Oil leak/exhaust backfire

[Justnflrs]

Took about a week off riding. I took my viva out today, started up fine. Rode around for about 20 mins at low speeds until I got to a backroad highway. I was going about 40mph I felt the exhaust backfire. If I rev pass 6000rpms in any gear it will backfire. Got back home and I noticed oil leaking out it the crankcase cover.

Just wondering what could be causing the backfire and oil leak? Would both be related problems?

Assuming I have to change the gaskets?

[Justnflrs]

Leak coming from the seam

[SpudRider]

Is the leak coming from the cylinder base gasket?

[Justnflrs]

Originally Posted by SpudRider

Is the leak coming from the cylinder base gasket?

Just the front right side of the cylinder base. (First pic)

[SpudRider]

The oil leak is not causing the engine to backfire. However, a loose exhaust header can cause an engine backfire on deceleration.

Try tightening the cylinder bolts. If that doesn't stop the leak, you will need to replace the cylinder base gasket, and since you need to remove the cylinder head, you will need to replace the cylinder head gasket as well.

[Weldangrind]

I agree with Spud's comments.

When it backfires, is it only when you close the throttle, or also when wide open?

[Justnflrs]

Originally Posted by SpudRider

The oil leak is not causing the engine to backfire. However, a loose exhaust header can cause an engine backfire on deceleration.

Try tightening the cylinder bolts. If that doesn't stop the leak, you will need to replace the cylinder base gasket, and since you need to remove the cylinder head, you will need to replace the cylinder head gasket as well.

Oh ok, I tightened the bolts earlier today and rode around and its still leaking. Guess I should replace those gaskets. Thanks for your help!

[Justnflrs]

Originally Posted by Weldangrind

I agree with Spud's comments.

When it backfires, is it only when you close the throttle, or also when wide open?

Mostly as I am opening the throttle around 6000rpms. It doesn't backfire as often during deceleration

[Weldangrind]

Would you also describe it as surging / hesitating? Is it relatively quiet, or does it make a big bang?

[Justnflrs]

Originally Posted by Weldangrind

Would you also describe it as surging / hesitating? Is it relatively quiet, or does it make a big bang?

More so hesitating, relatively quiet as I'm reaching 6000rpms, if I persist it will make a louder pop rather than a big bang

[Weldangrind]

Have you done any troubleshooting? New spark plug? New fuel filter?

[Justnflrs]

Originally Posted by Weldangrind

Have you done any troubleshooting? New spark plug? New fuel filter?

I have a new fuel filter, haven't replaced the spark plug yet. I'll try to replace it sometime today or tomorrow. Gonna see if any local shops carry the same spark plug

[Weldangrind]

Should be really easy to find a replacement NGK. Is there an NGK in there now?

[SpudRider]

I agree; I would replace the current spark plug with the NGK equivalent.

[Justnflrs]

Originally Posted by Weldangrind

Should be really easy to find a replacement NGK. Is there an NGK in there now?

The previous spark plug was an NGK. Replaced it with a new one and still got hesitant "coffing" from the exhaust during acceleration. I took off my fmf slip on exhaust to see if that would rule out anything. Rode around and still got hesitating around 6000rpms mainly in 5th gear followed by coding/backfire and it seems like the engine is hesitating at or above those rpms.