1988 220 bayou starting problem.

[mat_gon_jinn]

Hi all, I'm new and have read some 220 bayou threads, but nothing that covers what I need. The thing died quite a while ago and I just got around to pulling it halfway down to replace certain things (piston rings, honed the bore, one way clutch, primary clutch etc)... Put it back together, had quite a few ignition problems, fixed that, we now got spark but no go.

First problem was we had no spark because dog chewed up all the wiring, I couldn't figure it out so I ripped apart the whole loom in one angry sweep and started the whole lot again, with a new (second hand) cdi (which I'd tested the old one to be faulty)... Hooked it all up, beauty! She sparks, but man it was weak. At this point in time I didn't have a serviceable battery to carry the current, so was just pull starting it, and managed to get it running for maybe 2 minutes. Damn I was happy, it responded to throttle quite well and would even idle. Then it just died. There pulling away for half an hour without a single hint I finally pulled the plug out and wam, no spark... In the end I decided the coil was at fault so I went off and bought a coil off a pitbike, put it back on, you beauty! We got sparkage! Good strong blue spark. Stick it in, no go. Not a single hint out of the sucker. First trying it with choke, then with a bit of throttle, then with a bit of aerostart. The ******* wouldn't give a single hint. (This is with the starter motor by the way(new battery)). I've read on here some people couldn't get their's going with the starter but could with the pullstarter, so I gave that a shot... Still not a kick.

Now that you're up to speed (if you didn't get bored halfway through and leave)... Any ideas? I'm fairly mechanically minded, but this has me stumped. It doesn't make sense, I had it going for that time, and it crapped itself because it had no spark, now it has a spark, and it's just dead. I've checked the valve timing (just by looking in through the plug hole), it's fine. But anyway if it wasn't, it couldn't possibly jump out from before unless it's jumped a tooth on the cam chain. It puts out about 60PSI for compression with the throttle closed. It'd be quite a lot more with it open (if I'd remembered). I cleaned out the carby twice, all the jets are fine, throttle and choke slides are fine.
What I can't imagine is why, that when I had the carby off, I sprayed aerostart directly into the cylinder and cranked it. There is no way that couldn't fire. The only way I can see it not firing, is because of ignition timing. But if we had it going before, why should it be out now?

My biggest question is, if the CDI is faulty in such a way, can it still produce a spark, but at a very wrong time?

Well I pull the plug out from trying to start it, the tip is quite wet, if it was flooding for whatever reason, on initial cranking, you'd think it'd give a bit of a hint wouldn't you? I'm not the best with carbies, so what could cause flooding due to the carby? If the float valve wasn't shutting properly, it'd go out the overflow before it goes out the top into the cylinder wouldn't it?

Any help would be much appreciated...
Thanks you so much for reading that essay even if you can't help.

[MrGiggles]

60 PSI of compression is way too low. You need at least 100 to run. I would guess that is your problem there. Did you have the head looked at? Maybe you just have a slightly bent valve or a leaky head gasket.

[RCW]

The Bayou is very sensitive to having a fully charged battery in order to have the CDI function correctly and build enough energy to get the ignition coil to fully energize. Sounds like you solved that issue with a new battery, just make sure the battery is fully charged.

A bad CDI will not cause a timing change. If you have a strong spark, then it is working. If the spark plug does not spark when installed, then it is usually the spark plug itself that is bad. However, if the carburetor is misadjusted or dirty you can end up flooding the spark plug and not firing either. Enough flooding and you will need a new spark plug as the porcelain insulator will become contaminated and start bridging the spark no matter how many times you dry it out.

The overflow on the carburetor does not protect from high float levels. You probably should completely disassemble and clean the carburetor, and check all the jets and bleed holes to be sure they are clear of rubbish. Make sure the float valve needle is properly seating in the carburetor body. These carburetors use a non-replaceable float valve seat, and it that becomes pitted or worn the valve needle will not shut off properly and they flood.

Also check your starter plunger (choke valve). If it is worn it causes fuel to continue to dribble in the carburetor and will flood the engine.

If the woodruff key on the flywheel is sheared or missing you will be out of time and that could be your problem. The woodruff key shears if the engine kicks back, or just from old age.

If the timing chain has become loose over time and allowed the cam to jump timing, you will have problems starting. Same thing if the valves are adjusted too tight or way too loose.

Back to the CDI and ignition. There is a pulsing coil that both provides the timing reference and the trigger voltage to trip the CDI, if that gets loose or the electrical connections are not secure it can create a problem with getting one to run.

Another thing to check is your repaired wiring harness. If you are not using regulated power to run the CDI you will damage it from excessive generator output. However, if it is triggering the spark plug with a strong spark in the open I would suspect the CDI is good. If the circuits are not properly grounded you will end up with power problems too. I would double check my wiring repairs to the wiring to the schematic.

I am not sure of the coil you are using, if it is not matched to the available output of the CDI you can damage the CDI, or the coil may not saturate fully and the spark will look good on an open plug but fail under compression when the resistance is increased.

The key switch and kill switch can also create problems.

[mat_gon_jinn]

Thankyou so much RCW for the very detailed reply. At this point in time, I'm not at all worried about the ignition, everything's hooked up (apart from the engine stop switch just to make things easy), so basically there's wires going everywhere at the moment, the regulator is hooked up. So as long as the CDI won't effect timing, I'm not to worried about that (apart from you mentioning an incompatible coil buggering up the CDI)... At this point in time I'll say 'she'll be right'. Not a good attitude I know but still....

As for the woodruff key on the flywheel, I took the little timing cover off the top and had a peak in... Don't have a clue what I'm looking at, there's a few timing marks but I don't know what they mean, there's also a circle indent in it, which I used to lever a screwdriver in while a gave the pullstarter a pit of a pull, to see if it was nice and tight on the crankshaft... It seemed pretty nice and firm. I'm not sure if maybe it could have turned from it's original position and then lock itself on again. I really can't remember if I put the key back in or not.

I do have strong suspicions on the carby's part. Because the plug is quite wet when you take it out. What I can't understand though, is that we had it running that time, and now it just won't give a hint of life. What I've been doing is opening the fuel tap and giving the bowl a chance to fill up before trying, so if it is flooding, perhaps that's just giving it a chance to flood. So what I'll try is turning the tap on and cranking it straight away. I didn't really give a good inspection of the float valve and it's seat. Umm, yeah, if it's dodgy, would the fuel really just fill up and dribble straight into the cylinder? If so what I might do is take the carby out again, hook up the fuel and see if it fills up and runs out.

As for you mr giggles, yes 60 PSI is low, but it should be quite a lot higher with the throttle open (which I will also test again)... At least, this is what has been said to me by a bike mechanic... I haven't had a whole lot to do with small petrol engines.

I'll keep you posted

[RCW]

Since the advent of oxygenated gasoline fuel problems have been endemic. What could have easily happened is that a particle of varnish was deposited under the float needle after you got the machine started and run a bit, and is now keeping the float from closing that valve.

Another really common problem is a leaking starter plunger that enriches the mix for starting.

The synthetics used in 1988 were not compatible with the junk gasolines we have today, and you may even be having problems with fuel lines disintegrating and shedding particles into the fuel stream.