Export thread

danl1950

#1

D

danl1950

Hello,I have a Honda GX620 that has very,very little spark at the plug.I took the machine(board edger)to a small engine mechanic and he told me that both coils were bad so I bought 2 new coils,installed them and shazam,I've got the same problem.I've unpluged the kill wires and nothing changes.Anyone have any suggestions for this shade-tree mechanic?


#2

briggs

briggs

danl1950 said:
Hello,I have a Honda GX620 that has very,very little spark at the plug.I took the machine(board edger)to a small engine mechanic and he told me that both coils were bad so I bought 2 new coils,installed them and shazam,I've got the same problem.I've unpluged the kill wires and nothing changes.Anyone have any suggestions for this shade-tree mechanic?
Click to expand...

how dose the magnet on flywheel look is it rusty if so clean it up with some steel wool is the plug new


#3

robert@honda

robert@honda

There were a few Service Bulletins for the GX620, and some may or may not apply, depending on the serial number.

1. Air Gap: The ignition coil air gap to the flywheel must be set correctly, 0.4+/-0.2 mm (0.016 +/- 0.008 in.) Loosen the coil, place a long, flexible gap/feeler gauge (set to the proper thickness) under the coil, press and hold it against the flywheel, tighten bolts, remove gauge.

2. Spark Plugs: If run at low speed or under light loads, the original spark plugs may foul, or the engine oil may become fuel-diluted. First, be sure to check the oil level with the dipstick. Next, a hotter plug may help: NGK BPR2E2.

3. Later GX620's (serial 2007986?017570) had some failed rivets holding the decompression parts to separate from the camshaft. A new camshaft with improved rivets may be required. Only engines within the range are affected.

4. Later GX620's (serial 2000000?037853) may have cylinder #2 exhaust valve lifter issues. You can remove the valve cover, manually rotate the engine, and confirm if the exhaust valve is working. An improved lifter assy. is available if the old one has failed.

FYI, OTHER model Honda V-twin engines had an Emissions Recall for the ignition coils, but the GX620 WAS NOT part of this project.

If you'd like copies of these bulletins, drop me a PM with your email. If you are taking the engine back to the shop (and they are a Honda dealer) tell them to check Engine Service Bulletins #15, #19, #27, and #29.


#4

D

danl1950

briggs said:
how dose the magnet on flywheel look is it rusty if so clean it up with some steel wool is the plug new
Click to expand...

Hello briggs,yes the magnet was kinda rusty,cleaned it with emery cloth but didn't help.Thanks for your support.


#5

D

danl1950

robert@honda said:
There were a few Service Bulletins for the GX620, and some may or may not apply, depending on the serial number.

1. Air Gap: The ignition coil air gap to the flywheel must be set correctly, 0.4+/-0.2 mm (0.016 +/- 0.008 in.) Loosen the coil, place a long, flexible gap/feeler gauge (set to the proper thickness) under the coil, press and hold it against the flywheel, tighten bolts, remove gauge.

2. Spark Plugs: If run at low speed or under light loads, the original spark plugs may foul, or the engine oil may become fuel-diluted. First, be sure to check the oil level with the dipstick. Next, a hotter plug may help: NGK BPR2E2.

3. Later GX620's (serial 2007986?017570) had some failed rivets holding the decompression parts to separate from the camshaft. A new camshaft with improved rivets may be required. Only engines within the range are affected.

4. Later GX620's (serial 2000000?037853) may have cylinder #2 exhaust valve lifter issues. You can remove the valve cover, manually rotate the engine, and confirm if the exhaust valve is working. An improved lifter assy. is available if the old one has failed.

FYI, OTHER model Honda V-twin engines had an Emissions Recall for the ignition coils, but the GX620 WAS NOT part of this project.

If you'd like copies of these bulletins, drop me a PM with your email. If you are taking the engine back to the shop (and they are a Honda dealer) tell them to check Engine Service Bulletins #15, #19, #27, and #29.
Click to expand...
Good morning,thanks for the air gap info.I don't have a manual for this engine and have been unable to find that measurement.Broke a plug so I'm headed to town for 2 new ones and to see if I can find someone to check these coils,both old and new.I have a multi-tester and both sets of coils have the same ohm reading.Maybe I'm not using the tester correctly,I'm not very street-wise when it comes to electricity.Thank you for all the info.


#6

robert@honda

robert@honda

danl1950 said:
Good morning,thanks for the air gap info.I don't have a manual for this engine and have been unable to find that measurement.Broke a plug so I'm headed to town for 2 new ones and to see if I can find someone to check these coils,both old and new.I have a multi-tester and both sets of coils have the same ohm reading.Maybe I'm not using the tester correctly,I'm not very street-wise when it comes to electricity.Thank you for all the info.
Click to expand...

Try the hotter plugs suggested by Honda: NGK BPR2E2.

Here are the coil resistance measurements; note the Primary is in ohms, Secondary is in Kohms.

coilresistanceGX620_zps4f70acd8.jpg


#7

D

danl1950

robert@honda said:
Try the hotter plugs suggested by Honda: NGK BPR2E2.

Here are the coil resistance measurements; note the Primary is in ohms, Secondary is in Kohms.

coilresistanceGX620_zps4f70acd8.jpg
Click to expand...

I checked the ohm readings on the coils(old and new)and this is what I got.The old coils secondary,18.60 and 17.40,old coils primary 1.3 and 1.1.New coils secondary 18.49 and 18.71,new coils primary 1.5 on each coil.I wasn't sure that I was using the meter correctly because the readings I got weren't in the range you gave me so I contacted an electrician friend of mine and he assured me that the readings I got were correct.The readings I got were much higher on the secondary side of the coil,could it be that the new coils are bad also?I was asked today if there was some kind of module under the flywheel and I couldn't answer that because I haven't taken the flywheel off.Is there a module underneath the flywheel that's faulty causing these coils not to fire?If I unplug the kill wire and spin the engine over,the coils should fire,right?Hope I'm not being too much a bother to you,I just want to get this thing figured out.Thanks


#8

robert@honda

robert@honda

danl1950 said:
I checked the ohm readings on the coils(old and new)and this is what I got.The old coils secondary,18.60 and 17.40,old coils primary 1.3 and 1.1.New coils secondary 18.49 and 18.71,new coils primary 1.5 on each coil.I wasn't sure that I was using the meter correctly because the readings I got weren't in the range you gave me so I contacted an electrician friend of mine and he assured me that the readings I got were correct.The readings I got were much higher on the secondary side of the coil,could it be that the new coils are bad also?I was asked today if there was some kind of module under the flywheel and I couldn't answer that because I haven't taken the flywheel off.Is there a module underneath the flywheel that's faulty causing these coils not to fire?If I unplug the kill wire and spin the engine over,the coils should fire,right?Hope I'm not being too much a bother to you,I just want to get this thing figured out.Thanks
Click to expand...

Unlikely brand new coils are bad.

Keep in mind, the secondary measurement is in K-ohms, which is thousands-of-ohms. Check the scale selection or range on your meter and confirm it is displaying in K-ohms.

FYI, 7.8 K-ohms = 7800 ohms (move the decimal three places to the right) and 8.6 K-ohms = 8600 ohms.

I'm locked out of my service library right now, but will look into the flywheel / magnet area to see if there's anything odd there. Stand-by.


#9

D

danl1950

robert@honda said:
Unlikely brand new coils are bad.

Keep in mind, the secondary measurement is in K-ohms, which is thousands-of-ohms. Check the scale selection or range on your meter and confirm it is displaying in K-ohms.

FYI, 7.8 K-ohms = 7800 ohms (move the decimal three places to the right) and 8.6 K-ohms = 8600 ohms.

I'm locked out of my service library right now, but will look into the flywheel / magnet area to see if there's anything odd there. Stand-by.
Click to expand...
Took the coils,old and new,to a guy that had a coil tester and 1 of the new coils was defective,both old ones were good.Couldn't think of why these coils weren't firing,so I thought I'd try swapping sides,since both coils are identical on the outside.They're labeled "left" and "right",so I suppose they're wired differently on the inside.I put the "left" one one the right side and cranked the engine and had all kinds of fire,same on the left side.I was afraid it might put the engine out of time but it runs just fine.Please explain why they work on the opposite side that they've been running on for years,just don't make sense to my.


#10

robert@honda

robert@honda

The GX620 had a number of different coils, ignition, charging, etc., and they were subject to some running changes. Early GX620's had different left and right coils (different part numbers), and later models shared the same part number/coil.

If you could get me the serial number off the side of the engine block, I could narrow it down a bit more. It's in the form of: "GCAD-1234567"

gx620serialnumber_zps1dc95f0a.jpg


#11

H

hntrsr

danl1950 said:
Hello,I have a Honda GX620 that has very,very little spark at the plug.I took the machine(board edger)to a small engine mechanic and he told me that both coils were bad so I bought 2 new coils,installed them and shazam,I've got the same problem.I've unpluged the kill wires and nothing changes.Anyone have any suggestions for this shade-tree mechanic?
Click to expand...

The ground for the two coils are thru the diode engine stop(kill switch). Robert@Honda, he needs the test for the kill switch


#12

D

danl1950

robert@honda said:
The GX620 had a number of different coils, ignition, charging, etc., and they were subject to some running changes. Early GX620's had different left and right coils (different part numbers), and later models shared the same part number/coil.

If you could get me the serial number off the side of the engine block, I could narrow it down a bit more. It's in the form of: "GCAD-1234567"

gx620serialnumber_zps1dc95f0a.jpg
Click to expand...

I'll get the number tomorrow,I've seen it but haven't written it down.Kinda strange though,they ran on the appropriate sides for several years,then they quit,but they'll fire on the opposite side.The new coils have different part numbers printed on them,the old ones have different numbers stamped in them.Both new and old coils are different colors,gray for the left side and black for the right side.Thank you for helping with my problem.Dan


#13

D

danl1950

hntrsr said:
The ground for the two coils are thru the diode engine stop(kill switch). Robert@Honda, he needs the test for the kill switch
Click to expand...

I understand how the kill wire is grounded to kill the engine,but for the coils to fire they are grounded to the engine block,right?After I put the left side coil on the right side of the engine and the right side coil on the left side of the engine it ran fine.I just don't understand these coils quit working on the side they'd been on for years but will work on the opposite side of the engine.Polarity maybe?


#14

H

hntrsr

danl1950 said:
I understand how the kill wire is grounded to kill the engine,but for the coils to fire they are grounded to the engine block,right?After I put the left side coil on the right side of the engine and the right side coil on the left side of the engine it ran fine.I just don't understand these coils quit working on the side they'd been on for years but will work on the opposite side of the engine.Polarity maybe?
Click to expand...

I do not have a schematic in front of me but from the test you have done I think the diode engine stop(kill switch) has circuit in it equivalent to the old breaker points. I would also check the ground on thediode engine stop(kill switch).
Thanks,
Bobby


#15

D

danl1950

robert@honda said:
The GX620 had a number of different coils, ignition, charging, etc., and they were subject to some running changes. Early GX620's had different left and right coils (different part numbers), and later models shared the same part number/coil.

If you could get me the serial number off the side of the engine block, I could narrow it down a bit more. It's in the form of: "GCAD-1234567"

gx620serialnumber_zps1dc95f0a.jpg
Click to expand...

Finally remembered to get the number,got too many irons in the fire.There's 3 letters and a star above the serial number,they are,QDF*.The serial number is GCAD 2017531.Sorry it took so long.Got a question,is it possible that the magnet in the flywheel changed polarity?Both old and new coils wouldn't work in their proper places,but turn them around backwards by putting them on the wrong side and they work.Just a thought I had.


#16

robert@honda

robert@honda

danl1950 said:
Finally remembered to get the number,got too many irons in the fire.There's 3 letters and a star above the serial number,they are,QDF*.The serial number is GCAD 2017531.Sorry it took so long.Got a question,is it possible that the magnet in the flywheel changed polarity?Both old and new coils wouldn't work in their proper places,but turn them around backwards by putting them on the wrong side and they work.Just a thought I had.
Click to expand...

Magnets rarely fail, and I've never heard of one reversing its polarity.

A few bits that might help:

The serial number on this engine designates it as a "K1" engine, which is a later production model. K1 engines do indeed have different coils. First, be sure we're oriented on the correct side of the engine. Left and Right are as viewed from the fan/flywheel side, NOT the crankshaft/PTO side.

The left coil is gray, and has an 8.5 inch spark plug lead. The right coil is black, and has a 7.9 inch lead. The are not interchangeable or reversible.

When checking the coils (resistance check) you must remove the spark plug cap; leaving it on will give an incorrect measurement.

For the engine stop diode, here's an inspection procedure from the shop manual:

gx620k1enginestopdiode_zpsf94ff78a.jpg


#17

D

danl1950

robert@honda said:
Magnets rarely fail, and I've never heard of one reversing its polarity.

A few bits that might help:

The serial number on this engine designates it as a "K1" engine, which is a later production model. K1 engines do indeed have different coils. First, be sure we're oriented on the correct side of the engine. Left and Right are as viewed from the fan/flywheel side, NOT the crankshaft/PTO side.

The left coil is gray, and has an 8.5 inch spark plug lead. The right coil is black, and has a 7.9 inch lead. The are not interchangeable or reversible.

When checking the coils (resistance check) you must remove the spark plug cap; leaving it on will give an incorrect measurement.

For the engine stop diode, here's an inspection procedure from the shop manual:

gx620k1enginestopdiode_zpsf94ff78a.jpg
Click to expand...
I've often wondered about the right and left side of an engine,thanks for the clarification.The coils are gray for left and black for right,the new ones were marked,the old ones weren't,that's why I marked them so I'd remember.So when the new coils came in and I saw they were marked L & R,I assumed the engine was viewed left and right from the pto end of the engine because the old gray coil was on the left side viewed from the pto end.I don't know what is going on,one day it was running fine and the next it wasn't and in the end I had put the coils on the opposite side and they're working.The engine is running and that's what counts and now I had a set of brand new coils that I didn't need.When I checked the resistance in the coils I didn't take the cap off the wire so that's the reason my reading was so far off.Anyway,I sure appreciate you taking the time to help me on this thing.Take care and God bless.Dan


Footer Links 1

Top