Roached my motor - Any ideas?

Spoke to Edco yesterday, they are able to fix up my head no problems! Intake cam is fine as well :D They are going through the whole head and fixing the journals for $220 and change. Thats a whole heck of alot better than 7 bills for a new head :worthy:

Toldja.

Now look the oiling system over CAREFULLY.

After looking at the lubrication diagrams, I am about 85% sure that my oil pump is the culprit here. I pulled it out and noticed some scoring on both sides of the back cover from the rotors. Also, when I rotate the inner rotor there is a small spot of hesitation that takes a little bit of extra force to overcome. I can't imagine that this is correct. I have not had a chance to check the clearances yet, but I am thinking that I should just spend the $130 on a new pump and not have to worry about it. Thoughts?

I am thinking that I should just spend the $130 on a new pump and not have to worry about it. Thoughts?

My $.02......Spend the extra money.

When the big end rod bearing seized on my 03 YZ450, I also found minor scoring in the oil pump. So replaced the pump and all o-rings throughout the oiling system. I also made sure the oiling system was completely clean before reassembling. Now is NOT the time to cut corners.

Good luck! :D

Hello there

true, if that is the case but if the low end bearing of the connection rod seized is seems unlikely that the Oil pump is the culprit. I believe that the oil pump brings the oil to the valves and sprinkles it on the lower parts of the piston. If the Piston and the valves are oily the pump should have worked OK. The cranks should dip into the oil and lubricate the bearing. Correct me if I'm wrong.

Best regards

Arnego2

My $.02......Spend the extra money.

I have a friend's wr450 tore down for kick starter idler gear replacement and noticed the oil pump had a little rough place when rotated. Took it apart and found nothing wrong...put some oil in it and rotated away from the motor and it didnt have the rough place until the oil drained back out. Maybe that's normal. What do you think Grey?

Correct me if I'm wrong.

OK, you're wrong. The oil pump supplies oil directly to:

> The camshafts, via drilled passageways in the crankcase, cylinder, and head.

> The crank pin and big end bearing, by passing oil from the right side crankcase cover to the right crank axle, then through drillways to the pin.

> The transmission shafts, gears, bearings, and clutch, via a set of passageways leading from the crankcase cover, across the crankcase behind the cylinder, to the left side trans bearing pockets, and then down through the shafts.

The cylinder walls receive oil thrown off from the big end bearing, and the mains are lubed by splash and directed drainage.

Ended up ordering a new pump along with a cam chain. Should have the rest of my parts here in a few days and I'll start putting her back together.

Question - what do you guys use for assembly lube? I will be putting all the parts through the parts washer before reassembly so they will be totally clean. Should i just coat everything in motor oil or is there a special lube I should use?

I just use my normal engine oil for almost everything. The only exception is the cam lobes if I'm installing new cams and lifters, in which case I use a film of moly assembly lube paste.

I was just being nosey and read threw this:

1) I would use the NEW 12:75:1 CP piston. (i love it) Send Wisco back.

2) Do not use anything other than what is recomened by the manua. ( will hurt clutches)

3)I know aftermarket oil filters can be installed backwards. (just some thing to take a close look at.

From Greg

2) Do not use anything other than what is recomened by the manua. ( will hurt clutches)

Not really. Besides, moly assembly lube IS recommended by the manual.
3)I know aftermarket oil filters can be installed backwards. (just some thing to take a close look at.

Oil filters can only be installed backward if an aftermarket cover is used.

tdamore!!! why dont you learn how to ride!!! then you wont have those seizing problems!!! hahahaha j/k brother

i wont be riding for a couple weeks, i'll send you email on reason.

tdamore!!! why dont you learn how to ride!!! then you wont have those seizing problems!!! hahahaha j/k brother

i wont be riding for a couple weeks, i'll send you email on reason.

lol - I can only guess what happened. I am just waiting on my new flywheel and I'll be back in action

Took the scoot out for the break-in ride over the weekend and it ran like a top :bonk: I ran it hard making sure to vary the rpm's etc, changed the oil and let it rip for the rest of the weekend. Thanks Gray and everyone else who helped me while I was rebuilding it. No way I could have done it without the shared knowledge :bonk: :bonk:

One question:

1 - How much oil out of the crankcase breather tube is normal? I re-routed the tube back to my airbox and noticed some oil on my swingarm. I checked the oil like 40 times over the weekend and it was always within specs.

I did a search and it seems like a little oil is normal when you run the bike hard but I wasn't bouncing the bike off the rev limiter or anything like that.

In the end, these are the parts that were replaced\added:

New hotrods crank\rod assembly

New Wiseco hi-comp piston

New main bearings

New oil pump assembly

New cam chain

New cylinder

seals\gaskets etc..

Head repaired by Engine Dynamics :bonk:

New 10 oz. flywheel

Acerbis 3.3 Gallon tank (used off of ebay)

The head can be repaired, believe it or not. Send it to EDCo

Also, critically examine the entire oiling system.

My neibors 98 yz400f did the same thing, when I got into the bottom end I checked the oil pumps it was in bad shape and to be replaced. i suspect the pump faled while he was rideing and caused the large rod bearing to fail and it all came to a slow halt. Check that pump when you get in there.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now