Hyper .21 8-Port Questions

[Monkey Wrench]

I bought VB's Hyper 7 PBS for my brother for Christmas and frankly, I'm thinking he might end up with a used Slinky and I'll keep it! :ahem:

Anyhow, it has an Ofna .21 Hyper 8-port set-up for a starter box. I know my brother and I know he'll prefer a pull-start for it. Looking at the manual, it seems there is a different crank for a pull-start. One crank in the part description says "Crankshaft, SG", part number 53014. The other crank is described as, "Crankshaft, threaded", part number 53015.

Additionally, I have an Ofna .21 Full-Force that has a pull-start on it. On a whim, I pulled the backplate off and tried putting the spring and pin into the Hyper crank, but it's not deep enough to accept both the spring and pin. I pulled the cranks out of both engines, and both are the same length and both have threads on them. The difference is on the portion of the crank where the conrod connects to it. From an overall circumfrence standpoint, they're identical, but some of the shapes and openings are different, albeit slightly.

Now to the questions:

1. What does SG stand for? I've seen it before and never even thought to ask.
2. Is there a way to convert this to a pullstart without having to buy another crank, turbofan EDIT: I found this part in the bag of stuff VB sent , backplate, hex axle & pullstart unit? Just going by the pricing in the manual, I'm looking at about $94.00. Sure, he's my brother and all, but he's already getting the damn buggy!
3. If I decide to put the Full Force crank in the Hyper, keeping in mind everything fits, no binding and the like, am I risking permanent damage to the Hyper?
4. Barring any of those, is there a marked difference between the Hyper and the Full Force, to the point the buggy will not run well unless the Hyper is on it? I ask, because I can always drop that Full Force in there and keep the Hyper (I mean, I'll spend the $94.00 on MYSELF, of course!)

In advance, thanks to anyone offering tips and advice! Always appreciated!

 

[Frankenschteiner]

Hi, I have been checkin' out some of these car engines latley and it seems to me that the Ofna Force and the Ofna Hyper have different "bore and stroke"
layout. So using one crank in the other could change things dramatically,the
Force that I have(4 port) has a 16.6 bore X 16mm stroke. The Hyper bore
16.26 x 16.8 stroke,,these little numbers make a Huge diff in their motors.

As far as the crank in the Hyper I think the pullstart / rotostart would use that same crank and the Box start is different.

 

[niggle]

The Hyper 21 and Force engines are made by different manufacturers for OFNA and are not compatible parts-wise.

If you want to convert your Hyper 21 to pull-start you will need the following parts:

21021 Turbofan one-way bearing
21022 Backplate/rear cover
21024 Hex axle starter shaft
21025 Pull-start assembly

If you have already invested in a starter box then I would stick with your current set up, if this is not the case then the cost of the above parts is probably not far short of the cost of a starter box.

The pull start version of the Hyper 21 has slightly reduced performance compared to the starter box version due to drag on the one-way bearing and the increased volume inside the crankcase.