86 Virago 700 Backfiring??

[The_AirHawk]

Originally Posted by xv70086

No, Actually when i got it took off pretty fast. Now its slow off the line. Air is coming out off the pipe tho its blowing hard just not hot?

It's when the air STOPS blowing-out of the pipe that you know for-sure that you broke something.............

[longride]

Originally Posted by xv70086

Ok, I will go out when i get home in like a hour and a half or so. And check the plug and the ignition anything specific I should be looking for? Thanks again for all the help. -- Newbie

Look for black fouling on plug. Pull rear plug wire. Connect front plug to wire, but don't install in engine.Turn over engine with the ignition on, plug out and hold metal threaded part of plug on engine and look for a spark when turning motor over. No spark = no combustion. If plug looks good and sparks, time to look at fuel probem in that cylinder.

[xv70086]

Originally Posted by The_AirHawk

It's when the air STOPS blowing-out of the pipe that you know for-sure that you broke something.............

Well I found it the plug was fouled I guess. Man it runs like a brand new one now after the smoke got out at least. I just wanted to let you guys know I really appreciate all the help you gave me. --John

[xv70086]

Originally Posted by xv70086

Well I found it the plug was fouled I guess. Man it runs like a brand new one now after the smoke got out at least. I just wanted to let you guys know I really appreciate all the help you gave me. --John

Well guys seems there is another problem. I cranked it up and now it backfires from the front cylinder a little bit. For a lil while after I replaced the plug it ran good. Any thoughts?

[sachiwilson]

Backfire often means an air leak. Check the exhaust pipe's connection to the cylinder, and on down the exhaust to be sure it's solid and that there are no leaks along the way.

[Kenneth_Moore]

Originally Posted by xv70086

Well guys seems there is another problem. I cranked it up and now it backfires from the front cylinder a little bit. For a lil while after I replaced the plug it ran good. Any thoughts?

Something's fouling the plug. Possible sources:
Bad rings letting oil by.
Bad valve stem seals letting oil by.
Bad carb or FI adjustment causing too much fuel to flow into cylinder and fouling the plug.
Maybe not enough fuel causing a hot cylinder, and thus burning the plug.
Weak ignition system not creating hot enough spark to completely combust the fuel.

A compression test would tell you if you had an issue with the rings or the valves. The ignition can be tested by most shops cheaply and quickly. The fueling system can be a true journey of discovery.

Take your plug out and compare it to the chart you'll find on this link:

Spark plug diagnostic chart. - Ford Explorer Ranger Photo Gallery at Serious Explorations

The diagnostic you'll get from that can be very helpful.

[bbtowns]

Ken's got the right idea, read the plugs and see what they tell you. Sachi is correct about backfiring, though lean conditions can cause it as well. Check with the owner's group, there may be a pilot jet adjustment you can do to the carbs (without removing them if you're lucky) that might help, but if it's running rich it won't. Your plugs will tell you what condition you have. Your front cylinder will typically run a bit colder than your rear due to getting the majority of the air cooling (but the exhaust is not cold).

[mscuddy]

As someone who's owned a Virago ('82 750) you most likely have an air leak in that plumbers nightmare that is the exhaust system. Dump those trumpet shaped basoon looking deals and get some nice straight pipes from Jardine. They make a nice set, sound good too.

[silly]

I had the same problem with my bike same exact year i had low compression in the front cylinder so i finally tore it apart and noticed it was out of time as well im putting it back together now it seems to be fixed hope i could help

[MOKE1K]

My bet is it's in the carbs. Good luck let us know!