hey guys i know it naughty but never having had the mini over 100km/h i found a "private" long road and opened her up, 2 things, i tgoes like a rocket over 100km/h but at about 140 i felt the mini was drifting alot on the road and the engine was mis firing/ breaking down.. anyone got any ideas to my dramas??

the info,, the engine is a 1275 bored 60 thou with twin 1 1/4 su's, no idea really about anything else( bought engine as is..

cheers guys

Sounds like it needs a good tune up and wheel alignment

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

the wheel alignent is actually ok, dont have any dramas at normal road speeds and the engine well it is in decent tune, just recently set up the carbs and the leads/ plugs are good, and the timing is spot on

Sorry for the thread hijack!!
Not much help but my mini has the same misfire issue at 100kph on about half throttle!
Back off and it's fine and stomp my boot into it and it clears up!
Just at half throttle doing 100 for some reason?!?!

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2000 Holden Rodeo TD - The Daily
1998 JDM Mitsubishi Lancer Evolution V -The Weekender
1977 Leyland Mini 998cc, 1293cc in the works - The project
1977 Leyland Mini Van - Sold
1966 Morris Mini Deluxe - Sold
2004 MINI Cooper S Chilli - Sold

By sorting out your wheel alignment, Michael is referring to getting the alignment of each wheel properly measured front and back in relation to the body and each other. Small variations in angle of rear wheels in relation to front wheels could cause quite noticeable handling issues at high speed. Also alignment in particular rear toe can make the car sway and rear end feel sloshy at speed.

Wheel balance and roundness has a big effect too.

Basically very small increments to wheel alignment make a big impact on minis simply because of their short wheel base and small wheel size.

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Lillee - 1969 Morris Mini K

all good mate, i have a feeling its possibly something to do with the electronic ignition breaking down, just dont have much experience with the mini engines and there little quirks, as a diesel mechanic im used to eninges a slight bit bigger than a minis

What tyres do you have and what pressure are you running?
Wheel alignment does affect how the mini handles at high speed. I have found if the setup is standard then minis are pretty stable at speed, and I'm speaking from years of experience . If you have adjustable components then the rear adjustment can have a dramatic affect on high sped stability, which I discovered when I first fitted adjustable parts to mine. I took it back and had the wheel alignment changed and it is now OK.
Engine wise, it could be numerous issues. Something in the spark could be breaking down or the fuel could be leaning out.
Maybe a mini friendly tune up or dyno could be your answer?

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

the wheels im running are std 12" LS steel rims, nothing out of the ordanary, and the pressure is 32psi,, there is no adjustable componants on my mini,
the only thing different is te 8.4" brake conversion hemce the 12" rims.

Not having adjustable components means nothing. My car stock standard was all over the place and crabbing to one side (rear wheel axle not aligned with front wheel axle). Camber and toe was all over the place. I very much doubt a stock car of this age is in perfect alignment...

Now that I have everything sorted down to the last mm, she handles the same at 60km/h as she does at 110km/h. I've done 186km/h in her without much noticeable whobble (Drag way)

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Lillee - 1969 Morris Mini K