HELP! Bike Problem: petrol Leaking From Exhaust Joint

[desmondband]

Hi all,

 

my bike recent was found petrol leaking from the exhaust joint (full system). Half of the time does happen. When it happens, the bike will become powerless, voltage drop to 12.5 (when riding), idling RPM drop from 1.4k to unstable 1.1~1.2k.

 

my ride is super 4 revo, with PC5.

 

i bring it to shop but they also unsure what happen. wanted to quote me $900 repair, saying there's sometihing wrong with the priston.

 

any one have encounter this before???

 

despriate help

[white_angel]

leaking from where?

front header and engine part?

or

underneath along the fs?

 

check your block for leaks

 

worst come worst, change sleeve and piston if scoring damage

too serious

 

do check your carb, plugs and air filter first before attempting

to open up the top block

 

could be as simple as using wrong or defective plugs

(incomplete combustion, resulting in power loss)

 

first time hear petrol leaking from exhaust..

[Silent Hunter]

Hi all,

 

my bike recent was found petrol leaking from the exhaust joint (full system). Half of the time does happen. When it happens, the bike will become powerless, voltage drop to 12.5 (when riding), idling RPM drop from 1.4k to unstable 1.1~1.2k.

 

my ride is super 4 revo, with PC5.

 

i bring it to shop but they also unsure what happen. wanted to quote me $900 repair, saying there's sometihing wrong with the priston.

 

any one have encounter this before???

 

despriate help

 

Yes, the problem is likely due to one of your piston not working, but it's not likely because the piston got problem.

 

Don't let the workshop do anything first, $900 to do top overhaul is chop people one.

 

Check the wires connecting to your spark plugs first.

Then check the spark plugs themselves.

 

Let me explain why, using my own bone head experience.

I once took out my spark plugs to clean off the excess carbon on them for a better burn and better fuel efficiency, but forgotten to put the wire back on one of them, the engine could still start using 1 spark plug, but the idling dropped significantly from 1.5K RPM to below 1K RPM and the engine stalls after a while if I don't throttle the engine at idling. (Huh? Why like that one?!?!)

 

At that time, I didn't know I left one of the spark plugs unplugged, so I adjusted the idling screw 2 full rounds to make the idling faster until it goes back to 1.5K RPM. Then I went for a test ride. Every thing works as normal, except the acceleration instead of becoming better as one would expect after reconditioning the spark plugs got worse. I parked my bike and scratched my head and saw smoke coming out of the exhaust, alot alot of smoke!

I was so worried the exhaust will catch fire!

 

Then as the bike cools down, I saw some yellowish liquid drip out from the joint between the exhaust header and the end cam which I suspect was petrol, so I took a look around and found the wire to the spark plug on the left of the engine dangling around loosen, leaving the spark plug on the left uncapped.

 

After I plugged the wire back on, and restart the engine, the bike roared to life with the engine RPM shooting up to nearly 2.5K RPM at idling. So mystery of clean spark plug causing poor acceleration solved.

 

From what you said, it sounds like one of your spark plugs is not firing as normal, resulting in only 3 pistons working.

The 4th piston that is not working because of "No Spark" got it's UNBURNT petrol and air mix pushed out into the exhaust pipe after each engine revolution cycle, causing the leak. The problem could be a wiring problem like mine, or it could be spark plug is really fouled.

 

I suspect it's not the spark plugs themselves that is spoil, but rather the wires connecting to it is loosen or broken, causing the problem to be on and off, rather than all the time.

 

To trouble shoot

Unplug the cap covering the spark plug yourself first, then check to see if there is water or dust inside.

 

A friend of mine had water in his spark plug cap because the rubber on it has cracked. Water can get in and his bike starts and stop intermittently every time it rains, but bike can start after leaving it to sun for a few days!

 

Dirt, dust and sand getting in between the connectors can do the same thing too.

 

After checking the spark plug caps for water and dust, push the caps back onto the spark plugs as hard as you can then start the engine again.

 

If problem still there after checking, take out all the 4 spark plug caps and put a new spark plug into each of them, then start the engine to test if all of them works. If they are working properly, you should see a spark arching at the head of each the spark plug.

 

If you find one that doesn't work that's probably the cause of the problem, just change the spark plug cap only. Won't cost you $900!

 

If all of the spark plugs cap works with the new spark plugs, then take out your old spark plugs, they are probably fouled. Use the new ones that you just tested instead and go for a test ride. That should solve the problem.

 

If problem still there, I can't help you anymore, you will have to push to bike shop ask for professional help.

Edited September 23, 2012 by Silent Hunter

[desmondband]

Is exactly what I have faced! Omg.. At least happy to hear not the piston problem.

 

However, I have 0 knowledge on how to take out the spark plug cap is there any video around available so that I can try to DIY?

 

Hmmm.. Perhaps one last thing to think about it..

 

Revo is fuel injection.. Will it be due to the injector is faulty too??

 

Really thanks for all the information! At least brighten up my sunday

[Hydher]

You dont know how to take a spark plug out?

 

Just pull just not from the wires!

 

Ill suggest you go to planet motors

[Silent Hunter]

Take out spark plug CAP is like pulling out a USB cable like that.

Take out spark plug is like unwinding a screw, but with a size 18 spark plug tool.

 

If you need video, can try You-Tube, they probably have one on how to "hands on" DIY change spark plugs.

[haoKR]

Hi all,

 

my bike recent was found petrol leaking from the exhaust joint (full system). Half of the time does happen. When it happens, the bike will become powerless, voltage drop to 12.5 (when riding), idling RPM drop from 1.4k to unstable 1.1~1.2k.

 

my ride is super 4 revo, with PC5.

 

i bring it to shop but they also unsure what happen. wanted to quote me $900 repair, saying there's sometihing wrong with the priston.

 

any one have encounter this before???

 

despriate help

 

wa,which shop sia

mind sharing?

[Silent Hunter]

I don't know, but I feel like "Repairing" TS bike for just $900.