A better BE bearing for Suz 250/250 twins

[Vintageman]

It apears that engines that have more rollers in the connecting rod bearing are stronger? For example the Suz twins T250/T250/T350 and even GT380 don't have very many rollers per cage. I am sure there are more factors that make a high quality BE, but that looks to be one. For example some hi rel engines run cageless.

this is the part 09263-20020 = 20X26X16.7 I have sean it also stated as 20mmx26mmx16.8mm. I think the BE must be a little shorter than con rod width so the con rod rubs on thrust washers, not cage? so if I found a "Better" BE like 20x22x16 it should be OK.

Any Idea what a better BE is and where I can look at suppliers. Anyone have experience racing these twins?

Thanks

[Vintageman]

cage less no go for Big End. Low speed stuff higher load so only on small end.

So a cage is needed for BE. There appears to be two general (see NTN bearing) types of cages: one for higher speed for it has lower friction. Low friction design tends to allow more bearing per circumference.

Well the size (20X26X16.7) is an odd one and so far I am fining no other choice (only checked NTN must be others?)other than stock.

Again if anyone has experience racing these 250/205/350 twins and has found a better BE let me know.
For example when I did my GT750 I put the ones from the RMX250 I think even Bill Bune’s guys know of this and have them if you prefer.

Keep the RPMS below 9k is the moral of this story so far

[Suzukidave]

Maybe SKF ? they have a listing for Super-precision bearings http://www.skf.com/group/products/beari ... index.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

[Craig380]

Adrian Baker has won championships in the UK with his T20 racer: http://www.t20suzuki.com

I had a quick look and he doesn't mention beefed-up big ends - only converting the main bearings.

A long time ago I had a chat with Barry Hart, who was one of the guys behind the Sparton racing triples which were developed from the 380 motor. I recall he said the standard crank and rods were strong enough, but that the biggest challenge they overcame was stopping the main bearings 'chattering' in the crankcases at high rpm. I believe he said they machined the cases to use half-moon rings around the outer race as well as dowel pins to stop the bearings moving.

[Vintageman]

I had a quick look and he doesn't mention beefed-up big ends - only converting the main bearings

He uses TZ/RD cranks when racing. "Great Idea!" Check out what those Tz BEs look like.

He states “… only a few hundred miles mains fails…” The BEs not too far behind miles wise me thinks. Running only up to 9-10K RPM I find the BE fails not the mains.

I run mix (64:1) and injection on that bike. Maybe not enough oil? I think these guys run 15:1 or 20:1. I could not see where he says specifically. I think the failure mode it heat due to friction per previous post.

I still think there are better BEs if you want to extend you crank life at higher RPM...

I'll keep looking for another BE for the Suz crank. Chances are nil.

Put in a Yam crank!


Thanks for SKF.. alot of info here

[Suzukidave]

This is interesting about bearing speed related problems http://www.skf.com/group/products/beari ... index.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

[Vintageman]

Haven't had time to research this a lot further with manufactures. So far I am just going NOS BE and running no less than 32mm EX port height (verify 32mm is blueprinted to stock 7500 RPM peak).

What is clear is the cage design and machine finish (same with needle roller ends) is critical. These . Makes me nervous to buy an aftermarket BE ala rod Kit. The crank Pin is NA from OEM. So may need a kit for just for Pin but ding BE for NOS

I saw one BE that was 17mm long versus 16.7 mm.. wonder if that is a problem running as is?

[tz375]

When I had a few Honda CB77 cranks lightened and rebuilt years ago we had a few big end cage failures. The issue was that the rollers had a sharp end as if they were just cut off a length of steel and that sharp corner was machining into the cage and then a crack propagated from the corner.

The fix was simple but took time - I rounded the ends off each and every roller and then assembled the whole thing

[Vintageman]

[

The fix was simple but took time - I rounded the ends off each and every roller and then assembled the whole thing

Yes that is a great idea.

I think the high RPM BE design may not have more static load strength than lower ones. They have been designed to generate less heat due to friction be it design and/or higher machining standards.

I still wish I had time to call around and see if I find a high RPM one. I'll have to email them

what do you think about 17mm length in place where a 16.7mm is called out?

[Vintageman]

I think this will work and a better beairng maybe

KZK 20x26x17. I know 17mmm versus 16.7mm but maybe sand a little either sid eor use as is.

Now trying to buy a couple
I'll call timken

https://www.timkenstore.com/images/Scha ... 03P026.pdf" onclick="window.open(this.href);return false;

Here is a pic of one by someone else

http://www.bing.com/images/search?q=kzk ... de=overlay" onclick="window.open(this.href);return false;

[Vintageman]

What I think I have found so far... the bearing is small in dia. relatively for engine of this size and max load is limited for this reason from one vendor to the other.

Oh well is what it is

[Vintageman]

Supposedly some RG500 Suzuki's came with 20x26x16.8 Big End BE and high performance silver cage from OEM. I could not find it searching RG500 parts for number. I only see the Larger 22mm x 28mm x16.8mm.

Saw these on ebay and bought them. they verified cage size, but aftermarket (or not Suz branded).

I am having a gt380 crank redone and T350. Suppose I'll use. Gulp

If anyone finds RG500 OEM number for this size let me know...I prefer OEM. But snatched these

From pics the cages look just like OEM design but silver not copper. Some aftermarkets have a subtle cage machining difference. I hope just like ART piston Makes Suz Pistons

Again if you have OEM number do tell

https://www.ebay.com/itm/362011943121?ul_noapp=true" onclick="window.open(this.href);return false;