bearing failures

[dragzooks@indy]

everyone has a different opinion on why rod bearings are getting tore up on busas (especially on strokers)
compression, strokes, oil pressure, bearing design, etc, etc

lets discuss this and back up your reason/opinion

i've looked into most of these and there are holes in many
ran the oil pump gear, case studs, set em loose, set em tight---still smoked em

high compression doesnt seem to kill them on non strokers
turbos have a very "soft" effect on the crankshaft unlike a nat asp or nitrous engine which gets pounded so what lives under 3 or 400 hp in a turbo doesnt necesarilly apply

the busas uses the exact same bearing as an old cooled gsxr1100 (same part number)
ive built those with 7mm strokers and they live fine even with 350 hp and more on the bottle
so i dont think it is the part itself

what i am looking at now is the rod ratio
when you stroke an engine the rod ratio goes down unless you accompany the stroke with a rod that is lengthened
rod ratio=rod length (center to center) divided by the stroke (both must be in inches or mm to keep a meaningful comparison)

here goes

busa (stock) rod ratio       =1.90  (1.90:1)
busa +5mm stroke/stock rods  =1.76
busa +8.5 and stock rods     =1.67
   
to get the ratio back to stock you would have to increase the rod length by a little over .350" when adding 5mm stroke
not the easiest thing to do considering the stroke already raises the piston 2.5mm (.100")
so now you'd have to raise the cylinder almost a half inch (.450")
room in cam chain, stud/headbolt length, and engine mounting holes in the head become major issues
so what do all the engine builders on here think??
am i barking up the wrong tree thinking the rod ratio is killing the bearings when stroked?
back it up please

[dragzooks@indy]

cmon....nobody wants to touch this  

[THEMOTORHEAD]

THE GSXR OIL PUMPS WAY WAY MORE OIL THOUGH(LOW SPEEDS)
THE GUYS OVERSEAS RUNNING 12-1 OR SO ARE HAVING BETTER LUCK.
SO IT MAY BE SOME GET POUNDED.
I HAVE SEEN COMPRESSION MOTORS DO THIS.

THOUGH CRANK MFG COMPANIES CLAIM NO ONE HAS HAD ANY PROBLEMS.

[BADZXELEVEN]

So, if it has more low RPM oil pressure, a stroker will live longer than they do now?

[THEMOTORHEAD]

I WOULD THINK IT WOULD HELP ALOT
OR LESS COMP

[len]

dragzooks, I will have to prolly agree with you. the longer stroke with the shorter rod will lead to higher bearing speed, and larger latteral loads on the rod and bearing, . Dont know about the busa, but on other things, usualy the rod itself fails .probibly a combination of several things, . When you stroke the engine, you increase the piston speed, and if you increase the bore,and stroke, you have increased not only piston speed but also its weight . so you have a higher piston weight combined with speed to create a higher bearing load at high rpms.    .

[Jay]

As one who repairs a large number of cranks, I would say that the busa is low on the list of bikes that hurt bearings and journals.

And with the ones that do, the very vast majority are stockers. Strokers with bad journals are very rare, and I repair the competitions too, so I see a good example of what is happening.

The big pan with the swivle pickup helps a bunch. Most stroker motors also use these pans, so that is probably why they live so well.

Some of the leading shops have 5 or 6 strokers in rotation at any time, and they are not getting hurt or we would certainly hear about it.

GSXR1000s are killing cranks at a rate way higher than the busa. However, we have yet to see a 1000 stroker with damage. The number one repair we do is ZX11s.

Jay

[Jay]

As one who repairs a large number of cranks, I would say that the busa is low on the list of bikes that hurt bearings and journals.

And with the ones that do, the very vast majority are stockers. Strokers with bad journals are very rare, and I repair the competitions too, so I see a good example of what is happening.

The big pan with the swivle pickup helps a bunch. Most stroker motors also use these pans, so that is probably why they live so well.

Some of the leading shops have 5 or 6 strokers in rotation at any time, and they are not getting hurt or we would certainly hear about it.

GSCR1000s are killing cranks at a rate way higher than the busa. The number one repair we do is ZX11s.

Jay

[dragzooks@indy]

jay
we did a +5 (weld up)on a 84mm busa
high volume gear and case studs
lived half this season (street and track)
then destroyed one bearing and was well into the copper on the rest
clearances were mic'd and set correctly
not just coding up the letters on crank to the cases

another friend who runs basically the same setup in shootout (and has the pan and swivel pickup) only got 10 passes before he caught his in the copper when changing a shift fork
i know people with the 8.5 billets that pull their engines and change bearings every 10-15 passes causes they have already started to wear

talked to another board member here and he cant keep rod bearings in his stroker so he went back to running the stock crankshaft
maybe when these people encounter failure they are getting a bad taste in their mouth and go back to stock cranks
whatever the reason--it IS happening
at least around here with dragracers
and yeah, i've seen bone stock bikes come in knocking and needing new cranks and bearings

[A&J Performance]

I know a guy off this board, who has a stroker, that has street and dragged his bike for over a year, and never had a problem. He subscribes to the loose bearings school of thought.
I really don't get it. I have seen some failures but, you really can't just attribute it to one thing.
 Well Dennis says the old 1100 oil pump flows more, that should give us something to shoot for.
Joe

[dakinebusa]

Here is what Smokey says....

Take an old bearing insert and lay it on a steel block.  Hit it a couple times with a ball pein hammer at BDC.  Notice what happens.  The ends of the bearing pull in to a smaller diameter.  Smokey thinks detonation is like the hammer blows.  Causes the bearings to deform and the ends to pull in.  The edge created when the ends pull in acts as a sort of a chisel to remove the oil film from the crank journal.  Then the bearing wears and fails due to oil starvation and contact.

His answer...more bearing crush and don't ever detonate a high compression motor...ever!  All racing small blocks are line honed to increase bearing crush.

Sounds pretty plausible to me.  Most strokers are also high compression motors.  Detonation can happen so fast the tuner doesn't even know that it has happened and that the bearings have been hammered.  

I also think that the busa motor might have some oil flow problems.  Has anybody logged oil pressure at the far end of the oil gallery in a bike?

[Landspeed Larry]

Dragzooks: I agree with you. Suzuki has enough experience to design a motor with the proper rod ratio. The Busa is a torquer, not a revver. The more stroke you add, the more load on the rod bearings with the same rod length. Early TTS strokers used Honda XX rod journal sizes and they failed quite often so bearing area is not the solution. An engine builder I know sent bearings to Clevite to be examined. Their conclusion was that the Busa bearing was not of the highest quality. I assume Suzuki's testing showed a satisfactory level of reliability so they stopped there.BTW Pro Stock trucks used Acura rod bearings for reduced friction, but I am sure they changed them often. My Maxton turbo bike had no problems at 20+ lbs. in dozens of runs so I agree with the smooth push theory for turbos. I have a 10.5 mm stroker running at Bonneville (220MPH) which survived last year, but I gear it tall to keep the revs down. Drag racing's launch is inherently hard on cranks. I don't think more oil pressure is the answer. Keeping cool,non-aerated oil circulating is the best one can do.

[Steve A]

Nascar Chevy - 355 cu. in.) have about a 1:65 rod ratio and live at over 8,000 for 500 miles or so and the rods and pistons in one of those weigh a lot more than Suzuki 1300 parts.  Now thy are going to Honda bearings and smaller journal sizes and picking up 5 HP or so.

[len]

Steve,thats true, but 8000 rpms is a far cry from 10000. You have to look at piston speed, about 4500 fpm is usually the limit for longevety. and size is relitive . smaller pistons ,require smaller rods, ect, . The weight to strength  ratio is still close. and bearing size. Scrapping the oil off the bearings is possible but I would believe you would see signs on the ends of the bearings.More wear. But a shorter rod on a longer stroke has more lateral load, theirfore more bearing (oil film) pressure. What do the mains look like on the ones thats killing the rod bearings? And what type of oil and weight. Launch rpms, red line rpms? really need a lot more info. to see whats going on. As for the GSXR 1000's ,well they are GSXR 1000's , what more needs to be said.

[Steve A]

I was looking more at the ratios and the longevity on the V-8s.  A 1:9 is better than a 1:65.  I'd guess it might be poorer bearing material.  High oil pressure is not really necessary as long as there is adequate flow rate.

[len]

you mean theirs suppose to be oil in their?  

[len]

A person building a stroker or high hp motor from the ground up, realy ought to radious the oil ports and galleys, crank and case. So you get more volume. that goes back to basic hot rodding.and you really dont see much of it.Its the little things that count sometimes.  

[Steve A]

DDB:  It's not really necessary as long as you have no aversion to tearing your engine down constantly!!!

[len]

like I dont have anything better to do with my time. or spend money on. Hell if thats the case, just spread some grease on the bearings, just like the open rockers , Hell, it will make a pass, something else will prolly brake first anyway.----Steve you know as well as I do, Its the little things that make you win. details,. You cant win the round, if you cant make the     pass.

[Steve A]

You are absolutely correct.

[spdingtkts]

I know that some guys are running more oil in their crankcase. They add oil until it is at the top of the sight glass, then they add another 3/4 of a quart.

I think that modifying the oil galleys is a good idea, but I do not believe that it is the fix for the problem.

I know another engine builder that installs a restricter in the feed line to the oil cooler. He does this in order to increase the oil volume fed to the bearings.

I wonder about either removing the oil sprayers or restricting them on a normally apsirated engine. This should also increase the amount of oil to the lower end. There are plenty of engines out there that don't spray oil underneath the pistons.

[Steve A]

If the oil level is too high then the rotating parts will whip it into a froth and that doesn't lubricate well at all.  Plus, it takes a lot of power to whip it into a froth.

[MillenniumFalcon]

I have built several strokers in the Harley days and I am now gathering information on how best to go about doing it to my Suzuki. I first talked to the head machinist at Falicon. Rod angularity is a consideration and longers rods are recommended but not required. I also talked to Brock about it and he recommended going with the steel billet cranks and not the reworked cranks. I believe he used a Falicon in his Bandit that broke the 7 sec record. http://www.faliconcranks.com/

That being said I am not expert, that's why I talked to Brock and Falicon, but it seems to me there are a lot of variables like the rod length, oil supply, high compression, crank type, radiused oil holes, detonation and bearing clearance. You could get all but one right and still lose the bearings.

I think you have the right idea. Try to find out whose not losing bottom ends and see if they will share the technology.

[THEMOTORHEAD]

many have blocked the squirters

[Badbusa1]

Last year I spun #1 rod in my motor ( this is the furthest bearing away from the pump) upon disassembly I noticed a couple of things. The closer to the pump the better the bearings looked BUT all were in the copper. Between Journals 2 3 4 the cases were flexing and that had to be losing some oil. The rod bearings are the exact part # for oil cooled motors, so I doudt it is really a " bearing material problem"
 
    I disassembled my motor this year after the season was over and my bearings looked good nothing bad or out of the ordinary!!

   This is what I did to help the problem
1 high volume oil pump gear
2 modified the oil pump pressure relief valve
3 I put case studs to keep cases from flexing
( I knew the cases were flexing last year because the aluminium was blackend on those journals were the bolts went thru like they were rubbing)
4 all  loose bearings on rods only (green )
5 I made a oil line going from oil gallery on right side of engine above the sending unit to the #1 main that feeds the #1 rod. you have to have your engine disassembled to do this because you drill down thru the oil gallery out the bottom of the case, tap the hole run the line and your done..    

  this may not be the fix all for everyone but it took care of my problems, and I run the oil level to the top of the site glass( I would rather miss 1 or 2 hp than tear up an engine in the middle of the year!