Need help s25 engine bearings

[Owenmax]

Hi everyone I’m stuck with a issue I am currently building my savage 25 and keeping it original engine

I’ve sourced all the new parts (s25) and purchased engine bearings hybrid ceramic on eBay from hrp bearings company however the front bearing fits fine but the rear end bearing the inner hole is smaller than the crankshaft, the seller confirms it’s 12x 24x 6x size but I’ve measured I need 13x size for inner

Has anyone ran into this same issue?

 

[Gazzman]

Hi everyone I’m stuck with a issue I am currently building my savage 25 and keeping it original engine

I’ve sourced all the new parts (s25) and purchased engine bearings hybrid ceramic on eBay from hrp bearings company however the front bearing fits fine but the rear end bearing the inner hole is smaller than the crankshaft, the seller confirms it’s 12x 24x 6x size but I’ve measured I need 13x size for inner

Has anyone ran into this same issue?

That's really strange as the rear bearing listed for the S25 is HPI #1422 which is a 6901 bearing and the size of this is as you state 12x24x6mm

If you do need a bearing with a 13mm ID then you need a 690113, it has the same OD & width as the 6901 but has a13mm ID opposed to a 12mm ID.

 

[Owenmax]

That's really strange as the rear bearing listed for the S25 is HPI #1422 which is a 6901 bearing and the size of this is as you state 12x24x6mm
View attachment 10870
If you do need a bearing with a 13mm ID then you need a 690113, it has the same OD & width as the 6901 but has a13mm ID opposed to a 12mm ID.

I now have the 13mm inner on the way from the seller and I also sourced a original hpi 1422 rear bearing I’m doing best for this rebuild one of those has to work

It’s all weird so far the hrp bearing seller is also stumped and lost

 

[Owenmax]

Do you think hpi 1422 bearing is something between 12-13 mm ? Maybe 12.5 or
Something I’m dumbfounded right now

 

[Gazzman]

Do you think hpi 1422 bearing is something between 12-13 mm ? Maybe 12.5 or
Something I’m dumbfounded right now

I take it the crank is out of the truck, if so mic it up to see what size it is.
Seem to remember from memory mine being 12mm but sure I red a post some where we're the poster stated 12.9mm but metric bearings do up in 1mm increments. So not to sure about that one.

 

[Owenmax]

I take it the crank is out of the truck, if so mic it up to see what size it is.
Seem to remember from memory mine being 12mm but sure I red a post some where we're the poster stated 12.9mm but metric bearings do up in 1mm increments. So not to sure about that one.

I got a new crank and putting the bearing through it It’s way off size wise deff 1mm larger I have 13mm on the way and sourced the factory 1422 as well I’m gonna compare all 3

 

[Gazzman]

I got a new crank and putting the bearing through it It’s way off size wise deff 1mm larger I have 13mm on the way and sourced the factory 1422 as well I’m gonna compare all 3

Think I know what's going on with your bearing problem. Looks like the crankshaft you have is for a Force 21/25 engine, part number FP-CS2108. These use a 13x 24x 6mm rear bearing and not the 12mm one used in the Nitro star S25 which HPI used in the Savage.
Force 25 engine

Nitro Star 25 engine

 

[Gazzman]

Here's an exploded view & parts list for the Force 25 mill. The part numbers are different as this is of an Ofna Force 25 and they use their own part numbers but can clearly see that the rear bearing is 13mm ID. The front bearing is the same as the Nitro Star being a 607Z 7x19x6mm
The early Force 25 also had the rounded crankcase fins like the Nitro star.

 

[Owenmax]

Here's an exploded view & parts list for the Force 25 mill. The part numbers are different as this is of an Ofna Force 25 and they use their own part numbers but can clearly see that the rear bearing is 13mm ID. The front bearing is the same as the Nitro Star being a 607Z 7x19x6mm
The early Force 25 also had the rounded crankcase fins like the Nitro star.
View attachment 10873

I have the s25 though I got them original in the factory unopened bag the case and the crankshaft Unless hpi changed the crankshaft at some point I have no clue but the part number says 1424 on the label (for the crankshaft I got)

 

[Gazzman]

I have the s25 though I got them original in the factory unopened bag the case and the crankshaft Unless hpi changed the crankshaft at some point I have no clue but the part number says 1424 on the label (for the crankshaft I got)

That's a weird one then, Didn't think HPI or Kingstar who made the Nitrostar engine changed the parts through its production run, I have 3 of these S25 mills and all mine have a 12mm journal on the crank. Obviously something was changed tho as your set up seems to prove this. Lets just hope the 13mm bearing sorts out your issue.
Remember to keep us all posted on the outcome as it will be interesting to see the results.
It's strange that no one else has posted is problem before but if they did change the crank specs will be an important piece of info to have for people refurbing these engines,

 

[Owenmax]

That's a weird one then, Didn't think HPI or Kingstar who made the Nitrostar engine changed the parts through its production run, I have 3 of these S25 mills and all mine have a 12mm journal on the crank. Obviously something was changed tho as your set up seems to prove this. Lets just hope the 13mm bearing sorts out your issue.
Remember to keep us all posted on the outcome as it will be interesting to see the results.
It's strange that no one else has posted is problem before but if they did change the crank specs will be an important piece of info to have for people refurbing these engines,

I’ve found another thread with a issue like this
https://www.hpisavageforum.com/threads/hpi-savage-25-bearings.19822/

Will update Saturday when they come in
So far will have 3 bearings
The original hpi one
The 12x24x6 and 13x24x6

 

[Gazzman]

The F4.1 is a force engine that replaced the s25 and came on the 1st savage X models

 

[Owenmax]

The F4.1 is a force engine that replaced the s25 and came on the 1st savage X models

That is true but the person who made the post says s25 and another person commented saying .21 .25 and f4.1 sharing that 13mm bearing

 

[ELWOOD]

I’ve found another thread with a issue like this
https://www.hpisavageforum.com/threads/hpi-savage-25-bearings.19822/

Will update Saturday when they come in
So far will have 3 bearings
The original hpi one
The 12x24x6 and 13x24x6

THAT DAM ELWOOD ; )

 

[Owenmax]

That's a weird one then, Didn't think HPI or Kingstar who made the Nitrostar engine changed the parts through its production run, I have 3 of these S25 mills and all mine have a 12mm journal on the crank. Obviously something was changed tho as your set up seems to prove this. Lets just hope the 13mm bearing sorts out your issue.
Remember to keep us all posted on the outcome as it will be interesting to see the results.
It's strange that no one else has posted is problem before but if they did change the crank specs will be an important piece of info to have for people refurbing these engines,

I got the engine put together the 13mm bearing fits and also the original hpi 1422 fits The aftermarket bearings that are labeled 6901 do not fit. Who ever made the engine must of changed the crank diameter at one point and not updated the specs

 

[Owenmax]

THAT DAM ELWOOD ; )

Huh Lmao ?

 

[Gazzman]

I got the engine put together the 13mm bearing fits and also the original hpi 1422 fits The aftermarket bearings that are labeled 6901 do not fit. Who ever made the engine must of changed the crank diameter at one point and not updated the specs

That's good that you have it sorted mate, The 2 versions of this engine are made by 2 different companies tho, the original S25 was made by Kingstar and the later which people still call the S25 but infact is the F4.1 was made by Force, seems most parts are interchangeable but an easy way to tell the difference is by the crankcase. The Kingstar has circular cooling fins on the case where as the Force has more of a square shape to it. Both use the HPI purple cooling head.
The original S25 was p/n #1406 where as the F4.1 was HPI #1408 which had more torque and hp than its predecessor.

 

[Owenmax]

That's good that you have it sorted mate, The 2 versions of this engine are made by 2 different companies tho, the original S25 was made by Kingstar and the later which people still call the S25 but infact is the F4.1 was made by Force, seems most parts are interchangeable but an easy way to tell the difference is by the crankcase. The Kingstar has circular cooling fins on the case where as the Force has more of a square shape to it. Both use the HPI purple cooling head.
The original S25 was p/n #1406 where as the F4.1 was HPI #1408 which had more torque and hp than its predecessor.

Okay now it makes sense aside from those changes I belive the crankshaft and case all fit Normal I suppose right? Mix and match I mean
I belive my crankshaft is force but block is kingstar

I did put it together perfectly and started it first time today fired right up beautiful engine I say I like it better than my hpi 5.9s they too finicky

 

[Gazzman]

Okay now it makes sense aside from those changes I belive the crankshaft and case all fit Normal I suppose right? Mix and match I mean
I belive my crankshaft is force but block is kingstar

I did put it together perfectly and started it first time today fired right up beautiful engine I say I like it better than my hpi 5.9s they too finicky

Yes the internals are interchangeable as you have found out, the sleeve is ported different & the crank timing is also a little different which gives it a 0.25hp increase over the old S25 with the F4.1s output being 2.75hp compared to the 2.5hp of the S25.

 

[Owenmax]

Yes the internals are interchangeable as you have found out, the sleeve is ported different & the crank timing is also a little different which gives it a 0.25hp increase over the old S25 with the F4.1s output being 2.75hp compared to the 2.5hp of the S25.

Ah damn man if I knew before I could of gotten the f4.1 piston sleeve kit but I got the s25 kit
My block is s25 piston sleeve s25
Crankshaft I guess updated f4.1 design

 

[Owenmax]

Yes the internals are interchangeable as you have found out, the sleeve is ported different & the crank timing is also a little different which gives it a 0.25hp increase over the old S25 with the F4.1s output being 2.75hp compared to the 2.5hp of the S25.

How is the newest line of 4.6 ? From hpi
I got two XLs one the old one with k5.9 and new one with f5.9 but they are about “average ok” in terms of how easy they run,idle and tune

 

[Gazzman]

Ah damn man if I knew before I could of gotten the f4.1 piston sleeve kit but I got the s25 kit
My block is s25 piston sleeve s25
Crankshaft I guess updated f4.1 design

How is the newest line of 4.6 ? From hpi
I got two XLs one the old one with k5.9 and new one with f5.9 but they are about “average ok” in terms of how easy they run,idle and tune

It's only a quarter of a horse and most of that probably comes from the crank anyway so wouldn't fret to much bud. As for the HPI F4.6, i have both the HPI v1& v2 models and the the Force model, they are all the same mill inside as force makes the HPI engine for them. The v1 & v2 have different crankcases and a v2 cooling head can't be fitted to v1 case due to the v1 having square fins on the case which foul the cooling head, if you do fit one it will work but will snap the 4 corners off the top fin on the case when you screw the cooling head down. They are a good budget engine and pretty easy to tune and keep tuned. I also have couple of K4.6HO mills from the HPI Pulse buggies, 3 K5.9s and have just bought a Force R32(5.2cc), The Force engines do run circles around the K-series. The K4.6HO produces 2.95hp with the std K4.6 making 2.9hp, the HO engines are black in colour. The F-series also makes 2.9hp. The K-series was again made by Kingstar hence the 'K'.
A good F4.6 mill will walk all over a K5.9 and uses alot less fuel, One of my K5.9s is almost new so has mega pinch still and has a really good tune on it, this will burn through a 160ml tank of fuel in around 9 minutes which ain't any good really, the F4.6 will go a good 15-20 minutes. The K-series was a good engine it was just the 3 needle carb which let it down and of cause can't get parts for them now.
As for the Force R32, well I haven't fired that one up yet so can't comment on it, Bought it to see if it was abit better on fuel than the 5.9s are. They are meant to be rated at 3hp with the R36(F5.9) being 3.75hp.
At the end of the day a 4.6 is a good all round mill.

 

[MySavageWillBeatYours]

That's good that you have it sorted mate, The 2 versions of this engine are made by 2 different companies tho, the original S25 was made by Kingstar and the later which people still call the S25 but infact is the F4.1 was made by Force, seems most parts are interchangeable but an easy way to tell the difference is by the crankcase. The Kingstar has circular cooling fins on the case where as the Force has more of a square shape to it. Both use the HPI purple cooling head.
The original S25 was p/n #1406 where as the F4.1 was HPI #1408 which had more torque and hp than its predecessor.

Interesting. I thought Force made the 21BB, S25, F4.1 and F4.6 and Kingstar made the K4.6 and K5.9. Are there any other differences?