[Nlann]

Hello everybody, I recently bought a 2000 yamaha v star 650 that had been sitting for 3 years as a quick project. The first thing I did was clean the carbs, previous owner put stabilizer in it that was as green as antifreeze, resistant to carb clean, and corroded the brass in the carburetor. I then checked valve clearances, changed oil and put in new spark plugs. The bike will start and idle, I synced the carbs. But now the bike won't rev up, it reaches 1/2 to 2/3 the rev scale and pops and bangs out the exhaust. If I hold the throttle wide open it will rev up, then die to about 1/4 rev scale, then catch and rev back up. If I spray starting fluid in the intake it will rev no problem. I have checked for vacuum leaks, I replaced the intake boots and packed some grease in the carburetor throttle shaft seals to temporarily stop a leak there. I have no vacuum leaks, I checked timing as per the service manual and it is spot on. I put the timing light on both spark plug wires and it doesn't loose spark when it dies. To me it sounds like the ignition timing is retarding when just trying to raise idle, but at wide open throttle it just dies like it's lost all spark. Has anyone experienced a similar problem, should I be looking at buying a new cdi module? Thank-you for stopping and reading this, I hope someone can help.

 

[lesblank]

Couple things, did you ohm the TPS sensors? If they are out of spec it will definitely alter timing incorrectly. Also sounds like a pilot jet issue. Did you double check the small openings on the side of the pilot jets?

 

[Nlann]

Yes, I ohmed the tps sensor and set it according to the service manual. When I rebuilt the carbs I made sure I sprayed every single hole with carb clean and compressed air. I'm really hoping the stabilizer didn't corrode something to the point of affecting running. Here is a picture of what the carbs looked like when I pulled the bowls off

 

[lesblank]

Wow, that was nasty. Did you test the bounce on the float jets? I'm sure with that much gunk some got into the spring and possibly not opening and closing to maintain fuel flow when revving it. It's always hard to diagnose issues like this without being able to see everything.

 

[Nlann]

Thank you, I did not test the float bounce as I installed new float valves, I will pull off the carbs and check that tomorrow. I'll probably pull the whole carb back apart and make sure a piece of junk didn't get stuck anywhere. I've cleaned hundreds of carbs, but I've never had one as nasty as these. I had to soak them in carb dip in an ultrasonic cleaner juast to loosen whatever it was up.

 

[lesblank]

If you do take it apart, look at the PMS screw passage. I just got done chasing a carb issue and there was residual in the passage that was stuck and wouldn't let the PMS seat correctly.

 

[Oldcomputech]

Agreed with what Les said above. Most likely there are still bits of crap in it. Sounds like maybe the emulsion tube with the needle valve may be plugged.

 

[nozzledam]

definitely a carb issue ..I think you answered your own question when you said that it reves fine when you give it the old carb spray injection ....go over them with the old fine tooth comb ...maybe even soak them again...the banging or popping is most likely a lean situation ...if it still has problems when you get it back together disconnect one spark plug at a time to see if you can isolate if it is one carb or both sometimes you can tell buy exhaust pipe temperature difference as well...might be just one bad carb not necessarily both...

 

[Kennedytk]

Dumb question here, I read everything you did, fuel filter wasn't mentioned, it could be clogged, not letting enough fuel through at higher rpms, spraying fuel into the curb like you've done could be a sign of that

 

[lockit4u]

No, the cause was no air filters on . put pods on and ran ok.