I inherited an 05 CMX250 (rebel). It had been sitting for a long time unloved but with only 850 miles on it. I've done all the normal, changed out fuel, petcock, cleaned the carb. Before I pull the carb again, anything I'm missing? It will only run if I pull the filter and use my hand to obstruct the intake and then modulate the airflow. I have to block the intake almost fully for it to stay running. Thoughts or just pull the carb and clean the jets and float bowl again?
It's been garage kept its whole life, just not ridden. Boots were fine and all the rubber on the bike is in fine condition.
Does it seem to run “okay” when you’re modulating/restricting the airflow? If so, you either need to clean the carb or swap out the jets to something larger. Have you played with the mixture screws at all? I’m not a carb guru at all, btw - have just spent a decent amount of time with them over the past couple years.
Just a guess...you have a problem with the smallest jet in the carb or the "enrichener" circuit if it has that style.
Bike is all stock, so jet size should be fine. I can basically keep it running indefinitely with my hand. If there is a passage blocked would it run at all? I'll pull it and check the passages/enricher.
If the carb jets are all dirty again, check to see if the bottom of the tank is all rusted, and flakes are coming into the carb again.
Was the petcock in the "on" position when you picked the bike up? Are you sure all the jets, ports and passages in the carb are clear? Take a whiff of the oil. If it smells like gas, that's part of your problem... The carb's float valve may be/has been leaking. Fuel, instead of going through the carb's overflow, is traveling/has traveled into the cylinder, washing down past the rings and creating a vapor rich condition in the crank. That fuel will continue to create combustion problems until the oil is changed, even if the carb is spot on.
Appreciate all the responses. The pilot had gotten another piece of debris in it and one of the diaphragm passages was indeed blocked up. Oil was fine but plan on changing it before riding. When I replaced the petcock I put a new in-take fuel filter in, there was some surface rust that I spent time cleaning from the inside as best I could when I got rid of the old gas. Started right up after cleaning again and then made some adjustments to the mix to get the throttle smoothed out. Purrs like a little 250cc should now. Not bad for a free bike.
Just so you know, those things love to shear off exhaust studs. Make sure the mounts for the mufflers are tight and in good shape or all of the support for the exhaust is haning off of the 2 6mm studs. they won't last long and usually break flush with head.
If the tank still has stuff in it. You can put in some bb's or nuts, washers, bolts, etc. and shake it around for awhile to dislodge more of it? Not sure what fluid you should use, someone on here will probably know, maybe vinegar or some simple green?
If it is mild to mod rust, I've had great results with some simple wood acid (oxalic) you buy at the hardware store. Hot water I boiled on the stove. Will need to figure some way to plug the holes. Let it sit for 30 mins rotating it occasionally. Rinse out really good. +/- neutralize with baking soda though i never really bothered. Repeat for the other sides if needed. Always add the acid to the hot water.... do it the other way and you get a great imitation of an acid volcano spewing out of the tank.
It was pretty mild rust. I went the vinegar route and it worked pretty well. Flushed out with soap and water then almost boiling water followed by hair dryer to dry it before reflash rusting. Read a bunch of ways online but that worked for me. I didnt do the nuts/bolts step because the inside of this tank doesnt allow for easy spillage back out of the neck. Cheap free bike and I didnt think it was worth the effort.
Instead of loose nuts and bolts I use window sash chain. When done just fish a link and pull the whole shebang out in one step.
