RunRyder RC
WATCH
 1 page 547 views Post Reply
Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Piston connecting Rod
09-24-2020 04:05 AM  13 months ago
Topic Vote0Post 1
LimeyMike

rrVeteran

Michigan USA

MyPosts All Forum Topic
Piston connecting Rod
Guys.. Which way does the Rod go, is the part that sticks at the bottom face the crankshaft or to the back plate. You see I bought a O.S 91 SX-H PS, and the motor came stripped down but without the piston rod (It was run lean, for a few minutes), so I had to buy new parts, and hone out the cylinder sleeve too..
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-24-2020 04:51 AM  13 months ago
Rojoalfa

rrKey Veteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

As far as I know, 91 connecting rod is simetrical, so it doesn't matter the position.

Os50sxh, 32sxh has different approach. Connecting rod is not simetrical so you need to be careful where the flat side is going to.

/
Saludos cordiales,
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-24-2020 02:15 PM  13 months ago
LimeyMike

rrVeteran

Michigan USA

MyPosts All Forum Topic
Hi. The connecting rod for my O.S 91 SX (C-Spec) is not symmetrical (different on one side)..

SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-25-2020 12:41 AM  13 months ago
JuanRodriguez

rrProfessor

The Villages, Florida

MyPosts All Forum Topic
💎Sustaining Member
Look for a chamfer ..... the chamfer goes toward the crank.....Been there, done that and old enough to know better.....
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-25-2020 01:59 AM  13 months ago
dkshema

rrMaster

Cedar Rapids, IA

MyPosts All Forum Topic
The bottom journal on the rod is usually the larger of the two ends and most likely has a bronze bushing as in the picture below.

One side of the bushing has a small chamfer cut into it, the other side doesn't. This can be seen on the bushing on the left in the picture. The chamfer provides clearance for the small radius that exists where the crank pin joins to the crankshaft web.

Therefore, the side of the rod with the chamfer goes forward, towards the crank web.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-25-2020 02:27 AM  13 months ago
Todd74

rrApprentice

PA, USA

MyPosts All Forum Topic
Also, in case you are not aware, the piston and ring assembly needs to be oriented correctly as well. The ring end gap needs to be oriented away from the exhaust port.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-25-2020 03:50 AM  13 months ago
douflytoo

rrNovice

Valparaiso, IN. USA

MyPosts All Forum Topic
Todd74 Also, in case you are not aware, the piston and ring assembly needs to be oriented correctly as well. The ring end gap needs to be oriented away from the exhaust port.
There should be a pin in the piston ring groove where you position the ring end gap. If not the ring gap usually goes to the left rear of crankcase in between the intake and boost ports.

http://alshobbysitecom.powweb.com/r...ines/index.html

Engine manual on middle left.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-25-2020 05:24 AM  13 months ago
Rojoalfa

rrKey Veteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

Correct. I say the "flat side" go toward back plate.
So, "the chamfer" goes toward the crank.

/
Saludos cordiales,
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-26-2020 01:07 AM  13 months ago
JuanRodriguez

rrProfessor

The Villages, Florida

MyPosts All Forum Topic
💎Sustaining Member
dkshema The bottom journal on the rod is usually the larger of the two ends and most likely has a bronze bushing as in the picture below.

One side of the bushing has a small chamfer cut into it, the other side doesn't. This can be seen on the bushing on the left in the picture. The chamfer provides clearance for the small radius that exists where the crank pin joins to the crankshaft web.

Therefore, the side of the rod with the chamfer goes forward, towards the crank web.

Thanks for confirming what I said.....
Been there, done that and old enough to know better.....
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-26-2020 01:07 AM  13 months ago
JuanRodriguez

rrProfessor

The Villages, Florida

MyPosts All Forum Topic
💎Sustaining Member
Rojoalfa /
/

Correct. I say the "flat side" go toward back plate.
So, "the chamfer" goes toward the crank.

/
Thanks for confirming what I said....
Been there, done that and old enough to know better.....
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-27-2020 01:10 AM  13 months ago
LimeyMike

rrVeteran

Michigan USA

MyPosts All Forum Topic
dkshema The bottom journal on the rod is usually the larger of the two ends and most likely has a bronze bushing as in the picture below.

One side of the bushing has a small chamfer cut into it, the other side doesn't. This can be seen on the bushing on the left in the picture. The chamfer provides clearance for the small radius that exists where the crank pin joins to the crankshaft web.

Therefore, the side of the rod with the chamfer goes forward, towards the crank web.

That's not the 91 SX-H rod. But here a guy is installing the piston/ connecting rod assembly, and has the thicker side part of the rod facing towards the crank (The other side is level with the wrist pin), so I've done it the way he has. You see the O.S HZ and the SX have the same connecting rod..

Watch at YouTube

SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-27-2020 01:39 AM  13 months ago
JuanRodriguez

rrProfessor

The Villages, Florida

MyPosts All Forum Topic
💎Sustaining Member
As I stated before , the chamfer faces the crank ... period, end of story .....Been there, done that and old enough to know better.....
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-27-2020 07:58 AM  13 months ago
wjvail

rrElite Veteran

Meridian, Mississippi

MyPosts All Forum Topic
UKhelinoob ...here a guy is installing the piston/ connecting rod assembly....

Watch at YouTube

It's two o'clock in the morning and I just watched that video. Man I gotta start sleeping better.

The video is a seven minute tutorial on how to put a motor back together … and he never does get the sleeve in the motor. The video abruptly ends and the motor is in exactly the same condition as when the YouTube started. Pretty entertaining. I know everyone has to start somewhere - but why would you make an instructional video on something when you probably should be watching one instead?

Anyway... I'm still confused. The chamfer goes towards the backplate?
"Well, nothing bad can happen now."
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-27-2020 08:46 AM  13 months ago
dgoss999

rrApprentice

UK - Lancashire

MyPosts All Forum Topic
I go by the oil hole. It leads the rotation of the crank pin to pick up oil as it goes round!https://www.facebook.com/scale.skids.52
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
09-30-2020 01:52 AM  13 months ago
douflytoo

rrNovice

Valparaiso, IN. USA

MyPosts All Forum Topic
dgoss999 I go by the oil hole. It leads the rotation of the crank pin to pick up oil as it goes round!
Only halfway 'round. Think about it.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
09-30-2020 07:25 AM  13 months ago
wjvail

rrElite Veteran

Meridian, Mississippi

MyPosts All Forum Topic
Good lord...

The chamfer goes towards the crank. As several other have said - end of subject.

If you put the unchamfered side of the rod closest to the crank you stand a very good chance the rod will rub very hard on the backplate (because it doesn't go on completely) or the rod will seize on the crank journal because there is insufficient clearance (and therefore insufficient lubrication) at the journal's radius.

Who knew this thread would go on this long?

"Well, nothing bad can happen now."
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
10-01-2020 10:34 PM  12 months ago
LimeyMike

rrVeteran

Michigan USA

MyPosts All Forum Topic
wjvail Good lord...

The chamfer goes towards the crank. As several other have said - end of subject.

If you put the unchamfered side of the rod closest to the crank you stand a very good chance the rod will rub very hard on the backplate (because it doesn't go on completely) or the rod will seize on the crank journal because there is insufficient clearance (and therefore insufficient lubrication) at the journal's radius.

Who knew this thread would go on this long?

OK. I'LL have to remove the backplate and see..

SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
10-01-2020 10:47 PM  12 months ago
LimeyMike

rrVeteran

Michigan USA

MyPosts All Forum Topic
wjvail
UKhelinoob ...here a guy is installing the piston/ connecting rod assembly....

Watch at YouTube

It's two o'clock in the morning and I just watched that video. Man I gotta start sleeping better.

The video is a seven minute tutorial on how to put a motor back together … and he never does get the sleeve in the motor. The video abruptly ends and the motor is in exactly the same condition as when the YouTube started. Pretty entertaining. I know everyone has to start somewhere - but why would you make an instructional video on something when you probably should be watching one instead?

Anyway... I'm still confused. The chamfer goes towards the backplate?
He's just showing which way the connection rod does in.. Mine went on real easy..
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
10-01-2020 11:16 PM  12 months ago
LimeyMike

rrVeteran

Michigan USA

MyPosts All Forum Topic
Guys.. I've fitted the Rod with lump out towards the backplate. (connecting rod is closer to the crankshaft now) There is no chamfer on the lump side of the connecting rod, so I hope your all right or I'll be coming after you...
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 547 views Post Reply
Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Piston connecting Rod
Print TOPIC

 5  Topic Subscribe

Tuesday, October 26 - 6:26 pm - Copyright © 2000-2021 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online