TOPIC:

Hi,

I'm having trouble starting my 550-F2 up. I have spark on all 4 cylinders, however I'm thinking that the pilot air screw may be a little bit too far in.

Would that cause the plugs to get wet when cranking it over? If the mixture is too rich - it may not let the spark ignite it, right?

I've got some puffs of exhaust coming out when it *almost* starts, so thats what I'm thinking the problem might be..

I'm going to go through the checklist that George posted in KB02's thread though, just to be sure.

The battery does drop fairly quickly though, and after charging for a bit last night, it wouldn't go above 12V on the tach voltmeter.

I'll put it back on the charger this afternoon while I pull the tank off and check the air screws.

Does this make sense?

Your premise makes sense but the reason your plugs get wet is that the bike is cranking and making vacuum and fuel is atomizing and wetting your combustion chamber but not igniting.

Check your compression first then make sure you have spark... I am thinking that wet plugs means the carbs may not be the issue. Your air/fuel ratio when starting SHOULD be rich. Turn your air screws out 1.5 turns from lightly seated... they are not all that fussy... just adjust them and leave them alone and look elsewhere for the problem.

One sure thing that messes up starting is that the choke pickup circuit is gummed. I can't recall for sure but I think there is a choke pickup tube hanging from the bottom of your float bowl. Make sure the little openings in the tips of the tubes are clear. Then, there is a hole in the float bowl... there will be a one-way check valve that allows fuel to be drawn through. Make sure it is clear... you can squirt carb cleaner through the inside of the bowl and make sure it comes out the edge. If fluid doesn't make it through, drop me a PM and let me know...

Also make sure your plug gap is correct and clean the insides of your plug caps with contact cleaner and then put some dielectic grease in there. I have seen bikes hard to start because humidity and moisture gets in the caps and they short when first trying to start them.

Okee doke - thanks WG.

...now to devise a devilishly clever plan to skip out on work and try to get some *actual* work done..

Oh - Also, I did a compression check before trying to start it.

I got the following (c1/c2/c3/c4):
Dry: 75/75/125/100 (had been sitting a while with gas in the engine. I did the test when cycling some oil around to flush it out before putting new oil in)
Wet: 150/125/175/140

The 125/175 kinda bugs me, but the other two seem fine.

Post edited by: pyxen, at: 2006/10/16 10:35

Post edited by: pyxen, at: 2006/10/16 10:36

I am also having that same prob rite now, what a coincidence. Tell me whats up with the gunshot fire out of the tail pipe. I am scaring my neighbours

kzwolfsr, please start a new thread...

As far as the compression on pyxen's bike, I am not sure I follow what was done. You checked compression dry. How did you check? Was the throttle all the way open? Next, you said you "test when cycling some oil around"... what does that mean? Does that mean you put oil in the combustion chambers? Please verify the meaning of what has been done.

The compression numbers you note are not real good... the dry compression is such that the bike won't really want to run as the smaller displacement bikes generally should be closer to 150 PSI I think. The difference between cylinders is pretty far out of spec I would guess and all cylinders have very low compression except for the 125 PSI cylinder but that is also a bit low.

acutally I did forget to have the throttle full open, so I'm going to be taking the tank off this afternoon and doing it again.

The PO had gotten gas in the engine, which I hope isn't my current problem, so I drained that oil, put some 10W40 in, hit the starter a few times to 'rinse' it out. I drained that then put some 20w50 in as my final oil.

I did the compression testing when I was rinsing the engine out.

I'll get back to you after I try it again with the throttle wide open.

Okay.

1) Compression is looking better w/ wide open throttle - 150/140/135/130. Still a little low, but I'm thinking its still decent.

2) Float levels are good on 1, 2 & 4, but 3 is a little bit low. There was an air bubble I couldn't quite get dislodged, but it was decent, only a bit low.

3) I turned the pilot screws out another turn - so that's 2 then. I think I may go back in 1/2 and try 'er again.

4) I cleaned all the contacts on the coils, both the power and wire sides, cleaned the connectors on the right side of the bike. I put dielectric in everything.

There was a new change - the fuel and oil lights both came on this afternoon - they weren't yesterday.

With choke on full I nearly had it started..but it barely didn't make it. I'm still thinking that its the spark - and am considering putting in the coil mod for your site, George. Do you recommend it?

Thanks a lot.

Use a multimeter and check the resistance of the secondary side (spark plug wires). Measuring betwwen the two spark plug wires on one coil, the resistance should be around 20k ohms or less, if it is a lot more, then remove the spark plug caps from the wires and check again. There is a possibility that the spark plug caps are bad, I see that a lot on the older bikes.

That will cause a weak spark and hard starting.

Edit: I checked. Only 12K on each side, with the meter wires touching the copper needles in the coils..

Thats what I was supposed to do, right?

I tried it with ignition on and off - same result.

Okay - I tried it with boots on, and got pretty much squat, so then I tried it with boots off and got a nice 12-18K range depending on which coil.

So now I'm at replacing boots - should I go with new wires too?

Post edited by: pyxen, at: 2006/10/16 20:38

Post edited by: pyxen, at: 2006/10/16 20:53

pyxen, I don't quite follow what was done. Steell suggested checking secondary windings resistance through your plug caps. To do this, you touch the contact INSIDE the plug caps on the two plug wires coming off one coil. The resistance that you measured of 12K Ohms at the coil plugwire contacts seems OK to me but I don't know what it supposed to be for your bike but I am guessing the secondary windings in your coil is OK... what you didn't due is test the wires/caps. The resistance when you touch the contacts inside the caps should be about the same as inside the coils. If it isn't toss the wires and caps. I think Steell was suggesting hard starting due to bad caps but I would get rid of the wires as well... I am not sure this is your problem but is one line item that can be crossed off.

Hey,

I went back and tested the wires and caps as well. The wires tested well, but the caps barely moved the needle. I think my meter was fubar'd though, so I'm going to pick up a new one at lunch, as well as some new boots.

The wire connections (with the meter contacts inside the wires) showed around 15-18K on both pairs of wires - 1/4, 2/3.

On another though related subject - what does having the throttle open do when checking compression, or removing gas from a flooded cylinder? When I cleaned out the gassy oil that was sitting, I didn't have the throttle open, so could there still be a nasty amount of gas in the cylinder? I constantly find the plugs wet after removing them.

pyxen wrote:

On another though related subject - what does having the throttle open do when checking compression, or removing gas from a flooded cylinder? When I cleaned out the gassy oil that was sitting, I didn't have the throttle open, so could there still be a nasty amount of gas in the cylinder? I constantly find the plugs wet after removing them.

Opening the throttle all the way allows the maximum amount of air to flow into the cylinder, so your compression reading will be at its maximum. Having the throttle closed will reduce the compression reading.

Also, holding the throttle open while cranking will allow the maximum amount of airflow through the engine to evaporate and carry away excess fuel from flooded cylinders.