RECENT POSTS

New Main Bearings... How much is too much resistance ?

Joined
Apr 20, 2006
Messages
26
Likes
0
#1
So I just replaced my mains & seals in my bottom end of my 96 cr250 - I got the case halves back together and all seems good. I can turn the crank easily by hand and can feel the bearings are tighter and is a bit harder to to turn then before.

I just put my primary gear back on and torqued to 47lbs as manual sez and now crank is even more harder to turn. You can still do it by hand and if you try to spin it it wil go about 2/3 of 1 rotation before it stops.

I measured with feeler gauges on both sides and crank (between crank web and case)and measures 0.029 on right side and 0.035 on the Left.

should I be worried about this ? or is it normal ?
 
Joined
Oct 19, 2006
Messages
2,142
Likes
1
#2
New bearings will be a little tighter than old. The amount of resistance should be small, though. After you install the primary drive gear, you will also have drag from the crankshaft seal on that side. It will be slightly harder to turn, but were talking very slightly. It turns free with no roughness or binding? Resistance is the same through the entire revolution?
 

darringer

Lifetime Sponsor
Joined
Dec 2, 2001
Messages
1,029
Likes
0
#3
After re-assembling the case halves I have always LIGHTLY tapped both sides of the crank with a rubber mallet to relieve any stress from assembly. On more than one occasion I have heard a "pop" when doing this. Afterwards the crank turns freely with slight resistance from the new bearings and seal drag.
 
Joined
Apr 20, 2006
Messages
26
Likes
0
#4
There is no binding and it is the same resistance all the wall around, the resistance was more apparent when I put primary gear on. It was very little before as you described above. I looked at it again last night and it seems like the primary gear doesnt sit exactly flush with crank end. It looks flush but you can feel that it is not. I know the crank is bottomed out on the bearing - I guess it is possible some debris got under that collar when assembling (which I doubt) and that is causing primary to stick out more than it should.

I didnt try any tapping with rubber mallet so I can give that a try also
 
Joined
Jan 27, 2000
Messages
6,959
Likes
42
#5
darringer said:
After re-assembling the case halves I have always LIGHTLY tapped both sides of the crank with a rubber mallet to relieve any stress from assembly. On more than one occasion I have heard a "pop" when doing this. Afterwards the crank turns freely with slight resistance from the new bearings and seal drag.

One or both of your main bearings are not seated all the way down. Do as darrenger said and tap the case on the outside of the bearing with a mallet. I use a nylon mallet for this. Turn the engine on it's side to where the crank end is facing straight up. Heat the case around the bearing on the underside case and then tap around the bearing. The weight of the crank along with the tapping on the case should seat the bearing. Then flip it over and do the other side.
 
Joined
Apr 20, 2006
Messages
26
Likes
0
#6
I checked the collar and primary gear for debris and nothin is there, I have to get a torch and I will heat up around bearing and try tappin on case around it and let you guys know how it goes !
 
Joined
Apr 20, 2006
Messages
26
Likes
0
#7
I got it figured out, after looking closer I had the collar on backwards so that was causing it to bottom out on bearing, I flipped it around and now is good. I never really took note of which way it came off and the servicehonda micro fiche has it the way that I originally had it which is backwards.

thanks for your help guys