Ignition, battery connection, cdi causing bogging??

Gpsakry · Aug 11, 2020

I have a 91 Trailboss 250 2x4. It sat for almost 10 years and now I am slowly trying to resurrect it. The last time I had started it it had no power when in gear so I figured it was a carb issue. I bought a $25 carb kit, new plug and air filter and cleaned the carb and put new fuel lines and fuel filter on it. It started easily with the pull start and ran well in neutral, but fell flat on its face in forward gear, but ran like a champ in reverse.

I took the carb back out, double checked everything, put it back in. I read somewhere that running it with a dead battery can ruin the cdi so I was worried it may have happened to mine.

I disconnected the battery leads, after the last time I cleaned the carb and all of a sudden it ran great. Uh oh.

I bought a new battery, installed it and the starter works and it started and ran well. Thought my problem was solved. Turned it off and started going after the brakes. (they need to be mostly rebuilt; master cylinder is frozen after sitting so long).

When I was moving it, I had the same bogging issue start happening again. I turned the key to off. Not sure why, but my key doesn't turn the motor off, just the lights. For some reason this allowed it to start running like a champ again!

Don't want to just throw parts at it, but I am pretty confident it is an electrical issue and I am just wondering if there are any tests I can do with a volt meter to narrow down the cause of the bogging.

Thanks for reading my long winded post, just wanted to share as much info as possible.

LATEBURD HERE 2 HELP · Aug 11, 2020

The battery has nothing to do with running - the battery is only for the lights and starter motor

Unplug the black wire at the CDI box and see how it runs - note; you cannot turn off the engine until the black wire is plugged back in.

Gpsakry · Aug 13, 2020

It runs good with the black wire disconnected.

LATEBURD HERE 2 HELP · Aug 13, 2020

Start the engine, turn off the lights, unplug the key switch, plug the black wire back into the CDI unit and try running it - if it runs fine, replace the key switch - note; with the key switch unplugged you can still kill the engine with the handlebar switch - also, do not turn the lights on with the key switch unplugged - it could cause the lights to burn out.

Gpsakry · Aug 15, 2020

Ran good with the key switch removed. Ordered a new one on ebay for $11. Thanks latebird! I will report back if there are any further issues after I replace it, but I think you helped me find the "key" to the problem.

Gpsakry · Aug 26, 2020

Ok, installed the new key switch, and when I turn it to on, the red wire jumps and it makes a tinging noise. The neutral light also does not illuminate. Turned it off and haven't looked any further. Thinking it is something else that caused the key switch to fail. Wondering how to test the regulator.

LATEBURD HERE 2 HELP · Aug 26, 2020

Try this - unplug the key switch and jump (short) the red and red/wht wires together - does that give you a neutral light?
Note: red is hot, brown is ground, black is ignition kill and red/white is chassis power - chassis is powered up when red is connected to red/wht when the key switch is turned on. If you check continuity on the switch; there will be continuity between black and brown with the key off and continuity between red and red/wht with the key on.

Ignition, battery connection, cdi causing bogging??

Top Contributors this Month

Recommended Communities