Author Topic: Does this engine sound right after warming up? It's spewing white smoke!  (Read 672 times)

Offline jimbo98

  • Local Club Racer
  • *
  • Posts: 11
  • Karma: +0/-0
I know this is a fairly lengthy post, but I have been trying to get this bike running right for the past few months and have only been barely able to ride it. I'm no mechanic and have no previous experience with this stuff, but I just want to be able to enjoy the bike already. Any help whatsoever would be appreciated:

I have been slowly working on this bike over the past couple months. I thought I had everything with the carbs right today. I cleaned every darn orifice on the carbs several times over, made sure all the jets were clean as a whistle, set the float heights spot on, and I set the mixture screws to 2.5 turns out. Put everything back on the bike, and started it with the choke on. Here is the course of what happened upon startup:

1. Choke lever set on (My choke spring is a bit sticky so it doesn't stay 100% on but more like 85%, unless I hold the lever down)

2. Start the engine, it starts to idle, and I wait nearby as it warms up and slowly increases in RPM

3. Hits 2500 RPM and I pull the choke up ever so slightly to about 50%, and all of a sudden the RPMs increase quickly to 3500 RPM (that's weird, right?). Ok, so I let it sit at this state.

4. Now it's been about 15 minutes warming up and I go to turn the choke off. It sputters and dies. I figure this might be because I have the idle screw (throttle stop) fully disengaged. So I screw it in about one whole turn.

5. I try to start the bike back up on full choke, and it won't run, wtf. I set the choke at 50% and it starts now. I let it sit for about another 5 minutes and this is when I start to notice the bike is smoking, all coming from around the engine area. I ignore this for now, thinking it's just gunk burning off and will go away.

6. I turn the choke off, praying it will maintain idle, and miraculously it does. Idles at 1200 RPM with no choke, fully warmed up.

7. I let the bike sit and idle with no choke for about 10 minutes, observing the stream of smoke. It does not go away. No distinct smell, no distinct source, and no leaks whatsoever on the bike.

8. After letting the bike continue to spew smoke I decide to shut it off out of fear of damaging it. Smoke continues for another 2-3 minutes after shutting the bike off.

I've attached a youtube video of the bike after it has warmed up and it's idling at 1200 RPM with no choke. I know it's not that easy to spot, but there is definitely smoke coming from somewhere under the fuel tank.

I guess my main areas of concern are: Does this engine sound right? What could be the source of the smoke? Why is the bike running better on 50% choke than full choke? (It seems like it hits the highest RPMs at 50% choke, but if I push the lever either up or down from the midway point, it will begin to drop off)

Thank you so much to anybody that has the time to read this and help me out.

Offline herennow

  • Formula Extreme Racer
  • ***
  • Posts: 234
  • Karma: +4/-0
25 minutes is really looooooong time to idle and air cooled bike without moving.....

Have you gone through Me 72's carb tuning guide? Lots of things spring to mind but most are in his blog.

Offline Meukowi

  • Formula Extreme Racer
  • ***
  • Posts: 160
  • Karma: +1/-0
what does the smoke smell like? previous bike had a electric short and it smoked like hell, tho might not be with your case, might be running too lean and reach too hot engine temp to smelt plastic parts around there, if you really idle for 15mins. My bike sputters white smoke too from the exhaust at cold start, but not after a while warming up, guess thats just water condensation which vapors off.
i dont see any yt video here


SMF spam blocked by CleanTalk