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Discussion Starter #1
I picked up an 02 Vulcan the other day. It has 8000 miles on it. The previous owner said the bike had sat for over a year. He then brought it out of storage and started riding it. He said he rode it for a week or so and then he said he was cruising along at about 30 mph and he said something started squalling and the oil light came on. He then said that he pulled the clutch in and the engine died. I am kinda thinking that he noticed the oil light after the engine died but not sure yet. I have checked and I have good spark and seem to have good compression(however have not checked it yet). Also checked cam timing, appears to be good there. When I turn it over sometimes it will backfire through the carb and sometimes it will afterfire out the exhaust. However it only does this maybe once or twice and that's all. I even tried a little ether to see if it was fuel related and it made no difference. Any suggestions what I should look at first? I drained the oil (which was overfull) and checked the strainer and didn't find any metal or anything. Thanks to all!
 

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If only it had 6th gear..
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Oil was over full? Could it be that there was gas mixed in as well from severe flooding? Backfiring is a sign of that. Good spark, engine turns and seems to have good compression... I'd attack the carbs. Had a hell of a time with mine - same symptoms, backfiring and all. My carbs had both floats hanging up and not closing. Good luck. Oh, try disconnecting the small vacuum line on your fuel petcock and see if you can get it to run for a minute or two with just the fuel in the carbs. That way the petcock valve wont open and continue to pour more gas into your carbs.

Afterthought, "squalling".... wonder what he meant by that. I agree with your thought about the oil light. Probably looked at it afterwards. By the way, during my float dilemma, I was able to get my bike running by keeping the throttle wide open while cranking it, but had to keep the rpms really high or she'd choke out. Just some ideas for you.
 

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Linkmeister Supreme
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Welcome to the Vulcan madness Cricketo99.
I don`t have anything to add to Daves suggestions at the moment, but I am looking forward to hearing what you discover and what it takes to get your scoot on the road. :smiley_th
 

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Discussion Starter #4
I smelled the oil and it smelled like well, oil. Didn't have the faintest smell of gasoline to it. I had already tried to disconnect the fuel from the carbs and try to start it but no luck there either. No matter where I have the throttle when cranking it makes no difference. I will probably run a compression check before I do anything else just to rule it out. I went ahead and ordered a new set of plugs just to rule them out also even though the ones in it look new. Are these bikes like other small engines in that they fire the spark plug on both the compression and the exhaust stroke? I was thinking that maybe for some reason I am not getting spark on the compression stroke but am on the exhaust.
 

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If only it had 6th gear..
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No, only fires on compression. Are you thinking of a 2 stroke engine maybe? The other thing that comes to mind about your bike is ignition timing. It might be firing way too late after the power stroke and more towards or ever during the exhaust. I haven't messed much with the ignition on these v's so I can't tell ya what to look for but typically the pickup coils and magneto (not sure that's the correct name on these) timing can be completely hosed if the pin that locks the magneto position on the crankshaft shears off throwing the spark timing into oblivion. Could also be valve timing although I doubt it, but in that case I don't think the engine would crank smoothly at all and might make a ghastly noise too. I'm just guessing with some scenarios to look at. Curious, When you
crank it does it spin smoothly or hitch and Buck like someone jammed a pipe wrench into the works?
 

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Linkmeister Supreme
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No, only fires on compression. Are you thinking of a 2 stroke engine maybe? The other thing that comes to mind about your bike is ignition timing. It might be firing way too late after the power stroke and more towards or ever during the exhaust. I haven't messed much with the ignition on these v's so I can't tell ya what to look for but typically the pickup coils and magneto (not sure that's the correct name on these) timing can be completely hosed if the pin that locks the magneto position on the crankshaft shears off throwing the spark timing into oblivion. Could also be valve timing although I doubt it, but in that case I don't think the engine would crank smoothly at all and might make a ghastly noise too. I'm just guessing with some scenarios to look at. Curious, When you
crank it does it spin smoothly or hitch and Buck like someone jammed a pipe wrench into the works?
I don`t like to contradict you Dave, but I believe the plugs should fire on every rotation of the rotor magnets past the ignition pickup coils. Not sure that it matters if there is a waste spark during the exhaust stroke though. :confused:

The vn750 does not have a magneto, but an electronic ignition system that is not adjustable for timing. Timing can be checked with a timing light though, by taking off the stator cover.

A compression test of both cylinders will help confirm or eliminate some possible causes of the symptoms I think.
 

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Discussion Starter #7
Okay I figured by looking at the pickups inside the stator cover that it would have to fire every rotation, much like a lawn mower or other small engine. Unless somehow the IC or whatever it is called somehow knows when the compression stroke is and only tells the coils to fire then. Can I check the timing with a light without the engine running. The only thing I could find in the manual it says the engine has to be running at a certain rpm and the marks will line up. If I check it with a light with just cranking should the marks still line up?
 

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If only it had 6th gear..
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I don`t like to contradict you Dave, but I believe the plugs should fire on every rotation of the rotor magnets past the ignition pickup coils. Not sure that it matters if there is a waste spark during the exhaust stroke though. :confused:

The vn750 does not have a magneto, but an electronic ignition system that is not adjustable for timing. Timing can be checked with a timing light though, by taking off the stator cover.

A compression test of both cylinders will help confirm or eliminate some possible causes of the symptoms I think.
No problem at all Gordon, that's what this forum is here for... and I usually learn something from your posts to boot :smiley_th. It does make sense after thinking about the reed valves that there could be a need for a spark on exhaust to burn the unused gas on the way out. Was just putting some ideas out there to look for / discuss, maybe too much. Might confuse :blah:. Sorry if I did. Anyway, As usual I appreciate your knowledge and the knowledge of others and of course the willingness to help fellow members.
 

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Discussion Starter #9
Got it running today! I don't really know if I changed anything or not but I took both the pickups off and inspected them. I then checked compression (cold obviously), got around 110 on the back and 120 on the front. Not really sure if that is bad or good. Put everything back together and after I primed it with ether she lit. She doesn't run very well but if I keep it above 2000 it will stay running. Also oil light stayed on until I loosened the oil filter to burp it. I am kinda thinking that may have been what happened in the first place. No unusual noises or anything. Looks like I'll be diving into the carbs next. That leads me to another question. I am a diesel mechanic but am new to the world of motorcycles. The PO had put on aftermarket pipes and he said he jetted the carb. My question is what jets should be in there with just the aftermarket pipes? Thanks to everyone it seems like everyone on this forum is very professional and helpful. On any other forum there would have been a fight already in this post lol.
 

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lol, I know what you mean. I feel that Gordon is one of those guys you want to hang with. He always has good info and is gracious at correcting misinformation. You can find a ton of info on re-jetting carbs in the "carbs and fuel system" section of the forums. I removed my airbox and oem filters and found the info there to get the proper jets.
 

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Linkmeister Supreme
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Got it running today! I don't really know if I changed anything or not but I took both the pickups off and inspected them. I then checked compression (cold obviously), got around 110 on the back and 120 on the front. Not really sure if that is bad or good. Put everything back together and after I primed it with ether she lit. She doesn't run very well but if I keep it above 2000 it will stay running. Also oil light stayed on until I loosened the oil filter to burp it. I am kinda thinking that may have been what happened in the first place. No unusual noises or anything. Looks like I'll be diving into the carbs next. That leads me to another question. I am a diesel mechanic but am new to the world of motorcycles. The PO had put on aftermarket pipes and he said he jetted the carb. My question is what jets should be in there with just the aftermarket pipes? Thanks to everyone it seems like everyone on this forum is very professional and helpful. On any other forum there would have been a fight already in this post lol.
Your cold compression test yields low readings at 110 and 120 psi.
Specs call for 129-199 psi with no more than 10 psi difference between cylinders.
Warming the engine before a retest may give you more satisfactory results.

Regarding carbs and re-jetting I am no expert, but this is what I can recall of what others have posted here.

Common consensus used to be that just changing out the exhaust did not require rejetting.
The intake was the restriction in the system, not the exhaust.

Then we had someone join the group who had a rule of thumb for re-jetting that was something like this:
Changing either the exhaust or the intake usually requires an increase of 2 jet sizes. Changing both would mean an increase of 4 sizes.
(Is one jet size 0.002"? ie. from 0.040" to 0.042" pilot jets , or 0.140"- 0.142" mains)

For every 2,000' gain in elevation ASL you drop one jet size.

So if I earshaved and put on afterarket pipes, I would add 4 jet sizes, then subtract 1 (or maybe 2?) sizes for my elevation of 3,500 feet ASL. YMMV

Others may have more specific numbers to offer. :)
 

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Got it running today! I don't really know if I changed anything or not but I took both the pickups off and inspected them. I then checked compression (cold obviously), got around 110 on the back and 120 on the front. Not really sure if that is bad or good. Put everything back together and after I primed it with ether she lit. She doesn't run very well but if I keep it above 2000 it will stay running. Also oil light stayed on until I loosened the oil filter to burp it. I am kinda thinking that may have been what happened in the first place. No unusual noises or anything. Looks like I'll be diving into the carbs next. That leads me to another question. I am a diesel mechanic but am new to the world of motorcycles. The PO had put on aftermarket pipes and he said he jetted the carb. My question is what jets should be in there with just the aftermarket pipes? Thanks to everyone it seems like everyone on this forum is very professional and helpful. On any other forum there would have been a fight already in this post lol.
Vance and Hines ( Cruzer Pipes ) recommend going one size up on the main jet which would be a 136.
 

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Discussion Starter #13
Okay thanks everyone! I will check to see what jets he had put in it when I am in there cleaning them out. I am going to check compression again once I get it running right to see how much it comes up. I am guessing those specs are for a warm engine correct? Also the gauge I used was one of those cheap "push in the spark plug hole" types so it is probably a little higher than that.
 

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Discussion Starter #14
Also, on a side note, what type and weight of oil should I be using? Is regular diesel oil okay or do I need special motorcycle oil for the wet clutch? Like I said I know very little about bikes so bear with me.
 

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i run 10w40 penzoil in my bike
 

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Discussion Starter #16
The jets in the carb are 138 mains and 38 pilot. Will I be okay with these or do I need to step down a size?
 
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