Evening everyone,

My 85 FXWG is having some issues. First off, original carb and evo motor. Ok...backstory, father in law gave me his fxwg as a gift last year since he no longer rides. It had been sitting for 3 years prior to me getting it. This past May I took it to a shop that I trust and they went over it and did what needs to be done to get it on the road for me. Have ridden it all summer with no issues and have really loved it. This Sept I used the reserve part of the fuel tank finally and have hated life ever since. I emptied the gas tank and dropped the fuel filter/screen and MAN did that look nasty. Cleaned that off with carb cleaner as well as the carb, carb bowl and jets. The problem I'm having is this. It turns over and runs fine for about 5-10 minutes until it gets nice and warmed up. Then it starts coughing and backfiring as well as the pipe to the rear cylinder get's glowing red. I noticed today when I was taking the carb apart that where the idle jet is, it has a rubber plug. Should I keep that there? I took it off to clean that jet of course, but put it back on when putting it all back together.

I thought that the glowing exhaust usually meant too lean of a mixture, and that re-jetting or cleaning the jets usually was the solution. Now I'm not so sure. A point in the right direction would really help.

Thanks!

 

Sounds like the exhaust valve on the rear barrel is sticking or not fully closing when it gets hot. If this were the case, you will burn that valve quickly.
Do you have stock or adjustable push rods?

 

Be sure to check the intake manifold for leaks. That style intake, the "compliance fitting" type, was not a good design. I used to have to replace mine about once a year before I went to the newer style manifold. Spray some carb cleaner around the intake manifold when the bike is idling when it is warmed up. If the idle changes, you have a leak.

 

Yes, the pushrods are the original stock ones I believe. Pretty much everything my father in law has on the bike are all original.

Thanks guys for the quick reply. I'm going to try the manifold trick tomorrow.

 

That rear exhaust notorious for heat, I agree with one writer earlier, the rear exhaust valve or lifters need to be more than likely replaced. But the first step is looking for leaks, are you getting ticking when that rears cylinder gets hot?

 

Check the VOES switch and all the vacuum lines for leaks , it controls the timing doing what it's supposed to and when and sounds like you staying retarded . Early evo's where notorious for goofy ignition problems and that switch , cooked a lot of pipes & heads .

 

OK... just sprayed the some carb cleaner at the manifold around the insulator block portion and there was a definite difference in idle. NOW though, there's a chirping or wheezing sound every down stroke of a piston. I think I hear this the other day after cleaning the carb out, it wasn't this prominent at all. About the VOES... I'm looking at my service manual and the pic of the carb shoes a hose from a spot that I don't have a hose for on my carb. As a matter of fact, the only things I have that has a hose or a cable off the carb is my fuel line, my throttle cables and the choke cable. Something tells me I might be missing something here... I'm going to get in touch with my mech and have him order me a new intake manifold and insulator block if he doesn't already have something in stock.

Thanks guys.

 

So, you have an intake leak. You need to fix that before you further troubleshoot. The vacuum hose for the VOES should come off the intake manifold.

Really, that carb is not good. The manifold is not good. You would do a lot better to replace both witha CV carb from a later evo, or go with an S&S, but that would be more money. Those compliance fittings are pretty expensive all by themselves. I bought 2 of them and wound up replacing the manifold with my S&S years ago, but I still remember they were high. Oh, and buy the official factory shop manual for your bike. There is no substitute.

 

Sounds like a blown head gasket too . That chirping sound is a giveaway on an evo .

 

Forgot to say earlier Dr., I do have the Factory HD Service Manual as well as a Clymer.

After looking at the manifold and talking with my Mech, the probability of the manifold being bad is slim, but still a possibility. I'll cross that bridge when I come to it. Also, after looking at the manual and looking at the manifold, it doesn't have clamp to secure the compliance fitting to the manifold. My mech is thinking that it's an o-ring that cracked/broke that fits between the manifold and the motor.

Also, turns out that my carb has no VOES hose, just a switch in the rear...which I didn't realize what it was the other day when I was cleaning the carb. Turned it a few too many times in one direction most likely. He set me straight though... after seating the screw, 3 full turns will do the trick.

Hopefully this will do the trick for now. At the beginning of this season I had never wrenched a bike in my life.. always sent it to the shop. I've learned so much already...This is a heck of a lot of fun!

Thanks!