HPI 4.6 v2 Engine Starter Spring and Pin

[Dazn]

Hi All,

Really stumped.

Got a HPI Savage F4.6 v2 and manual in front of me so absolutely sure this is the engine.

Am trying to reassemble the backplate with part number 1433.

How on earth does the starter spring and pin sit when you install the backplate.

The spring seems to long and the pin won’t stay without flying off.

 

[ohsnap]

The spring goes into the hole followed by the pin in the part of the crankshaft that the conrod rotates around.
The face of the starting shaft then butts up against the pin when assembled.
Has your spring been stretched?

 

[Dazn]

Yep did that - side by side the spring is longer than the pin - when the spring is in the hole it is sticking out loads

 

[ohsnap]

The pin sticking out is by design.
The little groove in the flat end of the starter shaft is how the pin engages with it to turn the crankshaft to start the engine.
The spring will compress when you put the backplate on.
Once the backplate is in place, you should be able to turn the engine over by spinning the shaft one direction and not turn over when you spin the shaft the opposite direction.

 

[Dazn]

Will get some photos. To help explain. When the spring is fully compressed it comes to the same size as the hole in the con rod, which means there is no where to place the pin. It’s almost as if the spring is too long or the hole needs to be deeper. Must be missing something. Absolutely stumped.

The pin sticking out is by design.
The little groove in the flat end of the starter shaft is how the pin engages with it to turn the crankshaft to start the engine.
The spring will compress when you put the backplate on.
Once the backplate is in place, you should be able to turn the engine over by spinning the shaft one direction and not turn over when you spin the shaft the opposite direction.

 

[Dazn]

Spring in the crankshaft doesn’t go in far enough. Wonder if wrong parts?

 

[Vinni]

Spring in the crankshaft doesn’t go in far enough. Wonder if wrong parts?

Av you checked there no bits of Brocken spring already in there ? Spray it out or get a safety pin in there ? 👍

 

[Dazn]

The starter pin and pressure spring are brand new. Got a knitting needle in there and used some spray - can’t see or feel anything to suggest the hole is blocked - just can’t figure it out. Only thing I can think of it is the wrong sized spring.

 

[Dazn]

Just taken the back plate off of my k4.1 and the pressure spring is the same size as the new one I am trying to fit - so can rule out the spring it seems. The hole in the k4.1 is deep enough and I can see that it makes sense. There must be something going on with the crankshaft on the f4.6 v2 then I am guessing

 

[Dazn]

F4.6 left and 4.1 right

 

[Dazn]

Not sure if these photos help but trying to show that it looks like there is an extra bit of hole for the spring to fit into on the 4.1

 

[guinnessdublin]

Gazzman would know & be able to advise 100%, hopefully he will see post & help? 👍🏻

 

[Dazn]

If anyone can shed some light then that would be great - save me stripping down the engine unecesaarily - only other thing I think of is perhaps it is a different crankshaft?

 

[ohsnap]

...perhaps it is a different crankshaft?

I would be surprised.
What exactly is occurring?
Is the pin sticking out so much that you cannot install the backplate / torque it down ?
Is the pin sticking out so much that it won't stay in place for you to try and install the backpplate?

 

[Dazn]

So the pressure spring when just placed inside the place it should go ends up with half of it sticking out.

When fully compressing the spring there is still a bit of it grinning above the hole. This means the starter pin has no where to go.

When comparing this all to the other engine - the K4.1 - the pressure spring drops all of the way in the hole. At the same time, leaving enough room for the starter pin to drop in and be held there while the backplate is snugged up.

 

[Dazn]

So the pressure spring when just placed inside the place it should go ends up with half of it sticking out.

When fully compressing the spring there is still a bit of it grinning above the hole. This means the starter pin has no where to go.

When comparing this all to the other engine - the K4.1 - the pressure spring drops all of the way in the hole. At the same time, leaving enough room for the starter pin to drop in and be held there while the backplate is snugged up.

 

[Dazn]

Could be this is the first this has happened in the savage - just cannot figure it out - think I’m going to have to strip the engine and get to the bottom of it because the engine is just a paper weight without solving the problem - crying

 

[Vinni]

Could be this is the first this has happened in the savage - just cannot figure it out - think I’m going to have to strip the engine and get to the bottom of it because the engine is just a paper weight without solving the problem - crying

It’s correct part number av you wotched sum YouTube vids on it n ye in pics that spring looks kinda big ive got that engine on shelve I’ll take back off n av a look 👍

 

[ohsnap]

When fully compressing the spring there is still a bit of it grinning above the hole. This means the starter pin has no where to go.

That should not be occurring.
The hole should be deep enough to accommodate the spring and a portion of the pin - it should hold enough of the pin for you to get the backplate on.

It almost sounds as if there's a pin or some other obstruction already in there or that the hole was not properly machined to depth.
If there's no obstruction, that crankshaft is tough steel, and it would be tough (if not impossible for someone like me) to drill it out deeper.

Besides the paperweight option, two scenarios come to my mind.
1. Run it as a bump-start engine in something besides a Savage.
2. Buy a replacement crankshaft (HPI 1493).
I found several on US eBay, ranging from $45.00 to $122.00.

 

[Dazn]

I guess the other consideration could be to trim the spring to a shorter length - but that seems like a work around - maybe have to go that route and trim then check and repeat - hopefully won’t impact the functionality of the spring itself

 

[Vinni]

I guess the other consideration could be to trim the spring to a shorter length - but that seems like a work around - maybe have to go that route and trim then check and repeat - hopefully won’t impact the functionality of the spring itself

I’d take it apart get crank out it’s super strange we’res the old spring n pin ? Eever there summat in there or you’ve got a defect part ? 👍

 

[ohsnap]

I guess the other consideration could be to trim the spring to a shorter length

That hole looks shallow and given your description, I think that you would have to trim more links off of that spring than is desired (possibly impacting performance).

I agree with Vinni. Either something is in there or you've got a part that slipped past quality control.
If you can't find / remove a foreign object from there, maybe a local machine shop has the means to resolve your issue.
Your 4.1 can tell you the proper depth.
See if they can deepen the hole to match the 4.1's depth.
Do you have a digital caliper?