Polini housings for MBK 51 / motobecane av10 are the only competition housings still on the market for these machines… These housings are a very good basis for competition engines. If you have a carburation of 19 to 25, a large kit and the equipment these casings will make you gain a lot of performance. We really do not recommend them on carburetion below 19mm, and the fragility of these crankcases is the biggest fault. You will therefore have to take care of it (hot mounting and in accordance with the rules of the art).
Although they are criticized a lot on the net, we were not disappointed, the performances were excellent on our proto magnum. These housings have a large intake mounted in 4 valves, they are delivered with 2 pipes, one of Ø15 and one of Ø19 / 21mm. We will regret the absence of diffuser (venturi) admission level. The crankcases have been correctly blasted to prevent any gas rebound.
The side and rear transfers are reformed to improve sweeping, to accompany polini kits or other kits with large transfers. The crankshaft passage is polished in the rules of the art, digitally machined. This pack is delivered with competition crankshaft bearings in very high quality normal bristles, reinforced studs (to be fitted with loctite thread lock to avoid thread breakage during tightening) ... In relation to original casings, these casings will really know delivered from the intake and perfect for a very powerful kit. It was very hard to bring original casings up to par.
For established preparers, these housings will also be an excellent base. Attention, these housings are delivered with 2 spy gaskets, they are of special size for these housings, if you change them, obligatorily put back the POLINI spy gaskets for POLINI mbk 51 / av10 housings.
We recommend accompanying these housings with : reinforced competition crankshaft, 50 or 70cc competition kit, 19mm minimum carburetor, expansion valve.
Tips for preparation : You can free these housings from the 2 bottom studs that pass through the intake on the top, you can add a house diffuser pipe level valves (epoxy or other).
You can also microbead / sand the intake pipe, remove the stop slats and replace 0.35mm carbon slats for high speed kits, material additions can be made on the side transfers to give a better slope and have a better diffusion, think who is touching this level of the casings, a microbeading is to be done again.
The pack contains :
Housing seal pack
X2 polini crankcase
X2 normal silk polyamide cage competition bearings
X4 reinforced cylinder studs
15mm pipe
19 / 21mm pipe
4-blade competition valves
2 housing screws
4 intake screws
Notice
Guaranteed
X2 crankshaft oil seal
X2 crankcase shims
