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-   -   santa clause is coming to town and he needs help (http://www.chinariders.net/showthread.php?t=27863)

miatawnt2b 12-22-2020 07:44 PM

santa clause is coming to town and he needs help
 
The wife and I decided to shake down the 3 new 125's this afternoon. One of them just quit as she was going up a hill. Refuses to restart.

I haven't completely torn into it, but I've swapped a carb, spark plug and coil so far. All the parts from the dead ATV work fine on the good one.

On the dead ATV, I have spark and fuel flow, i've verified spark stops when you pull the emergency disconnect button. So I think the electrics are working, I'm wondering if it could have gotten out of time somehow.

Please, any help would be appreciated. I'm in a bind.

-J

JerryHawk250 12-23-2020 07:40 AM

More than likely it's a bad CDI. Try swapping one with the other to rule that out.

TxTaoRider 12-23-2020 09:33 AM

Or try swapping the suspect cdi box on to a running atv.

miatawnt2b 12-23-2020 09:54 AM

yep. swapped the regulator and the CDI from the dead quad into a working one. Fired right up. Put the ones from the ones from the good quad into the dead quad and still won't start. The only thing I haven't swapped is the engine at this point right?

JerryHawk250 12-23-2020 10:08 AM

You might need to adjust the valves on the one not running. It's possible that the valves are set so tight that the valves are not fully seated which equals no compression. This is common on just about all the china bikes and atv's.

miatawnt2b 12-23-2020 11:06 AM

yea, tried that also just now. They were indeed tight. same behavior though. Strange though that it was running perfect then just died without any notice. I'm leaning magneto (even though i have spark, who knows if its in time), but I really don't want to tear into it that deep without talking to the dealer first.

This is a real bummer.
-J

miatawnt2b 12-23-2020 11:13 AM

is it possible to pull the magneto cover without taking the engine completely out on a 125?

JerryHawk250 12-23-2020 11:15 AM

Did you check compression?
Also Someone else on here had an issue with the pick up sensor being set to far away. It still had spark but was weak. May be something to look into.

miatawnt2b 12-23-2020 11:34 AM

One thing I don't have is a compression gauge. I can feel pretty good puffs of air out the pipe.

China Rider 27 12-23-2020 11:49 AM

Coil partial grounding on paint

miatawnt2b 12-23-2020 12:19 PM

Quote:

Originally Posted by China Rider 27 (Post 351014)
Coil partial grounding on paint

coil is all plastic and just hanging there at the moment. not touching anything.

China Rider 27 12-23-2020 02:54 PM

Quote:

Originally Posted by miatawnt2b (Post 351017)
coil is all plastic and just hanging there at the moment. not touching anything.

Sounds like it does not ground by contact with the frame. Alot of the bikes, the coil is metal and grounds against the frame by mounting bolts, paint underlying can make for bad ground which will cause the weak spark.

miatawnt2b 12-23-2020 03:06 PM

Thanks for all your help guys. I really appreciate it. No luck yet, but hopefully I'll get it.
-J

miatawnt2b 12-23-2020 03:37 PM

swapped out the stator and pickup assembly from a good quad and still nothing.

TxTaoRider 12-23-2020 03:42 PM

Is the spark plug wet?

duck9191 12-23-2020 03:46 PM

take the nut off the flywheel and check the key, maybe it sheared when it died on the hill. Try some ether and see if it will at least pop. You can check the valve timing pretty easy, take the cam cap off and look at the timing mark on the flywheel.

miatawnt2b 12-23-2020 04:02 PM

should I be able to turn the flywheel by hand? I'm not sure how much compression these are supposed to have.
I do know that the cam rotates when I spin the flywheel, so I don't think the keyway is sheered completely.

duck9191 12-23-2020 04:10 PM

there should be resistance at least when turning the engine over. Normally when the key shears it will still look and operate normally but it will throw the ignition timing off due to the shift of the trigger coil

miatawnt2b 12-23-2020 04:27 PM

I'll probably have to dig in more later this evening. Kids are back from the grandparents and the quads are hidden away. I'll have to verify visually the valve timing with the flywheel. I have to be honest I did have a hard time using the .005 feeler gauge with the limited access of the round plugs. I attempted a few times to where I thought the gauge was between the tappet and the valve. I thought maybe that I wasn't really getting a good feel on the gauge, so one time I backed the adjuster out until I got a good rattle on the rocker. Then by hand I turned in the adjuster until I felt pressure against the valve, backed it out about 1/16 turn and set the locknut.

I do need to actually verify the timing though. gotta pull the main valve cover off so I can see the cam gear mark.

Emerikol 12-23-2020 05:40 PM

The pickup coil may be bad. That’s the only thing left, but testing it requires pulling the side cover. You can try to ohm it out, but I have had more than my fair share of coils fail and still ohm out within specs.

miatawnt2b 12-23-2020 05:46 PM

Quote:

Originally Posted by Emerikol (Post 351036)
The pickup coil may be bad. That’s the only thing left, but testing it requires pulling the side cover. You can try to ohm it out, but I have had more than my fair share of coils fail and still ohm out within specs.

nope, swapped the pickup when I swapped the stator. Everything comes off in the cover so it swapped as a working unit. My particular engine has the 6 coil stator assembly.

I know the only thing left is compression, and it was really the thing I thought for sure couldn't be an issue given the engine was running fine then quit without any catastrophic sounds. I'm going to set the motor to tdc, pull the spark plug and shoot some compressed air in the hole. That should tell me if I have compression or if air is leaking out the intake/exhaust or bottom end. (obviously have to take the oil fill plug out as well)

If I am getting no compression it makes me wonder if I floated a valve and "WHAM!"

-J

miatawnt2b 12-23-2020 11:42 PM

OK. I have a compression issue. I pulled the inspection plug on the flywheel cover and spun the crank counter-clockwise until I see the "T"

https://photos.app.goo.gl/jGsAycK3Q6nGTQ6y8
Then I verify I'm at TDC from the cam gear

https://photos.app.goo.gl/Yvo5kg2BPyGywYqQA

I pulled the spark plug and the oil fill, and shoot compressed air into the spark plug hole. I get air shooting out of the carb.

Then I rotate the crank 1 full turn. Again displaying "T" in the inspection port at the top of the flywheel cover.
The cam sprocket looks like this.

https://photos.app.goo.gl/zKRyzirziu65yfco8

Now I get air out of the exhaust & carb.

So... I think I have a problem. Any thoughts?
Without taking the top end apart, I think the intake valve is likely bent for reasons unknown. Just to prove to myself it wasn't an adjustment issue, I backed the valve adjuster all the way out so the valve can't close any further. Still air out the carb.

Emerikol 12-24-2020 07:35 AM

Quote:

Originally Posted by miatawnt2b (Post 351055)
So... I think I have a problem. Any thoughts?

I think the head is going to need to come off. It's possible that the seat detached from the head, but a bent valve seems more likely. If it's just the seat, you should be able to press is back into place and peen the soft aluminum of the head back around it. If it winds up being a bent valve, you may be able to carefully straighten it back out, provided the face and sealing surfaces aren't totally wrecked. Sounds like you've got a bit of a holiday project. Merry Christmas, let us know how it turns out.

miatawnt2b 12-24-2020 08:36 AM

Ordered a new complete head on amazon. 1 day delivery. $47.

I'm hoping I can get it on with the motor in the quad.

Thanks again everyone for your help so far
-J

JerryHawk250 12-24-2020 08:41 AM

Contact the deal as it should be covered by the warranty.

miatawnt2b 12-24-2020 09:21 AM

Yea, I am a little annoyed at the responsiveness of the dealer. I've tried contacting them the past 2 days and no call back. I understand it's the holiday, and they are likely buried, so I haven't blown them up on this forum... yet.

I wanted to try and get this working for tomorrow, so for less than $50, it's worth it at this point if I can make that happen.

I'll work on getting a replacement from the dealer after christmas if this works out and have one on the shelf as insurance.

miatawnt2b 12-25-2020 01:37 AM

Christmas is saved. The head arrived around 8. Started working on it a little after 9, by 11 it was running.

The piston slapped the valve, put several marks in the piston that I was able to smooth out with a dremel. I had to remove the top engine mounting bolt and lift the engine about 3/4 of an inch in order to gain enough room to remove the head. I'm pretty happy I didn't have to take out the motor.

Pretty pissed at the dealer. Not even a phone call today. Good thing I know my way around engines.

I'm just happy we'll have 3 happy kids instead of 2 happy and 1 disappointed.
I am planning on bringing the other two in the shop tomorrow before they turn them on and adjust the valves on them.

-J

duck9191 12-25-2020 08:15 AM

Guessing those valves were real tight then. Did you lash the other ones?

tknj99 12-25-2020 09:20 AM

Glad it worked out well! Sadly there are not many dealers that provide good basic after sale support or stand solidly behind the warranty they like to highlight in the ads.

Darth Racer 12-25-2020 09:36 AM

Glad to hear you got it sorted out miatawn2b. This was the worst case scenario I was trying to warn you about with waiting till Christmas morning to put them together. You managed to pull it all off in the St Nick of time..... good stuff.



Did you ever get the FNR issue fixed?

miatawnt2b 12-25-2020 10:12 PM

I did check the lash on the others before the kids were allowed to ride. They were very tight as well. They are now a little too loose likely, they do make noticeable valve train noise now. I would rather have them loose right now than too tight. I'll get back in there in a few days and true it up. I set as best I could with my .006 feeler, but I really have a hard time bending my gauge in there to get an accurate feel. Any tips? seems like a crap design to me with those round access plugs.

I'm going to try a couple more times to get hold of the dealer before I blow them up on here. I expect them to send a new head at least, as well as give me a good explanation as to why my 125cc quads I bought have 110cc engines. I am pretty annoyed at that.

I never got around to fixing or even looking into the FNR issue. It's not a huge deal, it does stay in gear. I'm wondering if it just needs some miles on it to loosen up.

I really appreciate the help everyone!

duck9191 12-26-2020 01:32 AM

Bent feelers help a lot. My Honda cruiser has the same set up with the access ports. Those engines come in multiple displacements, is that one marked 110ccm?

dirtbkr188 12-26-2020 08:15 AM

Quote:

Originally Posted by miatawnt2b (Post 351141)
I set as best I could with my .006 feeler, but I really have a hard time bending my gauge in there to get an accurate feel. Any tips?


The best $20 or so that I spent for good flexible feeler gauges is right HERE


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