Hit a wall at 4000 rpm - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 10 (permalink) Old 02-09-2007, 09:07 PM Thread Starter
 
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Hit a wall at 4000 rpm

Have a 01 vn750 that I just got. When I first got it on Monday, took it for a little ride and had alot of sputtering between 3000 and 4000 rpms. Almost stalls a couple times. After reading a little on here checked the plugs. Found all of them blackened. Went and got some new ones at advanced. All they had in stock were autolites so I got 4 of those. I pick up my Iridiums tomorrow morning, based on praises I read here. With new plugs in took bike for a ride. Now I hit a wall at 4000 rpms. I found myself with throttle fully open trying to get past 4000 but could not. The guy that I bought bike from builds custom bikes, he told me he change oil and cleaned the carbs. The bike has gas and the fuel filter looks good. Also I get alot of popping on right side after bike has been running for about 5 minutes. Also noticed a small pinhole on bottom of left exhaust. Any suggestions on what to check first?

Last edited by ryn6609; 02-09-2007 at 09:17 PM.
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post #2 of 10 (permalink) Old 02-09-2007, 09:16 PM
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The carb vent tube runs from a "t" between the two carbs to a slot in the right air filter, towards the back. If this tube is obstructed, your problem could happen.

Make sure the end of the tube is cut at a 45 degree angle and put it in the slot on the right air filter. Don't bottom it out in there, it's just supposed to hold it in a safe spot.

Check that first.

Jon

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post #3 of 10 (permalink) Old 02-09-2007, 09:47 PM
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I had problems with my Vulcan around 4000rpms when I had my air filter covers off.
Below 4000, it ran fine, but at or above and it ran pretty crappy.
Wouldn't hurt to see what condition the filters are in. (stock ones are known to begin to disintegrate after awhile)

Besides the tube Jon mentioned, check the carb boots too. Might have a small crack in one of them.


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post #4 of 10 (permalink) Old 02-10-2007, 08:04 AM
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After you check the vent hose (which seems to be a really common problem), and the areas Hyper mentioned, you might also check two things on the right side: first, make sure the exhaust is really on tight. If there's a leak, you'll get popping. Check the acorn nuts up at the exhaust header pipe, and also check to make sure the bands are tight where the pipes go into the premuffler chamber (the big chamber that sits right under the battery box). The second thing would be the air/fuel adjustment screw on the right side - if it's running lean, you'll get some popping. Turning the screw out (lefty loosey) may help - most folks are bottoming out the screws, then backing them out 2 1/2 or so turns. Beyond three, you run the risk of the screw falling out - so back it out slowly (and dont' lose count!).

That said, do the vent hose, filter, and visual checks first; then move on to the fasteners.

C
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post #5 of 10 (permalink) Old 02-10-2007, 07:52 PM Thread Starter
 
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Checked the carb tube today. looked like a brand new tube and it was flat on the end. cut a 45 degree angle in it and put it back. checked tank tube by seat had crud in it but cleared that out. Got my Iridium plugs in. In first I can get to 5000 rpms but it sputters, and any other gear 4000 is still my limit. I did notice some oil or what looked like it at the opening for the back plugs. Looked for the air/ mix screw is that the bronse colored screw undernieth the carb from the right?
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post #6 of 10 (permalink) Old 02-10-2007, 08:01 PM
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Quote:
Originally Posted by ryn6609 View Post
Checked the carb tube today. looked like a brand new tube and it was flat on the end. cut a 45 degree angle in it and put it back. checked tank tube by seat had crud in it but cleared that out. Got my Iridium plugs in. In first I can get to 5000 rpms but it sputters, and any other gear 4000 is still my limit. I did notice some oil or what looked like it at the opening for the back plugs. Looked for the air/ mix screw is that the bronse colored screw undernieth the carb from the right?
I believe that is the bowl drain screw. The mixture screw is behind a lead plug if no one has ever been in yours before.

You may have to join the Yahoo group if you haven't (highly recommend it). Two pictures are here http://new.photos.yahoo.com/ddhughey...60762315824853.

Thanks Dianna.

Jon

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vn750.com Member # 828

Rick's Stator and R/R
MF AGM Battery
Coastered
Degoated
Shaved & Jetted
Iridium's
MAC Tapered Staggered Pipes
Battery/Temp/Clock Gauge
Stainless Steel Brake Lines
Dunlop D-404's
23,XXX miles and holding pending gasket change (underway!!!)
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post #7 of 10 (permalink) Old 02-10-2007, 09:18 PM
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She has those pics on this site too. HERE is the right one, and HERE is the left one.
But yeah, wouldn't hurt to join there too !


AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC


"When life throws you curves,
Aim for the apex."

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post #8 of 10 (permalink) Old 02-12-2007, 01:04 AM Thread Starter
 
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I feel like such a DA. Jon you were right with your first suggestion. I thought the hose went into the square opening in the air filter box. Thats where it was when I took the cover off. Today I joined the yahoo group and saw in detail pic of where it goes. Popped it in the top hole and she runs like a charm. I got her off of ebay. She is a 01 with 8k and only problems are seat has a tear at top of passenger backrest and a pinhole in 1 of the exhaust pipes. It did come with a windsield and engine gaurd, which is coming off. I paid 2300. Is this a good deal? Thanks for the help.
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Last edited by ryn6609; 02-12-2007 at 01:11 AM.
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post #9 of 10 (permalink) Old 02-12-2007, 02:08 AM
and the Adventure Cycle
 
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Blue book price (in excellent condition) is $3465
That amount of miles is pretty low, average for that age is 27K (again, blue book #'s)
The shield & guard add a few $$'s, so I'd say (even with the minor issues you mention) that's a pretty decent price.

Glad it was an easy fix to get it runnin' good.


AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC


"When life throws you curves,
Aim for the apex."

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post #10 of 10 (permalink) Old 02-16-2007, 05:10 PM
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It's a good chance the PO was selling it cause of frustration with it not running right. I bought a KZ550 couple years ago that a kid had ridden a year and then decided to do his own maintenance and it hadn't started since. I bought it and took it home and started fiddling with it and he had put the fuel hose from the tank onto a vacuum port on the #4 carb! I put it where it belonged and plugged the vacuum port and it cranked right up. The kid sold it because he had just given up on it.

Sounds like a good deal you got!

Fergy
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