bogging & jerking at full throttle

new_bee · 09-23-2017, 02:07 PM

So previously I had a (some what-not identical) similar problem thatthat went away when I finally put a new diaphragm in the top of the carb. The previous person had pinched the rubber outer or ing sealing serf ace (the old diaphragm had expanded)..

The bike was running great for a couple hundred miles.

Now a new issue gradually developed, and I have been through the carb so many times, just beating my head against a wall trying to figure out what I could have missed.

Basically the bike runs well upto about 3/4 throttle, and if you accelerate fast from that point it starts immediately bogging down and jerking , feels like it is not getting fuel. If you gradually accelerate at that point can get it to slowly speed up to about max rpm/speed in each gear. Only notice the issue if heavy throttle, quick acceleration

-could throttle cable adjustment have anything to do with an issue like this?

-anything in particular I should pay extra attention to when I pull the carb apart again today? carb has been clean and no sign of any dirt or build up the 5-6 times I have been through it. All passageways not clogged checked with carb spray and air.

I have new fuel filter, no air leaks around boots, new plug, checked valve clearances, checked petcock screen, and tank is clean fresh fuel.

Any suggestions very much appreciated

blaine · 09-23-2017, 07:58 PM

Your MJ controls 3/4 to wide open......I would pay special attention to the slide & needle that they are opening all the way.

new_bee · 09-24-2017, 01:13 AM

Thank you. I have never found any dirt or junk in the carb, even the first time I went through it.

The main jet is definitely clear, with carb cleaner and compressed air.

The slide and needle seem ok, but I was mainly making sure they snap back down well..

I have a feeling a previous person may have tinkered with this part of the carb a bit. So I know I do need to go through it with a fine tooth comb..

I have the service manual and there isn't any info on checking out the slide.

I am concerned that it might not be assembled correctly per previous owner. I have followed the parts breakdown and everything looks correct. My concern would be air leaking through..And if all components in the right place.

Any thoughts appreciated!

blaine · 09-24-2017, 09:16 AM

Quote:

Originally Posted by new_bee

Thank you. I have never found any dirt or junk in the carb, even the first time I went through it.

The main jet is definitely clear, with carb cleaner and compressed air.

The slide and needle seem ok, but I was mainly making sure they snap back down well..

I have a feeling a previous person may have tinkered with this part of the carb a bit. So I know I do need to go through it with a fine tooth comb..

I have the service manual and there isn't any info on checking out the slide.

I am concerned that it might not be assembled correctly per previous owner. I have followed the parts breakdown and everything looks correct. My concern would be air leaking through..And if all components in the right place.

Any thoughts appreciated!

They may of got the MJ mixed up with the other one.......May be worth shifting them around to check..

Roadking · 09-25-2017, 10:48 AM

One thing that comes to my mind is float level. Sounds like a typical float level that is set too low. You would only have a problem once you opened up the throttle and under lower speeds never sense a problem. Even a mm or two can make a difference.

Maybe not but its a thought.

derbydave · 09-25-2017, 07:20 PM

I looked at the previous post and noticed that there is a fuel filter on your bike. have you tried removing it? it is possible the filter can't flow enough fuel at 3/4 to full throttle.

new_bee · 09-29-2017, 03:47 PM

After the 11th time going through the carb... Swapped out the main jet, carb slide/diaphragm , and the float assembly from a used carb at the motorcycle shop/junkyard. It runs beautifully. thanks for the help. I wish I knew which of the 3 did the trick.

As a plus, now I can remove & reinstall the carb in 5 minutes, instead of 45...

Roadking · 10-11-2017, 11:36 AM

Yaaaaaaaaaaaay

09-23-2017, 02:07 PM	#1
new_bee Junior Member Join Date: Jul 2017 Posts: 8	bogging & jerking at full throttle So previously I had a (some what-not identical) similar problem thatthat went away when I finally put a new diaphragm in the top of the carb. The previous person had pinched the rubber outer or ing sealing serf ace (the old diaphragm had expanded).. The bike was running great for a couple hundred miles. Now a new issue gradually developed, and I have been through the carb so many times, just beating my head against a wall trying to figure out what I could have missed. Basically the bike runs well upto about 3/4 throttle, and if you accelerate fast from that point it starts immediately bogging down and jerking , feels like it is not getting fuel. If you gradually accelerate at that point can get it to slowly speed up to about max rpm/speed in each gear. Only notice the issue if heavy throttle, quick acceleration -could throttle cable adjustment have anything to do with an issue like this? -anything in particular I should pay extra attention to when I pull the carb apart again today? carb has been clean and no sign of any dirt or build up the 5-6 times I have been through it. All passageways not clogged checked with carb spray and air. I have new fuel filter, no air leaks around boots, new plug, checked valve clearances, checked petcock screen, and tank is clean fresh fuel. Any suggestions very much appreciated Login or Register to Remove Ads
	0

09-23-2017, 07:58 PM	#2
blaine Senior Member Join Date: Feb 2010 Location: P.E.I. Canada Posts: 3,784	Your MJ controls 3/4 to wide open......I would pay special attention to the slide & needle that they are opening all the way. __________________ If at first you do succeed, try not to look surprised.
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09-24-2017, 01:13 AM	#3
new_bee Junior Member Join Date: Jul 2017 Posts: 8	Thank you. I have never found any dirt or junk in the carb, even the first time I went through it. The main jet is definitely clear, with carb cleaner and compressed air. The slide and needle seem ok, but I was mainly making sure they snap back down well.. I have a feeling a previous person may have tinkered with this part of the carb a bit. So I know I do need to go through it with a fine tooth comb.. I have the service manual and there isn't any info on checking out the slide. I am concerned that it might not be assembled correctly per previous owner. I have followed the parts breakdown and everything looks correct. My concern would be air leaking through..And if all components in the right place. Any thoughts appreciated! Login or Register to Remove Ads
	0

09-25-2017, 10:48 AM	#5
Roadking Member Join Date: Apr 2017 Location: South of Atlanta Posts: 50	One thing that comes to my mind is float level. Sounds like a typical float level that is set too low. You would only have a problem once you opened up the throttle and under lower speeds never sense a problem. Even a mm or two can make a difference. Maybe not but its a thought. Login or Register to Remove Ads
	0

09-25-2017, 07:20 PM	#6
derbydave Senior Member Join Date: Jan 2017 Location: KS Posts: 103	I looked at the previous post and noticed that there is a fuel filter on your bike. have you tried removing it? it is possible the filter can't flow enough fuel at 3/4 to full throttle. __________________ 2003 Suzuki GZ250 (Sold) 1986 Suzuki Cavalcade LXE 1986 Suzuki Intruder VS700
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09-29-2017, 03:47 PM	#7
new_bee Junior Member Join Date: Jul 2017 Posts: 8	After the 11th time going through the carb... Swapped out the main jet, carb slide/diaphragm , and the float assembly from a used carb at the motorcycle shop/junkyard. It runs beautifully. thanks for the help. I wish I knew which of the 3 did the trick. As a plus, now I can remove & reinstall the carb in 5 minutes, instead of 45...
	2

10-11-2017, 11:36 AM	#8
Roadking Member Join Date: Apr 2017 Location: South of Atlanta Posts: 50	Yaaaaaaaaaaaay
	0