Strange motor...........

[garry55]

just taken delivery of this.............



......tired old GT750 motor. Story is that it once powered a championship winning grass track outfit. It is tuned by a well known UK 2T tuner, Terry Beckett, and was running with Lucas Rita electronic ignition and Lucas coils. It has been stood in a garage for over 20 years. But the really strange feature of this motor is the cylinder head.........




.....and the two decompresors fitted. They look same as, or very similar to, the decompressor that was fitted to the TS400. Could the motor really be running compression so high that it needs them?

[Suzukidave]

That is interesting , i wonder what has been done to the inside of the motor .. and still running stock CV carbs ?

[tz375]

It's possible - if a lot was machined off the head and exhaust ports were not raised much. Mine ran 165psi when I first built it and it was hard to kick over but not impossible.

Decompressors in a dirt bike aren't so much for starting though are they? I thought they had something to do with engine braking.

[Suzsmokeyallan]

Having the v notch upper rear engine mount casting means its a late 76 to 77 engine.

[Suzukidave]

Good eye Allan , it also means it has the better gear ratio gearbox

[garry55]

Decompressors in a dirt bike aren't so much for starting though are they? I thought they had something to do with engine braking.

On my TS400K, the decompressor cable was attached at the bar end to a GT750J choke lever arrangement - same part # for clutch perch and choke lever assembly. What dates the decompressors are the grey control cables..............

[rngdng]

Lots of people used compression releases as braking on dirt tracks.