Backfire through carbs and 4,000 RPMs max.

[brianinpa]

I am running into a problem with the 1100 that has me losing what little hair I have left.

I was working on tuning the Solex carb before and I was only able to get 3500 to 4000 RPMs. The bike idles fine, but there is nothing in the higher RPMs and then the motor would backfires through the carb. I opened the carb and found a lot of rust deposits in the bowl, so decided to tear it apart to clean in and replace all the seals. After the rebuild, same thing... nothing changed. Just to make sure it was operator induced, I opened the carb up one more time and nothing jumped out at me as a problem.

That led me to think that some small passage in the carb may have been clogged, so I pulled the Solex to make sure, and I switched back to the stock carbs... Same problem. :head bang:

So, a backfire through the carb: too lean, timing, or catastrophic failure. To lean? Changed the fuel filter just to make sure it is getting fuel. Changed back to the stock carbs and the problem did not go away. Timing? I checked the ignition: the C5 is timed at T1 TDC and the ignition shaft does not move, so I have to assume that the little pin in in and working. Catastrophic failure? Tine ti check the compression: using my Harbor Freight compression test set that I am sure works GREAT as a paper weight, I found that I have the same compression readings that I had in May of 2014 when I used it last. As a reminder... 90 - 95 on all 4 cylinders and the bike was running strong all last summer and this year until the rotor bolt backed out. Back then I was pretty certain that the gauge was piece of junk, so I didn't put much faith in the number, only that all 4 cylinders were really close to each other. Seeing that I still have the same reading, I don't think I have a problem with a valve. I was certain I was going to find a low cylinder to point to a bent valve or something worse, but it just isn't there.

What am I missing? It seems to be backfiring on the right side, but all 4 plugs are black. Makes me wonder about the amount of spark I am getting. What should I be reading from the spark plug caps on the C5 ignition?

 

[dan filipi]

It sounds like ignition timing is retarded.
Which of the 3 curves are you running?

 

[brianinpa]

All 3. I have it switched so I can turn the switch and dial it up - usually on the base setting, but even while changing the settings, nothing changed.

 

[dan filipi]

Before the rotor bolt backed out, did it do this?

 

[brianinpa]

Not once. The only problem I had was the low MPG.

 

[slabghost]

Check to see if you had the TDC mark a little off or possibly 180 out. If the mark is just a tiny bit off it will cause ignition to be off several degrees.

 

[brianinpa]

slabghost » Sun Nov 08, 2015 8:38 pm[/url]":31nu0qev]
Check to see if you had the TDC mark a little off or possibly 180 out. If the mark is just a tiny bit off it will cause ignition to be off several degrees.

That's top of my list for tomorrow night. I've been second guessing myself all evening about being off by a little.

 

[mcgovern61]

slabghost » Sun Nov 08, 2015 8:38 pm[/url]":noxp6fn5]
Check to see if you had the TDC mark a little off or possibly 180 out. If the mark is just a tiny bit off it will cause ignition to be off several degrees.

My thoughts too!

 

[dan filipi]

Check the c5 power feed and coil feed wires are tight, ground also.
You could run the red straight to battery positive to rule out a weak power feed.

 

[Terry]

Can you use an inductive strobe type timing light to check the timing advance curve?

 

[joedrum]

ok ....its backfiring and the plugs are black ...this dont line up to me ....first thing id do is find another compression tester and ck compression again .....idont know how you havew c5 hooked up to bike ..b ut i would go strait to battery with hot wire to hook it up for time being ..as this will take old honda wiring out of play ....on hooch i had a relay at first and this didnt work good as the relay wasnt even getting enough juice to keep the swithch engaged and it would cut out ..today the c5 on hooch goes strait to battery and i have a 50amp switch inline to turn it on and off ...with c5 as long as motor not turning coils will not be on and theres no fear of coil damage ....or any damage to ignition if it is left on ...like it is with other ignition systems ....

for it to idle and not work at high rpm might be a program problem in the advance curve ..ive heard paul say if power is interrupted while running it can clear the programing ...

so if compression is good and timing right ..it would seem this might be the thing wrong ...there was a few times i was worried about that but i never did have any kind of program problem with the c5.....just my thoughts here

 

[Tom_Charlton]

If you're only getting 90-95 psi on the compression tests, I'm surprised it runs as well as it does. Normal compression on the 1100 is 140-175. Anything below 130 makes me suspect you either have a bad gauge or it's time for an overhaul (rings, valve guide seals, lap the valves, etc.) :builder:

Take a look at https://goldwingdocs.com/forum/viewtopic.php?t=8074 for good info on performing compression checks.

Good Luck

 

[brianinpa]

PurpleGL1200I » Mon Nov 09, 2015 8:32 am[/url]":34qmn0ff]
If you're only getting 90-95 psi on the compression tests, I'm surprised it runs as well as it does. Normal compression on the 1100 is 140-175. Anything below 130 makes me suspect you either have a bad gauge or it's time for an overhaul (rings, valve guide seals, lap the valves, etc.) :builder:

Take a look at https://goldwingdocs.com/forum/viewtopic.php?t=8074 for good info on performing compression checks.

Good Luck

Yeah, I am pretty sure the gauge is on the low end of the cheesy scare, but that's what you get when you only spend $15 for it. I haven't compared reading to the 1200 at all to confirm my suspicion, but knowing what compression I had in May 2014 and I still have the same readings now so at least it didn't get any worse.

 

[dan filipi]

I would compare readings with the 1200 for reference at least, but since it reads the same as last year I don't think that's the problem.

Did you do belts on this motor?
Timing okay there?

 

[brianinpa]

Belts weren't touched this time, so it leads me to something in the timing or ignition. I am going to recheck TDC and then go to the battery and recheck all the wiring.

 

[brianinpa]

I think I need to change the title of this thread to...

Wanted: Low mileage 81 GL1100 Motor. :crying:

There must have been more internal damage from when the rotor came off than what was obvious. When turning the motor through to check the TDC again, I noticed that the oil on the crank shaft had a silver sheen too it. Oh-no! I drained the oil and more of the same. So the motor is coming apart from the inside out.

Now it's time to make a decision: rebuild or replace.

 

[dan filipi]

Could that be old from the rotor bolt scraping aluminum off the case housing and not anything internal?

 

[slabghost]

Do you still have that 1000 motor? If so it might be just what you need.

 

[Denver]

Sorry to read of your luck, :Awe: hope you find a good replacement 81 motor, so you will have some spare motor bits, parts, & pieces. :yes:

 

[brianinpa]

dan filipi » Mon Nov 09, 2015 6:08 pm[/url]":2ch94wgh]
Could that be old from the rotor bolt scraping aluminum off the case housing and not anything internal?

When I drained the oil, there just seemed to be a lot of aluminum in the oil. Anything is possible, but now I am not certain of anything any more.

Do you still have that 1000 motor? If so it might be just what you need.

I wish. I sold that to another member here about 2 years ago to make room for the 1200.