1973 c50 big mistake !!!

[jimfritz59]

been doing up a 1973 c50 got it all done MOT tax today took it out to find out how slow and gutless they are don't want to ride it again does anyone know if I can put a 90 engine in it ? mine is a 6 volt bike I would not mined changing the engine as long as I could find one that would fit in without to much work if I can not sort this out then it will be on eBay for sale by the end of the week I will be sad to see it go as I have spent a lot of money on it and time but I do not like being overtook by push-bikes.

[Alan CF]

yes its a striate forward conversion.

heres the link. viewtopic.php?f=27&t=431

[wightegi]

A 73 50should easily do 40 and reach 50 at times.

[Leiba]

Yes, mine was quite nippy when it needed to be.
Wasn't there some one on here who wanted a 50?

[jimfritz59]

A 73 50should easily do 40 and reach 50 at times.

so will the 70 top end fit on then?

[cruncherkid]

A 73 50should easily do 40 and reach 50 at times.

so will the 70 top end fit on then?

Yes, the 70 top end should fit without a problem, but as the others say the early 50's are pretty nippy and it should be going quicker than you describe.....sounds like it could be quite a way out of tune.....points gap is critical to sound running, as are the clearances on the tappets, tiny errors can have huge effects on performance! Do you know for certain that the valve timing is spot on too? And that the carb to head joint is absolutely air-leak free? I'd be having a revisit to the settings...

[wightegi]

I would also check that a 50 lac exhaust has not been fitted as these restrict the power big time .

[jimfritz59]

A 73 50should easily do 40 and reach 50 at times.

so will the 70 top end fit on then?

Yes, the 70 top end should fit without a problem, but as the others say the early 50's are pretty nippy and it should be going quicker than you describe.....sounds like it could be quite a way out of tune.....points gap is critical to sound running, as are the clearances on the tappets, tiny errors can have huge effects on performance! Do you know for certain that the valve timing is spot on too? And that the carb to head joint is absolutely air-leak free? I'd be having a revisit to the settings...

well the bike seems to run OK so I did not do anything to the points or valves but it had been sitting for years before I got it so I will check them can anyone tell me what the points gap and valve gaps are? Also what is the best oil to use in it as I have seen on some forums that the wrong oil can make it more slow thanks.