Have to rejet AFTER Pamco ??

[Hairyblackdude]

Team,

Excuse any errors, typing this on the phone.

I installed a pamco on my 80 last weekend. The bike actually ran great before.. would stall every now & then & liked to be warmed up.. sometimes hard starting, but still fairly easy.

Anyway, install went great, wired up right. Auto advance mech moves freely & the springs snap back in place etc.. timing looks good, I've moved it slightly both directions & issue doesn't seem to change.

Now, when I'm riding the bike- I can feel a loss of power.. it doesn't pull cleanly thru the gears... light throttle is fine, but anything over 1/4 1/2 throttle, it just doesn't feel like it wants to pull. Kinda hesistates... To me, it almost seems like a lean conditon... the bottom half of any of the gears.

I have not been able to do any plug chops when its hesistating, but I took it out for a 15min ride with varied rpms.. the plugs ceramics were kinda gray/brown, top of the electrode was dry & gray...

So- the question is----could a pamco require a change in my jetting ??
The bike ran good before, I'm kinda wondering why I even bothered to change it.

Any other suggestions??

Your opinions are valued.
Thanks
_marc

 

[5twins]

I would go up one on the mains. Even a totally stock BS34 equipped bike is reported to run better when you do that. You could also try shimming the needles a little bit richer.

 

[ProSimex]

I would double check your timing

 

[pamcopete]

Hairy...,

Check that the advance timing goes to max advance at 3,000 RPM. If that is a new advance mechanism, then chances are the springs are too stiff and delay the onset of timing and full advance as well, which matches your symptoms.

 

[Hairyblackdude]

Thanks for the replies gentlemen.

I was able to tinker with the timing setting a little more yesterday.
Theres 2 marks on my bike. F & T- They are about 1/2" apart. I used the mark on the left- I think it was the F. Im not sure what the mark on the right is for, when the timing is advancing- it moves to the left, away from both marks. Ive read that people use the notch on the casing at the full advance mark. Hopefully, this is correct.

Anyway, at idle, the timing is right on top of the left mark- bounces JUST a hair back & forth.. I changed the timing & moved it a hair towards the left.. Like a 1/16" of an inch to the left of the timing mark.
The bike seems to be a little better, but theres still some flat spots, just not as bad as before.

I don't have a tach, so I do not know where 3000 rpms is.

I ran outta play time yesterday & back to work today, not sure when I'll get back to it.

If the bike runs better with the timing slightly off visually- would that be ok? Or would it indicate a problem & bike needs to be timed dead on.

Thanks.

 

[5twins]

The "T" mark is T.D.C. You use that for setting your valves. It has nothing to do with timing. The mark to the left of that is what's called the "F" mark but shouldn't be labeled as such on your 1980 model. It will have no letter label and be a "U' shaped mark on the plate. It indicates your idle timing "range". It's acceptable to have the idle timing anywhere within the sides of the "U" mark .....

..... but you must make sure that the timing doesn't go past the full advance mark regardless of where it sits at idle - don't even let it "bounce" past. For full advance, use the left side of the drain notch on the bottom of the case .....

That little tin plate with the timing marks is slot mounted and may have been moved. That means your idle timing and TDC marks may be off. Best to go by the full advance mark until you can verify the plate marks are correct. You don't need a tach. The ignition reaches full advance by about 3K. It goes no further than that no matter how much you rev it. So, just rev the bike up until it advances as far to the left as it's going to.

To verify that your little tin timing plate is correctly positioned, you're going to need to accurately locate TDC and make sure the "T" mark aligns. You'll need to use a degree wheel, piston stop, or dial gauge in the spark plug hole.

 

[pamcopete]

5twins,

It's possible that he has new springs with the new advance mechanism and if they are too stiff, full advance may be delayed past 3,000 RPM, which matches his symptoms, so I had suggested that he use a tach to be sure that full advance is reached at 3,000 RPM and not after. If, for instance, he does not get full advance until, say, 4,000 RPM then his timing will be retarded between 3,000 and 4,000 RPM. Retarded timing does show up as sluggish performance, poor acceleration etc.

 

[Hairyblackdude]

My bike definitely has 2 marks and 2 letters... I do not have the little "U" line like in your picture... My bike is an 80, G model- had the TCI pickup etc.

It has a T and an F, Im pretty much certain the F is on the left...

While idling and using the timing light, the line is pretty much dead over the F, It bounces back & forth slightly, but not as much as that "U" line is wide. I split the slight difference, but the bike seems to pull better when its slightly to the left of the F mark. We're talking hairs here !!!

Its kinda difficult to tell if it crosses over that full advance notch because it bounces around & theres a larger gap- hard to see exactly where it lines up.

I think I still have the tach somewhere, I could throw it on the motor to check RPMS.

Everything I installed was brand new in the bags- the whole assembly was brand new, springs, rod, timing mech etc.

I guess I should pop the cover off & see if I can make that Full advance line a little taller to help me line it up with the rotor & double check to make sures its not travelling past it. Its difficult to tell because the bike turns into a caged animal when any throttle is applied.
So, no matter what? If it goes OVER full advance, thats a problem??

Thanks for the input... I might see if I can actually take a video of it...

 

[retiredgentleman]

"Its difficult to tell because the bike turns into a caged animal when any throttle is applied."

Put a rubber mat under the centre stand, when test running at high revs. Keeps the bike in one spot. A cooling fan is a good idea also.

 

[CDNTX650]

i bought a new ATU...Stiff springs...Went back to old ones advance is where its supposed to be now.

 

[5twins]

Yes, hook a tach up if you can. I agree with Pete. If full advance is being delayed, that could be the cause of your problems. If the springs are too stiff, I'll bet that's delaying the initial advance, the point where advancing starts, as well. That could very well be causing the sluggish response in the lower part of the RPM range.

Yes, don't let full advance go past the mark, even the "bounce". Draw a line up from the drain slot or hold a straight edge there while using the timing light. Now you may think this is going to have you running slightly retarded at full advance but that's really not the case. Like many new bikes when they first come out, the 650 was faster and produced more power for the 1st couple model years. I think part of that was due to the timing. It was slightly different on those early models, retarded a few degrees compared to the later bikes. Setting the advance timing so the "bounce" doesn't pass the mark and the majority of the image is just below it puts the timing closer to that old spec. I did this on mine earlier this season. Top end and high speed performance is improved slightly. The 1st thing I did after re-setting mine was take the bike out for a good flogging (testing). It pulls the ton easier now than before. Here's the tech bulletin about the timing update .....