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Whadia Tink?

Tonerjockey

Tonerjockey

High Miler
GT Contributor
Joined
Oct 28, 2008
Messages
788
Location
San Jose
So the G5 is getn' vibraty. Goes with engine speed. All gears.
Slight backfire thru carbs on deceleration... sometimes carb cough on heavy accell/decelleration.
Checked carbs (PHF32 122 Main 50 Idle) Used to work OK... adjusting no improvement.
Dyna III timing 6 degrees at idle. A bit advanced but ...
Checked new NGK BP7ES with 300 miles on em:

Plugs2.jpg


The silver stuff is antisieze.

The right plug is damaged.

Looks kinda like detonation here... whatcha think?

Alex
 
Some questions:
How old are the plugs and how long have they been run?
did you do a plug chop and if so how and at what throttle opening?
Did you change anything in the last while?

To me they both look lean/advanced - unless they are pretty much brand new. It is not so easy to read plugs over the internet so this is just a wild ass guess.

To do a proper plug chop hold it at the opening you are interested in as long as is possible and then simultaneously pull in the clutch, cut the engine and close the throttle so the plug does not get washed by gas ruining the reading.

Detonation is usually shown by lean + little silver balls stuck on the ceramic. The little silver balls are bits of the piston actually sticking to the plug. It is getting much harder to read plugs since unleaded fuel became the norm. When you get the bike running properly I would cut back the crimping on the plug so you can pull out the ceramic and have a good look at the color the whole length of the plug and then you have a baseline.
 
If memory serves me correctly, the Dyna ignition has the ability to time each cylinder independently. Did you check the timing on each side? That right plug looks toasted, too lean or too much advance. The popping is indicative of a lean mixture. Without a change in carb adjustment, you may have a partially clogged main jet, or a throttle cable out of adjustment.
 
Checked carbs (PHF32 122 Main 50 Idle) Used to work OK... adjusting no improvement.
Dyna III timing 6 degrees at idle. A bit advanced but ...
Checked new NGK BP7ES with 300 miles on em:
Click to expand...

Sorry you already gave out that information. I guess target fixation on my part.

I guess the real question is was it running well and then suddenly stopped running well or did you do something and suddenly it started behaving as it does now? Or is this a new bike and you have no history with it?

6 degrees of timing is not a lot of timing but I'd set it back a bit to be safe. As John points out the dyna has two pickups so you have to check both sides. Also check that the timing marks are actually in the right positions - i.e. verify that TDC is really TDC. I had one bike where the markings were 10 degrees out!

It may be fuel starvation (plugged fuel filters ((check the tank as well as the one at the banjo at the carb)), low float, clogged jet) or a vacuum leak twixt engine and carb.

The 7ES is about the right heat - It is a non-resistor plug so you do need a resistor in the cap. 5k is about right. This will not cause the problem you are having though.
 
I was always surprised to find the inlet manifold rubbers (both sides of the carby) would loosen on a fairly regular basis on my last Cali.

Every couple of months it would develop a little cough/hickup with associated exhaust popping etc.
1 blade screwdriver and a quick nip & tuck, and all was well with the world again. :)
 
As has been written, hard to tell from a pic like that.

I would need a good shot from the side of the plug to see the earth strap but from what I see (guessing really) the RH side is way too advanced. G5's? Aren't they 2 deg BTDC, not 6? Whilst you are re-doing the timing check the advance is working fine too. Should get to max advance about 4500-5000rpm. If sooner get new springs.

I would also need to see down the moat to the fuel ring. Kidding yourself if you think you can read a plug showing what is shown.

Popping? Either too lean or there is an exhaust leak. Check the header collars are down tight but not up against the head. If so put another gasket in.

Ghezzis suggestion about the manifold rubbers is a good one. Sucking air in there would explain a lot.
 
Yesterday I replaced the 122 mains with 130... they were the closest next size up I had.
Replaced NGK BP7ES.
Warmed up engine and adjusted carbs
Road 50 miles on highway.


321G5Plugs.jpg


G5Plug.jpg


Vibration is very different.

I think these mains are too large. I'll get a set of 125's.

Also will check for vac leaks today.

BTW I clean off the antisieze before I put the plugs back in. :blink:

Thanks for all the insights. Carbs have always been trickey to me.

Alex
 
At this point I wouldn't focus on the mains. If you are in the ballpark with your main jets, then you can finetune later once the rest of the carb circuits are functioning correctly.
 
Isn't timing for a G5 supposed to be 2/33 ??

Have you timed it with a light at full advance??

Also make sure the pick ups for each cylinder are in synch.
 
Timing is now 3 degrees advanced. I havn't tried it full on yet. Good idea.

Both cyl time the same 3 degrees.

I can feel the vibes at idle .... but much more noticable at about 4,000 RPM. More noticable under acceleration load than cruise.

The prob still could be in carbs/intake system but I am starting to wonder about my Dyna III system. It's a take off from the race bike and I believe that I have probs with it before.

I'll try other Dyna III on the bike.

The adventure continues.... I would like to get this sorted out before mid April. I am in a pool tourny in Vegas and would like to ride the bike there.... bike needs to be all sorted out before I seriously consider that though.

Alex
 
I would check your full advance timing before changing parts. Static timing is just a starting point.

Just to be sure maybe double double check the install of the sensor plate and pick ups.

Also for a quick and dirty check of full advance line up the flywheel full advance mark in the inspection hole. Take out the plugs put them in the caps and lay them on the heads and turn on the ignition. Rotate the black pick up rotor clockwise until it hits its stop. The plugs should fire right at the point of hitting the stop.

This is a good way of seeing if you are close with timing.

Finish final timing with a strobe.
 
Just a thought. Vacuum leak on the intake side as mentioned before. A quick way to check, spray some carb cleaner around the intakes (flange gasket, rubber ) with the bike at idle, any change in rpm is a sure sign of a vac leak.
 
The saga continues.
Bike was getting worse... backfire, funky throttle response, and vibration still there.
Plugs showed detonation.

OK take it appart.

1st item of interest: Inside of timing chest cover:

Damagetotimingchestcover.jpg


hhmmmm what would make THAT damage?

oh... this would:

Keystuckincrankgear.jpg


Looks like a broken key from somewhere.

MOOP.jpg



Keys still in crank and oil pump...

This is a heavy key. Looks like I'll need to keep the dissasembly going.

Here's chain slack:

Timingchainslack.jpg


Old style tensioner...

Now to ID that busted key...

Any ideas what this key was?

Alex
 
Crank gear drive key....maybe.Its the only other key in the timing chest. Although Iv'e been led astray before by items accidentally introduced during maintenance work that were just lying around on the bench and somehow got in there. If it is the valve timing will almost certainly be out.Check for valve/piston interference.
Ciao
 
well the crank gear key AND the oil pump keys are in place!

I gotta agree someone left the key in the engine somewhere but ...

I bought the bike with 10 miles on the clock... and the engine, frame, wiring, tire codes, etc certainly supported that mileage..


Engine coming appart now.

Extreme crud buildup on right piston/head: (14K miles)

Crud2.jpg


Also discovered nick in the cam bearing face...

Camdamage.jpg


A mystery....

Alex
 
Alex,

You sure do have a mystery on your hands. I believe you are doing the right thing in just taking her apart and checking everything before she goes back together. Hopefully you won't find any more nasty surprises. I've got most of a T-3 engine under a bench (missing cylinders and pistons, but the cam grind is suspect). If anything from it would help let me know.
 
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