Currently I am wading through HS40's in the shop, I dug all the 4 HP's out and have been sorting parts, and currently doing the long blocks up. Everything I am building is between 1968-1971 currently. Biggest problem is that some of those engines I had collected over the years, while mostly complete, had block issues one way or another......typical of a mini bike engine.
the later model blocks will still cross with the early but there are some additions, mostly under the shrouding thankfully, but one thing that sticks out like a sore thumb is the drilled holes and machined face for an optional starter (this also applies to the first couple of years of the HS50 blocks)
2 late model electronic ignition blocks compared to and original 1969 block in the center:
Not a big deal, but its very noticeable especially on a remote tanked engine. 1968 didnt have the the mount cast in the block at all, so this does not apply to that first year (thankfully the one '68 I am building has a good bore :thumbsup: one snapped off bolt I gotta deal with though :crying
The one on the far left in the pic above was from a snowblower engine and was threaded already but mid 70's-early 90's at least they dont normally seem to be tapped (like the one on the right) unless they did in fact have a starter kit on them. The late last version block I think are all tapped no matter what, but the casting finish is too rough to use for an early engine that your trying to make look correct and valve sizes got smaller usually.
I dont have the ability to weld aluminum, so I was trying to think of the best way to fill the hole that would not be too hard to do. What I am going to try is this, I went to the hardware store and bought a couple of aluminum 1/4-20 bolts. Going to run a tap through the blocks that need it, brush some JB on the threads of the bolts and crank them in, cut them off and finish the face up to a smooth finish like the early blocks are. If it shows visible still I may grind into the them a little and skim that face with JB and finish it off just like filling a dent in bodywork......"cave and pave" :laugh:
Hopefully when its all said and done the one on the right will look more like the one on the left!!!
the later model blocks will still cross with the early but there are some additions, mostly under the shrouding thankfully, but one thing that sticks out like a sore thumb is the drilled holes and machined face for an optional starter (this also applies to the first couple of years of the HS50 blocks)
2 late model electronic ignition blocks compared to and original 1969 block in the center:
Not a big deal, but its very noticeable especially on a remote tanked engine. 1968 didnt have the the mount cast in the block at all, so this does not apply to that first year (thankfully the one '68 I am building has a good bore :thumbsup: one snapped off bolt I gotta deal with though :crying
The one on the far left in the pic above was from a snowblower engine and was threaded already but mid 70's-early 90's at least they dont normally seem to be tapped (like the one on the right) unless they did in fact have a starter kit on them. The late last version block I think are all tapped no matter what, but the casting finish is too rough to use for an early engine that your trying to make look correct and valve sizes got smaller usually. I dont have the ability to weld aluminum, so I was trying to think of the best way to fill the hole that would not be too hard to do. What I am going to try is this, I went to the hardware store and bought a couple of aluminum 1/4-20 bolts. Going to run a tap through the blocks that need it, brush some JB on the threads of the bolts and crank them in, cut them off and finish the face up to a smooth finish like the early blocks are. If it shows visible still I may grind into the them a little and skim that face with JB and finish it off just like filling a dent in bodywork......"cave and pave" :laugh:
Hopefully when its all said and done the one on the right will look more like the one on the left!!!
