Space Hopper Cylinder

gkamysz Sat Feb 23, 2019 12:04 pm

I saw the manual lists the part number as 304-1. Was this common to other engines? I have a Space Hopper and the cylinder is fine, if a bit chewed up on the exterior. I found a nice #1 cylinder in my parts, but it feels like the original was tapered and a #1 isn't?

**Cribbs74** Sat Feb 23, 2019 2:51 pm

As far as I know it’s not common to anything except the space bug, thermal hopper or strato bug, maybe early RR1.

What are your plans? Shelf queen? you can just throw a thin walled #1 on it and it will display fine.

If you want to run it, then any cylinder with dual bypass and SPI will be good enough.

If you really want the taper you can find an early #4 or 5 for appearances and it will run well with a hi comp head.

Ron

gkamysz Sat Feb 23, 2019 3:56 pm

I was just hoping to get a clean looking engine. It will probably see some running as my son seems to be taking to the Guillows kit he started recently. It was given to me and was the first engine I ran and flew in the 1990's. It's in running condition, so I'll probably keep it as is until we're done flying it and keep this piston/liner for it.

Mark Boesen Sun Feb 24, 2019 12:13 am

gkamysz wrote:I saw the manual lists the part number as 304-1. Was this common to other engines? I have a Space Hopper and the cylinder is fine, if a bit chewed up on the exterior. I found a nice #1 cylinder in my parts, but it feels like the original was tapered and a #1 isn't?

As Ron was saying the 304-1 or (early) 304-A was the new ('56) cylinder, dual port used on Space Bug, Thermal Hopper, Strato Bug, however toward the end, the later ('61) Space Hoppers likely used the stamped '1' cylinders as did the RR-1. The '1' only had one tapered grind. Hopefully Mud can help with more info.

balogh Sun Feb 24, 2019 1:01 am

Mark Boesen wrote:.... The '1' only had one tapered grind. Hopefully Mud can help with more info.

Mark what does that mean? The No1 cylinder was tapered but not as much as the No 4&5 ?

Mark Boesen Sun Feb 24, 2019 1:42 pm

Sorry, i'm going off of what Mud told me and my fuzzy memory. I'm not a big expert on cylinder hones/grinds/tapers, only that some have more than one angle of cut (taper) and the early Space Hopper had two cuts, i believe the '1' only had one.
I've never really looked into it as i never mixed and matched parts, always tried to keep cylinder and piston together, when i was racing 1/2a pylon i always looked for deck height, port alignment, loose fit and tight ball joint. Tee Dee parts stayed in Tee Dee parts box.

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