REVIEWED - Racing CDI (Blue Type)

[Cactus Jack]

I can't imagine a stock engine, be it a 50 or a 140 could rev out to 12,000rpm. My 125 seems to go to about 7-8. That's just on feel though, I haven't actually measured it.

Either way, in stock form, my Lifan 125 won't reach a rev limiter of any kind. It's limited by the engines max speed. It just won't breath any more and it certainly won't hit an electronic rev limited. Maybe a modified engine with valves, cams and ports all matched would make a difference. I'm really only interested in ignition advance which is where the midrange is at.

And for those who don't know, horse power looks good on dyno sheets, but torque actually wins races.

That's right - torque = acceleration and hp = speed . There's no point in revving an engine past its' max torque rpm thru the gears . You only really need to use peak HP to wind out past max torque for extra speed in top gear OR if you are staying in the gear you're in without upshifting down straights just before turns .

The valve spring tension , valve weight , cam timing + breathing ability are the ultimate rev limiters in any engine - but it's mainly the valve springs' ability to control valve float that sets the rev limit - that's why F1 cars use air operated valves to reach 19,000 + rpm .

The valve springs in most horizontal engines are too piss weak to reach 12,000 rpm - you only need to compare them to a stock XR75 spring to see that . As far as I'm concerned - you'd need to upgrade to a minimum of stock XR spring tensions to even dream of looking at anything like 11,000 rpm - and you'd need to go to 5 mm valve stems to handle the extra lbs reliably .

 

[AusJames]

So, can anyone answer me this..

Can you fit a CDI from a kitaco IRK (clone or genuine) WITHOUT having to fit the IRK? If it's just the CDI, can you literally unplug the stock one and plug in the kitaco one? Or is the wiring different?

 

[Divy]

i thought id give my opinion the the blue ebay cdi,

i brought one last week cause my standard one died, i personally felt like it gave my bike better throttle responce an made it run a lil better but it was only a very slight gain
i dont think it was a waste of money cause i needed one anyways an it did make some gains an it was only $36 posted

 

[daniel40]

divy if someone who didnt have a broken cdi would it be worth buying one??

 

[themountain]

divy if someone who didnt have a broken cdi would it be worth buying one??

..with a broken one of course ...they are not much expensier as OGs ...so...but the gain is still minimal.....got to have yor carbs dialed in ...thats more effective!!

 

[tubes380]

no you cant use the irk cdi just by its self as it has a different timing pattern to a magneto thats why they supply it with the irk.

 

[AusJames]

That's a shame. But most road racing guys in the US seem to think an IRK is also a good way to go, so I may end up going that way.

 

[Cactus Jack]

So, can anyone answer me this..

Can you fit a CDI from a kitaco IRK (clone or genuine) WITHOUT having to fit the IRK? If it's just the CDI, can you literally unplug the stock one and plug in the kitaco one? Or is the wiring different?

Theoretically you could as long as they are both the same voltage rating - you'd just cut the plug off the wires coming out of the stock ignition and put a crimp lug plug on both the pickup /trigger wire and the wire from the stock generator coil and plug them into the appropriate wires leading into the IRK CDI unit and seal the rest up or tape them off .
But it might be possible that the advance rate of the IRK CDI unit only suits the faster rev-up of the IRK - it might advance too quickly for the stock flywheel ignition . Just a guess .

The china IRK CDI units have 5 wires coming out of the CDI box - 1 white (trigger) ---- 1 red/black or red/white (+ to CDI) ---- 1 yellow /white or yellow/black (to coil) ---- 2 green (earth wires) .

The IRK stator has :

1) ~ A black wire coming from the generator coil which connects to the red/white or red/black wire going into the CDI unit . So you'd connect the red/white or red/black to the the stock stator coil wire .
2) ~ And a white wire coming from the pickup trigger which connects to a white wire going into the CDI unit . So you'd connect the white wire to the stock ignition pickup wire .

People with new IRK's might find this info of use as well :

IRK CDI box :

1) ~ The red/white or red/black wire goes to the coil on the IRK stator .
2) ~ The white wire goes to the IRK pickup/trigger .
3) ~ The yellow/white or yellow/black wire out of the CDI goes the the coil .
4) ~ One green wire goes to the kill switch and the other goes to ground on the frame .

You're probably better off to buy an IRK kit from ebay to try - they're cheap enough now . big50.com sells a weight adaptor kit and weights to tailor your flywheel inertia to suit different tracks .
They claim that there have been reports of the Chinese rotors flying apart but I haven't heard anything yet . Maybe someone else has and can fill us in . But ~ IF they've ever hit their rotor with a hammer or used the wrong tools to get it off - they can FORGET telling us their story because the word DORK BRAIN will get tossed back at them . Ha Ha Ha !

 

[AusJames]

Hi Cactus Jack,

thanks for the input. all good stuff. I've actually JUST fitted a Motovert IRK to my Pitpro 125RR lifan 1p54fmi. I haven't had any chance to test, but I have the Victorian titles this weekend with two full days of praactise and racing so I'll have plenty of chance to evaluate.

Having said that, I'm pretty impressed with the build quality of the Motovert one. It is a Kitaco clone and comes highly recommended. Weights would be a good idea for the flywheel to fine tune the smoothness of the input.

although I get the feeling it's sometihng I could get used to as I road a competitors AGB29 which had a full race spec motor, keihin carb, cam, piston etc and that had a IRK. Revved like nothing I've ever ridden and within probably 3 or 4 laps I was used to it.

I'll keep everyone informed

 

[Cactus Jack]

Hi Cactus Jack,

thanks for the input. all good stuff. I've actually JUST fitted a Motovert IRK to my Pitpro 125RR lifan 1p54fmi.

Hi Aus James ,

Is the Pitpro 125RR lifan 1p54fmi engine a crank clutch motor (lever up front) or a mainshaft clutch motor (lever at rear top) ?

You can lighten the rocker arms a fair amount on these engines to reduce valve float. That's an old XR75 trick . XR's have heaps stronger valve springs than Lifan springs and the lightened rockers are super reliable .