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My 89 vfr won't pass 3000rpm


89vfrrc24

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Hello,

 

my name is Carlos, im from Portugal. I am having a "big" problem with my lovely VFR.  It's all my fault. Probably something I did during the replacement of my starter clutch.

 

The process was done with some glitches. These glitches might have caused the problem.

Flaws:

a) put the starter motor washer in the wrong position, leaving the starter motor under pressure. I tapped the button a few times, hearing just one click. A user reminded me of the possible wrong position of the washer, so i ended up correcting the situation and the starter works without any problem.

b) during the installation of the starter clutch, I touched the start button and observed a short circuit that i really don't know where and what cause that.

Tests carried out so far:

pulse generators ok
only cylinder nr 2 turns off the bike when the pipe is removed
all cylinders have spark (I don't know if at the right time)
clean carburetors
gas pump ok

I leave some videos to help me.

thank you all

,

 

Carlos

 

https://youtube.com/shorts/85Umqiob8hg

 

 

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2 hours ago, VFR750F3 said:

Floats did you make sure they are working correctly.   Is fuel pump working.  Pinched fuel line.  

Thank you. Yes, all the floats are working. I pull the fuel pipe that goes to the carburetores and the pump sends many fuel. 

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Oh I forgot the spring and diaphragm. Nothing torn and is it lined up correctly with the vacuum tube..  When you push on the slide does it snap back or not.

 

 

vfr.jpg

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Second above post. Hard to tell what you were doing with the throttle as that was out of shot. Was the stuttering because you were working the throttle back and forth?

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8 hours ago, 89vfrrc24 said:

b) during the installation of the starter clutch, I touched the start button and observed a short circuit that i really don't know where and what cause that.

How did you determine you had short?

How did you fix this?
What happened to cause short in 1st place?

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a short will usually blow a fuse, so check all of them. were the carbs worked on recently ? the starter clutch you installed may be incorrect for your bike. compare the bumps along the outer ring with those on the  starter clutch you replaced.

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13 hours ago, jefferson said:

Second above post. Hard to tell what you were doing with the throttle as that was out of shot. Was the stuttering because you were working the throttle back and forth?

Hi,

 

thanks for the reply. The bike starts fine. After warming up, i try to open the throttle and the engine doesn't want to go up. The tachometer starts to show that behavior.

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11 hours ago, DannoXYZ said:

How did you determine you had short?

How did you fix this?
What happened to cause short in 1st place?

Sorry about the english, when i say short i mean like a spark or blown fuse, something flashed. Has i told you, i installed the washer in the wrong place and the starter clutch was not moving. I don't know if it was that... But the bike was running very well and it was only after this intervention that this behavior started  😞

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10 hours ago, squirrelman said:

a short will usually blow a fuse, so check all of them. were the carbs worked on recently ? the starter clutch you installed may be incorrect for your bike. compare the bumps along the outer ring with those on the  starter clutch you replaced.

The fuses are all great. The starter clutch was order from CMSNL, for that specific model VFR/K. there is no way to fail.

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14 hours ago, VFR750F3 said:

Oh I forgot the spring and diaphragm. Nothing torn and is it lined up correctly with the vacuum tube..  When you push on the slide does it snap back or not.

 

 

vfr.jpg

Didn't show any problem. and has i told before, never had problems with the fuel line. The only issue was the fuel filter that was cloged after sitting for some months. Notice that because i removed the gas tank, remove the fuel pipe that goes to the fuel pump and turn to on. no gasoline came out. Bought a new one from yamaha and after turn it to on, the gasoline started to pass.

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13 hours ago, VFR750F3 said:

Did you clean carbs after you replaced fuel filter or before.

Thank you.

 

Cleaned the carbs after changing the fuel filter.

 

I am hopping it's the cdi or i change the timming mechanically after pressing the stat button so many times with the starter motor badly fitted. 

 

I need to look for the TDC and see if the piston is on the top.

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On 2/16/2023 at 4:04 AM, 89vfrrc24 said:

 

 

Cleaned the carbs after changing the fuel filter.

 

 

could be your problem right there.  your symptoms suggests that one or more  vacuum slides are not rising properly to richen fuel mix with increasing rpm's.

 

if you remove airbox and filter, with engine running you should be seeing slides rise and fall with throttle movement.  its really hard to get old diaphragms properly seated in their grooves, so slides won't rise.  do you have access to an air compressor ?

 

you must try bypassing the pump relay as yours might have failed.

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6 hours ago, 89vfrrc24 said:

Have noticed that the fuel pump doesn't prime. She only works with the engine running... What do you think? Can cause that problem? Thank you

This is not EFI system with 3-sec prime and constant ON pump. It only pumps in time with ignition pulses to vary volume pumped based upon RPM. Verify pump is flowing sufficient volume:

 

1. drain each float bowl into separate containers. What are their volumes?

 

2. close bowl drains

 

3. manually run pump for 30-sec by jumpering pump-relay ON

 

4. repeat step #1 again. What is volume drained from each carb? Post 8 separate numbers

 

You may still have electrical problem:

On 2/14/2023 at 4:10 PM, DannoXYZ said:

How did you determine you had short?

How did you fix this?
What happened to cause short in 1st place?

On 2/15/2023 at 3:19 AM, 89vfrrc24 said:

Sorry about the english, when i say short i mean like a spark or blown fuse, something flashed. Has i told you, i installed the washer in the wrong place and the starter clutch was not moving. I don't know if it was that... But the bike was running very well and it was only after this intervention that this behavior started  😞

Again, what caused electrical short and how did you fix it?

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6 hours ago, 89vfrrc24 said:

Have noticed that the fuel pump doesn't prime. She only works with the engine running... What do you think? Can cause that problem? Thank you

 

Working as designed.  Pump only pumps if being cranked or running with the Fuel Cut Relay in place.

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1 hour ago, squirrelman said:

could be your problem right there.  your symptoms suggests that one or more  vacuum slides are not rising properly to richen fuel mix with increasing rpm's.

 

if you remove airbox and filter, with engine running you should be seeing slides rise and fall with throttle movement.  its really hard to get old diaphragms properly seated in their grooves, so slides won't rise.  do you have access to an air compressor ?

 

you must try bypassing the pump relay as your might have failed.

Slides that is what I said also the float bowl needles are very important.  I have been rebuilding VFR carbs for 32 years.  I have learned quite a bit for trial and error.  

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On 2/15/2023 at 9:20 PM, 89vfrrc24 said:

The fuses are all great. The starter clutch was order from CMSNL, for that specific model VFR/K. there is no way to fail.

Did you do what Squirrelman suggested??

Compare the Pulse Trigger bumps from the original Starter Clutch to the new one, make sure they are at exactly the same position and none have been bent or damaged with the install.

 

Question for the carby experts????. Looking at Calos's original video. Can a carby issue respond as fast as the Tacho needle is displaying Or does this point to an electrical issue??

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On 2/16/2023 at 9:05 AM, jefferson said:

I'm like you. I'm thinking the slides/diaghrams.

 

6 hours ago, squirrelman said:

could be your problem right there.  your symptoms suggests that one or more  vacuum slides are not rising properly to richen fuel mix with increasing rpm's.

 

if you remove airbox and filter, with engine running you should be seeing slides rise and fall with throttle movement.  its really hard to get old diaphragms properly seated in their grooves, so slides won't rise.  do you have access to an air compressor ?

 

you must try bypassing the pump relay as your might have failed.

 

On 2/16/2023 at 2:04 AM, 89vfrrc24 said:

Thank you.

 

Cleaned the carbs after changing the fuel filter.

 

I am hopping it's the cdi or i change the timming mechanically after pressing the stat button so many times with the starter motor badly fitted. 

 

I need to look for the TDC and see if the piston is on the top.

 

On 2/16/2023 at 9:02 AM, VFR750F3 said:

I still think its the carbs.  

 

very likely carb issue since 3000rpm problem occurred after carb work. Take video of your carb slides as you increase throttle. Vacuum increases with RPM and raises slide to add air and petrol. Does yours open fully like in this video?? 

 

 

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