Mikkh's WPB 125 CRF 70 framed build

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mikkh

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After riding the KX250 for two years I decided to start fixing and upgrading my CRF 70 framed Pitbike that sat in the shed for three years. The bike ended up in the shed because clutch basket exploded (thinking about how to convert primary clutched engines to secondary clutches for cheap as possible). Basically I am going to paint everything. The bike needs new suspension (will buy Fastace rear shock, but not sure about the forks yet). I am planning to use 150cc lifan motor that needs a new crank.

Current mods on it are OKO 26MM and 6 plate zonghsen clutch. Planning to uprade the suspension. Currently the bike has fastace bs58ar. Thinking about using gpx style forks in the front (fixed the original forks, but they´re not good, because no adjustaments and low-tech internals).




By the way does anybody know max oil volume for oil cooler?
 
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That bike look's alright.
I run my engine with about 100ml's extra oil due to the oil cooler
 
Taken into bits.





Few pictures from winter:)



 
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Does anybody know the max volume of oil cooler (want to use small copper radiator from bike or car) I could use without harm to pump (half liter, liter)? Does the oil cooler rise the oil level on the dipstick or just takes more oil? Where I could buy myself a new crank in Europe? I´m planning to use OKO 28MM because I´m going to use Z-40 cam with stiffened springs and do some porting work. Or is the OKO 26MM sufficient? Does the 4 plate clutch hold up the 150 or I need 5 or 6 plate clutch (couldn´t find 5 or 6 plate ones).
 
Wow looks like you've done a lot of work! I am interested to see the end result!!

Sent from my HTC_M8x using Tapatalk
 
Bought used FASTACE BS-58AR rear shock. Going to rebuild it soon (just to make sure, it is fully functional and doesn´t leak). Does anybody know where I could get a stiffer spring for it if it happens to be too weak for my use (the guy I bought it from used it on straight swingarm pitbike for mx so I hope it works well enough). Need to touch up some paintwork, buy Honda swingarm bolt (china ones have snapped before) and rebuild front forks (bought the same china forks in good condition I had before) or buy FASTACE front fork (in bad condition need of a rebuild, but fully adjustable.

I founded the crank for 67 euros and 4 plate clutch for 30, cheapest 5 plate one was 60.

What´s the verdict on huge oil cooler volume?
 
Hopefully I will assemble the rolling frame in a couple of days. Had to grind some of my welds off because the bolts didn´t fit through :( and I had to to some paint touchups becouse of that. Founded a crank for 57 euros. I believe that I am going to use Z160HO electric system and ignition. How huge volume oil cooler I could use? Has anybody used Honda swingarm bolts with success?
 
Has anybody used tubeless tire setups for pitbikes? I am planning to make tubeless setup for my bike. In the beginning it will be for rear tire, if it works then front too
 
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Since nobody answered my question about the 4 plate clutch i bought new 6 plate clutch :beerchug: . Has anybody used half liter to liter volume oil coolers? I bought the finned oil cooler, mounted it up and then found uot that the banjo bolt used on the hose was 8mm on the engine side not 10mm like my lifan. Bought the OKO 26 also (might need another intake manifold or adopter, because the one I bought is too large for my manifold).
 
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You might be able to take your oil cooler line's into an Industrial Hydraulic's/Pneumatic's hose shop or an Automotive brake's shop and have the end's changed over.
They aren't too dear.

You can buy new end's off ebay and swap them yourself too.

images




My cooler is pretty big, it's 280mm wide, core is 70mm tall, and is 40mm thick, the coolers' capacity is 200ml's

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Manifold wise you'll need a new one with a 27mm or 28mm id/, and make sure the angle's are right to clear your frame and tank etc.
You will also need a new throttle cable that has 150mm travel (wire poking out the end), and a bigger air filter 48mm i/d, Uni Filter's are excellent
And probably a bigger pilot and main jet too, depending on how far above sea level you are.
I used to run a #38 pilot and a #105 main with the needle clip on the second notch down on my Lifan 150.
 
Oh well I lost washer 23773/1P50FMG-2, the washer that sits between the countershaft 1st gear and it´s bearing. Does anybody know the dimensions?

By the way does anybody have lifan 150 or Zonghsen 155/160 or GPX125 stator plate, wiring harness and magneto for sale? PM me then.

Made some progress too.



This is the oil cooler I still want to use :p
 
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Judging by the 20mm countershaft gearbox i have laying around it should be 1mm thick washer? Is that correct?
 
The first one mention's it goes between the bearing and gear, so i think it'd be that, the thinner one
 
0.40 seems too thin too me. If I remember correctly the shim should be the same on lifan 50cc countershaft between 3rd and 4th gear.
 
The oil cooler I got was meant for one side of Pitster Pro LXR. Should it be enough? Or I need to hunt for something bigger? I found my lifan 50 countershaft shim, it was 1mm thick 17.3 ID; 24OD. Bigger OD shim shouldn´t hurt?

Could anybody check the shim thickness on their countershaft between the 1st gear and the bearing on the following engines :

Lifan 125 1P52FMI (start in any gear version)
Lifan 138 1P54FMI (since june 2009)
Lifan 140 1P55FMJ (since june 2009)
Lifan 150 1P56FMJ HS1P56YMJ
Loncin 156FMI
Jialing 125 type 1P56FMI
ZhongShen 140 1P62YMJ

Little offtopic: planning to convert the 120cc lifan engine which was on the bike originally to secondary clutch engine. I am planning to use the mainshaft off a lifan 140 and planning to weld the crank primary gear onto the crank using stainless steel wire. I am planning to weld only the clutch cover side because I´ve seen these crank ends snap of cleanly. Will it hold up the abuse or I should change the right crank half to one off lifan 140?

Also I have problems with Z160HO ORK ignition. The coil and pick up coil are on the outer limit of spec according to multimeter. The engine kicks back badly and doesnt want to rev at all (if I blip the throttle quickly it dies; if slowly it starts to pop and backfire badly with 1/4 of throttle). I have tried all new ignition components except for magneto and stator plate. By the way magneto has marks on the pick up tab like it has hit the pick up coil (the cam chain has worn into the engine side stator plate because it´s warped at the pick up coil. Should retarding the igniton by grinding the left side of the pick up tab off help or I´ll have to use new magneto and stator plate?
 
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I´m going to use the 1mm shim if it doesn´t bind when I tighten the cases together.

About the lifan 120 conversion I´m thinking that´s more reliable to use lifan 150 crank, piston, cylinder, side cover, countershaft, clutch gear and clutch for the coversion.
 
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