"Bonsai Bobber" needs your help!!!

[TexasHardcore]

'82 Yamaha 250cc Single

Ran great the other day, besides needing a battery...When jumpstarted, it would fire right up every time on the first try...

Ran out of gas down the street...spat & sputtered, then died...not enough juice to get it fired up again...

Installed New Battery
Cleaned Fuel Tank
Cleaned Tank Petcock Strainer & Reserve Valve Assembly
Cleaned Carburetor Thoroughly...very thoroughly!!!
Installed New Inline Fuel Filter
Installed New Spark Plug
Installed New Spark Plug Cable
Installed New Air Filter
Installed New Oil Filter
Fresh Motor Oil
Fresh Tank of Fuel

It's got Spark at the coil and at the plug...It's got Fuel to the carb...but it just cranks over...doesn't want to fire up.

Even with Choke ON...and/or WOT...even tried Starting Fluid...

Any Ideas??? I'm all out....
http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif

[lilbill]

if it's got spark try starting fluid and see if it will bust off. if it still won't start i'd say something happened to the timing. but if memory serves (and it's gotten real unreliable lately) the 250 uses crank triggered cdi ignition. if that's the case then my money is on a faulty cdi box.

[burndup]

...or a sloppy ground!

[cornfieldrodder]

The fact it wont fire on ether with good spark points toward timing or compression issues. Has the timing chain tension ever been adjusted? Most older OHC bikes need manual adjustment of the chain or even the auto-adjuster. If it is way off, it will allow for some suprisingly drastic timing changes. Do a compression check.
Remember to hold the throttle open when crancking for the test! Your service manual (you do have one, no) should have the spec for good cylinder pressure. It will probably be in the upper 100s. Does that engine have a compression release for kick starting? The calbles sometimes stick and keep the ex. valve just a little open

[monsterflake]

i had problems with a "weak" coil on a 650...it's probably worse on a single. it looks cool, though http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif. mf

[TexasHardcore]

I've checked all ground connections, everything seems fine.
I DON'T have a service manual...but bidding on one on eBay.
The bike ran great til it Spit & Sputtered...now nothing?

Is the CDI the "Rectifier/Regulator Assembly?"

I just don't see how ALL OF THE SUDDEN it wont run...

[Hellbilly_Buzzard]

when you cleaned the petcock, did you disasemble it? If so did you line everything back up correctly? Did you check to see if fuel is going to the carb?

[Hellbilly_Buzzard]

Is it trying to turn over??? Just not firing???

[TexasHardcore]

Yes, the assembly was torn down cleaned and reinstalled...the carb is getting plenty of fuel...

It just cranks & cranks...wont even TRY to start...

[lilbill]

[ QUOTE ]


Is the CDI the "Rectifier/Regulator Assembly?"

I just don't see how ALL OF THE SUDDEN it wont run...

[/ QUOTE ]

no, the cdi box (Capacitor Discharge Ignition) is a little black plastic "brick" about 3x1x1. one of the wires going to it will be red/black.

btw, everything runs like a top up until the moment it breaks http://www.jalopyjournal.com/ubbthreads/images/graemlins/cool.gif

[Hellbilly_Buzzard]

Did you double check the gap spacing on your spark plugs?

[TexasHardcore]

In That case..it's been replaced before...

Says "Badlands" although the paper label is peeling.

[TexasHardcore]

Sad thing is...the Badlands Co seems to only make Turn Signal Equalizers....maybe I'm looking at the wrong part ?

[TexasHardcore]

Pulled this of the web...

[Gotgas]

Ah, the joys of working on an '82... anything.


If the pistons are moving and the valves aren't, ain't much gonna happen. http://www.jalopyjournal.com/ubbthreads/images/graemlins/wink.gif Make sure the timing chain (?? - unlikely) or timing gears are still in harmony.

[cornfieldrodder]

Your 250 may be similar to my SR500. The CDI pigtail should be under the seat or tank, coming off one of the two rear harnesses near the turn signal flasher pigtail. As said earlier, the unit is 1X1X3 and probably hangs on a flat "tang" maybe on the battery box. Nothing like inexact descriptions and ideas, huh? When they go bad, there is usually no spark at all or it kills just after starting. http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif(damned annoying trait!) If you have a good spark when cranking it over, that should'nt be your problem.

[lilbill]

cdi box is #20 in your diagram. are you absolutely sure it died because it was out of gas ? sure sounds like a spark/timing issue.

[TexasHardcore]

It could have been a combination of both things...lack of fuel and timing issues...?? Maybe one triggered the other?? Hell I dunno...

I'm going to do do some hunting around for a cheap used CDI box and give that a shot...Bummer too, cause I destroyed the turbo on my truck last week, and I need some transportation!

[burndup]

now... couldnt he use a cheap GM HEI module in place of that expensive and difficult to find CDI box? or is it triggered differntly?

[TexasHardcore]

probably a different setup...

I found a website dedicated to these bikes...and on a message forum a guy had the same problems and he took the CDI box apart, and re-soldered the connections...everything worked after that...

So tomorrow I'll be trying that step...I also bid on a CDI on ebay "just in case"...

My brother said the jump starting could have caused the CDI to crap out...probably so...

I'll post with tomorrow's findings...

[CTFuzz]

If you "jump started" it with a running car, you may have fried the CDI box......!

[burndup]

Why would this be? Too high of voltage? 15 volts will fry it?

[TexasHardcore]

Yeah burndup...pretty much!

I jumped it a few times off my Dodge Cummins Turbo Diesel...twin battery setup, lol...maybe that did it!

I'm going to remove the CDI in a little bit and see about resoldering it...if that no worky...then I got one coming from eGay...

It's raining now anyway...no hurry to get it going now...

[TexasHardcore]

Took teh CDI apart, resoldered all connections...still nothing. Maybe it's fried... Now I wait til the one from eBay comes... http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif