My official testing of several different aftermarket CDIs
- Thread starter Venice Motor Bikes
- Start date
The arrow style reeds are only $22 on ebay... Pair that with a small Mikuni clone (& install larger jets), & you'll be very happy!
I've gotten pretty good at tuning & re-jetting carbs over the years... Like I said, I really hate those Delorto carbs!! (for some reason, they're way more difficult to tune than other carbs)
I wasn't kidding about the SBP pipes... You probably had OK results because the SBP pipe still creates a little back pressure (which makes the need for re-jetting the carb less dramatic). A straight pipe will need a extremely different size jet for the engine to run correctly again (& that's probably why you had poorer results from the straight pipe).
You're absolutely right about them being quieter though!!
If you insist on being a glutton for punishment with your current parts choices?, try increasing the jet size (a lot).
Popping & misfiring are almost always from a lean fuel mixture. (the stock CDI timing isn't the problem).
I took me many years of trial & error, & an uncountable number of blown up racing engines to finally know what I know now...
I'm just trying to steer you in the right direction (& possibly save you some money by not buying more parts that don't live up to expectations).
Good luck!!
I agree that the Delorto carb does nothing to improve performance, for me the stock nt or the bofang run a lot better and are easy to tune. I have no experience with the SBP pipe but have built several using the eBay type clone, I have three right now, all three from different manufacturers, if you add a silencer to increase back pressure they do improve overall performance.
Also, arrow style reeds? Please send a link for a arrow style reed intake.
Also, arrow style reed? Please send a link for the intake youre talking about.The arrow style reeds are only $22 on ebay... Pair that with a small Mikuni clone (& install larger jets), & you'll be very happy!
I've gotten pretty good at tuning & re-jetting carbs over the years... Like I said, I really hate those Delorto carbs!! (for some reason, they're way more difficult to tune than other carbs)
I wasn't kidding about the SBP pipes... You probably had OK results because the SBP pipe still creates a little back pressure (which makes the need for re-jetting the carb less dramatic). A straight pipe will need a extremely different size jet for the engine to run correctly again (& that's probably why you had poorer results from the straight pipe).
You're absolutely right about them being quieter though!!
If you insist on being a glutton for punishment with your current parts choices?, try increasing the jet size (a lot).
Popping & misfiring are almost always from a lean fuel mixture. (the stock CDI timing isn't the problem).
I took me many years of trial & error, & an uncountable number of blown up racing engines to finally know what I know now...
I'm just trying to steer you in the right direction (& possibly save you some money by not buying more parts that don't live up to expectations).
Good luck!!
Here ya go... https://www.ebay.com/itm/1243637544...uid=5ltfckvaRVa&widget_ver=artemis&media=COPY
Keep in mind that this might not work on your DIO reed cylinder
(But a new replacement cylinder is also very cheap). 
Here ya go... https://www.ebay.com/itm/1243637544...uid=5ltfckvaRVa&widget_ver=artemis&media=COPY
Keep in mind that this might not work on your DIO reed cylinder
Got one, will report soon!
So, after 132 posts on this thread, is there any consensus at all on what CDI to use for general use? Do you need a different timing curve (advanced vs retarded) for a high compression head? Or is spark strength the only thing you need to worry about to make the high compression head actually work. How about Grubee's "4th Generation High Performance Ignition upgrade kit" : "
www.grubee.net
". Can we just slap that cdi on to pair with the magneto and magnet rotor upgrade and be good to go? It's amusing as well as astonishing how much discourse in the motorized bicycle community on part upgrades. It seems that no matter what upgrade part you get, there will always be someone with a different opinion on the efficacy of the upgrade. I wish this wasn't the case as it really throws newcomers for a loop (I have personal experience). What are all of your thoughts? Cheers!
4th Generation High Performance Ignition upgrade.
3-piece High Performance ignition kit upgrade for a power balanced system. 1. Big 400V Microfarad capacitor CDI 2. Double flux density Rotor magnet 3. Special High KV MAGNETO coil. New shipment has just arrived arrive!!!!! HISTORY: In proven lab test the new "Gen 4" HP CDI & Magnum...
www.grubee.net
Also, anything to add with regards to the post before the one you replied to? Thanks!
Did you actually read this entire thread??? (or are you just here to promote the new Grubee ignition)?Also, anything to add with regards to the post before the one you replied to? Thanks!
Do me a favor... go back & read it all, (& take note of the dates).
I believe my message has been misconstrued (perhaps by fault of my own). I'm not promoting the new Grubee ignition system, just simply observing a new product and its potential for performance. Apologies if I came off as glib or insincere. I wouldn't be asking about a conclusion to the thread if I hadn't first thoroughly read it all. You see, there never really was an answer that showed up potently throughout the thread, just a bunch of singular takes. No consensus amongst the commenters was ever reached; I wouldn't be wasting your time if I had found a middle ground that was reached by all the commenters. No need to respond to this if you feel it isn't worth your time; time is money as they say. Cheers, Venice.
This thread is eight years old, & the majority of the commenters are no longer active members of this forum... Therefore, it's going to be impossible to get a consensus from them.
There was one guy in Florida who owned a small engine dyno & tested several CDI boxes... His conclusion was the same as mine (in the end)... The stock 'black box' works the best!!! (but you should already know this if you actually read this whole thread).
So forgive me, but I tend to question the motives of anyone who signs up to the forum & immediately digs up an eight year old thread just to post links to a company's 'hot new product.'
I totally understand; I came across this thread and became very interested in the content and I can now see how I could come off as a shifty seller who wants to promote their product (seeing as how my account is brand new). Thank you again for your time and reply; perhaps we could continue? If the stock CDI is indeed the best based off of your dyno tests and the dyno tests of another, would it still be the best under the condition of a high compression cylinder head? Higher compression would require a stronger spark to result in the performance gains you're looking for and the black stock CDIs are built for a stock motor cylinder head. If one were to install a fred head, would they not need a stronger spark CDI, better magneto, and better rotary magnet? As the piston is working up towards TDC, it's fighting against the higher compressive force of the air/fuel mixture with the high compression cylinder head. In order to circumvent this, one would need a stronger rotary magnet and magneto in order to jump the gap properly. This is a genuine question and has nothing to do with promoting the grubee ignition system upgrade (appreciate the skepticism from you in the beginning, truly). Let me know if I got anything wrong; thanks!
Last edited: