RECENT POSTS

98 yz 250 knocking and pinging no top end

Joined
May 7, 2007
Messages
9
Likes
0
#1
I got the bike out in spring and went trail riding at the end of the ride we heard a knock at idle figured it was piston slap so we put new piston and rings in and found the noise was still there mainly at idle when the bike is warm. We tore the whole thing down and thought maybe crank bearing but everything checked out ok once again assembled it and went out to ride and it started spewing antifreeze from the over flow so i went to a shop by where i was riding and they resurfaced the head and put it back togethor. went back to the wood and rode for a while and the bike is pinging and has no top end. and is getting real hot and spewing antifreeze once and a while. please help with any info
thanks
 
Joined
Mar 30, 2006
Messages
341
Likes
0
#2
You're bike is jetted to lean. Find out what the stock jets are for your bike and then find out what's in yours. Start with stock jets and lean out as need be. It wouldn't hurt to bump up to some higher octane fuel either. I just run marine gas in mine and it's ok but it depends on altitude and temperature.
 
Joined
Apr 8, 2007
Messages
292
Likes
0
#3
faulty rad cap could be causing the loss of coolant and thus resulting in a hotter running engine.
 

Rich Rohrich

Moderator / BioHazard
Joined
Jul 27, 1999
Messages
22,763
Likes
557
Location
Chicago
#6
Master of Faster said:
I got the bike out in spring and went trail riding at the end of the ride we heard a knock at idle figured it was piston slap so we put new piston and rings in and found the noise was still there mainly at idle when the bike is warm
If it's knocking at idle it's not jetting, or detonation or anything to do with combustion. There isn't enough of a load on the engine at idle to cause these types of problems. You have something mechanical that is vibrating, or a worn part that is rattling around.