Need some help. I think broke my bike. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 18 (permalink) Old 02-28-2016, 05:09 PM Thread Starter
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Need some help. I think broke my bike.

Hey guys I could use some advice. What I am working with is a 2004 vn750 and it was running fine before I decided to play mechanic. I have installed a new AGM battery and iridium plugs and also K&H air filters. With the new battery and plugs the bike was starting right up, better than ever. So here is how I went about breaking my bike. I moved the r/r without a problem, I did this because It was easy to do and I have had some troubles starting with the engine hot , like when I stop to get gas. I removed the emissions distributor thing and capped the hoses under the seat. I figured this is the same as coastering. I started having troubles at this point. The bike was starting with choke full off where previously I needed to have choke full on to start it. when releasing the throttle the engine rpms did not drop as you would expect they stayed high and then kind of came down slowly.I checked that the cables are working properly and checked for vacuum leaks but it all looks good. So anyway after tinkering around I decided to put the EPA stuff back and things are not getting any better. My current situation is that the bike will not start. it cranks and cranks and occasionally backfires but it wont start. read a few posts on the forum here and I tried a few things. I have adjusted the fuel/air mix screws to 2.5 turns. I emptied the bowls , I did the back blow thing. I filled the carb. with seafoam through the fuel lines coming from the petcock, I let that sit for about a day and a half, then I drained the bowls again and I did the back blow again. Sucking on the petcock vacuum line fuel comes out of both of the fuel lines so the petcock is working fine. The bowls are filling with fuel so I am pretty confident that the carbs. are working fine. I checked the spark plugs and they look wet, this concerns me, I cleaned them off and checked for spark, that is ok. So there is fuel and spark. The engine is turning over pretty strong it just wont fire up.Although the one time that it did manage to start the bike sounded like it was running great and the throttle was working as it should. But it only started that one time and that was a couple of days ago. I have been messing around with this for like a week now and I am pretty frustrated. I am not really a mechanic but I am fairly mechanically inclined or so I like to think, The wife has a slightly different opinion.Any advice would be appreciated.
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post #2 of 18 (permalink) Old 02-28-2016, 11:59 PM
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Originally Posted by Lungfishh View Post
Hey guys I could use some advice. What I am working with is a 2004 vn750 and it was running fine before I decided to play mechanic. I have installed a new AGM battery and iridium plugs and also K&H air filters. With the new battery and plugs the bike was starting right up, better than ever. So here is how I went about breaking my bike. I moved the r/r without a problem, I did this because It was easy to do and I have had some troubles starting with the engine hot , like when I stop to get gas. I removed the emissions distributor thing and capped the hoses under the seat. I figured this is the same as coastering. I started having troubles at this point. The bike was starting with choke full off where previously I needed to have choke full on to start it. when releasing the throttle the engine rpms did not drop as you would expect they stayed high and then kind of came down slowly.I checked that the cables are working properly and checked for vacuum leaks but it all looks good. So anyway after tinkering around I decided to put the EPA stuff back and things are not getting any better. My current situation is that the bike will not start. it cranks and cranks and occasionally backfires but it wont start. read a few posts on the forum here and I tried a few things. I have adjusted the fuel/air mix screws to 2.5 turns. I emptied the bowls , I did the back blow thing. I filled the carb. with seafoam through the fuel lines coming from the petcock, I let that sit for about a day and a half, then I drained the bowls again and I did the back blow again. Sucking on the petcock vacuum line fuel comes out of both of the fuel lines so the petcock is working fine. The bowls are filling with fuel so I am pretty confident that the carbs. are working fine. I checked the spark plugs and they look wet, this concerns me, I cleaned them off and checked for spark, that is ok. So there is fuel and spark. The engine is turning over pretty strong it just wont fire up.Although the one time that it did manage to start the bike sounded like it was running great and the throttle was working as it should. But it only started that one time and that was a couple of days ago. I have been messing around with this for like a week now and I am pretty frustrated. I am not really a mechanic but I am fairly mechanically inclined or so I like to think, The wife has a slightly different opinion.Any advice would be appreciated.
I waited for the experts to chime in on this, so realize first that i'm just some guy pretty much like you, and you have more experience now than i do with carbs.

It sounds like you have more than one problem all working against you at the same time. When i first got my bike, though, it had a very similar problem to what you described about the racing engine, but i was going about 35 mph down the road at the time and it went past red line while in between gears, sounded like a two-stroke, freaked me out, had to hit the kill switch then veer over to hear the most ferocious double barrel shotgun backfire i've ever heard in my life, followed by oil all over the place and the white smoke that comes with it.

After several attempts to debunk that problem, it turned out that the linkage between the carbs got screwed up and broken somehow and according to the mechanic, it had been rebuilt by "whomever" with homemade parts. During that debunking process, the throttle cable was replaced, several hoses were replaced, etc. In any case, there is a procedure in the service manual for synchronizing the carbs. Just saying all of this before hand so you can see why i would suggest it for the race condition.

Don't know if you've checked it or not, but my choke was initially hanging and steering to one side would increase RPM like throttling. That was fixed by routing the cables correctly. The "mechanic" put the ears on first and was either too lazy to take them off again, or simply figured it didn't make any difference, but he had them routed around the outside of the ear mounts on the right side. It was just enough tension to make a big difference.

Capping off BOTH of the lines to the fuel tank will mean the tank hasn't anyway to flow. When you said you disconnected the emissions, it sounds like the same as my Cali model since you connected "them". I might have mis-read what you meant though. But in any case, even with the emissions taken out of the system, there needs to be some way for the air to flow into the tank. On the Cali model with two hoses on the bottom of the tank, there is a return pump that does that trick while riding and which sucks fumes when the bike is coasting in gear ( vacuum situation ). It sends those fumes through the charcoal can and into the exhaust system to "blow up" ( mixed with air ) any fuel that failed to burn in the pistons ( or at least that's the intended way it works ). When coasting in gear, and the emissions hooked up, there is this popping that sounds like backfiring ( but a lot less noisy) and "that" is actually supposed to be how it sounds ( even though i hate it ). In any case, your fuel tank needs to be exposed to the open air either through the single hose, or by connecting it to the emissions system. If you *do* have the Cali model, with two hoses on the fuel tank's rear, they need to be connected correctly, i.e. they *can*/*might* be connected backwards which would shut it down just the same since there is a one-way valve in the gas cap for one that only allows it to suck instead of blowing anything back in.

Final note, make sure the battery is charged to its max even though it seems as if it's working "okay". I went through TWO brand new AGM batteries before i got one that would charge. The other one had set on the shelf at AutoZone for too long without ever being charged. It WOULD run the bike, but it would NOT ever charge more than "so much" because basically it had sulfide on its plates and once an AGM has gone "so low" without charging, it cannot ever get back to its fully charged state. You can charge it for three days for all it matters, it will "accept" a charge and act like it's charging, but in the end, it will only accept so many amps during the process and it's like spinning wheels. An AGM battery needs to be charged to full charge at least one time every 30 days ( according to the manufacturers and various articles i read ) and also, just being in the bike does not guarantee that riding the bike will charge it to its full potential. If you want to get the full life out of that battery, and under the presumption that it *CAN* still be fully charged, then get a trickle charger for it ( they charge slow at about 1 amp and turn themselves off by sensing the current the battery accepts. When the battery is cranking the starter motor, that fire in the spark plugs is going to probably be at its weakest.

Hope this helps and at least gives you some ideas.
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post #3 of 18 (permalink) Old 02-29-2016, 01:13 AM
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What's your voltage at?were the k&n's pods or stock replacement?

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post #4 of 18 (permalink) Old 02-29-2016, 11:29 AM Thread Starter
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I get 13.3 volts when fully charged and just replaced stock filters with the K&H. not pods. The bike cranks really strong just wont start. It does not take long to drop the battery voltage though. Just a couple of starting attempts brought it down to 12.5 volts. I had a look at the grounds and they look good. Everything is tight and nothing is rusty/ corroded.
Thanks for the reply roadhopper. The hoses that I capped are the ones that go to the reed valves. My bike only has one hose from the end of the gas tank and that one just is open , I did not cap that one. I replaced the EPA distributor thing and those hoses are all reconnected the way they were originally now.
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post #5 of 18 (permalink) Old 02-29-2016, 01:24 PM
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Quote:
Originally Posted by Lungfishh View Post
I get 13.3 volts when fully charged and just replaced stock filters with the K&H. not pods. The bike cranks really strong just wont start. It does not take long to drop the battery voltage though. Just a couple of starting attempts brought it down to 12.5 volts. I had a look at the grounds and they look good. Everything is tight and nothing is rusty/ corroded.
Thanks for the reply roadhopper. The hoses that I capped are the ones that go to the reed valves. My bike only has one hose from the end of the gas tank and that one just is open , I did not cap that one. I replaced the EPA distributor thing and those hoses are all reconnected the way they were originally now.
In a couple of weeks ( hopefully ) i will be pulling out the EPA stuff on my Cali model. The problem there is that i will need some routing diagram of how a normal model is hooked up without its EPA stuff. Does the leg-bone still connect to the shin bone?

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post #6 of 18 (permalink) Old 02-29-2016, 03:37 PM
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I like RoadHopper's note on the gas tank (as well as everything else he suggested). When I drained my tank I was able to get normal flow from the petcock for a little bit by then a vacuum would build in the tank and the flow would stop. Opening the fill cap is an easy way to break the vacuum to see if that's causing fuel starvation without having to fiddle with hose clamps. You do say that the carb bowls are filling, and your engine was starting with the choke off, so I don't think lack of fuel is your problem.

If you've got fuel and spark, the only thing missing for combustion is the the oxygen. It sounds like you had it running good after installing the new filters, so that also seems like a dead end. Still, if you're feeling brave and aren't in a dust cloud you might try briefly removing the filter and seeing if that changes anything. I don't know why new filters could be preventing air flow, but if you're at your wit's end...

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post #7 of 18 (permalink) Old 02-29-2016, 04:22 PM
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I don't know why new filters could be preventing air flow, but if you're at your wit's end...
Any chance old filter foam got sucked into the airbox or ducts? Maybe slip the intake hoses back and check there.

Too much oil on the K&Ns? Would behave like a choke, making it richer.

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post #8 of 18 (permalink) Old 03-03-2016, 02:37 PM Thread Starter
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Update: We are up and running. Just for the hell of it I put the original spark plugs back in and the bike started right up. After about 10 minutes of heavy pollution and white smoke she is running great. I took her for a spin around the block and no troubles. Now I had installed the DPR 7EIX-9 Iridium plugs gapped at .035 and they all had spark, just maybe not hot enough I guess. Are these the wrong plugs?

Now that we are back in business, I need to fine tune. The bike will only run with full choke, if I move the choke toward off the bike revs up. It is pretty much the opposite of what It should be doing or what it has done in the past. Any ideas or thoughts would be appreciated.
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post #9 of 18 (permalink) Old 03-03-2016, 03:23 PM
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DPR7EIX-9 Are the correct plug. No idea why they were not working for you.
Possibly they were fouled by all t your starting attempts, or were somehow defective. Most of us hear swear by them.

Not sure about your fueling issues. Where do you live by the way?

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post #10 of 18 (permalink) Old 03-03-2016, 03:39 PM Thread Starter
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Hi Knifemaker, I am in Cortland, NY. That is about dead center between Binghamton and Syracuse.I wonder if I didn't damage the plugs myself when I checked the gap. I read a post on here that that could be a possibility. I wonder if the bike will only run with full choke is it too much air because of the new air filters or maybe Fuel/air mix screws? Currently 2.5 turns.
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