Gas Gas 300 problem

[bluesboy]

I own a GG EC300 ‘03 here in the UK. I’ve had the bike for approx 10 months and love it. Unfortunately it has developed a niggling fault which I will try and describe for you in the hope that someone can help me pin point the cause.

The basic problem is engine misfiring. This is intermittent but is a real pain when it occurs. This is what happens…

1. Engine difficult to fire up and dies if you blip the throttle.
2. Won’t rev out when throttle is twisted at tick over.
3. A bit like leaving the choke on?
4. Feels like someone’s put a plastic bag over the air filter.
5. Very little power from standing start in 1st gear. If I do manage to get her rolling then it will run but very lumpy and will die if you don’t keep the revs up. Runs like a pig.
6. Runs great for months then fault appears for no reason. This has happened on and off for the 10 months I’ve owned the bike.

I’ve replaced the coil and kill switch but haven’t touched the alternator. I’m not convinced it’s the alternator as I guess this would either have a good (or bad) output all the time and not be intermittent?

OK - over to you guys. I’m assuming this is an electrical fault and causing a weak spark perhaps. Anyone think it could be carburation?

Looking forward to your replies.

 

[kdxjr]

I had a similiar problem on a GG125 turns out the rubber boot between the reed cage an carb had a crack in it.

I would bet its not electrical,also check your reeds and clean the crud(buildup) off the power valve.

 

[stroker]

a riding buddy had a 2001 EC300 that had a similar problem... he had water behind the ignition cover, if that cover is over torqued, it will distort slightly and allow water inside. once the water gets in it runs poorly.

Remove cover, clean and dry ignition, add a thin bead of silicone to mating surface when cover is reinstalled, and do not over torque it.

Let us know!

 

[JTT]

If you haven't already, check and make sure the vent lines from the carb are all clear of obstructions. Also check the powervavlve vent hose off the left side and make sure it's open and clear.

 

[bobit490]

all of the above. i'll be curious as to what you find, as i'm a Gas-Gas dealer here in the states. have you done any mods to it? i've had customers have problems in the carb. area. we installed LTR's jet kits and it improved the carburation immensely. not that it has anything to do with your problem. LTR's Power Valve cover has a better drain on it and it adds torque to the power band. let me know what your find. cheerio!

 

[bluesboy]

OK fellas - thanks for the replies so far. I will be taking a close look at the bike (probably 2moro). The more I think about it the more I'm convincing myself that it is carb related.
I did a beach race last year and taped up the air box to stop sand getting in but I think I over did it - big mistake - no power, wouldn't run cleanly etc.
The only mods I've done is to route the upper 2 vent lines from the carb into the air box to aid venting in river crossings etc. I put a small push-on fuel filter onto the ends of these 2 vent hoses to stop crud getting in but I doudt these are causing a restriction but I will investigate.
I've also fitted a little pouch (made from an old inner tube) that sits under the seat and above the air filter. This allows me to carry a spare plug & spanner plus small tools and access them through the side panel door. Again I doubt this is causing a big restriction to the air filter but will remove it and see if it cures the problem.
Any other suggestions gratefully received.

 

[gas gas jack]

in all seriousness, have you tried replacing the plug WHILE the problem is occurring? does this affect the symptoms you've described? this is "old school" of course, but what deposits show up on the plug? also, what jetting are you running? in the states, we've seen some improvement from just "lowering" the fuel level on some Gassers; that vent business is definetly worth looking at again- here in Minnesota, we commonly deal with crud clogging the vents(wet weather riding,...You don't ever have that in the UK, do you???), or frozen vents, which will affect the "float bowl pressure"- both situations causing symptoms as you describe. please let us know what you find jack

 

[bluesboy]

Gas Gas Jack...
Yep - swapped the plug over 2 or 3 times during my last ride out as the problem was occuring. Both plugs were new so couldn't give you any details as to the carbon build up colour. However the plug was nearly always wet with unburnt fuel when I took it out of the head.
Weather that day was around freezing and bike didn't warm up at all (could rest an ungloved hand on exhaust no problem) and this certainly didn't help things, but problem has happened on warm days too.
We get plenty of wet weather and mud (my favourite riding conditions as it slows everyone down to same speed as me!!!) so a clogged or frozen vent line is a possiblity.
Jetting is LTR and have discussed needle settings etc with Jeff so should be pretty close.
Will keep you posted...... :bang:

 

[RAH RAH]

Sounds like youve got some water in the carb or your powervalve linkage has come loose.

 

[gas gas jack]

just another thought,...take a look at the float valve needle- they have a "spring loaded" plunger (opposite from the rubber tip- it's the pin that the float presses upon) which may have "failed", leading to inconsistant sealing of the float valve-to-valve seat, which would leak fuel,...and match your symptoms.(of course, you would check the rubber tip to see if it's still in good shape, and tightly attached to the needle body) :cool: it's worth a look, jack

 

[bluesboy]

UPDATE
Think I may have more than one problem here.
Tried to fire up bike to see if problem still existed but no spark. Removed alternator cover to discover some water inside (first time ever). Cleaned and dried it out - spark returned then dissappeared again. Have decided to send alternator and pick up away to be tested.
Removed carb. A few beads of water in float bowl. Needle valve seat etc is fine. No blocked vents. Reed valve also checked and is fine.
When I removed alternator I noticed a bullet connection to the CDI unit behind fuel tank which wasn't as tight as I would have liked - could be something or nothing?
GAS GAS JACK
Could you email me off forum at bluesboy@smartemail.co.uk as I want to find out more about removing reed valve spacer.