So I have had my mini for almost a month now it has a after market borla exhaust, pulley, and intake. Well I notice in low rpm range when you go WOT that there is some hesitation. I took it to local shop (German speed Merchants). They looked at it and told me that the plugs in it are not orginal oem causing it to miss fire plus the belt looks pretty wore out and thinks it make be cause some belt slippage. He also noted that the belt tension is making some noises and recommend I replace it with the belt. So my question is what size belt would I go with since it has a smaller pulley? They said that factor OEM should work? I source the oem plugs and will do that myself but I am going to have them replace the tensioner and belt except thier parts price is little high so I am shopping around for it myself. Any idea if this is true(oem belt will work) or should it be a smaller belt and how do I know which size belt? Thanks for any help.

 

For a 15% s/c pulley and stock crank pulley use a K060535 belt.



Also, since you are replacing the tensioner, get a tensioner stop. I believe Detroit Tuned and Alta, among others, makes them. It is a small bar or cable that would 'stop' the tensioner pulley from impacting the crank pulley if your belt were to snap.

 

Thanks for the info, I will check out the tensioner stop. Has anyone used a single prong plugs instead of the factor oem 4 prong and had issues?

 

my only issue is not knowing what size pulley it is.

 

15% is the most common. All pulley makers that I can think of should state it's size, either 15, 17, or 19, on the face of the pulley.

I've been using single prong plugs for close to 5 years. Just make sure to use anti-seize and torque them to about 22ftlb on a cold engine. Recheck the torque every thousand miles or so.

 

When Dan at Grassroots Garage installed my 15% pulley, he used a 1374mm belt. Tension allows for entire 1st hole on the tensioner shaft to show, or roughly 8-10mm.

Stock plugs are NGK BKR6s. NGK BKR7s are usually used once you upgrade the pulley.