What effect do blown crank seals have on performance???

[19Brendan81]

I have been trying to fix a persistent problem I am having with my bike since I bought it…and that’s really low power before band. The jetting is stock, the airbox is modded and the pipe has been gutted. The KIPS are brand new, and are timed correctly. Top end comp is fine, its ignition timing is fine and plug is good.

I was wondering what effect on engine performance a blown crank seal has? The flywheel side one is fine, I have checked there a few times and everything is dry. But I am suspect of the gearbox one…after one trip the bike had definitely used a few hundred ml of oil over about 9 hours of riding.

The bike is hard to start when cold (20 or 30 kicks), but ALWAYS starts first kick when warm or hot. The Idle screw is wound all the way in, and the bike only just idles. And it seems that the harder I ride it, the better it becomes. Could a blown crank seal be causing these problems??

 

[McRider]

If the bad seal is on the clutch side, the engine will suck trans oil and smoke like crazy, eventually fouling the plug. If it is on the ignition side, it will blow oil out into the ignition and possibly screw something up there. Either way, there will also be a loss of compression and consequently power.

 

[Green Hornet]

What do you mean the PIPE HAS BEEN GUTTED??

 

[m0rie]

The 89-94 KDX's stock pipe has a double wall. You can cut the pipe open and remove the inner layer. The makes the stock pipe's power delivery real similar to the FMF torque pipe.

-Maurice

 

[19Brendan81]

Yeah gutting the pipe was an awesome mod, costs nothing too.

Well it doesnt foul plugs... man this thing has got me stuffed. I might just have to do a full rebuild, the bottom end is tired. If that doesnt fix it, I will cry.

 

[Yamadad]

If it's hard to start and just barely idles, plus the idle screw is "all the way in"; sound like I'd go through that carb with a fine tooth comb first.

 

[libskater]

check your rings and reeds