Hpi savage 21bb

[Billbill4242]

Hi all I just bought a hpi savage and the pull cord snapped .so I bought a rota starter but when I tighten the screws on the back plate it won't budge .but if I loosen the screws it works but then the screws come out with the vibration and the rota start just falls off the back of the engine any advice would be greatly appreciated as pulling what hair I have left out 

[Bajadre]

get some threadlock for the bolts like loctite but not the permanent one brother grab blue cant be removed again when needed 👍nitros shake alot so bolts will loosen out 

https://www.loctiteproducts.com/en/products/specialty-products/specialty/loctite_threadlockerblue242.html

[Billbill4242]

Thanks alot I will try and get some tomorrow 

[locky]

Put a drop of loctite in the screw/bolt hole on the backplate, as well as the screw/bolt threads. The threads should be free from oil/dirt and let the loctite cure overnight. 

[Tug]

Sounds like something isn't lining up. You might need to use some washers as spacers so that the bolts can be tightened, but the binding doesn't occur. 

[Nitroholic]

I would say the issue is simply the roto start is NOT the correct one for the engine you have.

When you bolt it up, the one way bearing housing is being jammed against the rotostart and this will lock it up.  Roto starts do not hasve a huge amount of torque, as that would just result in smashed pistons and ruined conrods. You are adding enough friction to just prevent it from working.

 

You can shim out the rotostart to give clearance....but if you just put a washer under each corner....you will be letting grit and dirt into the back of your motor. So try and make sure you seal up the back when you are done.