TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: johnny22 on May 26, 2014, 11:37:02 AM
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well guys, looks like this cylinder and crank are done. Ran very well for the time that I had it but time to move on. any input is welcome.
(http://forums.trx250r.org/vbulletin_imports/15_2076_2017-04-18_8661.jpg) (http://forums.trx250r.org/vbulletin_imports/15_2077_2017-04-18_8709.jpg) (http://forums.trx250r.org/vbulletin_imports/15_2078_2017-04-18_8168.jpg) (http://forums.trx250r.org/vbulletin_imports/15_2079_2017-04-18_5628.jpg) (http://forums.trx250r.org/vbulletin_imports/15_2080_2017-04-18_9112.jpg) Its pretty heartbreaking.... almost like a really bad breakup. But the bright side is that it took out my dads bike a couple times (his bike still has a lot of potential left in the setup), took out john safarians 420 a couple times and ran with a few alky shees and a beat a couple of 4 strokes this weekend
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Alot of guys don't think about replacing the wrist pin bearing or rod bearing when they do a rebuild. Does look like you were having fun up until this point.
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I have seen this type of connecting rod failure many time on the aftermarket connecting rods but never on an OEM Honda rod. Who manufactured the connecting rod??
Show us both sides of the connecting rod so that we can identify the con rod manufacturer.
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its a pro x rod by ESR. I will post pics of it once I get it apart. I cant get the rod to pull up. its sitting on the table still. haven't had the money to get it in a chassis yet. I was getting close but now this happened
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shit happens unfortunatly sometimes. thats first prox rod ive ever seen broke
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Johnny, want to sell the saber to pay for this little mishap????????
Did you get the lectron to run correctly? and John Safarian is a hoot. Him and his son stopped and shot the bull with us for a while.
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Haha nooo that saber is stay in with me man. Sorry. Nah I switched to my other carb. Didn't feel like dealing with it. Man john is awesome. Always fun talking to him and racing him
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Ahhh the life of a drag racer..."It's go or blow baby"....sorry about the carnage....
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haha right? lesson learned... onto the next one $$$ haha
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johnny what about cr500 rod next time. i thought about it on my 300 . even bought a old used snomo piston from ebay to see how i could make it all fit together . 19mm spacer plate would get a few strange looks :jumping0041:
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Johnny, I had a similar failure on my first oem drag cylinder. Lost the wrist pin bearing, then rod, then piston just as it appears you have. Bad feeling right there, something that doesn't let you forget quickly. I'm impressed she was hangin with Safarian's 420. NICE!!!
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Haha 19 mm plate would look fishy to every one. What are the options for an upgraded 5 mil rod?
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ktm 380 is a great rod too, much lighter than the cr500 with limited big end clearancing for strokers
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So both of those are definite upgrades over the pro x rod that was in there?
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380 rod is a expensive bugger at $250 and it can only be bought through ktm as far as im aware. theres also a 129 and 132 rod but i dont know much about them so maybe theres a aftermarket source so you dont break your wallet.
i got looking and found the 380 is plug and play on my ktm300 so ill probly give it a shot, its just a matter of adding the spacer plate. my intention was to dyno before and after with nothing changed but the rod only for curiousity to see what happens. ill set the cylinder back to the same height and try to keep everything as close to the same as possible. which reminds me i gotta make a dyno post and hopefully jerry or arlen can answer a question
(http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140209_173512_zpsf296eef7.jpg)
(http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140209_172954_zpsb0c57984.jpg)
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So both of those are definite upgrades over the pro x rod that was in there?
prox rod is good stuff so i dont think its a qaulity issue here. maybe you just exceeded its breaking point some how or possibly something went wrong with the wristpin bearing. ktm parts wont necesarrily be better qaulity than prox i dont think, but the beam and small end may be alittle thicker for more strength
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OK I get what you're sayin. I will probably just end up goinf with the same rod and same setup basically then, probably on alky though. from the looks of it and after talking to a buddy of mine he have me his opinion because he saw how many passes I make at once and it made sense. I ride it pretty hard most of the time and it may have just gotten too hot especially since I went down in jet size per someone else's advice. Don't really want to put any names out there since it's no ones fault but mine
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well it might not hurt to look into a beefier rod. i think theres atleast 3 different ktm rods that might fit but i dont have their dimensions off hand to see how they compare to your rod. . i have a 380 rod if you need to know anything about it but i dont have any info on the 129 and 132. you might check prox site and see if they list the specs on them rods
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I use after market rods as a last resort when I cannot find the dimensions I am looking for in an OEM rod. I have seen too many of these types of failures in aftermarket rods. Years of observations of hundreds of related failures points to poor designs, substandard metallurgy and quality control in the aftermarket connecting rods and cranks. Wrist pin bearing failures will not usually cause the rod to break like the one pictured unless you are drunk and completely oblivious to the noise the engine was making. These types of failures are the result of running a piston that was much heavier and at a much higher RPM than the rod was designed for or the heat treat was not right or they drilled the oiling holes in the side of the rod right where the stress is at a maximum. I think that being a mechanical engineer often gives more insight to the understanding of where stresses are located and if failures occur in those areas. Did the rod break through the oiling holes?
The quality control is higher in OEM parts. Engine manufactures have a lot more to loose when they produce the whole engine. Anytime I have ever had a problem like the rod pictured, the aftermarket parts manufacturers ALWAYS point the finger at the engine builder or the operator. They are sometimes correct when they point the finger at the crank builder, especially when the crank builder grinds the outside of the big end of the rod for case clearance for a stroker crank.
The price of an OEM rod could have been a big savings when you have this type of rod failure even if the OEM rod cost $500.00.
I am not saying that an OEM rod could have prevented this failure especially if the engine was over-reved with a big heavy piston.
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Hot rods now makes the 132mm ktm rods. You could even go to a yz490 rod its 137.5mm would need the right spacer. The yz490 you can only get through Yamaha so there not the cheapest. But the hold up well in my puma.
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Its hard to tell where it broke jerry. I havent found the other pieces of the rod and where it broke it hit something more than once so it doesn't show it. It doesn't looks like at broke at the holes though
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I never knew that you could run all those different ones. That's interesting
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490 rod uses 24mm lower and 18mm upper pin ? thats weird. normally the bigger engines use larger pins. but anyways at 137.5mm im not sure what plate you would use. maybe the .5" (12.7mm) thick and machine it down ? 135 rod seems alittle more straight forward. .375" plate which actually will measure closer to .385" then a .015" gasket on each side of the plate and you should be back to a pretty good cylinder height but you can always fine tune it with different thickness gaskets. id like to see the 129 and 132 rods. that might not be a bad choice either depending if theyre heavy duty enough. but which ever direction you go, i dont see one good reason to stay with a short rod.
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Here is a 132mm Ktm rod on the left next to a pro-x honda rod. I am not sure what set-up you go with in a 370 with the yz490 rod. I am pretty sure bubba Ramsey runs a 490 rod in his wife's 370. The 132mm ktm rod is pretty beefy.
(http://i1195.photobucket.com/albums/aa399/honda124/ktmrod_zps780fcf6c.png) (http://s1195.photobucket.com/user/honda124/media/ktmrod_zps780fcf6c.png.html)
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one on the left looks more sturdy for sure. so that 132 is pretty much a direct replacement for the 250r rod as far as the big and small end widths being the same so theres no machining needed to the rod or crankwheels ? whats the deal on the 490 rod. is it a direct replacment as well with no machining needed ?
check this out since were talking oddball projects. fitted a 144 honda rod onto ktm crank. originally it used a 140mm but it didnt seem up to the task :welcoming:
(http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140527_214847_zps8a9807a0.jpg)
(http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140527_214820_zps78087c1e.jpg)
(http://i1081.photobucket.com/albums/j357/doddledo/IMG_20140527_203354_zps87f2c9ac.jpg)
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My buddy dose all my engine work. He put a 132mm ktm rod in my polonda i dont think he had to do much machining other them the oil groves. To put a yz490 rod on a 250r crank there is a good amount of machining you have to do to the rod. But i do t think you do anything to the crank wheels.
Here is a new 490 rod then others pictures are going through machining next to my old rod off my puma.
(http://i1195.photobucket.com/albums/aa399/honda124/yz5_zpsa7400143.jpg) (http://s1195.photobucket.com/user/honda124/media/yz5_zpsa7400143.jpg.html)
(http://i1195.photobucket.com/albums/aa399/honda124/yz4_zpsc1768ec1.jpg) (http://s1195.photobucket.com/user/honda124/media/yz4_zpsc1768ec1.jpg.html)
(http://i1195.photobucket.com/albums/aa399/honda124/yz3_zps9c0bfad4.jpg) (http://s1195.photobucket.com/user/honda124/media/yz3_zps9c0bfad4.jpg.html)
(http://i1195.photobucket.com/albums/aa399/honda124/yz2_zpsc2063998.jpg) (http://s1195.photobucket.com/user/honda124/media/yz2_zpsc2063998.jpg.html)
(http://i1195.photobucket.com/albums/aa399/honda124/yz1_zpsf786aeba.jpg) (http://s1195.photobucket.com/user/honda124/media/yz1_zpsf786aeba.jpg.html)
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My buddy dose all my engine work. He put a 132mm ktm rod in my polonda i dont think he had to do much machining other them the oil groves. To put a yz490 rod on a 250r crank there is a good amount of machining you have to do to the rod.
Some builders do machine the KTM rod for clearance even though it fits without hitting. Maybe its the 4 mil I am thinking of. I have made many 2mm spacer plates for the use of the KTM 132mm rod.
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You may be right tony on the 4mm. Mine is on a stock stroke crank and I don't think James did much machining on the big end. It may have been narrowed a little but can't remember.
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stumbled upon this today. figured some of you want want to have a look
[video=youtube;fjgKtaX54gE]https://www.youtube.com/watch?v=fjgKtaX54gE[/video]
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Yz 490 rod on 4 mil crank and 78 mm ktm 380 flat top piston equals very small spacer plate with a pro-x or esr cylinder. The piston pin height is very high in the piston skirt I believe around .775 from the top vs over 1" on the 86 250r piston like everyone uses on the big bore pistons.
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They always run the best right before they come flying apart......! I watched your bike Saturday and it was running really hard, to bad that happened, maybe time to break out that saber....?
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thats right quick310r. haha i thought about it really hard and figured i barely have enough money to rebuild the 370 much less get the saber running and the chassis setup for it.
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Bummer johnny.
Interesting rod info.
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stumbled upon this today. figured some of you want want to have a look
[video=youtube;fjgKtaX54gE]https://www.youtube.com/watch?v=fjgKtaX54gE[/video]
I do not like using any of the aftermarket rods unless I cannot find an OEM replacement. If I have to make a choice I prefer Hot
Rods rod kits and cranks over Wiseco rod kits and cranks.
The premature failure of the crank in the video could have probably been prevented if the guy had checked the rod clearance before he installed the crank. The break-in procedure he used would not add life to any crank that has good machine work with the proper internal bearing clearances. No break in is required on good needle and ball bearings. If the crank failed because the con rod bearing clearance were too tight, it could need a 100 hours or more of run time to get the clearances where they should have been when he installed the crank.
We measure and inspect all of this stuff before we use ANY new rod kit or new crank assemblies. Our rejection rate for new OEM rods and cranks is less than 1%
Our rejection rate for aftermarket rods and cranks is around 30% to 40 %. Are you going to be one of the unlucky ones that gets one of 30% sub standard parts. Are you going to be one of the unlucky ones that buys one of the rod kits or cranks off Ebay or one of the online discount parts warehouses that liquidates the rejected parts. The rejects are not crushed or thrown away They find there way back into the hands of the inexperienced shops and customers.
I watched some videos of shops displaying their crank rebuilding skills. One idiot pushed the crank pin all the way through both crank halves on a Honda tin can crank because he did not have the right tools to separate the halves. This runs the crank pin hole that the failed pin was pushed through.
Another video shows an ill equipped shop where the guy is cutting the big end of the rod and crank pin in half using a disk on a die grinder
Another video I watched shows a guy truing a crank after pressing it together and only checking one end for runout. You cannot assume that the other end is true because the end you checked is true.
Another shows a guy rebuilding a tin can crank using a nice crank assembly jig and not checking it for alignment or "trueness". He said something like "the crank assembly fixture will usually get the crank within .003". That is not close enough. It could be your crank that he is working on.
In another video, the guys that is rebuilding the crank says he heard on another video that you do not need to get the crank alignment any closer than .002". This is another classic example of blind engine builders leading other blind engine builders.
I could not believe what I was seeing in most of these videos. Are these guys trying to impress potential customers or trying to warn potential customers not send them work.
I think that these guys should be spending money on the correct tools for the job and not video cameras. The time they are spending making videos would be better spent learning how to use the proper tools. Maybe they should stop watching videos on ways to do substandard work and spend that time learning how to rebuild cranks properly!!!
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It is a bummer but after talking with mat it sounds like it'll be ready for the 4th. He's doing his best to get it done. I just have to hold up my end and get him paid
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the problem i have with hotrods is the rod might be incredibly well designed with the best material but it appears that its still connected to taiwan bearing and crankwheels. so what good does that accomplish. not much imo. maybe the hotrods rod would be a good atlernative to oe rod if its installed on honda crank wheels (perhaps with a prox made in japan bearing and crank pin) ? i dont have that answer.
ive always considered prox rods close to oe in terms of qaulity. reason i use prox and not oe is because ive never found a place that sells cr500 oe rods seperate from the crank. you can buy every nut and bolt seperate but not a conrod. makes no sense
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the problem i have with hotrods is the rod might be incredibly well designed with the best material but it appears that its still connected to taiwan bearing and crankwheels. so what good does that accomplish. not much imo. maybe the hotrods rod would be a good atlernative to oe rod if its installed on honda crank wheels (perhaps with a prox made in japan bearing and crank pin) ? i dont have that answer.
ive always considered prox rods close to oe in terms of qaulity. reason i use prox and not oe is because ive never found a place that sells cr500 oe rods seperate from the crank. you can buy every nut and bolt seperate but not a conrod. makes no sense
The problem I have had with Hot Rod's connecting rods is the size of the big end of the rod are seldom the same. Some come through with taper in the big end. If you put a new rod or crank in and the one of the thrust washers fail prematurely it was probably because the bearing surface of the big end of the con rod was not straight. The taper in the big end of the rod will cause the rod to move to one side and overload the thrust washer causing the thrust washer to fail.
Some of the new con rods big end are too large making the clearance too loose and near the service limit when we take them out of the box.
Some of the new con rods are too tight and will fail almost immediately if the engine is run at sustained high RPM. If they are too tight we can hone them straight and to the proper clearance if the customer wants to spend the money for us to fix Hot Rod's problem. Hot Rod will not pay us to fix their mess and will tell you it was within spec when you send it back.