55 MPH at W.O.T. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 37 (permalink) Old 05-08-2011, 01:09 PM Thread Starter
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55 MPH at W.O.T.

I have checked the verses and searched the site, I'm not the best at finding info so if a link is all thats needed that would be greatly appritiated. Any way..

My top speed is 55 MPH. 5th gear wide open throtle. I can get there but its slow and realy realy chuggy. the bike starts with almost no chock and idles at 950 - 1000 beautifuly.

Shop says $235 for carb reiuld. I dont have the $$ and this shop is realy slow.


I have new plugs, new high octain fuel and seafoam. Just got new tiers mounted and have my military course renewal coming up on friday.

Not sure what else to do.

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post #2 of 37 (permalink) Old 05-08-2011, 01:11 PM Thread Starter
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Sorry bout the spelling, i am terible at it and i dont have word to coppy and past

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post #3 of 37 (permalink) Old 05-08-2011, 01:23 PM
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I'm doing a full carb rebuild as soon as I get the o-rings I'm waiting on. I'll take pics and document how it was done if you can wait a week or so.
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post #4 of 37 (permalink) Old 05-08-2011, 01:28 PM
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Quote:
Originally Posted by CLARK47 View Post
I have checked the verses and searched the site, I'm not the best at finding info so if a link is all thats needed that would be greatly appritiated. Any way..

My top speed is 55 MPH. 5th gear wide open throtle. I can get there but its slow and realy realy chuggy. the bike starts with almost no chock and idles at 950 - 1000 beautifuly.

Shop says $235 for carb reiuld. I dont have the $$ and this shop is realy slow.


I have new plugs, new high octain fuel and seafoam. Just got new tiers mounted and have my military course renewal coming up on friday.

Not sure what else to do.
First off the high octane fuel is not going to help. The bike runs fine on regular gas and that is what you should use.

There are a few possibles here. If the bike sat for awhile , yes, I'd say it is a carb issue. But first check the hose that runs into the back of your right airbox.. make sure it is there and to prevent it from bottoming out , cut the end off at a 45 degree angle and stick it back in.

Next your idle should be @ 1100-1150 rpms, you have it to low. I would suggest draining the carbs..theres a brass drain screw on the bottom of each, after they drain, tighten them back up and then pour some SeaFoam down each fuel line till it overflows and letting it sit overnight. Put half the can in the gas tank , reconnect your fuel lines and go for a ride.

Are you sure both cylnders are running? If one is cutting out that could make the 55 speed understandable.

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post #5 of 37 (permalink) Old 05-09-2011, 11:27 AM
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Sounds like running on one cylinder, do the obvious, check for gas and spark.
You just changed plugs so I would check for spark on all four plugs first.

Premium is indeed a waste of money, do yourself a favor and go back to 87 octane. Will actually do more harm than good. Burns too cold and deposits will form.

Jon

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post #6 of 37 (permalink) Old 05-09-2011, 12:16 PM
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Some good replies, but none actually fit the symptoms you describe. If the bike starts and idles, we can dismiss a lot of shi*. First, drain the carbs and make sure time and E-15 hasn't pooled water in the float bowls. No water? Then pull the tops off the CVK's and stare into the sun. See those little pinholes in the rubber diaphragm? The carb's are not able to sense a pressure differential beyond 1/4 of the forward butterfly opening.

And just for kicks, make sure the battery cables are clean and solid. It sounds counter-intuitive, but if the neg lead is wonky the R/R has a hard time feeding the system above idle and the ignitor/cpu goes to sleep.

Write back and telling me if I'm wrong. I'll walk you through a step by step troubleshoot per the manual. Don't spend $$'s with anyone until you KNOW the problem. Real OEM CVK parts are a lot less than $235...and despite all the hype it is not a big deal to yank the carbs...if indeed it is even necessary.

Time to get your hands dirty.
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post #7 of 37 (permalink) Old 05-09-2011, 01:55 PM
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Quote:
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Premium is indeed a waste of money, do yourself a favor and go back to 87 octane. Will actually do more harm than good. Burns too cold and deposits will form.

Jon
I thought all octane burned at the same temp (in same motor) the difference is that high octane burns slower ??
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post #8 of 37 (permalink) Old 05-09-2011, 02:55 PM
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@ Surak...it has the same BTU capacity/output GIVEN a complete(sic) burn cycle, higher octane doesn't BURN slower, it IGNITES with more difficulty, allowing for higher CR's and advanced timing with large valve timing overlaps. Power output is (in part) relative to the CR multiplier under the closed intake and exhaust curve.

In a low-po motor, higher octane fuel will burn "cooler" only because the flame propagation is not as violent as in a high CR motor. This is the lost $$ syndrome, as the high octane fuel will burn upon (after) ignition just as quickly as a low octane...but without advanced ignition timing and high CR and extreme valve overlap there's just no point to delaying that explosion. Other than emissions, which is a whole different set of molecules.
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post #9 of 37 (permalink) Old 05-09-2011, 03:28 PM
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@93750
Let me put this gently..U R Full of... figure it out so I'm not censored!

Once ignited, our dear dino fuel burns within a few degrees of f'ng hotter than Jessica Alba. Certainly, when you're talking about temps around 1800 degrees at the exhaust valve, the only way U R going to get "deposits" is if you have over jetted the carbs...and the CVK's on the VN are notoriously lean.

And, going to the absolute minimum octane fuel will result in some pretty nasty pre-ignition if your motor still has factory CR readings. Now, if you own a beater, previously owned crap that has not been rebuilt, then 87 octane will work just fine...and most of the GY6 Chinese clones are beating your ass off the line! On the other hand, if you have a clean and tight motor (get this guys, a rebuild for a 20 something year old motor is not exceptional) then 89 octane is the minimum. If you can burn 87 octane and suffer no knocks off the line at WOT when doing a torque pull from 1500 rpms, then your motor is fubar.

As are your assumptions.

You might also want to do a little research on the octane rating methodology from when the VN750 (1986) came to life and the current watered down reality of E-15 pump gas of 2011.

It ain't apples to apples.
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post #10 of 37 (permalink) Old 05-09-2011, 03:47 PM
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Are you saying the 2-8,000 members here who have been running regular 87 octane gas are full of s***?

I think you got it backwards.

KM

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