borrow one from a 250R that is in the shop. The bike runs great. I remove the new CDI and install the customers new Dynatech CDI...engine runs bad......customer brings me his old OEM CDI and I install it and the engine runs bad. Conclusion...old OEM CDI and new Dynatech CDI were bad.

The unfortunate part of this type of situation is, the customer has been working on this problem so long his new Dynatech is out of warranty.

I would estimate that around 60% to 70% of the new Dynatech boxes I have used on the 250Rs make the engine have a high RPM miss-fire.

Jerry Hall · « **Reply #3 on:** August 14, 2014, 11:40:07 AM »

Quote from: Bio86;40918

Anyone ever messed around with these? Stock ignition bike with no lights hooked up yet. CDI was bad when I picked it up, got a buddies oem cdi - fires up and runs great. Looking around to buy one and always wondered about the Dynatek so figured I'd just try the one out. It won't let me rev past 2/3 throttle, acts like a rev limiter. Wondering if my stator is weak and not giving it enough juice? I've played with plug gaps all over the place and my jetting is very close. I pulled my hair out messing with the carburetor thinking it was the issue at first.

Is there a good way to test it with the bike running or is ohm testing the best way?

Any thoughts are appreciated. I know OEM is the way to go but I already wasted money so just trying to get it working.

You need a peak voltage tester or an oscilloscope to check the voltage from the stator coil and pickup coil while kicking it over or while running the engine

Bowtie316 · « **Reply #4 on:** August 14, 2014, 11:48:02 AM »

Its a shame that 25 years later someone cannot reproduce a simple device like this. How hard can it really be?

Bio86 · « **Reply #5 on:** August 14, 2014, 12:24:41 PM »

Can you find new OEM CDI's ? Maybe I'll just eat it and call it good, I was going to try to run a new stator and rule that out but if it's not going to help then I'm not wasting money on that. I looked and couldn't find any decent looking OEM used ones at the time so I just picked up a Dynatek. I know for a fact that it runs perfect with my buddies oem one, so I know it's not a messy tune issue.

Bio86 · « **Reply #6 on:** August 14, 2014, 12:26:52 PM »

and just as an FYI to prove your point Jerry. I've already sent it back once, so this is my second non-functioning box.

The_Steve_Man · « **Reply #7 on:** August 14, 2014, 12:50:01 PM »

I have 3 you can try. Not sure if my harness is bad somewhere or the cdi's. I can send them to you and if you find they work I will make you a hell of a deal one.

Bio86 · « **Reply #8 on:** August 14, 2014, 01:01:59 PM »

Yah I'll test them for you. I'll end up buying a used OEM one anyway.

The_Steve_Man · « **Reply #9 on:** August 14, 2014, 01:04:06 PM »

Pm your info. I might be able to get them out today.

Bio86 · « **Reply #10 on:** August 14, 2014, 01:09:50 PM »

Sent. Glad to help out!