Vulcan 88 1500 only one spark plug is lean

[Danfarge]

HELP i have no idea what is going on. Please move if this is not the correct forum but i have a 1992 Vulcan 88 1500 it was a barn find i got it running and took apart the carb cleaned them up. I have a very weird issue going on. My rear right spark plug ( sitting on the bike right side) is white yet all 3 other plugs are not perfect they are a tiny bit rich but not bad at all but how is only one side of the cylinder running lean?!


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[DragonLady58]

OK...its hard as hell to 'read' spark plugs, unless you have experience. Make sure that the plug is the same # as all the others. Unless you index your plugs to your cylinder/valves and have a place to run your bike for a good 1/8th/1/16th miles, its all a general reading....
I'd say the things would be OK, if all the plugs are the same, both cylinders are at the same pressure, and no undue cam wear on the cams of either cylinder....

Put a few miles on the bike, tune her up with fresh plugs since she is running now, clean oil, clean filters. Run a can of seafoam thru the tank to clean the carbs some....since she's a barn find! Take it easy on her, put about 40 or 50 miles on her and look at the plugs again. The side of the cylinder thats closest to the exhaust pipe is usually the lighter colored plug. And that can be slightly lighter or darker if the gaps not pointed exactly at the CL of the exhaust valve closest to the exhaust pipe....
There are a lot of variables involved....

[Danfarge]

OK...its hard as hell to 'read' spark plugs, unless you have experience. Make sure that the plug is the same # as all the others. Unless you index your plugs to your cylinder/valves and have a place to run your bike for a good 1/8th/1/16th miles, its all a general reading....
I'd say the things would be OK, if all the plugs are the same, both cylinders are at the same pressure, and undue cam wear on either cylinder....


Put a few miles on the bike, tune her up with fresh plugs since she is running now, clean oil, clean filters. Run a can of seafoam thru the tank to clean the carbs some....since she's a barn find! Take it easy on her, put about 40 or 50 miles on her and look at the plugs again. The side of the cylinder thats closest to the exhaust pipe is usually the lighter colored plug.



Ive been working on cars and trucks for many years just new to bikes, i know how to read the plugs. There all new plugs and gapped perfectly I tore the tank off and cleaned it and sealed i just did put a little sea-foam in it. At first I couldn’t get her to run to great. Popping pretty bad from the rear cylinder but i was able to get her running smoother but still have a intermittent hanging idle so im checking for vacuum leaks im pretty sure i know which hose is the issue i just ran out of carb cleaner to test it The plug thats white is on the right side the exhaust is exiting in the left Its just weird ive never seen something like that But thank you for help ill let you know what happens.


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[mick56]

The right rear plug is not running the engine,same as the left front one is'nt.They are both called lost, or wasted sparks,as they dont go into the combustion chamber.They just sit in an enclosed tube,and do nothing.:cheers:

https://www.crypton.co.za/Tto%20know/Ignition/wasted%20sp.html

[Danfarge]

The right rear plug is not running the engine,same as the left front one is'nt.They are both called lost, or wasted sparks,as they dont go into the combustion chamber.They just sit in an enclosed tube,and do nothing.:cheers:



https://www.crypton.co.za/Tto%20know/Ignition/wasted%20sp.html



But that article said it does goin the chamber (which it does because theres fuel on them) and ignites during the exhaust stroke ie wasted but then it says it switches over and that one fires on compression and the other fires on exhaust so i still have something odd going on


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[mick56]

I thought that the tubes part 92066,were enclosed,and did'nt enter the cylinder at all.They sit alongside the camchain outside of it.

https://www.kawasakioriginalparts.com/road-bikes.html?blockref=99917-1514.B-04&machineid=4810&year=1992&model=VN1500-A6&country=EU

[Danfarge]

I thought that the tubes part 92066,were enclosed,and did'nt enter the cylinder at all.They sit alongside the camchain outside of it.



https://www.kawasakioriginalparts.com/road-bikes.html?blockref=99917-1514.B-04&machineid=4810&year=1992&model=VN1500-A6&country=EU



I just pulled all plugs they are all going in to the cylinder


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[mick56]

I just pulled all plugs they are all going in to the cylinder


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Well that's me baffled then mate.:cheers:

[Danfarge]

Well that's me baffled then mate.:cheers:



The link for parts was for euros, im in America. Maybe the us and cali bikes differ from Europe


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[mick56]

The link for parts was for euros, im in America. Maybe the us and cali bikes differ from Europe


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Not in that respect they dont.:tup:

[magicgrotto]

Take yu MEDS Mike LOL Its NOT a wasted spark system on a V twin with 4 plugs only on a 4 pot motor , @Danfarge the only thing I can think of is it depends on were the bike came from ?? because they had different MAIN jets , 110 front 112 rear OR 112 front 115 rear you will have to research it :)

[mick56]

Take yu MEDS Mike LOL Its NOT a wasted spark system on a V twin with 4 plugs only on a 4 pot motor , @Danfarge the only thing I can think of is it depends on were the bike came from ?? because they had different MAIN jets , 110 front 112 rear OR 112 front 115 rear you will have to research it :)

Bit early for the meds mate. :D So the plug tubes DO go into the cylinder then.I only had mine out once,a long time ago,and thought they were capped off.Obviously not.