07 crank bearings went out in only 20hrs

[honda250xrider]

Hi Guys,

I was wondering if anyone could help me out and give me some possible root causes as to why after 20hrs a brand new OEM crank/bearings/seals the crankshaft end would have up and down play. The rod is perfect and still within spec.

I will also make another note I spent over 2g on purchasing all OEM components at the last rebuild which was 20hrs ago (hour meter confirmed) I bought a new right side crank case, hinson clutch, entire OEM bearing set, cylinder head, valves, literal everything was replaced and it was basically a crate motor. I'm just stumped on why this would happen.

I have roughly 1mm or so side to side play and up and down play... enough to hear a little click or clunk sound.

I was running a new 12:5 JE piston for roughly 15hrs then I changed over to a new JE 13:5 compression piston for the roughly 5hrs or so.

Is there a way to measure the end of my crankshaft to know if it wore this down at all and if its still usable?

I plan on buying new OEM bearings but was wondering if anyone could help and tell me why this would of happened? I am running a heavier flywheel trail tech +7 ounce. The only thing I can think of if its perhaps out of balance and putting additional stress on the crank..

[LoonRider]

I'm curious if it was the different case halves. Usually you need to buy them in pairs.

What model bike and how hard were you running it

[willbilly]

I have been running a 9oz. flywheel and 13.5 J.E. and my crank has 200hrs. MX.  The flywheel should have no affect, and a higher compression should not wear out a crank in 20 hrs.  I think Loon is on to something. Do the case halves have to be matched? Misalignment? Anyone?

[honda250xrider]

Loon,

You may have a good point. I purchased a new eom right case half because the other had some damage.

How do you go about ensuring alignment? It would seem like there's not much one could do if it is out of alignment.

This is on a 07 crf 450

Edited September 28, 2014 by honda250xrider

[LoonRider]

Yeah I've always been told and heard that you need to buy matching case halves. Something that that are matched with each other or something?

[nzgsr]

Its fine to replace crankcase halves on these crfs. There are some bikes where its recommended to change both, but the crf450r is NOT one of them.

Does the crank have play just on one side?

Edited September 28, 2014 by nzgsr

[Eddie8v]

Why did you have to buy the new right-side crank case? I might guess there was some sort of nasty failure and perhaps pieces are still floating around in your bottom end from that event, or your oil pump is damaged, etc.

Edited September 28, 2014 by Eddie8v

[honda250xrider]

Thanks for the tips everyone. 

 

 

I think I found the issue... I didn't notice it right off the bat but it appears that the bearing walked out about an 1/8". I'm assuming a new left side crankcase is in order now. 

 

The crank only had up and down play from the left side. (stator side) 

 

is 1/8" side to side play normal with the bearing pressed all the way in? Does anyone ever shim from the crank to the bearing to reduce the side to side play? 

 

Thanks!

Lance

[nesc103y]

Thanks for the tips everyone. 

 

 

I think I found the issue... I didn't notice it right off the bat but it appears that the bearing walked out about an 1/8". I'm assuming a new left side crankcase is in order now. 

 

The crank only had up and down play from the left side. (stator side) 

 

is 1/8" side to side play normal with the bearing pressed all the way in? Does anyone ever shim from the crank to the bearing to reduce the side to side play? 

 

Thanks!

Lance

 

 

the drive gear bolt will tighten the crank against the right side engine bearing, and hold the crank in place.

All the Honda's I've rebuilt have had a small amount of up and down movement on the stator side.

even after replacing the crank and main bearings.

[Jon-D]

I never rebuilt a Honda motor, but the KTMs i have rebuilt had a side to side tolerance that had to be shimmed at the crank. the process was to put the half's together (with the crank installed), torque the bolts down, then measure with a feeler gauge.  If the tolerance was off I had to take it apart add or remove shims and re-assemble it. i only had to do this if i installed a different crank or a new case(s). hopefully the Honda's are easier to rebuild, but does your manual discuss this at all?

[MX450R]

I never rebuilt a Honda motor, but the KTMs i have rebuilt had a side to side tolerance that had to be shimmed at the crank. the process was to put the half's together (with the crank installed), torque the bolts down, then measure with a feeler gauge. If the tolerance was off I had to take it apart add or remove shims and re-assemble it. i only had to do this if i installed a different crank or a new case(s). hopefully the Honda's are easier to rebuild, but does your manual discuss this at all?

Thats not the case on the hondas. Like said above the right side bolt for the drive gear pulls everything to right side where it needs to be

[MELK-MAN]

i purchased a used 08 right side case half and installed on my motor, rebuilt, and no issues.

[Lead Head]

You can't even buy matching case halves from Honda, so I doubt that's the issue. I also doubt it's your case half.

[mrmoto35]

Thanks for the tips everyone. 

 

 

I think I found the issue... I didn't notice it right off the bat but it appears that the bearing walked out about an 1/8". I'm assuming a new left side crankcase is in order now. 

 

The crank only had up and down play from the left side. (stator side) 

 

is 1/8" side to side play normal with the bearing pressed all the way in? Does anyone ever shim from the crank to the bearing to reduce the side to side play? 

 

Thanks!

Lance

Most manufactures machine the cases together to obtain unity. Honda does not do that. They machine the cases separately and precisely so that any same year right side will mate to any same year left side. Otherwise Honda would list both sides under one part number forcing the consumer to purchase both. Anyone that has tried to purchase the vacuum release plate gasket knows what I am talking about.

 

Obviously no process is absolutely perfect 100% of the time but I would have serious doubt that the cases didn't match as long as the part numbers match. 

 

You do not mention purchasing a new crank. Is the crank new as well? If not do you have a good idea of how many hours the crank has been in service? The general consensus here is to replace the crank every 200 hrs... 

[Shawn_Mc]

Beyond just the center cases, the oil pump cavity needs to be inspected, the seal for the crank in the stator cover should be replaced and the oil pump relief valve should be inspected and cleaned too. It the oil pressure relief is stuck open, you wont have jack for oil pressure. Roller engines don't need a bunch, but the way the crank gets oiled, there is a restrictor in the end of the crank that reduces the amount of oil pressure fed to the rod and mains.

 

You can get a crank rebuild kit from Hotrods that will get you new mains for both sides. I've used it several times. Its the only way I've found to get the sleeve that gets pressed onto the crank behind the timing gear. What you don't want to do is just replace the left side main bearing without replacing the inner race. Its an incomplete fix doomed to failure as the damaged inner race will just kill the new bearing.

[Yodiracer]

Beyond just the center cases, the oil pump cavity needs to be inspected, the seal for the crank in the stator cover should be replaced and the oil pump relief valve should be inspected and cleaned too. It the oil pressure relief is stuck open, you wont have jack for oil pressure. Roller engines don't need a bunch, but the way the crank gets oiled, there is a restrictor in the end of the crank that reduces the amount of oil pressure fed to the rod and mains.

 

You can get a crank rebuild kit from Hotrods that will get you new mains for both sides. I've used it several times. Its the only way I've found to get the sleeve that gets pressed onto the crank behind the timing gear. What you don't want to do is just replace the left side main bearing without replacing the inner race. Its an incomplete fix doomed to failure as the damaged inner race will just kill the new bearing.

Shawn, the OEM crank I bought had the inner race already pressed on? plus I bought new OEM mains bearings.

[Shawn_Mc]

Shawn, the OEM crank I bought had the inner race already pressed on? plus I bought new OEM mains bearings.

 True, but...

 

Again, you need to verify oil supply as I mentioned in the first paragraph. A brand new crank and bearings wont last long without enough clean, fresh oil.

[FGR01]

You can't even buy matching case halves from Honda, so I doubt that's the issue. I also doubt it's your case half.

 

Exactly,  What everyone is missing here is that Honda uses a center gasket between the cases.  The manufacturers that don't use a gasket, notably Yamaha, machine their cases more precisely and use sealant (Yamabond-4) instead of a gasket.  That is why their cases are sold as a matched set.

 

Although, even some Yamahas that don't use a gasket still have case-halves available separately.  The newer YZ250's for example.  Damn things are like 600 bucks each!

Edited October 6, 2014 by FGR01

[lowmass]

Over the years Ihave replaced crank bearings 5 times between my 07 and 08 and replaced crank twice. EVERY time all new parts and one time new cases as well. EVERY single time the new parts had this suspect play on the stator side. EVERY time. The first time i replaced the bearings I went round and round trying ti find why they are so loose. Never got a good answer. However I never had an issue eather. Yes it sounds like I did have an issue from the number of repairs BUT were talking many seasions of very hard use. Never had a direct bearing related issue. All rebuilds due to other disasters and the new bearings etc had basically same play as the used ones. Yes theres a lot of play. Aparently its "normal".  

[Armbarn sailor]

Over the years Ihave replaced crank bearings 5 times between my 07 and 08 and replaced crank twice. EVERY time all new parts and one time new cases as well. EVERY single time the new parts had this suspect play on the stator side. EVERY time. The first time i replaced the bearings I went round and round trying ti find why they are so loose. Never got a good answer. However I never had an issue eather. Yes it sounds like I did have an issue from the number of repairs BUT were talking many seasions of very hard use. Never had a direct bearing related issue. All rebuilds due to other disasters and the new bearings etc had basically same play as the used ones. Yes theres a lot of play. Aparently its "normal".

once primary gear was torqued on mine all play was gone. 50 hrs later....all play is still gone.