Most likely culprit? Valve clearances or carbs?

[GelandeStrasse]

Hi Guys

Looking for help and ideas from old hands please :idea:

I have an '82 1100G garage find that I'm restoring and I'm currently trying to figure out what's preventing it from running on anything more than one cylinder.

Here's what I've learned so far:
1. Good sparks and on time. HT leads connected to the correct cylinders.
2. Rock hard inlet rubbers, now replaced with new ones.
3. Mucky carbs, now clean and blown through with compressed air, 'O'rings replaced throughout and float levels checked.
4. Compression OK.
5. Valve clearances closed right up, my feelers only go down to 0.038mm and that won't fit under any of the cam lobes (Lobes positioned opposing each other). Specs say 0.03-0.08mm.
6. No airbox

The symptom I'm getting is, it'll start up, but only firing on number four cylinder. I'm surprised it'll even run like that!

Any pointers to what I should look at first? I was thinking carbs but now I've cleaned them up and I'm still getting the same result. When the motor runs the slides move up & down freely so I'm hoping they are all OK but maybe there's something I've missed (I'm not too familiar with carbs).

So now I'm thinking maybe valve clearances but I've had engines before that'll still run (badly) even with no clearance and it doesn't explain number four firing correctly when the rest don't. The compression test results in psi were as follows:
cyl#1 95
cyl#2 100
cyl#3 75
cyl#4 100
I'm taking a guess that the variation is down to the clearances.

It'd be great to get some fresh ideas here cos I'm just shooting in the dark

Thanks in advance!

GSon

 

[Nessism]

Please check the newbie mistakes thread linked in my signature. You are making several.

For example:

1) you can not diagnose a bike with incomplete maintenance (adjust the valves).

2) the bike won't run for crap without the airbox unless you rejet the carbs

Short cuts are long cut when it come to performing maintenance.

 

[GelandeStrasse]

Thanks for the link, very useful info. I'll try to avoid stupid questions in future. Can I still get a little technical feedback on my question though. I fully understand the bike would run like crap as is but was hoping someone could confirm or not if the motor is so sensitive that tight clearances would stop it firing on three cylinders? Assuming the carb rebuild was ok.

At this stage in my game I'm still trying to find out if it's even worth bothering to invest what little cash I have on the machine.

TIA

 

[hampshirehog]

If the valves are too tight it is very possible that she won't fire. Do the shim hokey-cokey and I bet it'll only cost a few pennies.

 

[bwringer]

The answer is C) All the above, and then some...

Anyway, you can easily test to see whether you're getting spark to all four plugs. That would be an excellent first step, and the ignition system is pretty simple to diagnose.

It's also very, very common for people to do an incomplete job of cleaning carbs, so please excuse us for asking again: Didst thou follow faithfully EVERY detail of the Holy Scrolls concerning the proper cleaning of thy GS carbs?

 

[Dogma]

Yes. The next step will be to adjust the valves to see if the compression numbers come up.

You will also get some flack for calling the carbs cleaned when they haven't been dipped in carb cleaner (Berryman's) or an ultrasonic cleaner with appropriate solution. There are a couple carb cleaning tutorials around here that explain how. The one linked in Nessism's signature is quite excellent. Get the factory service manual from BassCliff's site (have you seen his welcome message yet?) if you want to study how the carbs work. It's not impossible to get them working with spray, but the odds are slim.

You're already into this thing for a set of intake pipes, so don't stop now just for the cost of changing shims. There is a shim swapping group around here somewhere, so they might be able to save you some money on new shims.

 

[GelandeStrasse]

Thou didst not follow exactly the procedure as one had not seen that excellent "how to" at the time. Thou shall start again, good practice!

It also says in the how to that the bike may not even run without the air box. Now I'm starting to see the pattern! Sounds like the gs is a very reliable machine but everything must be perfect for it to run right.

Thanks for the help guys

 

[tom203]

What do spark plugs (#!, #2, #3) look like after #4 carries on for a while- wet ,dry?

 

[hampshirehog]

You can easily get 'em to tickover without the airbox fitted. Just don't bother twisting the right grip.

 

[GelandeStrasse]

What do spark plugs (#!, #2, #3) look like after #4 carries on for a while- wet ,dry?

Number 4 looks normal but the others were dry. There was fuel in the float bowls and the float level is correct. Pilots/fuel ways blocked? I did check the pilot jets were clear with a piece of wire but I couldn't get them out. Again, hadn't seen the rebuild instructions at that point.

You can easily get 'em to tickover without the airbox fitted. Just don't bother twisting the right grip.

great, info nuggets like that really help.

I will get to the valve clearances but I'm now thinking the carbs are probably where I should start.

 

[DanTheMan]

Number 4 looks normal but the others were dry. There was fuel in the float bowls and the float level is correct. Pilots/fuel ways blocked? I did check the pilot jets were clear with a piece of wire but I couldn't get them out. Again, hadn't seen the rebuild instructions at that point.
great, info nuggets like that really help.

I will get to the valve clearances but I'm now thinking the carbs are probably where I should start.

Actually, take it from all the experts (we're all experts here, y'know), the carbs and valve clearances are so closely linked you can't correct one without the other being done as well. I got my 850 running pretty good, then she took a dump again on the way home from my last long trip in Sept, 2010, wouldn't run good at all the last 800 or so miles. My valves had tightened up so much everything was thrown off. Also, another side note on the valve clearances. Let's say you measure them and have a couple that are real, real close to the minimum clearance. Don't leave them that way, get the next thinner shim in there, the bike will run much better for much longer.
Anyway, that's my advice, take it or or do it again later, I got pretty good with taking it apart and putting it back together again.

 

[1_v8_merc]

Are you sure the carb mixture screws are set correctly?
Did you touch them or remove them when you cleaned the carbs?

 

[Brett]

Number 4 looks normal but the others were dry. There was fuel in the float bowls and the float level is correct. Pilots/fuel ways blocked? I did check the pilot jets were clear with a piece of wire but I couldn't get them out. Again, hadn't seen the rebuild instructions at that point.
great, info nuggets like that really help.

I will get to the valve clearances but I'm now thinking the carbs are probably where I should start.

If your pilot jets haven't been removed, I would recommend you get them out. I've never been able to clean them well while they're still installed in the carburetor. If you're having trouble getting them out, soak them with penetrating oil overnight and then go back at them. Kroil has worked the best for me, but it can be hard to find locally. Of course, you can always buy it online.

I was never able to get the #3 pilot jet out of my 850 and I always wondered if it was that big of a deal... Well, I finally just went ahead and drilled it most of the way out and then used an easy out to get the rest. Replaced it with a brand new jet and it ran much better. Got rid of some idling problems and a small flat spot right off idle. Made the bike much more pleasant to ride. I think the jet was only $3-$5 shipped off of eBay. Genuine Mikuni jet too.

 

[Nessism]

The bike won't run for crap without the airbox. Period. You can tape over the carb openings, leaving only about 20% exposed if you just have to listen to it run before committing funds, but it will still run like crap.

 

[850 Combat]

Are the coils wired to the plugs correctly? one coil 2/3 one coil 1/4?

The pilot circuits can be stubborn. You need to verify that all the passages are clear by spraying through the ones you can access, and verifying that it comes out of all the others. The air passage in the bellmouth, the pilot jet hole, and the progression holes at the butterfly.

 

[Steve]

Two questions in this first statement:

I fully understand the bike would run like crap as is but was hoping someone could confirm or not if the motor is so sensitive that tight clearances would stop it firing on three cylinders? Assuming the carb rebuild was ok.

1. Yes, tight valves WILL keep it from starting.
2. Wild assumption, as we have not yet heard whether you followed the "strip and dip" method of cleaning.

Thou didst not follow exactly the procedure as one had not seen that excellent "how to" at the time. Thou shall start again, good practice!

OK, this apparently answers the "did you dip them?" question, but in a negative manner.

It also says in the how to that the bike may not even run without the air box.

Not quite true. It will start OK, but will likely have problems responding to ANY throttle input.

You can easily get 'em to tickover without the airbox fitted. Just don't bother twisting the right grip.

See?

What do spark plugs (#!, #2, #3) look like after #4 carries on for a while- wet ,dry?

Number 4 looks normal but the others were dry. There was fuel in the float bowls and the float level is correct. Pilots/fuel ways blocked?

To me, this is rather conclusive evidence to show that your carbs are not clean enough to allow gas to flow through them.

I did check the pilot jets were clear with a piece of wire but I couldn't get them out.

There are holes on the sides of the pilot fuel jets that you can't poke with a wire unless you remove the jets from the carbs.
Besides that, there are small passages from the pilot jets to the mixture screw that you can't poke with a wire, either.
You HAVE to dip the carbs.

I will get to the valve clearances but I'm now thinking the carbs are probably where I should start.

Actually, you do them both at the same time. On the first day, start by stripping the carbs down to itty-bitty pieces, put the pieces for the first carb in the dip. Remove the valve cover, start measuring your clearances. Some guy named "Steve" has a spreadsheet that he offers that will help you record these. Look in his signature.

Remove your shims (one at a time, please) and record their sizes in the spreadsheet. When you find out what sizes you need, order them from the "shim club" on GSR or from Z1 Enterprises. (Z1 also has the best price on valve cover gaskets.) This is also a good time to order new o-rings for the carbs from cycleorings.com.

On the second day, remove the first carb's parts from the dip and rinse them in HOT water, then spray carb cleaner through the passages and follow with a blast of compressed air (wear safety glasses

). Put the second carb's parts in the dip.

On the third and fourth days, you can repeat the activities of the second day, but by the fourth day, you should have received your shims and o-rings. Finsh assembling your carbs, put your new shims in, re-check your clearances with the 'new' shims, start the bike.

The bike won't run for crap without the airbox. Period. You can tape over the carb openings, leaving only about 20% exposed if you just have to listen to it run before committing funds, but it will still run like crap.

Again, it will start and idle just fine without the airbox. If you really want to hear it rev, and maybe even go for a ride around the block, fold a shop rag in half and clamp it to the outer carbs, while keeping it taut over the inner carbs. This will work well enough for a quick ride, but is not accurate enough to do any jetting checks.

.

 

[GelandeStrasse]

Thanks loads for all hints and tips guys! What a great forum. I now have a plan of action to follow, yay! All that shooting in the dark business is frustrating. Now I have some benchmarks to aim for. This kind of info is not in any manual!

Thanks again, watch this space

 

[GelandeStrasse]

Just wanted to share my excitement now I've been set on the right path by GSResourcers!
Update: all pilots on cyls 1, 2 + 3 totally blocked and number 4 clear matching the symptoms exactly. Brilliant!

 

[hampshirehog]

Just wanted to share my excitement now I've been set on the right path by GSResourcers!
Update: all pilots on cyls 1, 2 + 3 totally blocked and number 4 clear matching the symptoms exactly. Brilliant!

Don't just clean those carbs. CLEAN them.....! Take your time and do a really, really thorough job; it'll save you time and heartache in the long run.

 

[GelandeStrasse]

Don't just clean those carbs. CLEAN them.....! Take your time and do a really, really thorough job; it'll save you time and heartache in the long run.

10-4 that, just waiting a couple days now while the release spray to works its magic on the pilot jets