Probably a complete noobie question!

[jonasblack]

I was riding today and as I was coming to a stop at a stop sign, i felt a pop of hot air on my right leg coming from the engine, and the bike turned off. I then pulled off to the side and let the bike sit a minute. She started back up no problem. I have heard and felt that pop on my leg before. What is it? Is it air blow off? I'm assuming I have to make some air adjustments?

 

[jayel]

backfire through the carbs? what kind of airfilters are you using?

 

[jonasblack]

K&N air filters

 

[5twins]

Sounds like a backfire through the carbs. Check your timing, it may be off a little bit. I'm not sure what an "air adjustment" is but you go ahead and make one if it will make you happy, lol.

 

[jonasblack]

Sounds like a backfire through the carbs. Check your timing, it may be off a little bit. I'm not sure what an "air adjustment" is but you go ahead and make one if it will make you happy, lol.

lmfao! me either!

i have my haynes manual... does that have carb timing adjustment?

i recently dropped my bike like an idiot, do you think that may have knocked the timing out of sync?

 

[5twins]

Timing is ignition, not carb related. However, this will only apply if your bike is a 1979 or older, or if you have a Pamco. The timing on the 1980 and newer models was fixed and not adjustable.

It could also be carb related. If your carbs are out of sync or not adjusted properly, that could cause some popping and backfiring.

 

[jonasblack]

Timing is ignition, not carb related. However, this will only apply if your bike is a 1979 or older, or if you have a Pamco. The timing on the 1980 and newer models was fixed and not adjustable.

It could also be carb related. If your carbs are out of sync or not adjusted properly, that could cause some popping and backfiring.

im going to try tuning the carbs first to see if that makes a difference, i mean my idle is running barely at 1 or .9, so maybe a few turns of that screw will aide my trouble!

 

[gggGary]

Are you sure both carbs are firmly in the intake boots? A lot of carbs have been blown off by a backfire. A backfire will often kill the motor filling the carbs with exhaust. Is your rubber boot on the vacuum barb?

 

[jonasblack]

Are you sure both carbs are firmly in the intake boots? A lot of carbs have been blown off by a backfire. A backfire will often kill the motor filling the carbs with exhaust. Is your rubber boot on the vacuum barb?

where do i find the vaccum barb?

 

[jonasblack]

is this the barb? this is exactly where I'm feeling the pop of air coming from, also the other side has one, but that one has a hose covering it. Am I missing a hose?

 

[gggGary]

Ooh ooh ooh I win with this months diagnose the problem with the least information contest! That barb gets a rubber cap over it AND the rubber cap MUST be held on with a decent quality clamp or it will get spit off again.
You can find the caps at the local auto store but watch out for crappy rubber that cracks and falls apart.
I have used a short piece of hose with a screw threaded in the end in a pinch.

 

[jonasblack]

amazing! thank you!!!!

im also noticing that the right cylinder is working harder than the left. I placed my hands in front of the exhaust to feel the pressure coming out of both and the left's air that gets pushed from the exhaust hits my hands much harder than the right side.

I adjusted my mixture to idle at 1.2, now do i need to adjust the "b" screw that adjusts both carbs?

 

[gggGary]

look up home made manometer on here.
Then go read, read, and read again the carb guide BEFORE you start adjusting. (see the tech section, carbs area) You need to know and use the correct terms for the carb adjustments and more importantly how they work and relate. It isn't rocket science but it IS fussy work that requires patience and exact sequences and procedures.
You have three idle (adjustments), mixture screws (2), idle speed screw, and synchronising screw.

Don't do any more adjusting till the cap is on the barb. Those barbs are used with various synch gauges to balance the two carbs. The hose on the LH barb connects to the vacuum port on the petcock. The vacuum diaphragm sometimes fails in the petcock allowing lots of gas to go straight into that cylinder, not so good.

 

[jonasblack]

Gary you're a life saver. I will do me research and then adjust accordingly. I'm pretty handy and love tinkering so I am looking forward to learning the ins and outs of my bike

 

[5twins]

Go to the auto parts store and get a pack of these vacuum caps in the size indicated for that open barb .....

 

[jonasblack]

i got exactly that! thank you!

only i got larger metal clamps, they seemed to be very durable.

Also, after i put the cap onto the barb, The bike's cylinders evened out very nicely, and she fires up first push of the ignition now. She also sounds so damn healthy, I can not wait until I take her for a ride tomorrow!!

 

[jonasblack]

I rode a few miles on her today, and damn there's a huge difference in power. Apparently, that cap must have been off for a while now

Could I have possibly done any carburetor damage by not having this cap on? I just want to check.

 

[gggGary]

Could I have possibly done any carburetor damage by not having this cap on? I just want to check.

Nope won't hurt the carbs at all.

You might pull that plug and show us a nice clear close up picture of the electrodes.

 

[5twins]

No, you wouldn't hurt the carbs, just the engine, lol.