Purchased a 99 Vulcan Classic 1500 a few weeks ago. It has 39K on it. Starts very good but choke must be used for 1st start. Seems to have too much engine vibration. After it warms the vibration is still the same. This is a vibration that is constant just sitting still.
Only known mods are Vance Hines 2into1 pipes, and a hyper charger. I ordered a full factory exhaust system and just finished installing it. (Man is it much quieter.) Removed the carb to check the jets and they are stamped factory. 135 & 45, so I don't think anything was done there. Checked the mixture screw and it was out 3 turns, so I turned it in one.
I removed all 4 plugs and the two rear cylinder ones were very black as if running extremly rich. My milage is only about 25. Installed new plugs but that did not make a change.
I am by no means a bike mechanic, but I do know engines. So if you need more information to assist in a diagnostic, please ask.
Thanking you in advance for any suggestions and glad to be a part of this forum.
Vibration probably is from a misfire. I have some questions:
1. Start OK, hot/cold?
2. Idle OK, hot/cold?
3. Backfiring at anytime?
4. Drive along oK, hot/cold?
5. Any other driveability issues, no matter how minor?
6. Back plugs...if you clean them, do they soot up right away?
6. Any other issues, even if seemingly unrelated?
The condition, as you describe, is typically an off-idle lean condition, but the black plugs do not support that.
One thing that you can try is to swap the two coils with each other to see if the problem moves. Check for a full 12v at the wire that goes to both coils. Also meter the plug wires for continuity.
Well I am finally back with the results of my most recent test & inspections. Here is where I am.
First, I could not stand the loud noise from the Vance Hines 2 into 1 pipes that were on the bike when I purchased it, so I found & ordered a complete factory exhaust system and changed that out. (Now I can once again hear), but that had no effect on the vibration problem. Next I checked the voltage at the coils and did resistance checks and they are both OK. Today I removed the carb, disassembled and cleaned. Both jets are stamped FTC for factory installed, a 142 & 45. Cleaned both with tip cleaners, checked float level and everything else. All OK. Reassembled and started. Engine idles fine but as I begin to give a slight amout of throttle, vibration begins and continues up to the high RPM range. When trying to ride is very uncomfortable as it vibrates all the time.
New observation: When I first started engine before connecting crankcase vent lines to air filters I noted a lot of pressure & vacuum from these hoses. After connecting all lines and putting everything back together, I started engine and unscrewed the oil fill cap. There is pressure, vacuum as if I have a direct cylinder leak into the crankcase. I understand there is a decompression feature on the front cylinder for cranking purposes. Could this be stuck in an open position? Is it supposed to close after starting?
Thanks again for any suggestions.
You have done some first class work in trying to track down the problem.
Decompressor holds the exhaust valve open a smidge, so will not contribute to crankcase huffing and puffing, which, depending on how much, is normal for an engine.
You should do a leak-down test just to make sure that the engine is sound, mechanically, although, the good idle seems to indicate it shouldn't be too far off.
A real close examination of the plugs would be in order to try and narrow down which cylinder might be the offender, if indeed there is one.
The black rear plugs speak of a mis-fire in that cylinder. Did you try swapping the coils?
Also, try measuring resistance of coil wires. I do not know what the exact specs. are for your bike, but they should all be very close to each other.
Another thing to try - Pull one plug from rear, ground against engine and check spark.
It should be fat and blue, not weak and yellow. If in doubt, check it against one of the front ones.
This morning I removed both coils and did resistance test on them. The results were almost the same on both, 2.6ohms on primarys and 22.4K on the secondarys. According to my manual that is right in the middle of the recommended range for both.
I did a spark test on each wire using a new plug grounded to the frame and the spark was very blue and good at all 4 test.
Started bike and let warm up and have noticed if I gradually increase fuel vibration increases, but when I reach a high RPM range it seems to smooth out. I am beginning to lean toward a burnt valve. As I said earlier it had V&H pipes on it when I got it and no rejetting had been done. I do not know how long they were on it but the bike does have 39K miles.
I do not have the correct metric adapter for my compression tester. I will try to pick one up today and do a compression test.
What are your thoughts on these results so far?
Front cylinder was a consistent 120 for 3 test. I found this confusing since the manual states it should be between 50 & 80 because of the automatic cranking compression release.
The first test of the rear cylinder was 125, second test was 65, third and there after resulted in 90. The manual states it should be between 120 & 150 for the rear.
Well, I am just as confused as I was before the test.