Runner crank reliability

Hi All,

I am considering fitting a malossi 172 kit to my 125 2-stroke

runner but have heard that the standard crank can break.

Has anyone fitted the kit to the standard crank and had no problems ?



The standard crank has had some flaws in them, but it seems to be random. If you want to be 100% then go to the malossi mhr crank, big bucks but it gives piece of mind. If you go that route youll need to replace bearings and seals (obvious) but replace the waterpump belt at the same time. Also, if the crank/ bearings are removed from the engine / not SET properly itll damage the casings / write the crank off in under 1000 miles!! I got my 180 cheap due to a motorcyclr shop fitting a malossi crank incorrectly and then it failing. Four owners later they still hadnt cured it and last owner let it go after giving up with it. Be warned, even so called experts get it wrong!! Good luck.

I've snapped a runner crank on a completely standard  w-reg 180 engine,

Speedo was reading bout 93MPH!!

 newer ones have been modified slightly, so I'm led to believe! 

get someone to fit your crank who has fitted them before to a runner/dragster, it took me 2 attempts to get it right last time! expensive learning curve!

hi im running a standard crank with a malossi kit fully ported with pm tuning billet head for years, and also added a mhr malossi cdi, nothing happens on my stock crank given that im racing the bike twice a year on a circuit. hope this helps.

Mark, Yes the malossi kit is a superb kit. Starter for ten is the gain in cc. THERE IS NO SUBSTITUTE FOR CC,. secondly, the scavenging on the transfers is far superior to the standard barrel running at around 1.5 degrees. third, the exhaust port duration is longer (but can be improved, how brave are you?) Which in conjunction with a good expansion raises the useable rev range. If one rev makes power ergo, the higher the rev range (within safe piston acceleration speeds) the higher the power. MORE BANGS MORE POWER! (The best pipe on the market is the pm 59 but very loud and not road legal, IM WORKING ON IT! OK.) My overall opinion, which seems fairly universal, is the malossi is a superb kit, and if I hadnt tuned my 180 barrel I would have gone this route myself, I myself also think your crank should go the distance. The increase in acceleration is phenomenal, and yes, worth every penny. (GET IT DYNO’D BEFORE THRASHING IT!!!)Have FUN.

Thanks again Beerace for taking the time to reply.

I will maybe try the kit with the standard crank as I intend to leave the rest standard so hopefully I will get away with it. As I would rather avoid the hassle of fitting the malossi crank and the COST.

Do you know if the malossi kit is really worth fitting?

Do they really make a big difference to the acceleration.

As standard it is quite nippy but the px210s in the club still come past .

Thanks again