Author Topic: Tip of the day series - RD rod bearings  (Read 1298 times)

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Offline SUPERTUNE

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Tip of the day series - RD rod bearings
« on: March 09, 2020, 12:10:16 AM »
On RD crank rebuilding, there are options to go to better bearings for the connecting rod replacing both stock upper and lower needle cages.
With stock engines modified up to air filters and aftermarket chambers only... stock bearings are fine.
Once you add cut heads or aftermarket heads, porting, big bore pistons, bigger carbs, aggressive ignition curves and any more advanced power adder's I would recommend with these upgrades on the rod bearings.

In this pic, the wristpin bearings to the left are stock RD type. These in the pic are Pro-X replacements and are exact copy's of stock OEM Yamaha just like the Wiseco's as well.
The Snowmobile ones I use for upgrade's have 2 more pins and 1mm longer for much better load handling in higher HP in RD engine setups.
Years ago we were able to use OEM Kawasaki H1-500 pin bearings that were like this, so was the LA sleeve H1's.... but are not available any more and with the supply market now when you order for an H1, they give you the RD type as it is the same fitment in physical size.
I was able to find a supplier 2 years ago, but have to pre-order 100 qty at a time. When I get down to about 10 on the shelf I place another pre-order for 100 more.

The lower rod bearing is also another weak link on the stock RD rod assembly with the stock lower rod bearing having 14 needle pins and the upgraded RM125 has 17 pins, the pins are 1/2 mm longer and are in a much stronger flat silver plated cage that doesn't crack like the stepped Yamaha type (Pro-X and Wiseco) that is copper plated.

So this has eliminated any rod failures in our race motors. When we did have a crank failure, it was always the rod bearings first...since using these better/stronger bearings now the cranks are lasting longer and when we do have a crank failure it's always a main bearing now. 

Chuck


RD machine work, boring, porting, cranks and engine building.


Chuck 'SUPERTUNE' Quenzler III
Team Scream Racing LLC
1920 Sherwood St. STE A
Clearwater, FL. 33765
cqsupertune@tampabay.rr.com

Offline Hawaii-Mike

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Re: Tip of the day series - RD rod bearings
« Reply #1 on: March 09, 2020, 12:22:23 AM »
Yay Chuck!

Offline Alain2

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Re: Tip of the day series - RD rod bearings
« Reply #2 on: March 10, 2020, 11:39:59 AM »
Can you use RZ350 rods on a rd350?
1973 RD350, 1977 RD400, 1979 RD400, 1985 MJ50, Goped Zenoah 30cc.

Offline SUPERTUNE

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Re: Tip of the day series - RD rod bearings
« Reply #3 on: March 10, 2020, 12:32:28 PM »
No, RZ/Banshee is 29mm big end rod bearing, RD is 28mm, RZ/Banshee rod is 1mm wider also on the big end at 17mm, RD is 16mm.
C
RD machine work, boring, porting, cranks and engine building.


Chuck 'SUPERTUNE' Quenzler III
Team Scream Racing LLC
1920 Sherwood St. STE A
Clearwater, FL. 33765
cqsupertune@tampabay.rr.com

Offline 350GUY

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Re: Tip of the day series - RD rod bearings
« Reply #4 on: March 10, 2020, 09:58:23 PM »
Good evening Chuck,

Excellent tech info, many thanks.
Quick question. Since the RM125 are 1/2 mm longer, are the thrust washers still utilized?

B'rgds,

Daryl

Offline Dvsrd

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Re: Tip of the day series - RD rod bearings
« Reply #5 on: March 10, 2020, 10:00:18 PM »
What about the rod itself? Before, some recommended TZ 250/350 rods. Those were more H-beam like in cross section. And TZ big end bearings as well, with silver plated cage and non-captive rollers.

Offline SUPERTUNE

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Re: Tip of the day series - RD rod bearings
« Reply #6 on: March 10, 2020, 10:35:29 PM »
Good evening Chuck,

Excellent tech info, many thanks.
Quick question. Since the RM125 are 1/2 mm longer, are the thrust washers still utilized?

B'rgds,

Daryl
How have you been Daryl?
It's been a while since we last spoke...

I use Pro-X rod kits and the clearance is close, but the stock rod bearings ones were a little short anyways so nothing is affected much.
Chuck
 
RD machine work, boring, porting, cranks and engine building.


Chuck 'SUPERTUNE' Quenzler III
Team Scream Racing LLC
1920 Sherwood St. STE A
Clearwater, FL. 33765
cqsupertune@tampabay.rr.com

Offline SUPERTUNE

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Re: Tip of the day series - RD rod bearings
« Reply #7 on: March 10, 2020, 10:48:21 PM »
What about the rod itself? Before, some recommended TZ 250/350 rods. Those were more H-beam like in cross section. And TZ big end bearings as well, with silver plated cage and non-captive rollers.

For sure a great option, but usually out of reach price wise for most RD engine builds and IMO not needed unless using a water cooled TZ topend with big power. The RM's are fine even for roadracing at 20:1 to 25:1 premix, also the Pro -X rods are lighter than the stock fatty rods, so that lowers the stress factor on the rod bearing load it see's.

 Pro-X rods are a slotted rod for improved oiling of the lower rod bearing.
Rod failures are not too common with this setup.
Chuck
RD machine work, boring, porting, cranks and engine building.


Chuck 'SUPERTUNE' Quenzler III
Team Scream Racing LLC
1920 Sherwood St. STE A
Clearwater, FL. 33765
cqsupertune@tampabay.rr.com

Offline 350GUY

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Re: Tip of the day series - RD rod bearings
« Reply #8 on: March 11, 2020, 10:01:23 PM »
Good evening Chuck,

Good to hear from you, indeed it has been a while.
Many thanks for clarifying, much appreciated. As always, you are on the ball!
talk soon.

B'rgds,

Daryl

Offline Rhino363

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Re: Tip of the day series - RD rod bearings
« Reply #9 on: August 20, 2020, 07:38:29 AM »
Do you have a part number for the rm125 bearings or what year of rm125 bearings?
Also Would I be able to buy 2 of the wrist pin bearings from you?
Thanks

Offline SoCal250

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Re: Tip of the day series - RD rod bearings
« Reply #10 on: August 20, 2020, 11:56:29 AM »
Do you have a part number for the rm125 bearings or what year of rm125 bearings?
Also Would I be able to buy 2 of the wrist pin bearings from you?
Thanks

Bearing info from Chuck that has been collected and updated over the years is posted in the Tech Library
79 Yamaha RD400F     77 Yamaha RD400D      91 Yamaha TZR250R
75 Yamaha RD250B     75 Yamaha RD200B (project)
75 Yamaha RD125B     75 Yamaha RD125B (project)
89 Yamaha FZR400      05 Yamaha FZ6
** 02 Aprilia RS250 Cup for sale
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Offline linker48x

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Re: Tip of the day series - RD rod bearings
« Reply #11 on: February 12, 2021, 07:27:26 PM »
Hi Chuck, long time since we have talked.  You don't mention the Kawasaki Jet Ski wrist pin bearings in the text here, and in the tech sheet linked here, the Kawasaki Jet Ski wrist pin bearings are marked as unavailable, but I seem to remember being able to find them by sniffing around the internet some.  But maybe that old stock is gone too, by now?  Anyway, hope all is great down in warm old Florida, Alaska is pretty chilly these days!  Miss racing too, getting old sucks!  Jamie