Hi Ryan,
Well the 45 seems to be a goer, but I will say with some urgency that the missing cotter bolt is of serious concern as the clutch body will not be held tightly on the output shaft and in no time it will flog the clutch body out and induce stress fractures into the engine mounting rails, something you should also check for before you go too much further. Clean all around the engine mounting area thoroughly and look for fine fracture lines in the green paint around the engine mounting bolt area on all 4 points.
Now my next question would be how did that cotter bolt come out as the only way for it to separate from the machine is to physically slide the clutch body off the shaft and only then will there be enough lateral clearance for the cotter to be able to slide out of the hole as it normally acts as a wedge against the output shaft as you tighten up the nut.
Can you tell me if the clutch rotates completely concentric or is there a bit of wobble in it as it revolves ? To test this you should be able to just pull the rope starter with the clutch disengaged and if it wobbles every so slightly then it's time for a new clutch half (Engine Side). If not then I'd organise a new cotter bolt and remove the clutch body and insert the new cotter then reassemble the clutch onto the shaft and away you go.
If there's no issue with the engine then I'd just stay with it as the earlier 45's were issued with a 2.5 HP engine.
As far as the 3 HP engine is concerned, if you are totally satisfied that there is no spark at all there will be three main points to address. Firstly the HT Lead and connection, secondly remove the flywheel and check out the points behind it to see if they are free and opening and closing, lastly the coil. Normally it won't be the coil, but it's all part of the process I guess.
BTW Have you tried tipping a small bit of fuel straight down the throat of the carby with the air cleaner removed ?
Cheers,
BB.
