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Old 11-26-2014, 07:26 PM   #1
smacdab949 OP
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Laugh Bike won't start (Sherco)

I have a 2002 Sherco 2.9 and it ran a few times, but now won't start. (novice trials rider, novice mechanic)

Looking for a list of things that I should be checking.

It was fouling the plug (kinda wet, but "not too bad" by by neighbor who knows more than I do). I was getting a tank or two, then would replace the spark plug and good to go again. But now it is not starting.

RYproducts was very helpful and suggested a few jets to replace. They also suggested 4 turns out on the fuel screw. I have cleaned the carb twice. It looks very clean. Though the last time there was a little dirt in there and I suspect that I didn't get the carb back into the fittings tight enough.

I also checked the spark with an auto spark tester (light bulb). It isn't too bright, but since it is for a car I am not sure if that is the problem. Because of the spark, I have not looked at the coil/stator. The coil is a expensive and I don't know how to test it. You just have to buy it (I think).

I also know the gas is getting into the carb as I pulled the hose and it was flowing.
I have removed the air filter just to try it.
I bypassed the kill switch (single wire) just to try it.

I am at a loss of how to debug this. One post said to put a few drops of gas in the cylinder. But I am not exactly sure what this is testing...so I haven't done it yet.

I have double checked the gas/oil ratio (80:1). I am riding the bike mostly on trails, but I do rev the engine as I have heard others say this clears things out. I could do this more I am sure...

Also, the engine has worked very good. Lots of power, never noticed any power delivery issues.

thx for any suggestions!

ps
I am in CA, so lewissport is (somewhat) local. They are experts so I can bring it there, but they are not open on weekends, so really hard for me to get there...and I would like to learn how to fix the bike as I get the impression trials bikes need a lot of attention ;-)
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Old 11-26-2014, 07:54 PM   #2
lineaway
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Cool2

Do you turn the gas off when you park it?
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Old 11-26-2014, 08:23 PM   #3
broncobowsher
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Quote:
Originally Posted by smacdab949 View Post
I have a 2002 Sherco 2.9 and it ran a few times, but now won't start. (novice trials rider, novice mechanic)

Looking for a list of things that I should be checking.

It was fouling the plug (kinda wet, but "not too bad" by by neighbor who knows more than I do). I was getting a tank or two, then would replace the spark plug and good to go again. But now it is not starting.

RYproducts was very helpful and suggested a few jets to replace. They also suggested 4 turns out on the fuel screw. I have cleaned the carb twice. It looks very clean. Though the last time there was a little dirt in there and I suspect that I didn't get the carb back into the fittings tight enough.

I also checked the spark with an auto spark tester (light bulb). It isn't too bright, but since it is for a car I am not sure if that is the problem. Because of the spark, I have not looked at the coil/stator. The coil is a expensive and I don't know how to test it. You just have to buy it (I think).

I also know the gas is getting into the carb as I pulled the hose and it was flowing.
I have removed the air filter just to try it.
I bypassed the kill switch (single wire) just to try it.

I am at a loss of how to debug this. One post said to put a few drops of gas in the cylinder. But I am not exactly sure what this is testing...so I haven't done it yet.

I have double checked the gas/oil ratio (80:1). I am riding the bike mostly on trails, but I do rev the engine as I have heard others say this clears things out. I could do this more I am sure...

Also, the engine has worked very good. Lots of power, never noticed any power delivery issues.

thx for any suggestions!

ps
I am in CA, so lewissport is (somewhat) local. They are experts so I can bring it there, but they are not open on weekends, so really hard for me to get there...and I would like to learn how to fix the bike as I get the impression trials bikes need a lot of attention ;-)
Spark plugs are not normally tested with a light bulb. Typically you lay the spark plug on the head and kick it over and look for a spark. Not sure of a way of testing for a spark with a light bulb. Might want to go back and look at the spark or lack there of for the problem.
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Old 11-26-2014, 08:37 PM   #4
nwcycle
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Could be

Lots of time the flywheel key will get sheared.......
If it has spark, you could pop the carb off altogether to eliminate that issue, and spray a shot of carb cleaner into the reed area ( Also reeds could be broke or old and stuck open ) give it a kick, if it fires up and runs a sec, well you know what to do now......
If you do leave the fuel on, it could be flooded, lay the bike sideways, both side to spill out all fuel in the carb.
put a new plug in it, and you dont even have to tighten it, put cap on, NO CHOKE, hold throttle WIDE open before you kick it, do not let go or roll throttle when you kick it. this will most likely give it a shot of air that it might need and fire off, when or if it does, kill it, tighten plug back up.. go out do wheelies.....
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Old 11-26-2014, 08:41 PM   #5
lineaway
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Sounds to me it floods when parked/always. Modern bikes do not go through plugs.
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Old 11-26-2014, 08:50 PM   #6
nwcycle
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Quote:
Originally Posted by lineaway View Post
Sounds to me it floods when parked/always. (Word)
Modern bikes do not go through plugs.
No, but if its was flooded then he wiped out the plug.....
Now Lineaway where is my super cool Team N M jersey at?


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Old 11-26-2014, 09:20 PM   #7
NMTrailboss
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Now Lineaway where is my super cool Team N M jersey at?
Yeah Bob...where is his super cool Team NM Jersey?
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Old 11-26-2014, 10:17 PM   #8
smacdab949 OP
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Quote:
Originally Posted by lineaway View Post
Do you turn the gas off when you park it?
yep
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Old 11-26-2014, 10:20 PM   #9
smacdab949 OP
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Quote:
Originally Posted by broncobowsher View Post
Spark plugs are not normally tested with a light bulb. Typically you lay the spark plug on the head and kick it over and look for a spark. Not sure of a way of testing for a spark with a light bulb. Might want to go back and look at the spark or lack there of for the problem.
I bought a tester at pepboys for 5 dollars. It lights the light when there is electricity. I didn't have a buddy to help and I can't give it the full kick and see the spark...I will try to find a "volunteer"
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Old 11-26-2014, 10:26 PM   #10
smacdab949 OP
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Quote:
Originally Posted by nwcycle View Post
Lots of time the flywheel key will get sheared.......
If it has spark, you could pop the carb off altogether to eliminate that issue, and spray a shot of carb cleaner into the reed area ( Also reeds could be broke or old and stuck open ) give it a kick, if it fires up and runs a sec, well you know what to do now......
If you do leave the fuel on, it could be flooded, lay the bike sideways, both side to spill out all fuel in the carb.
put a new plug in it, and you dont even have to tighten it, put cap on, NO CHOKE, hold throttle WIDE open before you kick it, do not let go or roll throttle when you kick it. this will most likely give it a shot of air that it might need and fire off, when or if it does, kill it, tighten plug back up.. go out do wheelies.....
I have not looked at the reed area (actually didn't know they existed...I did mention I was a beginner at this ;-)

Since I cleaned out the carb, the fuel got removed, so I don't think it is that.

I also heard to pull the plug and then slowly kick it to get clean air if you think it is "flooded". I have done this.

I am going to remove the carb. Had no idea you could do this!
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Old 11-27-2014, 03:50 AM   #11
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Take the carb off, and take it apart. Take it completely apart! All jets out, float assembly, needle, EVERYTHING! Take pictures, or get an exploded view somewhere online if you need it, to put it back together.

Clean that thing like you were going to eat dinner out of it.

Reassemble, and give it a try.
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Old 11-27-2014, 07:14 AM   #12
lineaway
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Originally Posted by nwcycle View Post
No, but if its was flooded then he wiped out the plug.....
Now Lineaway where is my super cool Team N M jersey at?


Also I am open week ends, so send me the motor :)
I have no idea, I have not had one in ten years! I do have my original one from `95.
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Old 11-27-2014, 07:46 AM   #13
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The plug should be of the hottest available heat range like NGK BP5ES or BP4ES. I've been using the RC14YC Champion plug in all my trials bikes. Simple, light, cheap, and hot!

You either have spark or not. Very simple. Check it is the dark, new plug removed with the threads touching a frame ground like the head fasteners. The flywheel key is something to check if you have spark (and can smell fuel from the exhaust) but it won't start. It'll spark but at the wrong time. I had that happen only once in 40 years.

If you do not have spark, then you can chase down wires and connectors. Make sure the plug wire is not zip tied to a frame member so hard it is smashed (it'll arc to ground there, especially when the bike is wet). You can check each wire connector too. Pull them apart then stuff them with Vaseline and put back together. No more potential for corrosion and an open connection. If you suspect the kill button simply disconnect it. A kill button is simply a momentary contact switch on the bars, one wire coming from the coil, the other going to a frame ground.

Hope this helps.
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Old 11-27-2014, 01:59 PM   #14
dhubbard422
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A couple of things to note...

Jets and orifices on a trials bike carb are small, tiny even. It doesn't take too much to clog a passage, especially if the gas was old and/or if the filter could be bypassed. You've had a couple of suggestions to completely disassemble the carb and clean it really well... in order to really clean it well, you'll want to let the carb soak for a while (overnight) in some nasty solvent, scrub it with brushes, probe the small passages with thin wire and use high air pressure to blow out all of the jets and passages.

Make sure that the floats are adjusted properly and that they flow fuel. I've had several trials bikes that run best with a minimal amount of fuel in the bowl which means that the needle is on the hairy edge of shut. I had an '02 Sherco (bought new) but that was a few years and many trials bikes ago and I can't remember the settings I used, but I remember that I could run the bowl dry with a high speed blast down a fire road, so the floats were probably set low in the bowl. I also thought that the stock jets were fat and I went down several sizes on both the main and pilot.

Put a fresh BP5ES plug in it and make sure it sparks as suggested by motobene, if it does and you get the carb truly clean, it'll probably start.

Trials bikes are damn near bullet proof. Especially, if they get even a minimal amount of routine maintenance.

Oh, BTW... gas is crap these days. I like running AV gas (LL100) in trials bikes as it doesn't have junk in it, it has decent octane and it is stable.
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Old 11-27-2014, 06:41 PM   #15
ericm
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Usually the problem is the idle jets are partially clogged with varnish from stale gas. It's extremely unlikely for the igntion system to fail from sitting around.

The orifices in the idle jets are so small that it's difficult to clean them. It's easier to buy new ones if they're available.

Avgas has a lot of lead in it. I'd run 50/50 unleaded race gas and pump premium. You can use fuel stabilizer if the bike sits around.

When you stop riding for the day run the float bowl empty by turning off the fuel tap 1/4 mile from the truck and letting it idle until it dies. That way there won't be much gas in the carb to go stale and leave varnish.
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