2011 TE310 Motor stopped under light load

The bike has 2,500 miles on it. Was at the end of a short 45 mile ride. It just stopped while at less than a 1/4 throttle. When I hit the starter I knew I was in trouble. It was spinning fast like it had little back pressure. Also when I hit the starter with lots of throttle it does backfire so I know it's got spark. My immediate thought was that the auto decompression system got funky. I also read about one guys shear pin shearing off and throwing the timing off. I tried to start it after it cooled down with no change. There were no strange noises when It stalled. My initial thought was, I'm out of gas?

Any thoughts or tips? Whats next?
Thanks in advance.

if you can 'kick' it through easily with your hand- you probably got a compression problem.

A compression test will give you a clue to these:
bad ADC (good call).
broken timing chain.
stuck valve.
broken valve spring.
broken cam (rare).
cracked head.
blown head gasket.
loose or broken sparkplug.
hole in piston.
broken rings.
cracked cylinder.
(also a loss of oil/pressure can cause the above problems; what's the oil level? does it smell brunt?)

other non-compression related stuff:
bad manifold.
sheared flywheel key.
pulse coil intermittent
coil intermittent
bad sensor (TPS, MAP, CTS)
some electrical fault (eg. short or broken wire; battery or connections)
check your kill button and wire.

if it doesn't backfire anymore, check the FI system: pump, filter, hoses, injector

did you (unknowingly) overheat it? check the coolant

good luck. keep us updated and let us know what you find.

Haven't found enough time to break down it down but, I hand pushed the kick and it had compression until I used the electric start. It made the whining fast sound and when I hand pushed the kick it had no resistance for about 5 full pushes then regained compression. I don't know what to look at but the ADC seems to be a likely suspect or a sticky valve.

Your first action before all should be inserting compression gauge and doing dry and wet tests...

I pulled off the valve cover yesterday and am somewhat confused. I may be mistaken but the actuator seems to be about 180 degrees off? Notice it starts at the recessed spot at about 90 degrees then when I trip the actuator, instead of going flat it goes to the full hump. Please correct me if I'm missing something. The video at the bottom is a KTM and does the opposite which makes sense. Please start the bottom video at 1:09

I was right, well at least about Trenchcoat 85 usually being right. #5, a broken valve spring, main exhaust side. My guess is that as the inner and outer springs move around sometimes they would align enough to make the valve seat for a turn or two. As for the actuator pin. That defies mechanics. The flat side should show when centrifugal force moves the arm outward. I don't understand how it could run with one exhaust valve not fully closing in between strokes?

Now I have find out where to get 1 new valve spring set or should I get 4? Also, at 2,500 miles since the heads off I think I should get new rings but again. Anyone recommend a parts supplier?

you know, if you already have the head off, I'd do a full valve jobs with new seats, springs and (SS?) valves. The redheads have valves designed by Del West, I believe; your blackhead has the titanium valves and maybe weaker springs? Anybody remember?

Might as well throw some rings in while you're there too (OTOH- probably not that big of a deal).

good luck.

Thanks for the vote of confidence! But really, you called it- I just listed a bunch of reasons for low compression. With a compression problem (like you found) the reason pretty much had to be on that list somewhere.

BTW, I added "loose or broken sparkplug" to the list, for future readers. sheesh- can't believe I left that out.

They only sell a top end kit. It's about $360 for piston, wrist pin and Circlips. I went by my old shop today and got a resounding vote to sell and get the new FE 350. Just need one more vote from the electoral college. Hope she completes the sweep for votes.

Yep- that would be my next bike too if I was in the market. very nice. OTOH, $10K is a chunk of change... will they take the TE in on trade?

And can you take an elector out for dinner & drinks and influence the vote? try the phrase "...for the good of the economy" or even better- "...think of the children"

Is a green issue the old bike is unenvironmentally sound to repair

I was able to push the small set pin
back to the opposite side and below you can see it working properly. Notice the flat spot appears when the actuator is activated.

(180*) next time you have the valve over off, check to make
Sure that you check and verify a proper installation. Here is the correctly working actuator.

Below is the wrong from factory decompressor actuator.

I'm not sure if your starter system is the same however my 2009, TE310 had a similar problem.

If the bike is in gear does it have compression when you try to move the bike? If so, it's not a decompressor issue.

If the kick start and starter slip or spin without turning the motor over then you have a worn out spring on your starter clutch. It's a cheap fix but takes a bit of time.

The kick start and electric starter gears drive a one way clutch on the crankshaft output gear. The clutch is an array of pawls held engaged by a garter spring that grab in one direction and slip if rotated in the other direction. If this spring wears out and loses tension then you get the symptoms you describe. To fix it you need to remove the kick starter then Right Hand Side engine cover to expose the clutch and starter gears. Now remove the clutch springs, plates and clutch basket (RH thread). Remove the freewheel hub from the crankshaft gear (LH thread). Then pull the sprag (one way) clutch off the crankshaft gear hub assembly. Then remove the one way clutch from the inside of the hub.

Problem found: There is a spring (same as a fork seal garter spring) that is supposed to hold the pawls firmly on the starter outer gear so it is engaged with the crank hub. Under normal conditions once the engine starts, centrifugal force expands the pawls so they disengage from the starter gear. The spring had stretched and was stuffed. I pulled the garter spring from a 50mm Inside Diameter seal (cost $5) which was the correct length and thickness and replaced it on the clutch.

Put it all together and viola!

You can also get a complete new sprag clutch from a Honda dealer. Part number 28125-MT7-004. A stuffed looks like the attachment below. On a new one the spring is tight. Make sure you note which way it goes in so you insert the new one in the correct direction.

Note: The later models have a different system that engages the flywheel side instead however still uses the same one way clutch.

Hey MXImage... was the ADC on the valve whose spring(s) broke? that would make a bit of sense.

I wonder if you picked up some HP?

Something is not cosher here. If this is an assembly error from factory i not see how this motor would run for 2500 miles off roaded like that un noticed. I am assuming this cam was out at least once for valve shim replacement, when was that done?
BTW look like spring failed being actuated twice normal frequency. Inspect that valve also...

I've been wondering the same thing. Though I have a new bike I can't wait to fire it up and feel the difference. I will also give me a better benchmark to compare the old and new bikes by.

How could it run is the million dollar question. Wayne, Malcolms mechanic, asked the same thing and so did I but the fact is it did run and it did come from the factory that way. To further confuse speculation, the springs that broke were on the opposite valve, not the one actuating valve.

Lots of great info here. Having searched for problems myself I'm sure that your info is going to help others. Thanks for putting out so much detailed info.

hmmm- I'm not so sure that this is such a great mystery. First of all, these motors (xlites especially) are known for the ADC not working if the valves are on the loose side of the specification. Second of all- they start and run fine at low rpm's with the ADC working... so why not at high rpm's? It's not like the ADC is letting the majority of the compressed mixture pass by... I'd guess (*guess*) it's more like 10%. And I bet it's closed at TDC when the major burning is going on (or maybe even BTDC)

hell, the ADC valve might be getting some cooling during use.

BTW, notice in the video of the (bad) ADC that you're not getting a full 90° of travel.

Love that new 350!

I'm thinking that your decompressor hypothesis is probably correct or in the ballpark. Losing some of the "bump" from the initial combustion but enough for it to run pretty good. It also might explain why the carbon was not baked on hard. I also noticed that the thermostats o-ring is popping out inside the cooling chamber and not seated. I don't think I've ever heard the fan come on and I'd bet that has something to do with it. I'm really thinking my bike was made in Italy on a hangover monday.