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Discussion Starter #1 (Edited)
I put my rebuilt carbs back in...then took them out to connect the throttle cable....then put them back in again.

I started it and once warm, I adjusted the mixture screws for highest RPM. (I started them at 2.5 turns). It feels like it took 2 more turns to run.

I have stock pilots, 1 shim and 138 main jets. It had good throttle response, but runs rough. I currently have no air filters on for this video. I did not add coasters or marble the vacuum lines. See video.

Thoughts? Rich? Lean?

https://photos.app.goo.gl/v5y5Kj8RMCGKjd4m6
 

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Well I don’t have my carburetor put back together, i feel like I opened up a cascaron and expect to put the pieces of confetti back together to make a picture of a carburetor.
 

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I put my rebuilt carbs back in...then took them out to connect the throttle cable....then put them back in again.

I started it and once warm, I adjusted the mixture screws for highest RPM. (I started them at 2.5 turns). It feels like it took 2 more turns to run.

I have stock pilots, 1 shim and 138 main jets. It had good throttle response, but runs rough. I currently have no air filters on for this video. I did not add coasters or marble the vacuum lines. See video.

Thoughts? Rich? Lean?

https://photos.app.goo.gl/v5y5Kj8RMCGKjd4m6
They don't usually run very well with the carbs open, no filter. There are ports at the carb intake. I wouldn't do any tuning until it's got filters on.

It sounds like maybe it needs the needles shimmed more. But it may behave differently with filters. Pipes are open or punched out, right?

edit: Is that duct tape on your gas cap? :)
 

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Discussion Starter #4
It sounds like maybe it needs the needles shimmed more. But it may behave differently with filters. Pipes are open or punched out, right?
Pipes are otherwise stock with the mufflers removed. I'll put the filters on and try it again tonight. Thanks!

edit: Is that duct tape on your gas cap? /forum/images/smilies/smile.gif
HAHA no. I repainted and haven't put on the clear coat yet, so the masking tape is still on there.
 

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Pipes are otherwise stock with the mufflers removed. I'll put the filters on and try it again tonight. Thanks!



HAHA no. I repainted and haven't put on the clear coat yet, so the masking tape is still on there.
:grin2: Thought you were going Red Green on us.

 

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Discussion Starter #6 (Edited)
Love that show!!!

I looked at it briefly this morning and discovered I never tightened the carb boot clams!
It may just be a vacuum leak.
That would explain why it took a lot of turns on the mixture screw to get it to run properly.

I like my neighbors too much to rev it up at 7am, so I'll try it again tonight.

Edit: I snapped a picture of two plugs (left is rear, right is front)
 

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Not too lean looking so far.

Yes, the air leak could cause top end lean out and popping.
 

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Discussion Starter #8
I tightened the carb boots and tried again. It ran better, but still not quite right. I sprayed around the boots and the idle would drop, so the boots themselves are leaking.

Given the age of the bike, I think pulling my carbs to rejet opened up Pandora's box! All these old rubber pieces were fine if they weren't disturbed, but now that I have moved them, they aren't sealing again like they should!

I am going to replace the rest of the rubber on the bike, and try again.
 

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proper alignment of the boots is critical. there is a bump on the boots that must *I REPEAT MUST* be lined up with the bumps on the heads at the intake ports. if you dont get that right, the boots will leak. no matter how much you tighten them
 

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proper alignment of the boots is critical. there is a bump on the boots that must *I REPEAT MUST* be lined up with the bumps on the heads at the intake ports. if you dont get that right, the boots will leak. no matter how much you tighten them
got that right. there is a post about someone's bike running at 4k while idle. i had a similar issue and my carb boots weren't lined up. i don't know how to use forums well enough to direct you to the pic i took, but it shows the alignment marks. can't upload here cuz it says i already uploaded it...
 

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Discussion Starter #11
Hmmm, is one alignment mark width off enough to be the sole cause of a vacuum leak?

I do know that both leak, and only one is slightly misaligned.
 

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Hmmm, is one alignment mark width off enough to be the sole cause of a vacuum leak?

I do know that both leak, and only one is slightly misaligned.
Yes.

If there are no cracks in the rubber and no gouges in the aluminum and the boots are correctly located and the clamps tight, then there shouldn't be any leaks.

The boots must be lined up right, front to front and rear to rear.
 

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Discussion Starter #13
I'm ready to sell the bike over how difficult it is to pull the carbs on this thing! If I get it back in and it still leaks....I might just pay someone to fix it.

Even the aligned boot leaked, but I'll try once more.
 

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Discussion Starter #14
Ok, I resolved the vacuum leak and synchronized the carbs. I adjusted the mixture screws for fastest idle (3.5 turns). When I ease on the throttle, it goes fine from idle to 4k, then drops a bit before struggling on up to redline.

Idle throttle response is snappy though.

https://photos.app.goo.gl/gjHQGttAK35q1e8c6
 

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FREEBIRDS MC CENTRAL NY
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Goats belly with mufflers removed able earshave? Probably should rejet.

Sent from my A502DL using Tapatalk
 

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Discussion Starter #16
Goats belly with mufflers removed able earshave? Probably should rejet.

Sent from my A502DL using Tapatalk
No mufflers, straight pipes out of GB. I rejetted mains to 138, and added a shim.
 

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No mufflers, straight pipes out of GB. I rejetted mains to 138, and added a shim.
Might have to up the secondary jets too.

Sent from my A502DL using Tapatalk
 

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Might have to up the secondary jets too.

Sent from my A502DL using Tapatalk
Was going to say ... Maybe add shims on the needles. Couldn't hear the audio but watched the tach.
 

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Discussion Starter #19
Might have to up the secondary jets too.

Sent from my A502DL using Tapatalk
Was going to say ... Maybe add shims on the needles. Couldn't hear the audio but watched the tach.
It starts popping above 5k. I was still adding throttle as the RPM remained relatively constant. I didn't slow down on the throttle until about 7k, so as not to overrev it.

More shims? I figured the shims I have were causing the problems.
 

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It starts popping above 5k. I was still adding throttle as the RPM remained relatively constant. I didn't slow down on the throttle until about 7k, so as not to overrev it.

More shims? I figured the shims I have were causing the problems.
If it's still behaving as it was in the first video, it seemed lean there. But since there's no audio in the second video, you may be right and it's running rich now that the carb boots are right.

The needles are tapered and pass through the main jets, so the higher they are lifted, the more fuel flows through the main jets. Adding shims lifts the needle higher, so more fuel.

Edit: Here's an annoying video with decent graphics describing the action.

 
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