87 fourtrax 70 no spark - Honda ATV Forum
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post #1 of 8 (permalink) Old 04-18-2010, 07:31 PM Thread Starter
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87 fourtrax 70 no spark

Picked up a fourtrax 70 for the kids yesterday. Needless to say they are more than anxious to get going but no spark. I cleaned up all the grounds and checked and cleaned connections. The grounds and kill switch seems to funtion ok. Key was eliminated wires are just connected together. How can I tell if there is power to the coil? What would be the first place to start on this problem cdi, stator, pulse generator? I pulled the side cover but didn't have a flywheel tool so thats still on there. It was suprising clean inside no rust. So are the aftermarket coils and CDIs for sale on EBAY junk or will they work.
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post #2 of 8 (permalink) Old 04-18-2010, 08:08 PM
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I ran into this problem a couple of months ago with the same quad model and year.. First of all I relocated the groung from the bottom air cleaner housing bolt to the frame. I sanded all the paint from the area and connected it there. I then unplugged the CDI cleaned the contacts as best i could and coated them with Die-electric grease I reinstalled them and I had fire. I would clean all your connections again....

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post #3 of 8 (permalink) Old 04-18-2010, 09:05 PM
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post #4 of 8 (permalink) Old 04-18-2010, 09:07 PM
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Welcome to the forums.

Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!

You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.
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post #5 of 8 (permalink) Old 04-19-2010, 07:38 AM
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there is a static test that you do pretty quick on the IG coil as well. if you have a multi meter, set it to ohms and check resistance from spark plug end (secondary side) to primary side should have about 7-10k ohms with no cap and around 14kohms with spark plug cap. and then check between 2 primary post, (if it has 2) should be about.5 or so
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post #6 of 8 (permalink) Old 04-20-2010, 06:47 PM Thread Starter
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Still no fire

Thanks for the help. I tried relocating ground. Checked continuity on all wires. Re-cleaned connections, checked coil it ohmed good and also tried coil from another machine. Some of the black wrap around the copper on one side of the stator looks like it may have got hot? Also, cleaned everythign up in side the LH side case. Still no fire. Is there an ohm test for the stator? I just tested across the ends of each side and had almost no resistance. How do you do it? I found something that said to check pulse generator by b/y wire and frame ground. I did that and it was @95 is that acceptable what i saw said it should be in the 200-300 range. I would think less is better right? Am I down to the cdi? I have a friend with a 87trx125 will the cdi work off that it has a different p/n that mine. Is that something to do with having a battery? Will it work just to see if I get spark before I drop $130 on a new one.

Last edited by gatorguy; 04-20-2010 at 06:50 PM. Reason: added to it
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post #7 of 8 (permalink) Old 04-26-2010, 07:48 PM Thread Starter
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70 runs like a champ now. Bad coil and also the DA I bought it from had the wires for the key switch tied together. Honda key is off when grounded so didn't work so good like that. Pretty obvious once I had a wiring diagram.
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post #8 of 8 (permalink) Old 02-08-2013, 03:07 PM
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Hi, just read your post and I have the same thing with no spark and the previous owner took the key slot out.
So... Should I twist the 2 wires from the key together? or not?

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