Connecting rod bearing siezed on 01 426

13 replies to this topic
  • obxnc

Posted March 30, 2006 - 06:35 PM


My torque monster siezed the lower connecting rod bearing.

What would cause this??

I am not splitting the cases until the new assembly arrives so now is the time to get all of the information. I have read the manual and it states that I will need some special tools for the crankshaft removal/installation.. Then I have read some previous posts where they were not needed. Anyone done this without any special tools??

So far I have the right side case off (the one that exposes the clutch) and the clutch removed. The left side cover is off too. The engine is out and on my table. I removed the head and cylinder. The head and piston top has tons of carbon on them. I am going to clean them up good and put a new set of rings on. A hot cams exh cam will also be going in. Everything else (so far) looks pretty good with no wear marks at all.. All of the gears look fine on the counterbalencar, oil pump, primary drive gear, kickstarter. Once i crack it, what are some things to look for on the "inside"?

Thanks for all of the help so far... :thumbsup:

Before long, I should be riding again... :thumbsup:

  • BC61

Posted March 30, 2006 - 08:29 PM


It does require special tools and if the crank isn't pressed right it could starve for oil. I had mine done by Andrews Motorsports. Labor was about $300, the parts are expensive.

I purchased my bike used so I don't know the complete history of the motor but it only showed signs of normal wear, no hot spots from oil starvation or anything that would really tell why it stuck the rod bearing. The rod bearing is a roller bearing and something in the rollers gave way. Decided to do a complete rebuild and replaced everything in the motor except the cams and a crank half. There are several things to look at when you have the motor apart. Look at the crank half with the timing chain gear teeth. They can wear excessively. Look at the piston skirts for wear marks. They will tend to show wear if the air filter wasn't cleaned regularly. If you are getting into the head check the valves and seats.

Good Luck!

  • obxnc

Posted March 31, 2006 - 04:16 AM


Thanks for the quick reply. By the way, where are you at in NC??

I am not splitting the crankshaft and replacing part of it. I just purchased the whole assembly. My local dealer said the price would be about the same if I either bought a new assembly or sent mine off with a new connecting rod and bearing. So I just opted for a complete new assembly. There is some bluing on one side of the connecting rod bearing. I guess when I pull it all apart, I can really research it. I think I am going to split the cases this weekend. I have the crank, rings and gaskets on order. I should check out the tranny gears/forks and put those on order if needed.

Like the famous Honda commercial......I wanna ride.. :thumbsup:

  • obxnc

Posted March 31, 2006 - 04:21 AM


I forgot to mention... I talked to the head mechanic at my local dealer and he has seen this once before.. On an 03 450. He called a Yamaha tech and they said it could be caused by running low octane gas. And you should always add octane booster to your gas... :thumbsup:

Anyone want to throw their two cents in on that one????

  • BC61

Posted March 31, 2006 - 05:30 AM


I'm in Charlotte. Does the crank assembly you bought come with a new bearing and rod already on it?

  • ctheojr450

Posted March 31, 2006 - 06:19 AM


My friend just siezed his lower crank bearing on his YFZ450---He runs 87 in it sometimes----I always run 91 or above

I guess if gas is predetoniating due to low octane, that must put a lot of stress on the crank rod and bearings....

My 2 cents goes into buying the better gas for my bike (I have a 426 also)

  • obxnc

Posted March 31, 2006 - 06:27 AM


BC61 - It is the complete assembly with connecting rod (no need to press anything apart) and it was 339.00. The mechanic said that I would spend close to that repairing the one that siezed.

I am definitely with ctheojr450.... Nothing but the good stuff from now on. I am guilty of buying the 87/89. I would rather spend the extra dollar each fill up than the 440 I already have invested in parts for this rebuild.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • chris288

Posted March 31, 2006 - 07:56 AM


My 01 426 also seized the lower rod bearing... Always ran premium...

Octane booster is basically useless... it will raise 87 a tiny bit but do nothing for 93...

  • BC61

Posted March 31, 2006 - 07:56 AM


Good to know in the future. Does it come from Yamaha?

  • mkporn

Posted March 31, 2006 - 08:54 AM


When splitting the cases, most of the time you will not need anything to special other than a flywheel puller. Sometimes they are stuborn and a pain, this is when a case spliting tool or a steering wheel puller works good. When putting ebvery thing back together there are a few tricks to it so everything will go together like butter and you don't need to use a press.

Put the crank and the main bearings in the freezer for a hour or two.

Clean up the case halves and make sure every thing is in order and in place as if you are ready to put the halves together. (make sure the o-ring for the oil galley transfer tube is in there).

heat the case halves where the main bearings press in. (at this time have a 2" round slug of steel heating on the kitchen stove for later). do one half at a time. Heat it up and take a main bearing out of the freezer. Install it in the heated half. It should drop right in with out problems, if it sticks, a couple of quick taps with a soft blow hammer will help. Repeat on otherside.

Run a small thin coat of quality (three bond) liquid gasket around sealing surfaces of cases.

Now get your very hot steel slug off the stove and place it on the inner race of your freshly installed main bearing (side with all the tranny gears installed). This will heat and expand the bearing race. Remove the crank from the freezer and drop into the heated main bearing (should slide right in) While installing the crank in one side have your hot steel plug heating the other bearing race. Once the other half is ready to go, put your case halves together (little tappy tappy and it will go right together)...... Your are on your way to riding. :thumbsup:

  • yogist

Posted March 31, 2006 - 04:47 PM


I have an 01 426 and stories like this make me nervous.....
I change my oil frequently and maintain the bike well...
I do use regular unleaded...Is there a desighn flaw in the lower rod bearing assembly..?? Or oil pump..?? This part of the bike is old technology..
I dont hear stories of gears chewing up or rod bearings going on the other bikes, Say Honda for instance...I know they have a top end problem with their valves and heads...But bottom end trouble ..I dont know..
I suppose I could sell it, or just get used to the fact that one day its gonna happen..Then I suppose it will be a learning experiece splitting the cases and diving in...Any thoughts on preventitive maimtenance for the bottom end..??

  • BC61

Posted March 31, 2006 - 05:15 PM


change your oil frequently and make sure it doesn't run low

  • yogist

Posted March 31, 2006 - 06:47 PM


I change my oil every 10 to 15 hours, and its barely dirty when I change it...
I keep my filter clean and change it out every other oil change..

Are the bearing in the lower end rod Substandard, anybody ever try a higher quality bearing..?? Just curious..

  • obxnc

Posted April 09, 2006 - 06:42 PM


Here is what I found... That is alot of stuff to remove to crack the cases. On the inside, there was some metal shavings in the bottom. Every gear in the tranny was perfect and showed NO signs of wear, all of the bearings were also tight and smooth.
On the crankshaft, I read in a previous post about blueing on the side of the connecting rod. Well, that is not indicative of it getting hot in your bike. The new crankshaft had the same blueing. Must happen during the manufacturing process.
Only special tool I used was the flywheel puller. I made my own crankshaft puller (to seat it back into the left case bearing).
All in all, it was an awesome experience. Started the project yesterday at around 2pm. Had the motor completely rebuilt by 1am. Also put in the HotCams exhaust cam.
Today, I installed the motor and put the whole bike back together. Now that took forever and I recommend taking pics of cable routing, wish I would have..
All in all, after it was put back together and all of my fluids full, I kicked it.....and it fired right up...Everything was perfect, except I crossed my throttle cables. Twistin up to get some gas.. Switched those and now it is done. I only ran it easily for the first couple of minutes. Then i rode it around for about 3 minutes. Now I will change the oil tomorrow and see what comes out... Hopefully it is all good. The cam swap is awesome. Highly recommended!!!!!

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