rough running popping on throttle roll off

[Siberiancat]

Ok background. Coming out of the winter this year once it warmed up I noticed my baby being nosier then normal. I do not winterize her because I rude her dailt. The best way I can describe it is she sounds like a diesel. Hard detonation and she doesn't run smooth anymore. Wife and I took a ride and had rear coil give out. After she cooled coil started firing again. 35 miles later when I got off at hiway exit had white smoke coming from pipes. Ok so I changed the head gaskets and right head gasket was blown. Got her all bolted back together and still not smooth plus when I roll off throttle I get pop pop pop out of the pipes. Also a new development when I get to 70ish mph I swear it sounds like a knock coming from the engine. If I lower my head to get out of wind I cant hear it anymore. ( I'm 6'5" wind hits me dead in face) my mehcanic fried says it is likely a exhaust leak.it is only there it I cruise if I give it gas to accelerate of roll off throttle the "knocking" goes away. Any ideas? Help me gl1200 gurus! Please!

[Frank]

What do the plugs look like? Did you replace that coil?

[Siberiancat]

What do the plugs look like? Did you replace that coil?

All new plugs but all uniform tan color and I haven't changed coil yet.

[bs175dths]

Ok background. Coming out of the winter this year once it warmed up I noticed my baby being nosier then normal. I do not winterize her because I rude her dailt. The best way I can describe it is she sounds like a diesel. Hard detonation and she doesn't run smooth anymore. Wife and I took a ride and had rear coil give out. After she cooled coil started firing again. 35 miles later when I got off at hiway exit had white smoke coming from pipes. Ok so I changed the head gaskets and right head gasket was blown. Got her all bolted back together and still not smooth plus when I roll off throttle I get pop pop pop out of the pipes. Also a new development when I get to 70ish mph I swear it sounds like a knock coming from the engine. If I lower my head to get out of wind I cant hear it anymore. ( I'm 6'5" wind hits me dead in face) my mehcanic fried says it is likely a exhaust leak.it is only there it I cruise if I give it gas to accelerate of roll off throttle the "knocking" goes away. Any ideas? Help me gl1200 gurus! Please!

several issues:
not smooth running, at what RPM is it not smooth, or is it throughout the entire rpm range?
popping at throttle roll off
at what rpm is 70ish? can you duplicate the sound at home while the bike is stationary?

the rough running may be several things depending on the rpm, so this needs to be narrowed a bit to help us out
the popping at roll off is either an exhaust leak OR the anti-backfire device under the carburetor assembly. Check the exhaust for leaks first cuz it is the easier of the two to do. Be thorough. Start with a cold engine, start the engine, then run your hand around the part of the exhaust you can reach and feel for the leak. Do this carefully because the exhaust can get hot very fast. Pay close attention to the muffler area which joins the two sides of the engine, and the welded joint where the individual cylinders meet on each side.
if you can't duplicate the knocking sound while the bike is stationary and it only occurs at 70ish, try creating it at 70ish in different gears. (4th or 5th) It may not be a function of rpm, but of ground speed (the running gear, tranny, rear end, universal joint)

The idea here is to eliminate possibilities and narrow the field of possible offenders.

Do some experimenting and let us know.

-Ride On

---

..... I forgot to mention......
an excellent check of the coils is to run the bike in a darkened area. Any arching from the coils or the high tension leads will be easily detected. Leaks of this type put on a neat 'electrical' show.

[Siberiancat]

Ok the popping is at all rpms. If I'm doing 60 (3000rpms) I can hear the "knocking" just quitley. The rough trimming is across all rpm ranges most noticable at low rpm. Will check for exhaust leaks tomorow to give bike time to cool. Thanx for the replys .

[Frank]

Are you sure that you got the timing right when you put it back together?

[bs175dths]

Retracing your previous steps may uncover the solution. At least it can be a sanity check.

One or more of the carburetors may be trying to digest a particle or two of a foreign object (rust from the tank or dirt)
Depending on the condition of the carburetors and the amount of downtime for the other repairs, the throttle needle pistons may not be gliding as smoothly as they should for a smooth running engine.

Checking the sync of the carburetors may give you a direction to travel.

I have read one owners concern about losing oil pressure as rpms go up, but it was only one owners concern.

[Siberiancat]

Checked timing several times since I had belts off its dead on will sync carve when I have the cash for carbtune thanx for all the replys

[bs175dths]

is there a memeber near by who has the tool to loan you?

[Siberiancat]

is there a memeber near by who has the tool to loan you?

Not that I have found

[Frank]

I don't think a carb sych is your problem. You could have a bad cut off valve, a dirty carb, plugged idle jet. Plugs sound good so I don't think it's electrical. Exhaust is a possibility.

[admin]

The noise you are hearing might be normal intake noise. While driving, with the tray removed, try opening the cover on the false tank and listen for an increase in noise as you open the cover. Alternatively, you could be hearing crankshaft noise if the oil pressure is low or there are excess clearances between the bearings and the crankshaft.

[old gold]

http://s1302.photobucket.com/user/Tcharl...b.jpg.html

is there a memeber near by who has the tool to loan you?

Not that I have found

I saw your post about synchronizing your carburetors and the lack of a tool near you.
I built a sync tool from PVC and clear plastic tubing. I used the larger PVC tubing as reservoirs to keep the ATF fluid from being sucked into the engine if a hose came off. The idea is to adjust each carburetor so they all pull the same amount of vacuum at an idle. You need to pinch the plastic tubing almost closed to minimize vacuum fluctuations and allow the fluid to calm down. Alligator clips, vise grips, plug the tubing with something with a small hole in it, etc.

Plagiarized from a post by Wingandaprayer (with my adds)

“If you have a bike stand and can do this while seated on a chair, well it doesn't get much better....
Remove the lower fairing panels, both sides (if you have them)
Remove the chrome trims above the carbs.
I like to remove the right side air bulkhead it takes a little kaniffling to wiggle it out. (but not required)
The vacuum port screws are low on the intake runners just above the heads.
(Attach the vacuum lines to the carbs to be synched, using the adaptors listed below)
Synch the left side carbs to each other, synch screw located between the carbs.
Synch the right side carbs to each other, synch screw located between the carbs.
Synch the right carbs to the left, synch screw located aft of the right rear carb.”

you will balance your #2 card to the base(#4) carb, then #1 carb to #3 carb, and finally the right bank (#3) to the left bank (#4).

The vacuum fittings can be had at several online sites:
http://www.usplastic.com/catalog/item.as...Mgod3UoAUQ,
http://www.motionpro.com/motorcycle/partno/08-0218/,
http://www.amazon.com/Motion-Pro-08-0013...B000OO4PVM,
http://www.carbtune.co.uk/carbaccs.html

Tom

[admin]

You can also pick up one of these www.carbtune.com for $100. and they work better than any other carb tuner I've ever used.

[Siberiancat]

Ok I have a few exhaust leaks gonna get on tomorrow. Vic I will try your suggestion tomorrow after I nail these exhaust leaks down. And the carbtune is what is on my wish list just after the head gaskets now needing a rear tire lol it keeps getting pushed back. Thanx again all.