Light backfire

[bronko37]

On this 84 aspy there is. A mild backfire from time to time at high rpms. I notice it the most when down shifting. Dad said it did it when he owned it as well.

Thoughts?

 

[dan filipi]

Backfire out the exhaust, or back up through the intake?

 

[Ansimp]

Carbies, valves, spark or just crap fuel.

 

[bronko37]

dan filipi » Mon May 26, 2014 8:05 pm[/url]":nq6f9spc]
Backfire out the exhaust, or back up through the intake?

Sounds like its back out the exhaust dan.

 

[bronko37]

Ansimp » Mon May 26, 2014 8:24 pm[/url]":330b4fwh]
Carbies, valves, spark or just crap fuel.

Bike only has 30k miles on it. Runs great. Maybe as simple as a valve adjustment?

 

[dan filipi]

1200 has hydraulic valve adjusters which are automatic. Doesn't mean a valve isn't hanging open to some degree though.
Firing out the exhaust I'd say it's running too rich on one or more cylinders. The raw gas builds up and explodes in the exhaust.
Also could be an ignition wire crossfire I suppose.

 

[bronko37]

Ok guys the weather is changin and im gettin closer to tearin into this 84 aspencade. Gonna keep me busy this winter. Im thinking that the backfire has something to do with the vacuum so i plan on replacing the vacuum lines and such in the cold months. Gonna have her torn down and do some brake work and maybe give a good carb cleaning. I see there is quite a bit of "extra" lines from carbs to heads to exhaust. Looks like the start of the emissions controls (84). I feel like a pretty solid wrench on a gl1000 but this will be my first wrenchin on a 1200 with Tupperware so im trying to start researching now. What sorts of things are important to know specifically to these bikes?

Thanks guys.... Look forward to workin with you thru this bike as well,

 

[dan filipi]

The usual wiring problems for one.

I'm not sure what year 1200 it is that has a weak rear wheel bearing housing, maybe someone else can answer that.

If you pull the motor, open up the ignition housing and have a look at the condition in there.
I've seen a few rear ignitions get pretty rusty.

1200 is a great bike all around.

 

[Joep]

Sounds like a rich mixture slightly on deceleration.. allowing hot gas to ignite it in the exhaust...I could do this with my magna on purpose.. kill the run switch.. roll throttle and then put on run and get a kapow out of the exhaust... the 84 was the year that they had bad bearing mounting on rear wheels..and once you get the Tupperware off the bike looks like the 1000.... lol

 

[joedrum]

yeap 1200 carbs are quite the different deal ...ignition can by problem ...lack of parts is on table ...1200s are geared great ....you will do fine im sure

 

[bronko37]

Yea, I stayed up late last night reading up on the service manual so I would be more familiar with the bike (sick in the head, I know). I am sure the knowledge I have gained working on my pair of 1000s over the course of this year will serve me well working on this 1200. I want to get it all tip top so the wife and I can take a trip to the Smokeys next summer, shhhh it's a surprise...

I noticed what I thought was a slipping clutch but then later deduced that it is a problem with the hydraulic clutch system returning slowly. So I will have to take that all apart and clean it as well. Need a rebuild on the master cylinder and probably the slave cylinder as well to get that running correct. When you shift without the clutch, no problems, when you use the clutch and really get on the throttle there is just a bit of "slip" before the clutch fully grabs. Got some sticky in my system some where.

Its all the little things like this that I am going to tackle over the cold months. Tires, brakes, clutch, vacuum lines, carb clean/rebuild. You know, the usual Goldwing stuff. Thinkin about painting it all black too since Im gonna have it apart.

 

[tom foreman]

great project,i have a 85.and a 82.. :builder: :builder:

 

[bronko37]

Wow Tom, that 85 looks pretty cool in the buff like that. I will post some picks of my two rides. I need to get them up in the my rides banner anyway. The 75 that I have on there I don't own anymore. I rebuilt it and sold it for a wopping $200 profit!lol

The value in that machine was what I learned while working on it.