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Post by scottkooi on May 22, 2011 11:26:03 GMT -5
Ok fellas- I can't get the idea of getting a performance cdi out of my head, so I have a couple of questions. First- after installing a bbk, hp carb., etc.. is it necessary to upgrade from the stock cdi with the rev limiter cut? Second- upon searching for aftermarket cdi's, I have discovered that the ones that are recommended for the percieved motor in my scoot(I have not been able to find the id stamp, found the serial # though) do not have the same plug configuration, but one that does have the right plug set-up for what's on there now lists different models and manufacturers. What sets precidence on this?
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Post by reveeen on May 22, 2011 12:32:27 GMT -5
Here is my "take" on a "performance CDI". (my only experience being a $80 Malossi one for my Zuma, and several, "blue", made in China anodized alloy ones, wearing various names, in various configurations that I paid $2 each).
They all offer no RPM restriction, and fire the plug on the leading edge of the flywheel timing tab at an idle (rather than firing towards the middle/end of that timing tab).
So, I guess you can say that they advance your engine timing without any work (slotting the holes on your pick-up and setting your timing with a timing light).
In my case, I bought them so cheap that here they are "regular" replacements.
I have seen several available with dip switches (supposedly to allow you to "customize" your timing curve). I have not tried one of these, and would like to, but am not interested in shelling out the extra money.
Here is "the problem"....... you are fooling with an engine that has detonation "problems" (that "we" cured with a colder plug and premium fuel) by advancing your timing you are going to find yourself detonating again. The "cure" this time will be taking the engine apart and lowering the compression. Do you really wish to "go" here?
You typically buy the CDI that matches your electrical plug configuration.
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Post by scottkooi on May 22, 2011 14:38:35 GMT -5
Thank you for the input. I think I hear exactly where you're coming from and I may just leave the cdi alone. I have to admit that I am all over the place with modding and customizing my scoot, and I probably don't have the best ideas. Reveen, I am heeding your cautionary input- thank you. Cvt seems like a better place to mess right now.
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Post by reveeen on May 22, 2011 15:50:18 GMT -5
I *think*, with the extra power you claim to have, an up gear might be a worthwhile thing.
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Post by scottkooi on May 22, 2011 16:11:24 GMT -5
Thanks for putting more stuff into my head reveen! Is there a thread that covers up-gearing? I think I'd have to do some research, then find a new mechanic to help me out with a project like that.
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Post by 90GTVert on May 23, 2011 8:07:41 GMT -5
Just a note on the CDI and how "necessary" they are for those of us without rev limiters. I've gone over 70MPH and never swapped the CDI out. Others here have done a lot of impressive things as well without ever changing the CDI. If it's rev limited, by all means ditch it. Otherwise, expect little to no gain. One other bad thing is that some stock CDIs will retard timing at RPM and a lot of the aftermarket ones don't to my knowledge. So if they fire on the leading edge of the reluctor for a slight advance and keep a flat timing curve, you may really have issues if your engine is on the edge. Some gearing info... 49ccscoot.proboards.com/index.cgi?board=transtech&action=display&thread=945Database (as this shows, you'll wanna check what you have now so you know what you're dealing with because it varies)... 49ccscoot.proboards.com/index.cgi?action=display&board=transtech&thread=1265&page=1 |
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Post by reveeen on May 23, 2011 9:01:20 GMT -5
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Post by scottkooi on May 23, 2011 17:17:14 GMT -5
Thank you very much for the info. I ordered my clutch and contra springs today, on vacation next week and plan to change them while I have time to do it and play with it to find what works best. I also plan to test the compression, do a squish test, and trouble-shoot the freaking electrical if I get it back working the same way as it was when he got it.
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