Author Topic: Another Bogging at full throttle post  (Read 1544 times)

Ruckenstein

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Another Bogging at full throttle post
« on: December 10, 2021, 03:50:09 AM »
Long time lurker.


So I’m banging my head against the wall. 
49cc agility bogs at full throttle

120 psi compression
Valves adjusted .003 in, .004 ex
Kicks over and starts right up also starts up easily with battery
Cleaned carb twice.  Still bogs.  Then I put a new Chinese carb. Sounded exactly same as kymco carb.
Tried 2 different cdis.  Sounds exactly the same. 

Have sprayed for air leaks. Found none.

Tried revving with exhaust off.  Still bogs at wot.

Petcock tested great. Gas is fresh.  Oil level is perfect.

Stator is putting out 13.8 volts if I recall.

Tried 2 different coils. Still bogs.

Plug looked very new.

Anyone ideas are welcome!

CROSSBOLT

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Re: Another Bogging at full throttle post
« Reply #1 on: December 10, 2021, 01:25:02 PM »
Air filter condition? Try with filter removed? By starter tested or inspected?
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

Ruckenstein

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Re: Another Bogging at full throttle post
« Reply #2 on: December 10, 2021, 07:38:58 PM »

Thank you for the idea.  However…
I’ve tried it without the air filter and a better looking newish air filter.  Same results.

CROSSBOLT

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Re: Another Bogging at full throttle post
« Reply #3 on: December 10, 2021, 09:10:43 PM »
Thank you for the idea.  However…
I’ve tried it without the air filter and a better looking newish air filter.  Same results.
Okay, ruled out air filter. What about the by starter? That is, the electric choke?
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

Ruckenstein

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Re: Another Bogging at full throttle post
« Reply #4 on: December 11, 2021, 02:55:37 AM »
It was tested and is plunging properly. 

What would happen if it had jumped time?

CROSSBOLT

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Re: Another Bogging at full throttle post
« Reply #5 on: December 11, 2021, 07:34:29 AM »
What is your plug gap?
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

Ruckenstein

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Re: Another Bogging at full throttle post
« Reply #6 on: December 11, 2021, 02:33:33 PM »
Brand new plug .025 if I recall

JJJoseph

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Re: Another Bogging at full throttle post
« Reply #7 on: April 06, 2022, 09:16:14 AM »
It may not be fuel.  Small engines can overheat at WOT, and start to seize up as the pistons swell from the heat.  This is common on small-bore bikes, especially if racing!  It's not unusual.  It's hard on these things to ride them at WOT for longish times..  It hurts!

punktnet

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Re: Another Bogging at full throttle post
« Reply #8 on: May 02, 2022, 09:52:24 AM »
Long time lurker.


So I’m banging my head against the wall. 
49cc agility bogs at full throttle

120 psi compression
Valves adjusted .003 in, .004 ex
Kicks over and starts right up also starts up easily with battery
Cleaned carb twice.  Still bogs.  Then I put a new Chinese carb. Sounded exactly same as kymco carb.
Tried 2 different cdis.  Sounds exactly the same. 

Have sprayed for air leaks. Found none.

Tried revving with exhaust off.  Still bogs at wot.

Petcock tested great. Gas is fresh.  Oil level is perfect.

Stator is putting out 13.8 volts if I recall.

Tried 2 different coils. Still bogs.

Plug looked very new.

Anyone ideas are welcome!

Fixed it?
Sounds like lack of gasoline. Clogged jets / level needle issues, faulty petcock, clogged filter or fuel lines.

Onekneedown

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Re: Another Bogging at full throttle post
« Reply #9 on: August 15, 2022, 04:46:53 AM »
What size is the carb and what size is the main jet?

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