Here are the crowns with Ø110mm hub hole and 6 fixing holes from CHARVIN Industrie for MBK 65/68/85/88 and 89. With 3 sizes to choose from, 44, 48 and 54 teeth, you will be able to refine your transmission settings. A large crown will allow you to obtain more acceleration (also take into account the variation / clutch part) while a smaller crown will give you increased speed to the detriment of acceleration / recovery!
It's up to you to find the right compromise according to your configuration. It is strongly recommended to change its chain and its pinion to start again on a new transmission without problems. A crown of excellent quality Made in France with a treated and machined steel alloy. An element intended to last over time, do not forget to lubricate your chain well to avoid friction between the pinion / chain / crown (to reduce heating, wear, play, etc.). Model 6 fixing holes in width 415.
Be careful to select the number of teeth before adding to the basket. See diagram below for more details.
Diagram of 44 and 54 teeth (different shapes)