Carb Noob

[TheCafeKid]

So CafeKid reveals that I am a moron.

Not only was I using a crappy set of feelers that went no lower than .127, but I had been measuring with two blades stuck together.

After grabbing a better set of feelers and double checking that I was only using ONE blade each time. I find that my clearances are a bit scattered. A couple of them are too wide and a couple are too tight. 4 valves are out of spec, and a fifth is pretty borderline on the wide side.

As for impact drivers, I do not have a compressor. My power drill has a "hammer" setting. Perhaps I will drop a driver bit into it and take a shot.

Not a moron at all sir. You're simply learning. Just a few years ago I didn't know any of this stuff either. Once I found this place, got my hands on a shop manual and started learning, I became a bit.. Obsessed about learning as much as I could. Being a "hands on" type of learner, I went from adjusting my valves to buying a used 750 motor to tear down and rebuild to teach myself. From there I tried to help as many people as I could to learn even more. It's addicting.

One thing, are you following the manual proceedures for checking the clearance? The cams need to be rotated manually by turning the crank with a wrench to "unload" the valves to check propper clearance. Otherwise your measurements WOULD be all over the board. It's very rare to have a loose clearance on the eight valve motors like yours. Usually, the clearances tighten up as the valve "tulips" in toward the head. Your best friend is a shop manual. I believe BassCliff has one available for download on his site, if you don't have a hard copy. Those manuals will teach you more than you think, and once you get a grasp of the workings these motors are honestly pretty simple and quite easy to work on, as far as it goes.

 

[MisterCinders]

Not a moron at all sir. You're simply learning. Just a few years ago I didn't know any of this stuff either. Once I found this place, got my hands on a shop manual and started learning, I became a bit.. Obsessed about learning as much as I could. Being a "hands on" type of learner, I went from adjusting my valves to buying a used 750 motor to tear down and rebuild to teach myself. From there I tried to help as many people as I could to learn even more. It's addicting.

One thing, are you following the manual proceedures for checking the clearance? The cams need to be rotated manually by turning the crank with a wrench to "unload" the valves to check propper clearance. Otherwise your measurements WOULD be all over the board. It's very rare to have a loose clearance on the eight valve motors like yours. Usually, the clearances tighten up as the valve "tulips" in toward the head. Your best friend is a shop manual. I believe BassCliff has one available for download on his site, if you don't have a hard copy. Those manuals will teach you more than you think, and once you get a grasp of the workings these motors are honestly pretty simple and quite easy to work on, as far as it goes.

I have the Clymer's and have reviewed the other manuals on BassCliff's site.

I am turning the motor to rotate the cams. Once I got past the wrong feeler gauge problem, my clearances revealed a mixed bag. At least three of them fall into the .051 <> .063 range (within spec), a couple are <.038 (too tight), a couple are >.127 (too loose) and one is around .103 (too loose, but close).

Positioning the cam for measurement is a bit confusing, though. Clymers says to point the cam straight up and measure the gap. Others say to point the cam away from the valve/shim and measure that gap. I will re-check my results using both positions, but they looked to be the same. Is one better than the other?

 

[Big T]

So CafeKid reveals that I am a moron.

As for impact drivers, I do not have a compressor. My power drill has a "hammer" setting. Perhaps I will drop a driver bit into it and take a shot.

Hah!

Where do you think we get all this knowledge? By screwing up things, of course.

As Mop Bucket points out, the impact driver I refer to is like a fat screwdriver with interchangable tips. You put the tip into the screw, apply a bit of torque by hand and bash it with a hammer. I can't say it works every time, but it may.

 

[raistian77]

BTW When I start a repair I now order new fasteners along with the part. If they are screws I try to order SS Allen head replacements. Z1 sells a kit with alot of the major fasteners you will run across. I try and not reuse any fastener I have had to take a impact driver to. (its a good way to end up with a headless screw)

 

[MisterCinders]

Yeah, I ordered new fasteners with the o-rings. Then get the tank off to find that 3/4 boots have the new fasteners already. Of course, it is that fourth boot that is the problem. If I can succeed where the PO failed, and extract the old screws, I will complete the change over to Allen heads.

 

[raistian77]

Yeah, I ordered new fasteners with the o-rings. Then get the tank off to find that 3/4 boots have the new fasteners already. Of course, it is that fourth boot that is the problem. If I can succeed where the PO failed, and extract the old screws, I will complete the change over to Allen heads.

Good deal, thats what I did. A change to allen heads was a godsend for me, cant get mad though lol I will bet Suzuki never expected their bikes to be running 30+ years later

 

[KEITH KRAUSE]

DO NOT use the Clymers valve adjusting method. Use ONLY the factory method and follow it exactly. Checking clearances by rotating the motor more than necessary and only checking with the lobes pointing up will give you false reads. Please don't waste time and maybe screw up the job/burn a valve. Trust me. To shorten my post (in a hurry) I'm sure you can do a search and find the factory method.
Don't try re-using the cover gasket as you'll just get leaks. On the new gasket, wipe a THIN layer of bearing grease on both sides and this will help it stay in place and will help with future removal. THIN layer is good enough. You MAY have to buy new half moon gaskets on the ends too. They commonly leak when disturbed. Applying a thin amount of permanently pliable sealant to them can help (use sealant with new moons too).
As for the stripped manifold bolts, I have to say I've never damaged one that much to offer a sure fire fix. You now know one of the problems many of us have faced. These bolts require a GOOD fitting bit in an impact driver tool (hammer type is fine). Biggest problem with the tool is finding room enough to get in a good whack. I'm not sure just how much material you have left but if you can grind in a new slot that's deep enough to hold a bit that fits VERY WELL then the proper use of the impact driver should loosen it. If not, then I can only suggest carefully removing manifold material just around/under the bolt head until you can get a SOLID grip with QUALITY channel locks (not vice-grips). I've loosened many stuck bolts over the years in other applications by using channel locks, adjusted correctly and a death grip on the handles. I don't have much experience with solvents and chemicals to help loosen parts but if you have then try applying the product first and let stand for how long they say. Heat can help too but be careful.
As for the carb "main and jet needle" issues you mention, I'm not sure what you've got. Stuck main jets in the carb body?? Or are you still talking about the float bowl drain bolts but using different parts terminology?
Sorry if I missed some stuff but I'm in a hurry and didn't read all the posts. You're not alone. Old bikes.....old ANYTHING, requires various levels of work to get right. If previous owners were butchers then you have a challenge.
Be sure to follow that FACTORY valve clearance method!!

 

[TheCafeKid]

I have the Clymer's and have reviewed the other manuals on BassCliff's site.

I am turning the motor to rotate the cams. Once I got past the wrong feeler gauge problem, my clearances revealed a mixed bag. At least three of them fall into the .051 <> .063 range (within spec), a couple are <.038 (too tight), a couple are >.127 (too loose) and one is around .103 (too loose, but close).

Positioning the cam for measurement is a bit confusing, though. Clymers says to point the cam straight up and measure the gap. Others say to point the cam away from the valve/shim and measure that gap. I will re-check my results using both positions, but they looked to be the same. Is one better than the other?

I will agree with Keith in saying the Clymer manuals version is a bit silly, and requires turning the motor over many times. The Manufacturers shop manual says to turn the motor so that certain lobes are up, and certain lobes are flat, this unloads the entire cam shaft. I don't remember which, but you then can measure so many, and then you need to turn the motor another 180* to measure the rest. The idea here is that you've unloaded the entire camshaft, no valve spring pressure against it so your readings are more accurate. Having said this however, out of my own morbid curiosity I recently measured using both methods. And the differences in results were negligible. Within .01mm I'd have to guess, as I don't have gauges that go that low. I would stick to the factory manual were it me, but in lieu of that, I'm not entirely sure using the clymer manual would result in a burnt valve. Not trying to be argumentitive or anything.

Also Keiths advice regarding the screws and jets is quite good. If you're jets are that munged up, I'd suggest getting new MIKUNI jets (available from Z1) in the correct stock sizes to replace them. Generally, if they've been beaten on that badly, I'd question their integrity. Just my .02

 

[KEITH KRAUSE]

I can only vouch for my own experience with trying different methods of adjusting the valves. The very first time I ever adjusted my valves I thought why couldn't I just crank away and measure them all pointing up? The gauge seemed to slide in better if you know what I mean. So I did. Something bothered me about the whole thing and I decided to take it to the local Suzuki dealer who I actually trusted and I'd rode with the lead mechanic before. They returned it the next day and said a couple were adjusted too tight. Long story short they said the method I used would give inaccurate reads. Just use the accurate and easier factory method.
Since then I played around with it a couple times (just curious) and found the same thing again. The differences in the two methods, depending on just what each clearance is, could result in adjustments not in the factory required range. Generally, I found that adjusting them the non-factory way ended up in adjustments that were tighter or too tight.

 

[MisterCinders]

DO NOT use the Clymers valve adjusting method. Use ONLY the factory method and follow it exactly. Checking clearances by rotating the motor more than necessary and only checking with the lobes pointing up will give you false reads. Please don't waste time and maybe screw up the job/burn a valve. Trust me. To shorten my post (in a hurry) I'm sure you can do a search and find the factory method.
Don't try re-using the cover gasket as you'll just get leaks. On the new gasket, wipe a THIN layer of bearing grease on both sides and this will help it stay in place and will help with future removal. THIN layer is good enough. You MAY have to buy new half moon gaskets on the ends too. They commonly leak when disturbed. Applying a thin amount of permanently pliable sealant to them can help (use sealant with new moons too).
As for the stripped manifold bolts, I have to say I've never damaged one that much to offer a sure fire fix. You now know one of the problems many of us have faced. These bolts require a GOOD fitting bit in an impact driver tool (hammer type is fine). Biggest problem with the tool is finding room enough to get in a good whack. I'm not sure just how much material you have left but if you can grind in a new slot that's deep enough to hold a bit that fits VERY WELL then the proper use of the impact driver should loosen it. If not, then I can only suggest carefully removing manifold material just around/under the bolt head until you can get a SOLID grip with QUALITY channel locks (not vice-grips). I've loosened many stuck bolts over the years in other applications by using channel locks, adjusted correctly and a death grip on the handles. I don't have much experience with solvents and chemicals to help loosen parts but if you have then try applying the product first and let stand for how long they say. Heat can help too but be careful.
As for the carb "main and jet needle" issues you mention, I'm not sure what you've got. Stuck main jets in the carb body?? Or are you still talking about the float bowl drain bolts but using different parts terminology?
Sorry if I missed some stuff but I'm in a hurry and didn't read all the posts. You're not alone. Old bikes.....old ANYTHING, requires various levels of work to get right. If previous owners were butchers then you have a challenge.
Be sure to follow that FACTORY valve clearance method!!

OK - now I am nervous. I have used the Clymer method to check these valves and have gone through multiple tests to try an get things right. That is a lot of hand-turning already (though always in the clockwise direction). This is harmful? And inaccurate?

The Clymer method says check the valves with the cams pointing north.

The service manual is consistent with this:

​

The "A" position is the same as Clymers. If my measurements are consistent after double checking from the due north position, can I work from those?

Is the problem with Clymers the "due north" position or the greater amount of hand-turning?

Having already turned the engine several times, can I rely on the measurements at hand, and take the lesson of "more measuring, less cranking"?

As to the jet problem, this is the "hot brass-on-brass" love that won't be denied:

​

On three of the carbs, the main jet and needle jet will not separate. I removed the o-ring and confirmed with air/spray cleaner/wire strand poking that all passages are clear. Unless I can separate these lovers, I will need to replace the needle jets to change or replace the main jets.

For the related problem with the float plugs, I can try to exploit the metal differences in heat reaction to loosen the threads. Here, both parts are made of brass (more like cheese, amirite?), so I assume that won't work.

 

[BassCliff]

Hi Mr. MisterCinders,

The (8 valve) valve adjustment guide on my little website describes the factory procedure (properly position the lobe, measure two clearances). There's a lot of information in the addendum too. Let me know if you have any questions.


Thank you for your indulgence,

BassCliff

 

[MisterCinders]

Huzzah! Found a nice set of new float bowls.

 

[TheCafeKid]

Huzzah! Found a nice set of new float bowls.

I like this guy. Tough times and a frustrating PO problem and yet he's positive and enjoys the little wins. Perfect attitude for a GS owner/mechanic. And make no mistake Mr C, you're on your way to being one. Lemme know if you have any more needs, I just sorted the garage to get everything ready for the big chill and found a bunch of spare VM bits from my various 750 projects.

 

[KEITH KRAUSE]

Mistercinders, I've tried both ways to measure/adjust valves, and after I did the job the non-factory way a trusted mechanic said some of my adjustments were off after re-checking the factory way. I know there's info that says the lobes can be checked in either of two positions but it's my experience that the measurements should be taken according to the factory method only. It's not about how much or how little the crank is turned, it's about accuracy and my tests have shown different methods gave different reads.
As for your stuck mains, if the bikes intake/exhaust is stock then you don't need to change them. If they're clean inside then it's not a problem now. Just be real careful cleaning/rebuilding the carbs as you don't know who's had their hands on them. Check the floats for being even on both sides (sometimes tweaked/bent slightly) and be sure to check float levels before re-assembly. I'm sure someone here has factory float level info for your model (don't trust any other info source). A tip from someone who knows: Before installing carbs on bike, set them on a level surface and fill with fuel to check for any leaking or stuck float valves, etc. I've had carbs completely separated and found that the infamous VM "T" fitting would leak after being disturbed.

 

[raistian77]

Mistercinders, I've tried both ways to measure/adjust valves, and after I did the job the non-factory way a trusted mechanic said some of my adjustments were off after re-checking the factory way. I know there's info that says the lobes can be checked in either of two positions but it's my experience that the measurements should be taken according to the factory method only. It's not about how much or how little the crank is turned, it's about accuracy and my tests have shown different methods gave different reads.
As for your stuck mains, if the bikes intake/exhaust is stock then you don't need to change them. If they're clean inside then it's not a problem now. Just be real careful cleaning/rebuilding the carbs as you don't know who's had their hands on them. Check the floats for being even on both sides (sometimes tweaked/bent slightly) and be sure to check float levels before re-assembly. I'm sure someone here has factory float level info for your model (don't trust any other info source). A tip from someone who knows: Before installing carbs on bike, set them on a level surface and fill with fuel to check for any leaking or stuck float valves, etc. I've had carbs completely separated and found that the infamous VM "T" fitting would leak after being disturbed.

23mm-25mm Gasket removed. Set both sides the same. I usally set to 24mm gives me a margin of error. Also make sure that the float is just resting on the needle, do not push the float down to compress the needle spring.

 

[MisterCinders]

Mistercinders, I've tried both ways to measure/adjust valves, and after I did the job the non-factory way a trusted mechanic said some of my adjustments were off after re-checking the factory way. I know there's info that says the lobes can be checked in either of two positions but it's my experience that the measurements should be taken according to the factory method only. It's not about how much or how little the crank is turned, it's about accuracy and my tests have shown different methods gave different reads.
As for your stuck mains, if the bikes intake/exhaust is stock then you don't need to change them. If they're clean inside then it's not a problem now. Just be real careful cleaning/rebuilding the carbs as you don't know who's had their hands on them. Check the floats for being even on both sides (sometimes tweaked/bent slightly) and be sure to check float levels before re-assembly. I'm sure someone here has factory float level info for your model (don't trust any other info source). A tip from someone who knows: Before installing carbs on bike, set them on a level surface and fill with fuel to check for any leaking or stuck float valves, etc. I've had carbs completely separated and found that the infamous VM "T" fitting would leak after being disturbed.

OK, if the additional cranking does not aggravate the problem, I will re-check the clearances tonight with the service manual process.

As to the jets, the bike has V&H pipes and stock airbox with a new filter. I will replace those jet assemblies once I find new ones. Will go with the existing jets for now.

Having rooted out two major problems -- valves out of spec and mangled throttle slide -- I should be able to get back in action with some fresh fuel this weekend and salvage a few rides before the winter. If so, I'll tear her down again then for more tinkering, jet replacements, maybe a better air-box, some new paint, change the seat, mount oil slicks, smoke screens, rocket launchers, etc.

Thanks again.

 

[raistian77]

OK - now I am nervous. I have used the Clymer method to check these valves and have gone through multiple tests to try an get things right. That is a lot of hand-turning already (though always in the clockwise direction). This is harmful? And inaccurate?

The Clymer method says check the valves with the cams pointing north.

The service manual is consistent with this:

The "A" position is the same as Clymers. If my measurements are consistent after double checking from the due north position, can I work from those?

Is the problem with Clymers the "due north" position or the greater amount of hand-turning?

What you need is for example the lobes of exhaust 1 and 2 to NOT be touching the shims. One will point vertical, the other horizontal.
Then the same for intake 1/2 then exhaust 3/4 and then intake 3/4.

Look at your pic above pretend that you are looking at the engine from the right side and the A and B are how the lobes should look, with A being cyl 4 and B being cyl 3.


Dont feel bad, I had to have that explained to me also. I was used to doing cars which are not set up that way.

 

[BassCliff]

Hi,

Stock specs for GS carbs can be found in the chart below.

Suzuki GS Series Carb Specs

Valve adjustment procedure:

Valve Adjustments (8 Valve)

Thank you for your indulgence,

BassCliff

 

[KEITH KRAUSE]

Mistercinders, not trying to give you more work but feel you should know.
If you have a V&H megaphone, it flows better than stock, enough that it will change the air/fuel ratio. In my opinion, the jet needles MAY need richening about 1/2 position but I don't feel it's necessary. Yes, the pipe will lean that circuit out some but I feel the A/F ratio will still be OK. Testing is always best to determine.
But as for the main jets, the main circuit will be effected more. The mains only effect performance from 3/4 to full throttle position so keep that in mind. I realize your mains are stuck solid.
Again, it's my opinion that your bike won't run dangerously lean while on the mains but performance will be compromised. You may not feel it but the bike will be lean at those throttle positions. Generally, a quality pipe/stock intake combo requires at least one full size (5) increase to two full sizes(10).
Also, if you can't do a vacuum tool synch, then you must do a careful bench synch before re-installing the carbs. I don't know how much VM info you are aware of but a bench synch is mandatory. I have a post around here that details it if you need it. It was in Hoomgar's thread titled something like: "GS1K rejet/bad fuel economy attn Keith Krause"? Reply #36.
Look at the mains and there should be a number stamped into them. The 750's should be 100 I believe or 102.5. If they are, then try to separate the mains if you can without creating worse problems.

 

[MisterCinders]

Thanks, Keith, for the update.

I did spring for a vacuum synch tool and plan to bench synch AND vacuum synch the carbs when I reinstall.

For the main jet situation, I cannot read the numbers on them because the tops are pretty mangled. Stock jets are supposed to be 100.

A friend suggested throwing the stubborn jets into the freezer to see if that will help separate them. Has anyone tried this before? Is it worth a shot?

According to the PO (who, to be fair, is not the villain, the gorilla carb work predates him), the bike was running a bit rich.