Sudden power loss when throttling.

[xishuo]

Hi guys,

 

Im experiencing this sudden power loss when i throttle. Just replaced the jets, washed carbs, cleared exhaust, changed oil pump, changed eo, changed coolant and brake pads. Basically all wear and tear just done up.

 

Then was told by mech that its because of leaks in exhaust. So any pro here can advise how much it takes to furnace the leaking exhaust or how much can i get one from scrapeyards? Model is a 1997 honda shadow ace. Please dont advise me to sell cos the bike is really good and im truly loving it.

 

Thx thx!!!

[lucius]

leak? as in external cracks and opening? u can try diy glue it with epoxy steel.

[ChaoPuzzy1968]

Hi guys,

 

Im experiencing this sudden power loss when i throttle. Just replaced the jets, washed carbs, cleared exhaust, changed oil pump, changed eo, changed coolant and brake pads. Basically all wear and tear just done up.

 

Then was told by mech that its because of leaks in exhaust. So any pro here can advise how much it takes to furnace the leaking exhaust or how much can i get one from scrapeyards? Model is a 1997 honda shadow ace. Please dont advise me to sell cos the bike is really good and im truly loving it.

 

Thx thx!!!

 

try your air filter......?

[chris 525]

Could the air-fuel mix be to rich. That would definitely cause you engine to lose power when you throttle.

You indicate that you changed jets and did things to the carb.

 

A shadow is 4-stroke, if so, then cracks in the exhaust will only make the engine louder and not contribute to your loss in power when you open the throttle. The other things you mention (I dunno what is a eo) will not contribiute to this symptom.

 

I would also change mechanic.

[MiddleAgedBiker]

Hi guys,

 

Im experiencing this sudden power loss when i throttle. Just replaced the jets, washed carbs, cleared exhaust, changed oil pump, changed eo, changed coolant and brake pads. Basically all wear and tear just done up.

 

Is this a bike you just bought, or have you used it for awhile and this happened suddenly? If you've used this bike for sometime already, did it always behave this way? Also, did you modify anything in the carb? Changed jetting, needle, etc.? Would you happen to know if the carbs are CV (Constant velocity) type or slide carbs? If CV, the diaphragm could've been punctured when you serviced it. Even a pinhole sized tear can cause this to happen.

 

Believe it or not, a bad battery can also cause this to happen. Do you have a volt meter? Test the voltage across the battery terminals at idle, at 2500rpm and at 5000rpm and report back.

 

Then was told by mech that its because of leaks in exhaust.

 

How does he know? Did he spot a leak in your exhaust? If so, did you ask him to show you where? Exhaust leaks are easy to spot. Like another poster said, if the leak is caused by rusting or holes in the pipes, it'll show up as a louder sound. If it's leaking at the exhaust manifolds, just hold a lighted cigarette in a windless place, and let the smoke rise up the exhaust manifolds. Any exhaust leaks would blow the smoke away, and is easy to see.

 

So any pro here can advise how much it takes to furnace the leaking exhaust or how much can i get one from scrapeyards? Model is a 1997 honda shadow ace. Please dont advise me to sell cos the bike is really good and im truly loving it.

 

I recommend brining your bike to Ah Chong at Planet for a check. His troubleshooting skills are very good, and he's an honest guy. In my experience, he doesn't try to scam you to get you to replace parts. In fact I've never met such an honest mechanic in my 20 yrs of biking. When a part he replaces doesn't solve your problem, he doesn't even charge for it. He just keeps the part and fixes your old part back.

[kuwaiyert]

leak in the exhaust... is he refering the out air flow..?? ... how bout the spark plugs..?? seems you didnt mention that .. cause uneven firing also lead to power lose... hope it helps..

[xishuo]

Oh thx for all the replies. Eo is the engine oil, I also changed my air filter recently. Spark plug was checked and is in good condition. Battery also checked. I'm not sure bout the carb type but this symptom had been there since I took over the bike.

 

Regarding the exhaust. He didn't show me where but he says that the hole is causing insufficient back pressure to the piston when I suddenly give my bike a higher than usual rev.

 

Guess I'll need to try other mechs. Will give planet a go.

 

Thx all again!!

[xishuo]

Oh thx for all the replies. Eo is the engine oil, I also changed my air filter recently. Spark plug was checked and is in good condition. Battery also checked. I'm not sure bout the carb type but this symptom had been there since I took over the bike.

 

Regarding the exhaust. He didn't show me where but he says that the hole is causing insufficient back pressure to the piston when I suddenly give my bike a higher than usual rev.

 

Guess I'll need to try other mechs. Will give planet a go.

 

Thx all again!!

[dark_angel]

is it like a sudden drop of power then power back again when u open throttle?

if so it could be the surge of air flow into the engine when u open throttle.

 

Had this pro b4, u can go ah chong there to rectify it lah.

one of the mechanic help me to tape up one of the airway, so that actually solve the pro and bike is ok now.

heard frm him, 400 cc had this problem all along.

[xishuo]

Thanks bro. That's the exact feel of how the bike handles. Waiting for this weekend to go and seek help.

[chris 525]

The back pressure created in the exhaust is very important for a 2-stroke engine, but for a 4 stroke engine not. And a shadow is a 4 stroke engine.

 

This is even more reason for you to consider another mechanic.

 

It sounds like your fuel/air mix needs adjusting or fixing.

 

Checking the spark plug can also indicate if your fuel-air mix is correct. Maybe this link will help

 

http://blog.carlist.my/wp-content/uploads/2010/09/reading_spark_plugs.jpg

 

 

Oh thx for all the replies. Eo is the engine oil, I also changed my air filter recently. Spark plug was checked and is in good condition. Battery also checked. I'm not sure bout the carb type but this symptom had been there since I took over the bike.

 

Regarding the exhaust. He didn't show me where but he says that the hole is causing insufficient back pressure to the piston when I suddenly give my bike a higher than usual rev.

 

Guess I'll need to try other mechs. Will give planet a go.

 

Thx all again!!