No power, fouled plugs

[lhanscom]

Ok, first, I have a 77 GS750, I'm trying to get going after sitting for a few years. It has the mechanical carbs (VM?). It also has the Dyna electronic ignition upgrade, and a 4 into 1 Kerker megaphone on it. I've taken the carbs off and cleaned them up, although they looked extrodinarily clean already. She idles fine. Plugs are black. I took it out on a ride, and power is lacking, as in I can barely get it to take off, but once it's going I managed to get it up to 50 or so, but it didn't really pull at any time. So I figured I'd pull off the airbox to see if there was any difference. Well the plugs did start changing to white, but there was no difference in power. I checked the battery voltage, and it was at 13 vdc with the engine running, although the battery does die, I'm thinking the battery may just be dead, since it sat for 3 years, discharged. So I'm thinking this may have to do with a cold spark vs a mixture problem. Thoughts? Next steps, anything? Thanks!

 

[earlfor]

Re: No power, fouled plugs

I think if the battery sat for 3 years in a discharged state, then its more useful as a paperweight than it is as a battery. I would put a new battery in the bike first thing. You cannot diagnose anything accurately with a bum battery. Your problem could be nothing more than low voltage.

Earl

Ok, first, I have a 77 GS750, I'm trying to get going after sitting for a few years. It has the mechanical carbs (VM?). It also has the Dyna electronic ignition upgrade, and a 4 into 1 Kerker megaphone on it. I've taken the carbs off and cleaned them up, although they looked extrodinarily clean already. She idles fine. Plugs are black. I took it out on a ride, and power is lacking, as in I can barely get it to take off, but once it's going I managed to get it up to 50 or so, but it didn't really pull at any time. So I figured I'd pull off the airbox to see if there was any difference. Well the plugs did start changing to white, but there was no difference in power. I checked the battery voltage, and it was at 13 vdc with the engine running, although the battery does die, I'm thinking the battery may just be dead, since it sat for 3 years, discharged. So I'm thinking this may have to do with a cold spark vs a mixture problem. Thoughts? Next steps, anything? Thanks!

 

[Anonymous]

I have the exact same problem on an 86 honda rebel 250 I am working on. I have a brand new battery in it though, so that is not my problem. Plugs look black. Have to get rpms up pretty good to get going but once going it is ok. Not much power though. Basically the same symptoms as above. Being I have a new battery and I have ripped apart the carbs like 7 times to clean them out and blew them with air, cleaned the air filter and a fresh oil change, what else could be my problem? I'm thinking bad jets. On this rebel there is a needle that is adjustable from outside the carb. It is located on the bottom front of the carb. When I turn it in either direction, it does nothing at all. Shouldn't this increase/decrease the idle when turned one way or the other?

Any help for me too would be great.

Jim

 

[redliner1973]

For the Honda, first check the choke, it can fall out of adjustment and whilst the handle shows 'off', the choke is really 'on' causing a rich mix. the only other place I can think right off is float valves and petcock. Jets usually don't go 'bad', but get clogged instead. resulting in a leaner condition, or richer if your idling in the main jet area instead of the pilot jet area. :twisted:

 

[Hotblack]

Earl, you look a little... strange today. Are you feeling alright?

 

[redliner1973]

he does have that Gene Simmons thing going on doesn't he??!! :twisted:

 

[lhanscom]

Ok, I changed the battery, and it helped quite a bit. Now I have something weird happening. Num 1 and Num 2 are fouled, Number 3 and Number 4 are white. So it's on different coils, so they're alright. I rechecked the air screw settings, and they're all the same. I checked the sync, and it's close enough not to be the problem. I would expect the the carbs to be running a little lean, as it has the Kerker 4 into 1 on it, so I think it's probably the rich cylendars that are off. So what's next?

 

[earlfor]

I got tired of wearing the disguise, this is the real me.

Earl

Earl, you look a little... strange today. Are you feeling alright?

 

[earlfor]

Youre right, its not your coils or points that are the problem. Of the two conditions, (1 and 2 fouled) and (3 and 4 white), the more pressing concern is 3 and 4 being white, That is BAD! Fouled will not hurt anything and you have time to fool around and find out what is wrong. White is a big NO NO and you dont have time to mess around. Get the airbox back on the bike Immediately!!! If that does not get the center ceramic color on plugs 3 and 4 back to light brown or at least a tan, then you have a lean induction problem or blocked passages in the carb.
There is no such thing as synchronization being close enough. Either it is right, or it is not. What vacuum at what rpm are you pulling?

What are your pilot fuel screw settings and airscrew settings? do you know your jet sizes? What clip is your needle in? Are you running NGK B8ES plugs? Are you static timed on the F1 and F3 marks?

Earl
P.S. Not trying to give you a hard time here, but its not going to run long in one piece if the plugs are burning white.

Ok, I changed the battery, and it helped quite a bit. Now I have something weird happening. Num 1 and Num 2 are fouled, Number 3 and Number 4 are white. So it's on different coils, so they're alright. I rechecked the air screw settings, and they're all the same. I checked the sync, and it's close enough not to be the problem. I would expect the the carbs to be running a little lean, as it has the Kerker 4 into 1 on it, so I think it's probably the rich cylendars that are off. So what's next?

 

[skip]

Are you running NGK B8ES plugs? Are you static timed on the F1 and F3 marks?

Earl
P.S. Not trying to give you a hard time here, but its not going to run long in one piece if the plugs are burning white.

Ok, I changed the battery, and it helped quite a bit. Now I have something weird happening. Num 1 and Num 2 are fouled, Number 3 and Number 4 are white. So it's on different coils, so they're alright. I rechecked the air screw settings, and they're all the same. I checked the sync, and it's close enough not to be the problem. I would expect the the carbs to be running a little lean, as it has the Kerker 4 into 1 on it, so I think it's probably the rich cylendars that are off. So what's next?

Ihave used a degree wheel and static timed my bike before but i cant find it now. when you use the f1 and f3 marks do you just pull the plug rotate the crank and wait till it sparks .then rotate your pickup till it sparks at the line for f1 and f3? or do you use the the T marks? I have a dyna s and it dosent retain the the indicater (pointer) like the stock unit does

 

[lhanscom]

Thanks. Where do I find the fuel screw, and what do I need to do the timing? What is the proper procedure for this?

 

[earlfor]

The fuel pilot screw is underneath the carb protruding at the front edge of the float bowl. 1 3/4 turns out is good ballpark starting point.

To static time it, all you will need is a 19 mm wrench, a flat blade screwdriver and a continuity light.

Static timing is done with the engine NOT running.

The contact breaker plate is located on the right crankshaft end under the small round cover. You will see three screws holding the breaker plate. The screws are located at 12, 4 and 8 o'clock. Note the 12 oclock screw is in a slot. Loosen all three screws, Rotate the breaker plate so that the 12 oclock screw is centered in the slot. Tighten the three screws.
Take a 19 mm wrench and rotate the crankshaft clockwise until the point gap on the left pointset is at its widest gap. (DO NOT ROTATE THE CRANKSHAFT WITH THE SMALL BOLT ON THE END OF THE CRANKSHAFT!)
Loosen the screw holding the left pointset. With a feeler guage, set the point gap to 14 thousandths. Tighten the pointset back down.
With 19 mm wrench, rotate the crankshaft until the gap on the right pointset is at its widest gap. Loosen hold down screw on pointset and set with a feeler guage to 14 thousandths. Retighten screw.
Take a continuity light and clip one lead to ground on the frame or battery and clip the other lead to the wire terminal on the left pointset. At the top of the breaker plate, you will see a timing window. (about a 5/8" hole in the breaker plate.) Rotate the crankshaft clocklwise until you see the F1 mark align with the timing mark on the case. (if you have no timing mark on the case...my 750 does not, the timing mark is the left edge of the 12 oclock bolt head) Turn the crankhaft until the F1 mark is in alignment with the timing mark or the left edge of the 12 oclock bolt head. Loosen the three screws on the breaker plate located at 12, 4 and 8 oclock. Rotate breaker plate until the light just goes out. (you have left the crankshaft sitting still with the F1 mark aligned with the case timing mark) Tighten the three breaker plate mounting screws.

Unclip the continuity light lead from the left pointset and clip it to the wire terminal on the right pointset. Rotate crankshaft clockwise until you see the F2 mark aligned with the timing mark on the engine case. If you pass the mark in your engine rotating, go around again. Do NOT back up.
With the F2 mark aligned, loosen the hold down screw on the right pointset and move the points until the continuity light is just going out. Tighten the pointset holdown screw. Youre ALL DONE.

More precise timing can be done with a timing light and the engine running. For setting maximum advance, you would time to the F4 and F3 marks at 2500 rpm with a timing light.

Earl

Thanks. Where do I find the fuel screw, and what do I need to do the timing? What is th
e proper procedure for this?[/qu
ote]

 

[Hotblack]

he does have that Gene Simmons thing going on doesn't he??!! :twisted:

He does have the tongue, but I was thinking I've seen him somewhere else... like Hogan's Heroes.

 

[redliner1973]

he does have that Gene Simmons thing going on doesn't he??!! :twisted:

He does have the tongue, but I was thinking I've seen him somewhere else... like Hogan's Heroes.

Yea, but the tongue kinda stuck out!!! :twisted:

 

[Anonymous]

Hey Earl,

He's got the Dyna ignition.

Steve

 

[earlfor]

Well Hells Bells. In this case, since the engine does idle, the easiest thing to do would be to connect a timing light to 1 cylinder and check through the timing window at any rpm under 1500. The F1 mark should align with the mark on the crankcase for cylinder 1 and the left ignition module. For adjustment on the left module, rotate the breaker plate/mounting plate. Counterclockwise rotation of the plate advances timing and clockwise retards timing. Then connect the timing light to either cylinder 2 or 3 to and look through the timing window to see that the F3 mark is aligned for adjustment on the right module. You will need to loosen the cap screws holding the right module and move it in whatever direction is needed. Movement of the module of .010" is equal to 1 deg of timing. Once the inition timing is correct, you can further refine timing by setting the engine to run at 2500 rpm (with the throttle adjustment knob between the carbs) and with a timing light check the timing on the advance marks. That would be F4 for the left module and F3 for the right module.
Adjustment proceedure is the same.

Earl

Hey Earl,

He's got the Dyna ignition.

Steve

 

[lhanscom]

Thanks, I'll check that out. However, I think I found my problem, it has to do with me being an idiot :evil: . When I took the carbs off to look them over, I opened one of the bowls, and was amazed to see that every thing looked very clean, so I opted for the shortcut of just putting them on the bike, and see how things went. Figured, hey if one is clean, they all are, right? :roll: Wrong, DOH! I took them off again tonight, and figured I'd go thru the entire thing. I found the 2 lean cyls had the idle jets partially clogged. So that explains that. On the 2 rich cylindars I found that on one, the idle jet, and main jet were clogged completely, I'm not even sure how this one ran at all, but it did idle some. The other had a clean idle jet, and a completly clogged main jet. I figure what was happening, was when I opened the throttle the cyls would die completely, fouling the plugs. I haven't put the carbs back on yet, as I have to replace a couple of O-rings on the fuel screws. BTW all the fuel screws were set at 1.5 out, except one (cyl 4) that was 3.5 out, that was a lean cyl, but not as lean as cyl 3.

Next time no "shortcuts" for me.
Thanks again for all your help.

 

[Hotblack]

My Stepfather has a handy euphamism for that sort of thing - it's called "a case of operator trouble". It comes in handy for me every day, I hope it helps you too. :wink:

 

[dgeorge]

In the computer field we call it a id 10 t error (ID10T) :lol:

 

[earlfor]

Ah Haaaa, glad you found your problem. I would hate to see you with burned exhaust valves. I believe the first rule of wrenching should be, make no assumptions.

Earl

Thanks, I'll check that out. However, I think I found my problem, it has to do with me being an idiot :evil: . When I took the carbs off to look them over, I opened one of the bowls, and was amazed to see that every thing looked very clean, so I opted for the shortcut of just putting them on the bike, and see how things went. Figured, hey if one is clean, they all are, right? :roll: Wrong, DOH! I took them off again tonight, and figured I'd go thru the entire thing. I found the 2 lean cyls had the idle jets partially clogged. So that explains that. On the 2 rich cylindars I found that on one, the idle jet, and main jet were clogged completely, I'm not even sure how this one ran at all, but it did idle some. The other had a clean idle jet, and a completly clogged main jet. I figure what was happening, was when I opened the throttle the cyls would die completely, fouling the plugs. I haven't put the carbs back on yet, as I have to replace a couple of O-rings on the fuel screws. BTW all the fuel screws were set at 1.5 out, except one (cyl 4) that was 3.5 out, that was a lean cyl, but not as lean as cyl 3.

Next time no "shortcuts" for me.
Thanks again for all your help.