Piff, Paff Poof

[b717doc]

1982 GS1100GL(z)....Replaced cylinder base gasket, cylinder head gasket, valve cover gasket, and rings. Went through carbs, replaced float valves, disassembled and cleaned 100%, re-assembled (never separated carbs). Has good compression, and a "Super-Trapp" 4 into 1 exhaust.
Bike has good acceleration, but "studders" very slightly while accelerating. Plenty of power when throttle is rolled back, but when slightly reduced, very consistant "Piff, Paff, Poof", and other assorted backfiring coming from exhaust outlet in back. Very annoying.
#2, 3, and 4 plugs appear to be lean or hot from appearance, #1 plug not sooty, but seems a little rich. The 2 center pipes are now purple in color (which may or may not be normal). Seems something is hot somewhere.....Engine will not maintain constant idle speed, adjust to 1500, 20 seconds later, engine dies....adjust to 1600, idle speed rockets to 2200.... Sprayed boots between carbs and head, no increase in rpm noted, verifying no vacuum leaks.... SOOOOOO I guess my question is, does anyone recognize these symptoms? I did NOT check the float levels on the carbs, thinking they were not that critical...Could float level affect mixture and idle speeds? Put 85 miles on bike, thinking problem would work itself out, but no joy,,,,symptoms still present. Camshaft position in relation to TDC verified several times, and timing seems correct, with good cylinder compression. All plugs firing healthy blue spark......At dead end for now, don't want to damage engine, any help will be appreciated.....This too will pass

[mark]

Can't address all your issues, but float level is very critical...it needs to be right.

[braindead0]

Indeed.. Float levels can affect jetting at all throttle settings. Get those straight first.

And with an aftermarket exhaust, if it wasn't rejetted.. good odds it's running lean anyway, not to mention that they probably came lean from the factory (I know my '83 KZ-750 did) to keep emissions down.

Check the float valve seats, make 100% sure that the floats in all carbs can stop the flow of fuel properly... perhaps one is flooding out a bit.

[b717doc]

Got carbs in my car today, will sneak out here in a bit and set the float levels (I'm at work). Checked Valve clearances, 4 were good, 4 were off, or so I thought.....I was actually measuring in inches, when the book was calling for millimeters. Neighbor to the rescue again....He brought beer and most important, his brain...as I apparently lost mine somewhere. We took all the shims out, re-formulated equations, and got all shims where they need to be, re-installed camshafts (for the 9th time now), hopefully will get a run in tonite. Gotta be better, can't get worse :arrow:

[b717doc]

Dropped it, thought kickstand was full down....dammit......broke clutch handle.....Great...

[gspaul]

OK! Your going in the right direction, most people think that the valves are the last thing you do,but it is the first .
Out of spec clearances does make it hard to track down or correct any problem you may have.
Not shure why you would need to take the camshaft's out though?
As far as carb jeting for a super trap, it depend's on how it's been adjusted, as in how many disc's are in the muffler,if it's a healthy roar I would go up one full size on the main jet's( eg.So if it's 110 goto 115)
And raise the needle one notch ,and adjust idle mix to suite.

[b717doc]

Hey GS Paul, don't know about all the jetting numbers, or where I would get them, but that seems to be the general consensous around here, that the jetting and or the Supertrapp could be the problem.....Engine run after valve clearance adjustment failed.....no help, popping and sputtering from exhaust still present, with an occasional pop from a carb, associated with "studdering" while accelerating. Around 4500 rpm, "power band" kicks in and giant smile appears across my face....Just the lower end has problems.....Would love to have the original exhaust on the bike, as well as the original airbox just to see if that is the problem..... Almost seems like the timing is off, but with #4 cylinder (same as #1, right?) is at top dead center (compression stroke) and the index on the crank is per the clymer, the arrow on the exhaust cam is pointing right, along with 20 pins in camchain between "3" mark on intake cam, and "2" mark on exhaust cam. We checked this several times, and per Clymer, the timing on this system is "factory set" and not adjustable....Seems like the cylinders are getting hotter than normal....don't know how to correct this....Buddy bringing in synchronizers tomorrow, but don't see why they would need synchronizing if they were never separated?!? Float levels set per Clymer...... [-o<

[braindead0]

Woah, no original airbox? That'll muck up your jetting big time, if you're running 'socks' or 'pods' on the back's of the carbs, you're going to need to go with bigger main jets (probably several sizes) and raised needles at a mininum, may need a new pilot jet as well. Perhaps someone here has a recommended starting point.

Air-box mods make a huge difference in the amount of vacuum that you're jets will see at various throttle openings, which will lean our the mixture big time.

[gspaul]

What braindead0 said.............
as for a carb sync, even changing jet's requires one.
No airbox eh! You have work ahead of you,

[b717doc]

Installed impromptu hand made "airbox" made of cardboard. Wrapped K&N filters with styrofoam and installed inside cardboard box. All hesitation and sputtering/studdering gone, nearly dropped bike on initial acceleration....Made HUGE difference...bike runs flawlessly now, however, idle still not solid.....just when you think the bike is idling steady, it drops down and dies, but fires right back up......
Located air box at local "junkyard",,,,,$75.00 they want for it....guess I gotta have it, as the impromptu airbox is not acceptable appearance wise.....Friend brought synchronizing tool to me today, will attempt to sync carbs, but can't understand how to get to the adjustments with tank installed......maybe this adjustment will correct idle???? Living and learning these bikes pretty fast now......

[gspaul]

You have to take the tank off to do the sync, some people make a small gas tank , I just put my tank on the work bench, and useing a joiner and a length of hose, extend the gas line. dont forget to have the petcock on prime, and blank off the vacumn nipple at the carb's.

[b717doc]

Vacuum nipple???? There's a small screw on each intake manifold that I had to remove and make nipples to hook up my synchronizers.....don't see any other "nipples"..... Carbs are pretty much synchronized....or together. Lots of white/bluish smoke coming out of pipe when accelerated. Next step is to purchase an airbox....can't see how that will get rid of my smoke problem....but I will try......

[gspaul]

The vacumn nipple comes off the inlet side of the #2 carb, and connects to the fuel petcock.

[duaneage]

That 75.00 is the best money you'll spend. pods and pipes take patience. The aftermarket pipes are not too bad but boy the pod filters take a lot of tuning.

How are the intake boots? Did you check and or replace the rubber O-rings against the head? 1.81 apiece from the dealer, almost like a tune up item they are.