jammin-johnny

Member
Feb 23, 2004
21
0
Hello everyone,
My 97 honda has a fluctuating idle. It surges when I am slowing down and when the bike idles it revs up and down. I think its sucking air, but I don't have pressure testing equipment. I checked the carb insulator and it is clean and tight. Any Ideas on how to identify an air leak somewhere on the engine? Also If it might me a crank seal, which side causes the engine to run lean and which side causes it to run rich?
Thanks.
 

kuritaro9

Member
Nov 7, 2004
107
0
also,i would suspect a leaky crank seal under the flywheel.pretty easy to replace.my bike did the same thing,and thats what was wrong. :cool:
 

nickyd

Member
Sep 22, 2004
873
0
everybody's right!!!! confirm you don't have a leak externally via a soapy water solution and then go after that crank seal! (the magneto side)
 

nickyd

Member
Sep 22, 2004
873
0
kuritaro9 said:
also,i would suspect a leaky crank seal under the flywheel.pretty easy to replace.my bike did the same thing,and thats what was wrong. :cool:

were you able to replace it w/out splitting cases?
 

Toothmech

Member
Oct 21, 2004
37
0
You don't have to split the cases. Just pull the flywheel, and stator plate. Drill a small 1/8" hole into the existing seal on opposite sides of the crank output shaft(don't go too far and damage the aluminum case). Then thread in screws(sheetmetal) that binds tightly in the holes you drilled. Grab the screws with pliers and yank, the seal should pop right out. Clean the sealing surface and tap the new one in with a rubber mallet/ deadblow hammer and a piece of PVC pipe that matches the outer diameter of the seal. Be sure not to hammer the seal too far in. Some bikes have a flange that the seal seats against, others don't, so I recommend measuring how far the seal was set into the case prior to removal and relplacing it to that depth. Reassmble and pat yourself on the back for fixing the problem. Hope this helps.
 

nickyd

Member
Sep 22, 2004
873
0
Thanks Toothmech - I've done that for the tranny seal (output shaft) tons of times....I've always seem to have gotten to bikes with fried top ends due to the leaky seal and have been forced to split the cases due to this issue...Just was wondering if someone out there had done the seal pull with the sheet metal screw as you mentioned - now I know and I'm all over it next time I suspect that seal is beat.
 

darringer

LIFETIME SPONSOR
Dec 2, 2001
1,029
0
On the '97, when replacing the seal behind the flywheel, it is possible to tap the seal in too far and block off the oil passage for the main bearing. Just install it so that it's flush with the case flange. That way the passage is not blocked. Too deep, and you'll be splitting the cases.
 

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