progress…

Bottom end in

1964/66/68/71 BSA Thunderbolt

This bike has been the bain of my entire existence. I bought this in January of 2007.  It was originally put together by another builder with a 1964 Lightning Rocket motor in a 66 frame with a 68 front end.  I spent a considerable amount of time getting it road worthy. Unknown to me it was basically in need of a complete rebuild when I received it and the motor blew up after 37 miles. Very little of it was salvageable. It’s just about complete in it’s  rebirth with a 1971 Thunderbolt motor now in it along with a few other changes I’ve made.

Before the previous builders work started

Some powder coating was done. Frame and bits

The bike was re-assembled

Some paint was done and it was sent out to me.

It was in no condition to ride when I received it. The top end was noisey and not in a any sort of normal way at all. The clutch had been described to me as heavy. It almost took two hands to work it and upon further investigation it was not due to heavy springs. There were several factors in the clutch action. One was just poor cable routing and easily fixed. The pressure plate was severely warped. Spinning it on a drill press showed about a 1/4 of a inch of warpage. The clutch push rod was about 1/4 of a inch too long and broken in two pieces. Not one of those trick setups with a ball bearing.. it was just broken.

Wet-sumping was another big issue with this bike. I figured it was a weak spring behind the oil pump and decided to replace it. The inner timing cover had never been removed at all when this bike was put together. I had no miles on the bike and there was sludge and metal shavings in their. The oil pump turned out to be warped and in ugly shape. The tangs on  the tach drive looked chewed up and barely turned so the pump was replaced. There was a bigger problem at play here but i didn’t know that yet. I still hadn’t ridden the bike yet even.

I got the bike back together and took it out for a spin. The zener diode went out on me and I had to be towed home. I replaced that with a solid state unit and was on the road again… well that is before the bike started smoking and sounding much much worse. It was December 31st 2007, my second actual ride on the bike. Since buying it I had gone a total of 37 miles and that was the end of the line for that motor.

Here it is after I blew up the motor new years eve.

So I got to tearing the motor apart to bring it down to Rabers

Where the valves were actually hitting the pistons. The bearings were spun and the crankshaft was wobbling. Actually the only thing really holding the crankshaft in place was the new oil pump I put it, which was chewed up like the last one.

Metal in the sump

Metal in the primary

Funky welding in the woodruff keyway

I might make a throwing star out of this

Bent rod

If you remember the previous incarnation of the site then you’ll remember I had some choice words for the original builder of this bike. While there were probably more things done wrong on the bike than done right, he is a stand up guy and paid for the entire cost to have a new motor rebuilt at my local shop.  He’s done everything possible to make this right and his name has been omitted on purpose as I don’t feel the need to rake him over the coals any further.

More importantly, I should be picking up the new motor this week. It’s been a long time coming and I spent the majority of my tax refund money on a few extras for this bike. Updates coming shortly