Helix CN250 no start By apothecary (Read 6,274 times)

[apothecary]

Well I've been referred here by a member of another board. So a quick run down of the issue I'm having.

I bought an '87 Helix the owner said the only problem was the cam chain had snapped. So the price was too good to pass up and everything else seemed kosher on the bike.

Start looking into the issue of the cam chain to find it DIDN'T in fact snap but popped off the the cam sprocket. The reason it did so was due to the right side bearing self destructing.

So I removed the side cover to start the replacement of the chain (I still thought the chain had snapped at that time). I found the oil pump chain had also removed itself from position. So I removed the flywheel, the oil pump shaft, the starter gear, the starter idler gear, and both chains.

Though not broken, the cam chain WAS bent so I'm glad I had a new one on hand. Replaced the cam chain and put the oil pump gear and circlip back in place along with its chain. Reinstalled everything else. Add oil, add coolant, hook the battery back up, turn the key, hit the button NOTHING...

Replace the battery and try again. The starter solenoid/relay clicks but the engine doesn't turn over. Battery is registering 13.2 volts now. The solenoid makes a rather loud and quite audible click when you hit the start button.

I've double checked the off/run switch to ensure it's in RUN position and I KNOW the bike turned over prior to me working on it. I've tried with the kickstand down and the kickstand up with no difference (I don't remember which way it's supposed to be anymore).

The only other thing I've noticed is the horn isn't working either. I'm not sure if these are related or if the horn doesn't work unless the engine is running or if I just have a bad horn.

I'll be arcing the starter relay tomorrow to see if it's the relay or if it's some other problem but I HAVE checked the ground from starter to battery and it's giving a good solid connection. The other thing I'll check when attempting to start is voltage at the starter when hitting the button.

Anyways if anyone can shed some light, I'd really appreciate it. Thanks.

Ok, patience not being my greatest virtue when working on something like this that I've been trying to get going for a few weeks now, I went outside with a flashlight and pliers and tried arcing the relay/solenoid. No joy. Starter STILL didn't turn over. I'm wondering if I did something to bind it up or if it's just gone south...

[JR]

Well you just took the words out of my mouth. If the solenoid is clicking in then it's more than likely good. I went and looked the wiring diagram over on the helix and just like a lot of scooters you must have a brake handle pressed for the scooter to start along with the kickstand in the up position.

Now a simple test, unhook the battery lead from the solenoid to the starter, hook up the volt meter to this leg and hit the starter button and see if it is indeed passing voltage.

But with a good battery at 13.2 volts and you crossing the solenoid and still no start you've just said it yourself. While putting it back together you have managed to get something in the wrong position or you've got a loced up starter?

But just for kicks lets see if you do have good voltage through the solenoid and go from there.

JR

[apothecary]

Ok I'll give that a shot tomorrow. It's dark now and I've never been good at holding a flashlight and turning a wrench.

It just baffles me that the starter worked great when the guy was showing me the bike and just from sitting and me doing that work on it, it's gone south? Maybe I knocked it when I was reinstalling everything but I'll check voltage tomorrow and if I'm getting good voltage I'll likely pull the starter tomorrow and thing about pulling it apart.

[JR]

Know what you mean and most of the time when one goes back you'll find some little simple thing that was missed.

But if you don't see anything then you can test the starter by either putting it on a bench and using a good 12 volt battery or by hooking up the lead from the sloenoid and making sure it's grounded well and hit the start button. It could be a locked starter but lets hope not.

JR

[apothecary]

Well just tested the relay the way you described and I'm getting 12.7V on the output side to the starter. Looks like it's time to bench test the starter and see what happens.

A bench test (though MUCH cruder than the one you described) shows me the starter is working quite well. So now to get that pain in the backside reinstalled and see if maybe I just had it jammed a little...

Ok well another update. I got the starter back in (THAT was a pain I NEVER wish to experience again). Took the left engine cover off (Why the HEX didn't I do this in the FIRST place...) and the engine is locked up tight as can be. Can't turn by hand or wrench. I'm wondering if I overtightened the not on the opposite side of the motor? The engine turned easy enough before I put the flywheel back on... Looks like it's back to the drawing board and a removal of the RIGHT side again with fingers crossed I didn't do any MAJOR damage in my attempts...

[apothecary]

Ok good news and bad news. Good news, I'm not sure WHAT exactly happened but as soon as I took the side off, the motor started spinning. Put everything back in place and it's still spinning. It's cranking over now just fine.

Bad news, I think I have no compression. The timing is right but the engine is still spinning easy as can be. AND to top it off, my carb just started leaking fuel. So back to the drawing board...

So I'm guessing the valves are bent. Is this a strong possibility knowing that the cam bearing shattered while the engine was running? I thought these weren't a non-interference engine so valves were highly unlikely to be bent...

[alleyoop]

At this point I would take the Valve cover off and put a towel or something to catch any oil squirting out and Crank the engine and see how the Valves are working. That will also very that your oil pump is working and pushing oil up to the valves and cam. By the way did you ADJUST the valve gaps, if they are to tight you will loose compression.
Alleyoop

[apothecary]

I hadn't thought about that. No I haven't adjusted the valve gaps yet and those can be done without even removing the cover. I guess I assumed that since it ran before the cam self destructed, it would run now as is. Let me review that procedure and give it a shot.

[apothecary]

Ok, I adjusted teh valves all the way in which SHOULD have given me a closed position on the valves through the entire cycle right? Still no compression. I'll take the tester out tomorrow and get readings on it but I'm not holding any hopes. I have a feeling the previous owner did some valve damage.

[alleyoop]

Well now just take the valve cover off and see if you can see anything wrong with the Rockers. If it turns over that easy you can turn it over by hand to see if the valves are moveing up and down or stuck down and just the rockers are moving with the cam.
Alleyoop

[apothecary]

Actually the CN250 has a VERY different valve train. The rockers are attached to the valve cover. I can watch them move at least somewhat without the cover off as I watch the adjusters move if the bolts are loose. Otherwise there's no way to see the rockers moving. I'm going through the service manual tonight to see if there's a good measurement for the height of the valve stem from the top of the head while in place to see if there's a possibility I can measure the valve length to tell if it's fully seated.

[JR]

Gonna go with Alley on this one, also it's starting to sound like more damage than was originally thought but lets hope not. But you're still making progress as it will now turn over again.

JR

[apothecary]

JR, if you look at the service manual on the CN250, I can't observe the rockers in motion. The rocker shafts go through the valve cover and the adjusters are actually on the outside. So if I remove my valve cover I'm also removing the lifters.

[alleyoop]

Apothecary,
That is fine what you want to see are the valves stems and springs. If they are stuck down you will definitely see that the springs are COMPRESSED and that means the valves are OPEM.
If you take the rockers off the valves should actually be closed because there is nothing to push them down and compress the springs.
Alleyoop

[apothecary]

Just did compression tests. Throttle wide open. 0 compression. That's right, nada, zip, zilch, the big goose egg. Watched the intake valve as the engine turned over and it's popping up and down and from the sound of it, the exhaust valve is working as well. So either rings, piston, or rod I'm guessing. I'm thinking of pouring a little trans fluid down the spark plug to see if it seals up and gives me anything.