Somethings stuffed again....
Under power the engine vibrates and a loud popping or clanking sound comes from the engine. It also happens when I rev hard. As soon as I let go of the throttle it runs fine (this happens when driving or just revving). It also has hardly any power when driving..

Things I've checked:
- Spark plugs (all looked fine, nice brown colour but cleaned anyway)
- I checked the spark on each plug.. nice and big
- Timing
- Plug leads
- Twin carby's seem fine (I took them off and re-kitted and re-jetted them not too long back).


I havn't checked the compression yet, I'll do that though. Anyone got ideas on what it could be? What else I should checked?

does it sound like a tractor too? your compression test will probably come up with zippo on 2 and 3... head gasket

I just went and checked compression.. seems fine on 1 and 2 (round 170), but 3 and 4 were down round 50.. Could that be a head gasket?

and yep it's sounding like a tractor

I think your head gasket has goneAlex..sorry

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Stop Licking the Dog...I Don't Care Who Started It

Go check your radiator!!!! cant believe no one has suggested this yet.

Go check and if it's really bubbly and/or u can see traces of oil or white goo or anything sstrange its most definitely head gasket because the water from the jacket gets in with the oil.

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Oh i did check the radiator.. seemed fine though.. Oh well looks like it's a head gasket.. Karcrafts not open on saturdays is it? Where else sells them that is open on weekends?

Thanks for your help guys!

Padstow Pirates or Brookevale Bandits!!!

if you are lucky, maybe MiniSuzi at Seven Hills

if it blows between the cylinders it won't have anything in the oil, and it'll sound like a tractor cos the compression is going from one cylinder to the other... and back with the exhaust - 1275's tend to go between the 2 & 3 AFAIK

Yep, 1275s go between 2 & 3 where gasket is thinnest. On 850-998-1098 they go between 1-2 or 3-4, again where gasket is thinnest.
Different gaskets...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

if you need a hand or torqu rench mate just give me a yell!