replacing drive sprocket bearing

[storman]

Hi at the min i am dropping the engine to replace the drive sprocket bearing is there a quicker way of replacing this or do i need to open the full engine as hynes manaul says
First bike ive worked on (usally cars) any help will be great Thanks

[reelrazor]

Naw, Haynes is right..gotta split the cases to replace that bearing.

MY concern would be "WHY is that bearing shot?" (and what else is toast too)..

Best case scenario is that you KNOW the chain was run waaaaay too tight for quite a while

worst case: poor oil service intervals and EVERY trans bearing is shoddy, and the mains and rod bearings aint happy either (unlike cars-these and most bikes-have a common oil supply to both.

[storman]

The chain hadn't been oiled in a while throughout the winter
Thanks

[pefrey]

The chain not being oiled would not affect the bearing you speak of. Why do you think that bearing is no good?

[storman]

The guy i bought it of said it was gone and the bike had been in his barn for 3 years didnt get a chance to fix it the chain was rusted solid but the engine stared on first pope just charged the battery and put fresh fuel in. Thinking of dropping the engine and bringing it to a bike machanic to do the bearing and check it over. Have ya any idea how meny hours it would take to fit the bearing
Thanks

[DonTZ125]

More than the bike's worth - a full engine tear down at a shop?? You'll pay the better part of a thousand dollars in parts and labour, quite possibly more. The PO is clearly an idiot; put the bike back together with new chain and sprockets front and back, THEN see if you need to take drastic measures.

[storman]

Is there no way of checking the bearing without rebuilding the bike. If I took the front sprocket off and checked the main shaft for movement and could I also visually check it sorry for all the questions
Thanks

[storman]

Just taken the sprocket cover off to see if I could check the bearing there is alot of oil in the housing and I can move the shaft about 3 - 4 mm up and down looks to me the bearing is shot

[pefrey]

I think it would be well over $1,000 if it involves cracking the cases.

Oil in the cover could just be chain lube accumulation. The 3-4 mm of movement does not sound good. I am looking at a schematic of the transmission right now. Click on "Proceed to Catalog" and look at the "Transmission" page for your bike. It appears there are two bearings. If it's the first one it almost looks like you can access if from the outside.

http://www.yamaha-motor.com/sport/myyam ... there.aspx

[storman]

Just had a look there it does look very close to the edge its temptimg to try to bang it out

[storman]

Just able to a mechanic of a mate he said if I through the engine down to him he will fit the bearing and gaskets for £150 Happydays keep yas posted

[pefrey]

I hope it all works out for you without too much cost or hassle.