Hi all, I am looking for any advice that someone might kindly throw at me becuase I am spent. Think of this long post as an application, becuase if you can fill it out right you will be my new best friend :-)

I hadn't ridden my 97 Magna (8k miles) for a few months becuase of a flat tire, stolen tag, and so on. After a little coaxing it started up and ran great. I changed the rear tire, lubed everything up and cleaned the air filter. While the airbox was off I thought, meh, lemme spray a little carb cleaner int eh throat, just for surface gunk. After reassembling everything it wouldn't turn over. I figured it was just the carb cleaner burning off so I kept cranking. While cranking I heard a horrible noise that sounded like the engine coming to a dead stop. I fearfully cranked again (worried I would find a seized engine) but nope, sounded perfectly normal and kept cranking. Nothing.

I checked and had spark in all cylinders. Fuel was vaporizing in the cylinders. Without any other ideas I started disassembling further. I removed and dismantled the carb to be sure it was as clean as new, and it definatly is now. I checked all my vac lines, fuel lines, etc. Rechecked for spark. Reassembled bike. Still nothing. No combustion at all. Cranks nice, vaporizes fuel, and sparks.

Whats left? Timing and compression. Well, the ICM is preset, from what I gather you can test the timing but not really adjust it, just replace the ICM. I haven't tested yet (light gun seems buried in the garage), but I am doubting the timing suddenly went so far out of whack I wouldn't get any combustion.

I have to buy an adapter for my compression gauge tomorrow to check that. From what I have read elsewhere no one has had one of these engines actually fail. And again, it sounds normal when cranking...no combustion though.

A last ditch starting effort yielded one more finding. While starting I heard what sounded like a push of air come from the exhaust. Like a backfire without the 'fire'. I thought I was nuts and cranked again, after a few seconds it did it once more, right after I let my finger off the start button.

Any ideas? I am really at a loss. The timing at compression seem so unlikely but I don't know what else to try. Thanks much.

 

if that's a downdraft carbed magna, it should fire if it has fuel and spark... of course spark could be on the weak side. is there a chance that you can try a new battery? are the plugs overly wet after cranking? if the carbs are DUMPING fuel in those cylinders it wont fire. One additional thing is to see is you possible have a blown head gasket... if its sucking in water it probably wont fire either.

is that gen Magna a gear driven cam set up or chain driven?

 

batt seems fine and I have been running it off a high amperage charger/starter anyways. spark seems normal enough, though my frame of reference is somewhat limited when it comes to bikes I guess. it cranks fast and strong though.

I didn't notice excess gas, seems to be flowing just right. plug is only real wet after prolonged attempts. I haven't checked the crank case for coolant/water but the head gasket seems unlikely being as how I drove it into the garage the same morning this all happened. (though, that being said nothing seems likely)

 

another thing that seems unlikely but is a possibility is that the cam chain jumped a tooth or three... that is if this is a chain driven system and not gear driven. If you get the opportunity to try and do a start with your bike feeding off a battery tender or another battery(jump form a car), try it. it doesn't take long to do and can rule out a weak battery. I have seen bike crank like normal and still not start until the battery is FULLY up to snuff. Usually this is symptomatic of a big twin, but your v4 might suffer from a weak battery also.

 

if you've got spark, fuel and a decent battery but still no combustion i'd want to make sure there is compression... so hopefully your compression test reveals something. i'm pretty sure this year magna has a chain driven cam, so it may have skipped as schu mentioned.

 

I have had the batt charging for a full day and night now and it still wont start so I am confident about the power.

As far as the cam chain I plead ignorance. Outside the engine and tranny I know my way around, once I get inside I am pretty much a fool. If I recall there is a position indicator on the side of the crankshaft. If that it in the right spot then am I good or should I still check with the timing gun?

Seems a smaller (10mm I think) adapter for my compression gauge is not an easy local item to come by so I still need to find one of those. Lets say my compression is off, what does that point to? Stuck valve, bad rings, what else?

Unless I am overlooking something major, or the ICM is bad (and the service manual doesn't even list a method of testing it), it seems I am dealing with something pretty serious then right? Even the ICM is one pricey piece for that matter.

 

What method are you using to check the spark? I was just thinking, you might be showing HT power in all four of your leads but the plugs themselves might be toast?
Are you seeing a healthy spark centered between the plugs' electrodes?
Im asking because I had the same symptoms as yourself with a small inline four bike recently (with downdraft carbs). After getting it running and even cleaning the plugs, one day it just refused to start, even pushing it.
In this case the plugs were old, soiled, porous, damp with gas, had been lying idle a few years, and had a small weak spark which was arcing to the side of the electrode.
I replaced the plugs and the bike started within approx 0.46 seconds of pressing the button and ran like new.

i see some talk above of it grinding to a stop and cam chains etc, best of luck with all that if its the case.. ugh! hopefully its somethin small

 

The plugs don't look brand new, and I tried cleaning them with gas and a brush. I am planning on replacing them tomorrow though, just because its a cheap and easy thing to try (well, easy on 2 of the cylinders). The plugs seem to make it run fine before, but I guess weirder things have happened.

Edit: To more accurately answer your question, to check for spark I am just grounding out the plug and watching for spark between the electrodes. Again, it looks good, but for $8 its a nice thing to rule out for sure.

 

Did you figure out what was wrong with it? I am having similar trouble and need more ideas what to look at. I thought it was my carbs but still not sure.

 

sorry about not updating this particular thread.

oddly enough it turned out to be the plugs. I can't recall the last time I was so confused by a mechanical blunder. the plugs worked fine one min and then not so much the next. I guess it just hit the breaking point. I was so desperate that I grabbed plugs driving past the auto parts store and put in 2 first 9the easy ones) and it started instantly. changed out the 2 others and it's been running great since then.

go figrue.