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Won't Start, Plugs Dying?
Posted: Tue Apr 19, 2011 7:19 pm
by DKAudio
I just bought a 1985 Aero 50. I rode it for about 10 miles and then it wouldn't start anymore. I checked for spark against the block and it was good. I took out the spark plug and saw that there was no spark so I replaced the plug. I have only riden the scooter twice since that (put on maybe 10 miles) and the new plug is bad! The tip looks whitish/brownish, kind of fouled already. I am using normal 2 cycle injection oil. What is going on? I bought this thing for $750 and am regretting it big time.
Re: Won't Start, Plugs Dying?
Posted: Tue Apr 19, 2011 8:18 pm
by Bear45-70
Is the air box on the carb with the air cleaner in it?
Re: Won't Start, Plugs Dying?
Posted: Tue Apr 19, 2011 10:23 pm
by DKAudio
Yes, it has both. It was cleaned and oiled by the previous owner right before I bought it.
Re: Won't Start, Plugs Dying?
Posted: Wed Apr 20, 2011 1:34 pm
by DKAudio
I'm getting nervous, I just want a reliable fun scoot to take to work and save on gas, the very reason I went after this pricey Honda Aero.
The 2 cycle oil I got is Quicksilver Marine Outboard Premium but it says for all oil injected and pre mixed 2 cycle air cooled engines, including chainsaws, marine motors, weed whips, mopeds, etc.
Any ideas? Here is a pic of the 4 day old plug with about 10 miles on it that failed already...it is a NGK BP6HS
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Re: Won't Start, Plugs Dying?
Posted: Wed Apr 20, 2011 10:02 pm
by Bear45-70
Don't use marine TCW oil in your air cooled scooter. It is not made for the temps an air cooled motor sees.
You can not read a plug this way. You need to do a proper plug chop or any info you get means nothing.
Re: Won't Start, Plugs Dying?
Posted: Wed Apr 20, 2011 10:47 pm
by DKAudio
As my post above says...the oil I'm using says for air cooled engines.
What do you mean "you can't read a plug that way"? I hooked the coil up to the plug so I could watch it and there was no spark. I grounded the wire to the block and the spark was great, the plug is definitely bad after 10 miles.
Re: Won't Start, Plugs Dying?
Posted: Wed Apr 20, 2011 10:54 pm
by Bear45-70
DKAudio wrote:As my post above says...the oil I'm using says for air cooled engines.
What do you mean "you can't read a plug that way"? I hooked the coil up to the plug so I could watch it and there was no spark. I grounded the wire to the block and the spark was great, the plug is definitely bad after 10 miles.
First off no TCW oil is good for an air cooled motor, totally different requirements. Oh and I worked for years as a certified Mercury Marine mechanic and Mercury does not make such and animal, especially their Premium oil.
Here troubleshoot it yourself.
http://www.hondaspree.net/other/Aero50_SM_85.pdf
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 8:04 am
by DKAudio
I'm not disagreeing with you and I hope it is something that easy. However, I promise that the jug says for all air cooled 2 cycle pre mix or oil injected engines. I did drain the oil tank and the main line going into the oil pump yesterday night. How do I go about getting the oil out of the pump and the short line from the pump to the carb? I also read in the manual when refilling you need to get all the air out of the lines, I think it walked you through that procedure.
I already have the manual and troubleshot it, carb is getting gas, coil is good, that brings me to the spark plug that was bad.
Thanks
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 10:26 am
by noiseguy
DON'T USE THAT MARINE OIL IN YOUR BIKE. YOU ARE GOING TO DESTROY THE ENGINE.
Pull the line from the pump to manifold. Blow that out too. Then remove the pump, hook a clean hose to the inlet, and blow through that (with your mouth) to clear the pump.
Get to a Honda shop and buy some GN2 oil. Dump all that premix marine oil out of the oil tank, oil lines and pump, and refill with the right stuff. Bleed per service manual procedure; when it's working you'll get a drop every 5 seconds from the pump at idle.
I'm certain this will fix your problem. That marine oil makes a *complete* mess inside the combustion chamber. Usually the plugs come out oily and fouled as well... apparently not in this case.
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 12:21 pm
by DKAudio
Great thanks for the help, I'll work on it tonight.
I'm going to write that oil manufacturer, mopeds IS listed on it.
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 8:44 pm
by kylebo
I would try a champian RL87YC spark plug. I had this same problem to my 86 aero turned 9995 mils running tcw3 only and 86octain 10% ethonal no problem
that cheep plug is worth a try
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 8:53 pm
by Bear45-70
kylebo wrote:I would try a champian RL87YC spark plug. I had this same problem to my 86 aero turned 9995 mils running tcw3 only and 86octain 10% ethonal no problem
that cheep plug is worth a try
Even though I have always be a Champion spark plug guy, DO NOT use them in your scooter. NGK BPR6HSA or a BPR6HS is what you need to use. Also you need to preform a compression check on your engine. Manual says 114 minimum.
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 10:17 pm
by DKAudio
noiseguy wrote:DON'T USE THAT MARINE OIL IN YOUR BIKE. YOU ARE GOING TO DESTROY THE ENGINE.
Pull the line from the pump to manifold. Blow that out too. Then remove the pump, hook a clean hose to the inlet, and blow through that (with your mouth) to clear the pump.
Get to a Honda shop and buy some GN2 oil. Dump all that premix marine oil out of the oil tank, oil lines and pump, and refill with the right stuff. Bleed per service manual procedure; when it's working you'll get a drop every 5 seconds from the pump at idle.
I'm certain this will fix your problem. That marine oil makes a *complete* mess inside the combustion chamber. Usually the plugs come out oily and fouled as well... apparently not in this case.
I removed the oil pump and drained all the lines. I blew into the inlet to remove the oil from the pump. However, in the manual it says there should be an o-ring to seal around the pump and there was none. Does anyone know if this is a common size and if I can get one at an auto parts store? I'm also having trouble finding Honda GN2 oil in my area (55420).
Finally, should there be any grease along the shaft that goes into the pump? It looks like there may have been at one point, I would assume the top portion gets lubricated from the 2 cycle oil itself but what about the end that goes into the block?
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 11:09 pm
by mousewheels
Finally, should there be any grease along the shaft that goes into the pump? It looks like there may have been at one point, I would assume the top portion gets lubricated from the 2 cycle oil itself but what about the end that goes into the block?
Oil up the gear, and slide it in. On the crank side, the oil pump shaft is inside the crankcase. It gets lubricated by the 2 cycle oil inside, along with the ball bearing on crank. You can see how the worm drive on the crank is inside the ball bearing below:

- Aero_Crank.JPG (19.88 KiB) Viewed 7712 times
Re: Won't Start, Plugs Dying?
Posted: Thu Apr 21, 2011 11:21 pm
by noiseguy
You can find the o-ring around. Either carefully measure for it, or pull up the microfiche on one of the parts sites. Honda lists common part sizes (like o-rings) in the microfiche. Probably ID and thickness... take a look.
Just make sure to get the oil at a motorcycle or scooter shop, and that it's for oil injection engines (Honda dealer tried selling me HP2 once, which is premix only. They don't always know their products.)