New grips, cleaned the carb, added fuel.... smells like gas.
Farts. Needs a new fuel valve, and I was hopeful the carb gaskets would be ok but they’re not. Double farts. Flooded it. So I recovered what fuel I could before it all fell out and I’m off to order parts. It’s hot out anyway.
Did confirm spark though so there is some good news.
Major win! My enthusiasm and progress has gotten the guy I bought this bike from to start getting his running again. It’ll be a few weeks as he needs to reseal his forks and replace his brakes due to them being soaked in fork oil. Still, stoked!
The only thing better than riding dirt bikes is riding dirt bikes with a buddy.
Parts arrived! And even better than that, the service manual arrived! So I got home, helped get the kids washed, fed and put to sleep and went out to play.
Problem number one: leaking fuel valve... FIXED!
Problem number two: leaky/overflowing carb... FIXED!
Verified fuel in the carb, verified spark, kick kick kick, nothing. The manual says the next step is to check compression so I’ll do that when I get my hands on a compression gauge. But my thinking is that I shouldn’t be able to turn the compression release lever by hand and maybe that is an indication of a stuck valve. Maybe I’m wrong, but it would explain not starting and this bike did sit for a long time. I’ll check that theory later this week maybe.
Check the valve clearances. These bikes get tough to start when the valves start getting tight. The locknut style adjuster is super simple and easy.
In reply to 2002maniac :
That is the plan, since I have the manual and a set of feelers at home and the compression tester is in my dad's tool box 30 minutes away. Shouldn't take more than a few minutes to pull the tank and check the valves. Hopefully that is the issue because that is the end of the easy stuff. Video if it fires up!
Fuel system functioning as intended. Valves are moving freely and adjusted to specs. Still nothing.
Ether... nothing. I have spark. Both the new plug and the old plug are gapped properly and both provide a nice hot spark. So, I begin to suspect that while it is firing, it is not firing at the correct time. It’s been a decade since I’ve torn one of these engines apart and I don’t remember if there is any adjustment in ignition timing. Time to read the book I suppose. So much for “ran when parked”. This is giving me a harder time than any Honda should.
*edit. Glad I bought the book. Step by step instructions on installation of the ignition system should get me close enough to get it to fire up. That is providing that my wild ass guess about bad ignition timing is accurate. Trying hard to get this heap running before my nephew comes to visit this weekend.
My previous spark verification was pulling the plug, putting the lead on it, grounding the threads and turning the engine over. Not the most bulletproof test. I finally got around to putting a meter on the coil. Results were inconsistent. As in sometimes the primary coil read on the high end of acceptable and sometimes didn’t read at all. Coil seems to have a short. New one on order.
New coil made no difference. In trying I did discover something though. The bike felt the same to kick over either with or without a spark plug. I couldn’t find a compression gauge but I did attempt a leak down. No air escaped. So then I think wtf, could the timing have jumped somehow? The thing ran when it was parked, so I don’t know how it could have. Anyway. Pulled the covers, lined the flywheel up with its marks to be sure of tdc and wouldn’t you know it? The ignition rotor wasn’t even close. Timing jumped. So I loosened things up, pulled the bolt out that holds the timing tensioner in place and re-timed the thing. I noticed that the cam sprocket looked a bit chowdered though but it should be fine right? Assembled it again and kicked. Felt way better. Like I had compression. Kick kick kick, burbles! It’s gonna start. Kick kick kick, the compression seemed to disappear. Damn. Cam sprocket seems to be too far gone. Gotta order a new one. Odd problems but solvable I think.
In reply to barefootskater :
Take it far enough apart to replace the crank sprocket, that is where the slippage happens. Remember it wears twice as fast as the cam sprocket
.
In reply to TurnerX19 :
Good advice. It does require a special flywheel removal tool but maybe I can improvise.
Now go get on the AMC boards and buy a decal like this:
Been a minute. FIL got the quads going and I've been taking #1 out on rides a few times a week which has really gotten me wanting to get this bike fixed.
Back in December I got a new timing chain and both sprockets and they've been sitting since then. Finally got out today with proper equipment to remove the flywheel and found the culprit.
The tensioner is supposed to be in one piece. Luckily I can get it and the chain/sprockets replaced without even removing the engine.
Carnage:
case has seen better days but imma just send it. I've seen worse work just fine. Sprockets are toasted as is the chain:
You could shave with some of those links.
Anyway, I didn't order a new tensioner when I got the other parts because I'm a bit of a hack. Off to remedy that now. Still love the bike. Love the fact that I can get this far into the guts with the engine still mounted.
Tensioner showed up yesterday. At the parts store today I picked up a baby 3 jaw puller. So when I got home I was able to get the crank sprocket off without too much of a fight. It is an interference fit on the crank with no key or pin for aligning it, just a little arrow that was pointing to the leading edge of a tooth on the sprocket.
Once the old gear was off I put the new one in the oven in a vain attempt to ease installation. I'd say I was pretty successful too. Everything lined up well. Then I put over three cans of brake clean through the case to flush out as much as I could and started reassembly. The manual says to remove the engine and then the head but that's just extra work. I was able to shimmy the new tensioner into place and snake the new chain down from the top and around the sprockets without any real difficulty. The old chain was quite stretched and had a lot of looseness to it. I have new oil and some ethanol free fuel but it's late and I didn't want to wake anyone. Hopefully tomorrow I can find a few minutes to see if I actually fixed anything.
Oil and fuel and still won't start. I verified spark again, gave the carb a quick clean since it's been sitting since November with corn juice in it. Even pulled enough covers to verify cam timing. The weird thing is it gets noticeably easier to kick over if I hold the throttle open leading me to believe the cam is advanced a tooth too far despite the marks all lining up as they are supposed to. I monkeyed with it until the dark got to be irritating and called it a night. I think I'll try moving the cam back by a tooth next and see what happens.
I did get one rather large backfire. The kind where fire shoots out the exhaust, so that was pretty neat.
Someone check my thinking.
When I installed the new timing set I was very careful to get everything lined up and synced properly, flywheel tdc mark aligned with the indicator and the cam sprocket lined up with its index mark on the valve cover, engine turned over by hand several times to make sure that everything stayed put and was correct. Still the bike won't start despite fresh fuel, confirmed spark and more than enough compression. So I start thinking: the old cam sprocket has slotted holes and the sprocket was advanced all the way (cam fully retarded). The slots are just visible in the photo below:
. The new sprocket (Honda part, possibly superseded from an older design) has two holes which are not slotted.
The bike is quite noticeably easier to kick over with the throttle open which leads me to believe the cam is too far advanced and the exhaust valve is closing too early and the intake is opening while the piston is still on the exhaust stroke, forcing air backwards into the carb.
Im not home yet and not sure I'll have time tonight to adjust the timing and retry starting it.
Anyway, does my theory sound plausible? I'm not running on a lot of sleep this week but I've been obsessing on this today.
In reply to barefootskater :
Can you check the orientation of the bolt holes and mark against the old sprocket or did you already scrap it?
In reply to Patientzero :
Checked. It's good.
barefootskater said:In reply to slowbird :
Thanks! The pocket is functional but really only there because my old jeans didn’t have much real estate left that didn’t have holes. If I ever get the thing street legal I’ll probably use it to stash registration and unsurance cards.
Stick them in a Ziplock snack bag :)
In reply to Greg Smith (Forum Supporter) :
Good thoughts!
So I've been puzzled by this thing. This morning I got out and moved the cam timing back one tooth and it didn't make a difference. At least it still wouldn't start, even on ether. That tells me there is a problem with ignition. I have double and triple checked and I have spark at the plug. I also cannot think that even if I have the cam 180* off would make a difference that it should matter since the ignition rotor is keyed to the cam so the ignition timing is tied to the valve events. But then I start thinking if maybe the ignition unit (CDI) is somehow seeing the crank in the wrong place (not sure it's even possible). The flywheel has embedded magnets and rotates around 6(?) copper coils. Again, I can't see how it could make a difference but I think the next step is to turn the cam 180 and see. If that works I'll be shocked but I'm running out of ideas.
How are all the grounds? As long as it was sitting maybe rust is causing the coil to not get a good ground through the head? Forgive my ignorance but this is a 2 stroke right? I know engines just not dirt bikes.
In reply to Patientzero :
Grounds seem good. Bike is a four stroke. I have spark, but the bike won't fire at all, not even with starting fluid.
Success!
So I popped the rocker covers off and rotated the crank until it said tdc and the ignition rotor was in the "I just fired 6* ago" position. The rockers should have some play at this part, .002 and .003 specifically. Which is just enough to feel movement. I got nothing. So I rotated the crank once and wiggled the rockers and wouldn't you know it, movement! What the hell? The rotor is keyed to the cam and has only one possible position.
So on these bikes the ignition advance system lives in a little space over the end of the cam. This housing comes off as a unit so that the cam can be removed without the ignition timing being changed. The system is a sleeve (the keyed part) that slides over the end of the cam. The sleeve has weights which swing out to provide the ignition advance much like any distributor. The rotor sits over this sleeve and can be removed if you hold the weights out but I never remove it because it's a bit fiddly to put it back. The rotor, I learned today, can in fact be 180 off. I discovered it was. Switched it around and the bike started first kick. Then died because the tank was off and it ran the carb dry. But I put the tank and seat back on and filled the thing full. AND WENT FOR A RIDE!
I missed riding more than I remembered. So good. Wheelies, climbing the hill I hike up with my son. Blasting gears. So good.
I didn't get anything done on the challenge car today but it was a great day all the same. Video incoming.
This made my day!!
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