i might have a big problem....please help

bkmarsha

so i got the bike out for the spring and did a carb clean job that seemed to help the bike but another problem has arose

1. the left cylinder backfires when the throttle is in the rested position. when i give it gas the backfire goes away i have tried to fix this by adjusting the mixture screw but have been unsuccessful

2. the bike wants to idle high (between 2500 and 3000) after it gets warm but is fine when the engine is cold i have tried to fix this with the idle screw but have been unsuccessful

3. this is my biggest concern...while the bike idles and is in the backfire stages it produces a white smoke out of the left tailpipe. i believe this is burning oil but am not sure

Any help on any of these problems would be great

also wondering if it is good for me to ride it in the shape it is in now (will i cause more damage to me or the bike)

rhilker

Backfire is usually associated with air getting into the exhaust. Check and replace the seals on the exhaust. Worked for me.

oldbikenut

I replaced the rubber boots between my air filter and carb(the old ones were hard as a rock) and I also replaced the boot between the air filters. I believe your bike may be running lean, it may be getting to much air. My bike was idling high after warm up like yours until I sealed up the intake. With the pods you put on I believe you need to adjust the carb for the increased airflow, did you do this?

bkmarsha

i bumped up the main jet size (from 135 to 137)and i feel that i may also need to bump up the pilot jet to but not sure

what about the white smoke

xsjohn

Emgo Pod Filters can be a real disaster........especially the small cone ones...........have you tried taking them off and see what happens......and if they are the problem and you have tuned to them you would probably have to retune.............

xsjohn

bkmarsha

i ran the bike for a couple days with no pod filters and i seemed to have the same problems as i have with them on

i was careful to insure that the air intakes were not blocked by the air filter boot

xsjohn

One of 3 things come to mind...........ATU sticking or weak springs.......or the pilot circuit needs cleaning............sure sounding like ATU problems though.......

xsjohn

xjwmx · Last edited by xjwmx on April 26, 2009, 3:49 pm; edited 1 time in total

bkmarsha wrote:

2. the bike wants to idle high (between 2500 and 3000) after it gets warm but is fine when the engine is cold i have tried to fix this with the idle screw but have been unsuccessful

I had a problem like this with a different Yamaha.

When the bike is warm and idling high, adjust the idle stop screw so that it idles a little over 1000.

Then, when the bike is cold, you should be able to get the idle up by means of having the choke pulled out. ---If this won't happen, then carefully check the valve clearances---.

I'm guessing that will solve your idle problem. If it does, then address the smoke issue separately. If it doesn't, then the smoke and idle issues might have some common cause that you'll have to uncover. I can say that oil smoke is ususally blue though, not white. If the weather was cold, it might be normal water vapor rather than smoke.

Retiredgentleman

I had a high idle when the engine was hot. Here's what I did, and solved the problem.
Check for any air leaks around the carbs.
ake sure the ATU is lubed and moving freely.
Check points gap and timing, using a timing light.
Adjust the air/fuel mixture screws using the dead cylinder method.
Adjust carb synchronization using a manometer.

bkmarsha

that is the advance timing unit correct

could this also be the reason for the smoke

bryant · Full Member Joined: Apr 01, 2009 Posts: 86 Location: KY

you can check for leaks around the carbs by spraying some wd40 on the boots. if it dies or tries to die, you have a leak.

(that's how i do it anyway, im sure there's a proper way but that works for me.)

xjwmx

An exhaust valve open during the intake stroke is a huge air leak. Check your valve clearances. Just a few thousands can make the difference.

bkmarsha

upon further inspection today i have found

1. the smoke appears to have a slight blue tint

2. the atu springs appear to be worn and look like they have minor surface rust

3. also i attempted to use the dead cylinder method and it worked to set the right side (left plug wire removed) but as soon as i removed the right side wire the engine died not sputtering or stalling just instantly dead

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