BR250 spark issue?

[Hair Bear Bunch]

The trike has been running well for a while but let me down today.
It started from cold straight as always but after 15 mins or so spluttered to a stop. That sort of suggested a fuel issue but a shortage of tools where I was precluded an immediate carb clean so I thought no harm in taking the plug out and it was wet. Fresh plug started straight up and ran it for about 10 mins then cut out. Went through 5 spare plugs like this running for as much as 5 mins or little as 30secs, runtime becoming less each time and plug always coming out wet, producing a weak spark when spun over, and refusing to restart on the old plugs. I suspect the carb could do with a clean (time didn't allow) but I'm thinking the coil pack may be failing? Is there any way of testing without replacing?
The only thing different from previous rides is a new gel battery fitted yesterday but as the old battery was totally dead I can't believe this has any bearing on it not running.
Any thoughts would be appreciated.

A quick lesson in how to feel stupid!
1, Buy a new battery.
2, Check old battery is dead (7v), no dash lights, no start.
3, Check new battery (13v).
4, Fit battery.
5, Try battery, no dash lights, no start.
6, Check battery (13v).
7, Remove battery and head off to supplier to complain.
8, Halfway to supplier, have a 'lightbulb' moment and return to trike shed.
9, Refit new battery, select neutral, dashlights come on, machine starts.
10, Doh!

[barnett468]

.
put the bike in the shade with the plug on the cylinder head and connected to the coil wire and turn it over and tell us if the spark is pale blue or yellow . . if its yellow that is a problem if it is also weak as you mentioned.

you can check the ignition coil and the exciter coil in the stator with an ohm meter against the factory spec which is in the free online manual below . . the more ohms, the better . . you should also check the gas level in the float bowl.

http://www.oscarmayer.net/atc/manuals/
.

[Hair Bear Bunch]

Thanks, the spark is yellow and weak, that said I don't recall it ever being anything else!
It'll probably be a few days now before I get back to it, I'll let you know how I get on.

[Hair Bear Bunch]

Thought I'd begin with the easy things so chucked out all the old plugs that were kicking around and put it a brand new plug with a nice blue spark. It starts straight away and runs - Yay!
Ticks over nicely and runs up to about 1/4 throttle. Beyond that it starts hunting badly. I had a similar issue when the little rubber bung in the float chamber came out. I've stripped the carb down and it was spotlessly clean and the bung in place, reassembled and no different. Still feels to me like a carb issue now though. Ran out of time today but I'll try to check the float bowl level next.

[Drakesfear]

I had a similar problem myself with the throttle issue. I had to readjust my valves, they were far too loose and the high RPMs made them float.

[mendoAu]

Here's a thread that you might want to read:
http://www.3wheelerworld.com/showthr...ent-MythBusted

Maybe the new battery with more juice going thru the cdi is causing it (the cdi) to be unable to produce a constant charge to the coil.

[Hair Bear Bunch]

Thanks All,
Drakesfear, I wouldn't have given the valve clearances a second thought! Definitely worth a look.
MendoAu, some good reading there, time for coffee and biscuits methinks...

Rob.

[ps2fixer]

How is the new plug doing? Nice and light brown, or is is dark and/or black? Kind of sounds like the float might be sticking open and flooding. The junk plugs didn't help anything of course lol.

[Hair Bear Bunch]

Haven't got back to it yet but I'll update when I do.
rob.

[mendoAu]

Two easy things to try.
Take the drain bolt out of the bottom/side of the carb bowl and drain into a container. There should be a constant drainage. If not turn the petcock to the reserve position. If not disconnect the fuel line. If you get fuel thru both positions of the petcock than it's your carb float. If no flow replace your tank filter. Better yet put an in-line filter and trash the tank filter but not the whole filter, the tube needs to remain so that you have a reserve in the tank.

[Hair Bear Bunch]

Got to it this morning...
Fuel flow from tank good (both main and reserve), through inline filter and delivery pipe good.
Pulled the new plug, still looks new but it has only been run for probably no more than 5 mins on it.
Checked the valve clearances - that was a right pain in the *rse of a job - all good.
Pulled the carb again as it was bugging me that I might have missed something, and gave it another going through. All I can say is I can't see anything obviously wrong.
Got it running and no difference whatsoever but I was out of time and needed to be packing up so turned the fuel off to run it out and as it always does when the fuel gets low the revs start to rise but no hunting - grabbed the throttle and opened it up and it started hunting but at much higher revs before cutting out. I'm now thinking as Barnett suggested float bowl level so that will be the next port of call.
Just snagged a second hand oem carb cheap from the net so by next time I'm in the shed I'll either have a replacement carb to try or a source of spare bits! I'll let you know.

[Hair Bear Bunch]

Having now read the thread about cdi boxes, I'm looking at what is available should I need one and I'm seeing lots of boxes at various prices.
Is it safe to assume that the 4+2 pin arrangement I have, and the 4+2 pin boxes on offer will have the same connection arrangement - ie 'plug and play' or are there pitfalls I have yet to see?

[ps2fixer]

85 harnesses had the round 6 pin cdi plug, 86+ had the 4+2 pin setup. There are quite a lot going on in the CDI, so most likely it will run best with a good OEM one, but they are getting harder and harder to come by and even NOS will have shelf life wear (the caps go bad in them). I personally haven't done it yet, but some other members here have used CDI's intended for Chinese quads. Dirt cheap, but it might take 2, 3, 4 of them before you find one that makes it run right.

CDI effects the following (I might miss some things, I'm not an expert on them)

Ignition Timing
Rev Limiter (race ones sometimes are not limited)
Power source must match (regulated 12v dc vs non-regulated AC like a 185S would have (guessing here lol)) - from my understanding for this point, one style is large, and the other is about 1/2 the size generally speaking.
Kill switch wire hooks up to the cdi too in some models, some need to be grounded to be killed, others need to be an open connection (more modern hondas for example) - I think most Chinese based machines are the same as the 3 wheelers

Good news though, from my understanding, hooking up the wrong cdi won't hurt anything, just the machine won't run.

From my own personal experience on these, I tried one chinese CDI on a 350x and it would idle but not the greatest, and above 1500-2000 rpm the engine would just die out. I'm not sure why, but my only guess is the timing curved too quickly and was firing before TDC. The one I bought was the 4+2 style, and sadly I don't have a 86+ big red to test on to say if it would work or not.

Oh one other point for the 85 big reds, you can switch the connector from the 6 pin round to 4+2 style, you just have to remove the pins from the old connector and plug them into the new connector (~$6 + shipping). I do have an 85 big red I could try this on, I'd just have to plug in the cdi 1 pin at a time and hopefully not short anything out.

BTW your sig is funny, but I don't think 50% of people understand binary, even after reading the sig .

[mendoAu]

I updated my posts on the "cdi myth" thread. Not sure if the 85 round six pin has different wire colors but my 84 round six wire has now been replaced with a cheap square five pin with the mods/soldering done from this thread...runs great.
http://www.3wheelerworld.com/showthr...thBusted/page5

[ps2fixer]

I updated my posts on the "cdi myth" thread. Not sure if the 85 round six pin has different wire colors but my 84 round six wire has now been replaced with a cheap square five pin with the mods/soldering done from this thread...runs great.
http://www.3wheelerworld.com/showthr...thBusted/page5

That is the thread that gave me the idea of using a china cdi on the 350x . About 90% sure the 85 big red would be the same colors as the 84, not sure about the pin out though as that caught me by surprise before on a 250r harness I made.