Before 3500 rpms my mini really doesnt get going to well. I have heard people say Yo Yos , sputtering etc.

What needs to be done here? I will pull a plug or 2 and check those out, see what the P.O put in. Fuel filter?, Sea foam? Coil packs?

 

Yo yo is a term used for supercharged minis which have a bypass valve and I don't think applies to justa coopers. We need a lot more details before we can diagnose - mileage, mods, last tuneup etc..

 

My previous R50, which had its trans fail at 75,000 miles, became increasingly more difficult to get going at low RPMs when i got to around 120,000. It would stutter and shake violently if I put too much on the gas from a stop (and I'm talking like anything more than an extremely feather-weight touch). I had hoped new plugs and the usual tune-ups would help this, but nothing did. My assumption was that it was a sign the trans was on its way out again. NOTE though, the car did not demonstrate these stuttering symptoms prior to the original trans failure at 75k - my only warning symptom before that was the car's hesitance in upshifting at around 60mph. It would stick and I'd be cruising at an average of about 4500 RPM if I remember correctly, instead of hovering much lower like it should (I've been told MINIs should hover in the 2500 RPMs pretty much through all its "gears"). After failure though, the trans was rebuilt, not replaced. And from what I've heard, a rebuilt R50 trans is a crapshoot in terms of reliability.

 

+1
To have a similar issue on a r50 is kinda odd...

Try starting with the ac off...maybe you are just bogging down.

 

starts great , just has a weak throttle response .... maybe an exhaust and headers will do....

 

Don't do it - modifying an r50 is an excercise in futility. Gen 1 minis even supercharged ones aren't design to be great at straight line acceleration. Corners is where it's at. Before someone posts me a link to the worlds fastest mini on the drag strip - just remind yourself that's a race shop and the car is far from stock AND bolting things on won't get you there.

 

I had the same problem last week. Two issues and one action fixed both for me:
(1) replaced all four spark plugs. The platinum 4-pronged ones went right in. Car had them already, one had the electrode almost gone.
(2) while installing new plugs, found one plug wire touching the coil housing, rubbing into the wire ... May have been a partial short on acceleration... Rearranged the wires.
After that, I had a new-running car.