Jump to content
Sign in to follow this  

Rebuild question

Recommended Posts

I have a 05 crf450r it I have put about 50hrs on it since I bought it a year ago. I put a new top end on it a year ago valve job and piston. I don't really know the past history. I have an oil migration problem tranny to engine side out the breather. Any ways I need to replace the seal. Should I go further than just replacing the seal? Should I do a complete bottom end rebuild? What parts would I need to do this? What special tools. I want to have everything in advance so I can ride.

Share this post


Link to post
Share on other sites
I have a 05 crf450r it I have put about 50hrs on it since I bought it a year ago. I put a new top end on it a year ago valve job and piston. I don't really know the past history. I have an oil migration problem tranny to engine side out the breather. Any ways I need to replace the seal. Should I go further than just replacing the seal? Should I do a complete bottom end rebuild? What parts would I need to do this? What special tools. I want to have everything in advance so I can ride.

i would just replace the seal and ride. My valves didn't even move till i had 80 hours on my 08, and i got the bike used. at about 90hrs, the intakes were junk and i did a top end at that time, was luky i did. the piston was pretty worn and had a good groove in the front. so much of "when to do.. " stuff is based on your maintinence and how you ride the bike/conditions you ride in.

there is a VERY good detailed thread on this very subject, and shows how to avoid putting the updated seal in WRONG. very easy to do.. search the thread "oil migration" or something like that. i started the thread and posted a couple pictures of the seal.

Share this post


Link to post
Share on other sites

Your problem is not really the seal at this point. The stainless steel spring on old seal is chewed up and made it's way to other parts of the engine. Usually the seal twists sideways and a hunk of metal filings will enter the engine bearings.

That seal need a good bonding locktite and can be prone to fail if not installed properly. Use the newer style seal due to the double lip design.

Share this post


Link to post
Share on other sites

search OIL MIGRATION

There is 2 places it migrates from : balancer seal, right crank seal.

When you split cases, use a new seal on the balancer and 2 new bearings. Otherwise you will be doing the job shortly. But since you dont want to split cases again, this is what you need:

But replace both seals (balancer and right main seal) , new balancer bearings (both sides), new right side cover gasket and left side cover gasket, and O ring for the dowel behind the water pump. That will fix your problem.

Share this post


Link to post
Share on other sites

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
Sign in to follow this  

×