difference between a 98 cylinder and a 2001

S

sgauthier

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Joined
Feb 12, 2007
Messages
363
Age
62
Location
southwest, ontario, Canada
can someone please explain to me what the difference is between a 98 and a 2001 cylinder. i know the rings are the same and the pistons are same size except i think the coating is done differently or is the intake port on the pistons a different size as well.

thanks
 
01 has 1mm higher exhaust port and .5mm higher transfers. 01 also has locater dowels for the exhaust valve holder bracket.
 
74nitro. i was told by Bender (were i bought the cylinder which is an 8DN-00 casting for my 2001 700 srx) in Zurich, Ontario that they are the same and they make no difference on the dyno. the only difference is the dowels for the power valves. i don't know what to do. it's together and running but i need to do a plug check but not sure if i should push it or not.
 
It won't hurt anything to run, but what I stated about the port heights is 100% true. I worked at a Yamaha dealer during those years and I have all that information in the Yamaha technical update books.
 
I agree with the info above. The porting changed a little. Should only be a very small amount of HP difference per cylinder. The 98, 99 motors made 138 HP. Then 2000, 2001, 2002 made 143hp.
 
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