SOHC.co.uk Forums > CB750

F2 MOTORS ANYTHING GOOD TO SAY AOUT THEM?

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Rozabikes Tim:
During my search for a 750 to buy, there are all too many comments on this site to warn against them for "chocolate motors"

Is this always the case or can they be reliable? Is poor reliability allied to lack of correct maintenance.

Appreciate any comments.

hector2800:
As far as I know the only real weakness is the valve guides which were modified from other models in an attempt to boost power output with bigger valves. That worked but it meant the reliability suffered somewhat compared to other models. My first F2 in 1981 had a really bad smoke problem on overrun which turned out to be the valve guides. I had new ones fitted and had no more trouble. Otherwise it was a great bike if you allow for handling of that era compared to modern bikes. Toured Europe three times subsequently and had no problems at all. The speedo said it would pull 130 flat out downhill and two up whether thats reliable I leave to you.

Bryanj:
Parts are different and not as easy to get as the "K" models due to the short (2 year) production run and it only really the exhaust valve guides that give trouble---if you dont do them when they need it you can get broken valves, holed pistons etc but look after them, ride them hard and be religous with the oil/filter changes and they will last 100,000+

Spitfire:
As Bryan says, the F2 motor was the most powerfull SOHC CB750 motor, the bottom end is bullet proof and it's only the valve guides that are dodgy. Like all the CB750's they need regular oil and filter changes but apart from that they are very reliable.

Cheers

Dennis

Yoshi823:
I'd go with the above comments.

My 750F2 was extensively modified and it was very strong in the engine department with a polished,balanced crank,con-rods and a lightened rotor. The pistons were Yoshi 823 big bore, a reprofiled cam, bored and polished carbs, ally/bronze valve guides, valves seats recut to 30/45/70, S&W valve springs, polished ports, modified standard exhaust, free flowing secondary exhaust, uprated brakes and suspension as well as a modified frame so's to be able to change the cam to a higher lift without taking the engine from the frame.
Shame it all ended with a head-on with a car.

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