CDI box install and test (I expect to break 100mph)

i just wonder how many other electrical parts are interchangeable between the lifan and honda.

also...why aren't the sportsbike guys all over this like white on rice??

[culcune]

Did someone say "broken ricebowl"....

couldn't resist!!

[DirtRoadKing]

Back from death but still the young living being...

[Back_From_Death]

Originally Posted by zapkin

also...why aren't the sportsbike guys all over this

Because unfortunately Porterz Customz is not on the sports bikes forums yet so they did not hear about the latest news! j/k

But seriously thats it, I think it was born here and they just don't know about it yet. They would prolly benefit even more from it then we do because they do all on road and all high rpm gear pulls. Maybe someone should be nice enough to let them in on the secret.

[SpeedSouth]

8O



Welcome back, Portez.

[IronFist]

I thought the serious guys were into computer driven inhancements. Like cars, I thought the big guys would be tuning their bikes with laptops. Peeking output at the right times for their gear ratios. What do I know, I have points.

Seriously, even if the pinout is different, there must be a cdi out there that would do a better job than the stock one. Who says that the one Back_From_Death is using is best? It might be, but the optimal one might still be out there. You guys seem to be getting results, but which cdi will give the best results, and there's lots to choose from. Try not to burn out your bikes and ride safe :roll:

[CRidin]

On EFI bikes like my Harley You change the map or buy a Power comander. I assume they do something simular on the efi sport bikes.

[TeamCheap]

Well i have to agree with OB1

Ok, now, here is the shiznit..

The ultimate rev limiter is valve spring float, ie rpm beyond the ability of the valve springs to close the valves properly.

Since the motor is a rather simple mechanical device, and a CDI cannot change transmission of final drive gear ratios, a CDI can only get you to that maximum rp.m before valve float in a faster time.

Any additional rpm gained by the lack of a CDI rev limiter ENDS at valve float.

Those additional rpm do in fact equate to MPH.

The question is, do chinabikes have a rev limiter in the stock CDI? I know what a motor sounds like when it hits a rev limiter. I say they dont. Neither do the mainline brands for any of the small displacement bikes. Do you really think they leave 20% of the potential power untouched? Have you ever actually heard a bike hit the rev limiter?

The gains by using an aftermarket CDI are clear to me, as far as I know I am the FIRST one here to run one. I use the same one on my Lifan 200 that I use on my heavily modded XR100, and use the extra power by CHANGING THE FINAL DRIVE RATIOS to the achieve the maximum top end.

My 100, carrying 250+lbs, will beat a stocker carrying 70 lbs, every pass.

The aftermarket CDI is a good mod, but let's get serious, please. There are simple limits to the performance of any motor.

The aftermarket CDI's will increase performance but there are still those mechanical limits to deal with.

I for one never got to wind it out I only got it up to 65 and it still had a quit a bit more throttle and it wasnt the bike being limited it was the sheriff and the temps limiting me.
I also have done a few mods that have already helped my bike very noticeably so the aftermarket CDI perfromance increase may not be as noticeable on my bike.

But as I have said "more testing is needed" and looking at the weather forecast lets see thunderstorms today and saturday(sucks) temps near 70(good) but sunday looks clear and temps in the 60's which would be far better than the 46 I had.

[elroyjetsn]

The rumor is that these pushrod bikes have engines and trannies based on the old trusty Honda GC125!!! Intended for reliability cranked by about 10HP and pushing 60mph tops. 8O

Wouldn't want to experience busting a transmission at 80 or 90 on a GY!!

Breaking a gear tooth at 65 with a semi bearing down on you would be bad enough! :(

We just buried a local 21 year old with the need for that kinda speed. He lost control when a cager tried to move onto an exit ramp between 5 sportbikes trying to wind down from sprint up i81. The kid clipped his buddie"s rear wheel in front of him, went airborn to be stopped by a bridge abbutment.

Those of us with pushrod bikes should use caution with how hard we push these motors. :wink:

[ob1]

LOL!
I dont deny they make more power. Power that gets you to the same speeds as before, only in a shorter time. The only way a CDI box makes more speed is by allowing more rpm.

Stated quite simply, from the moment the fuel air mixture explodes and forces the piston down it is all a simple mechanical motion, one that can be mathematically predicted as the force produced is channeled through the reduction gears into the final drive and expressed as a rate of speed.

Any additional speed through more rpm can be mathematically predicted as well. The approximately 33% gains in top speed reported are suspect, especially without changing the final drive sprocket ratio.

Oh, and Porterz, my 200 will whip your 200, geared for offroad racing and the mods I have done, it already whips Honda 200's, drop a few teeth from the rear sprocket...because when it is all said and done, my HYBRID weighs close to 60lbs less than your chinabike. HP-to-weight ratios are hard to argue.



Aint she purty?

[katoranger]

This thread is starting to go downhill. Don't make me lock it. :roll:

Allen

[CRidin]

But notice when it started on the downhill.

[katoranger]

I did, but will give it a chance to recover.

Allen

[ambassador]

I don't think a stock 46t rear sprocket is going to get anyone up to 80mph, the first place to start is taller gearing.. I had a 42t sprocket on my bike when I put the new CDI on and the combination of the 2 is what allows it to rev longer and higher through the gears..
If your going to gear a bike taller there are going to be sacrifices made to the tranny, excessive plate wear etc. as long as your not riding WOT all the time I think wear could be minimal.. Only time will tell...

[a1a5115]

One thing about owning a china bike is that you have alot of opportunity to learn about your bike (and engines). When I first read the post about "I broke 83 today" I started looking for a way to advance the timing without slotting the sensor bracket. That's when I found out about the CDI's with electronic advance.
All engines need spark advance. At 1500rpm the piston goes up and down 25 times a second ! At 2500rpm it's 41 times a second, 4000 rpm it's 67 times a second and at 6000 rpm it's 100 times a second and so on. Since the compression stroke is only a half an rpm, it would occur in 1/200 of a second. (5 milliseconds)
Without advancing the spark, there simply isn't enought time for the combustion to occur fully. On the China bikes the timing is fixed at 8 deg which is OK for about 2000 rpm. I don't know why they don't use electronic advance, except that the fixed timing is cheaper. I bought a CDI for a Honda XR100 off Ebay for $37.00 and it made a big difference. It advances the timing to about 24 deg at 4000 rpm and is maxxed after that. Some racing types advance the timing much more. I have not top ended my bike. At 55mph it has plenty of throttle left. But the lower end power is much improved. This is a worthy mod.
Just my $1.02 Good luck