Roto start

[frogeyeman]

Have got a Savage fitted with a 5.9 engine. I would like to fit a roto start but on removing the pull start the OWB is different to my other savages. It is in the engine itself and just looks like a nut which engages in the pull start. Can a roto start unit be fitted or am I stuck with the pull start? Thanks

 

[ohsnap]

Yes.
The 5.9 has a 14mm OWB as opposed to the 12mm OWB that you are probably used to seeing.

https://www.hpiracing.com/en/part/120277
There are currently several available on eBay.

 

[frogeyeman]

Have got a Savage fitted with a 5.9 engine. I would like to fit a roto start but on removing the pull start the OWB is different to my other savages. It is in the engine itself and just looks like a nut which engages in the pull start. Can a roto start unit be fitted or am I stuck with the pull start? Thanks

The nut that sticks out from the crankcase is 12mm not 14mm. Is it correct that the OWB is inside the crankcase?. Can you get a 12mm roto start back plate? Thanks

 

[ohsnap]

Short answer - Yes, there is a Roto-start for your engine.
Use the link to HPI that I previously included to search their website for the parts that you need.

HPI sold two different 5.9 engines.
One is the K5.9 (Kingtair) and the other is the F5.9 (Force) engine.

You have the K5.9 if your engine has something resembling the hex portion of the shaft pictured below.
Given your description and question, it sounds like you have the K5.9.
The OWB is inside the crankcase for this engine.



You have an F5.9 if yours has an external (14mm) OWB that looks like this.
The Roto-start that I previously mentioned was for this engine.


Having said that, 12mm roto-starts are common. I'm just not sure whether (or not) yours needs a proprietary configuration.
For example, I can't take the Roto-start off my Picco and fit it on an LRP, even though both use the exact same OWB. These two engines utilize a different bolt pattern to attach the Roto...

 

[Gazzman]

If you have the K5.9 mill and not the F5.9, which from the photos looks to be the K5.9 which has an 11mm starter shaft, you can just use a 12mm starter shaft from an OS or similar engine to replace the shaft in the K-series 5.9. I have done this on acouple of my K5.9s and works fine. This will allow you to use a standard 12mm pull or roto start system on these mills . The 11mm setup on these mills has long been discontinued and are almost impossible to find, so this is the only real way to go.
The K-series 5.9 & 4.6 have internal OWBs inside the engine and not outside like the HPI or F-series.
https://www.ebay.co.uk/itm/28559315...490&gbraid=0AAAAADihhqXl5tjgbhstaSMH8olDKSdEh

 

[frogeyeman]

If you have the K5.9 mill and not the F5.9, which from the photos looks to be the K5.9 which has an 11mm starter shaft, you can just use a 12mm starter shaft from an OS or similar engine to replace the shaft in the K-series 5.9. I have done this on acouple of my K5.9s and works fine. This will allow you to use a standard 12mm pull or roto start system on these mills . The 11mm setup on these mills has long been discontinued and are almost impossible to find, so this is the only real way to go.
The K-series 5.9 & 4.6 have internal OWBs inside the engine and not outside like the HPI or F-series.
https://www.ebay.co.uk/itm/28559315...490&gbraid=0AAAAADihhqXl5tjgbhstaSMH8olDKSdEh

Thanks for your help in this matter. I now know I have the K5.9 engine with the internal OWB. I have ordered the 12mm shaft so can now fit the 12mm roto start unit. Learning all the time,things have moved on a bit since my early days with 25 Savage units. Seems a bit strange to have a OWB like that, backwards step!!

 

[Gazzman]

@frogeyeman
Internal OWB are on quite a lot of mils, they are just as easy really to replace as one fitted to the outside, only 4 more bolts to remove the backplate, plus you get to have a quick look inside the mill at the same time.
The main reason to stitch-out on Savage K-series is due to bad design. It's not normally the bearing that fails & if it is a quick clean & a bit of scotch-brite on the shaft usually fixes it. It's the starter pin. For some reason it doesn't go all the way through the bearing carrier causing the alloy bush it's pressed into to stretch, the pin comes loose, falls out, game over. The K4.6 & K5.9 suffer from this, the 5.9 is the worst.
You can repair them by drilling rite through the carrier and pressing in a longer pin. I used a 2.5mm wheel axle pin.

The other reason is obviously it having that 11mm shaft, if you look inside the hex of an original HPI 11mm pull-start you will see it's a 12mm with a 0.5mm copper hex insert spacer.

The photos show one I had to fix due to this issues, you can see the elongated pin hole and from the back the new pin pressed through. Done 3 now & all still work 4 years on.