78 GS1K Carb Rejet? Bad Fuel Economy - KEITH KRAUSE!

[KEITH KRAUSE]

Regular "car" timing light. That's what I still use to check my Dyna once in a blue moon. We set my bud's Norton 850 point gap the other day with just a feeler gauge actually. I can give you the point gap (dwell) and timing info straight from the factory manual if you like. They do you use their own tester/light. Don't know if that technically changes the procedure info? It's still much easier to explain with the pic's pointing to things.
The tappet clearance is made by installing the correct thickness of shims. This adjustment is very important to performance. I've made several posts about it in the past, including a detailed procedure. You need a tappet depressor tool to change the shims. About $30. If you want the procedure, I can send that too. Your mechanic/builder should do this as part of the rebuild though.
I just rinse off my floats in gas. I can't imagine needing anything else to clean them off. They can't be that bad?

 

[Hoomgar]

Keith a couple things I think I am confusing you on just so I don't have you all mixed up with my questions. So sorry about that.

Your mechanic/builder should do this as part of the rebuild though.

This is a new bike were working on here. Not my project bike. I am not opening the engine on this thing unless absolutely needed. And my mechanic doesn't even know I have this as that could affect the work he is doing for me on my project bike. Please see this thread: http://www.thegsresources.com/_forum/viewtopic.php?t=34175

The tappet clearance is made by installing the correct thickness of shims. This adjustment is very important to performance. I've made several posts about it in the past, including a detailed procedure. You need a tappet depressor tool to change the shims. About $30. If you want the procedure, I can send that too.

Tappets, I simply do not know what they actually "are" but I will look them up. I wasn't asking about how to adjust them but just what they are. I assume from your last post they are somehow related to the valves? That means under covers! I won?t be looking at them. I was only asking what they were, I'm easy

I can give you the point gap (dwell) and timing info straight from the factory manual if you like.

Manuals, I have them all! Factory, Clymer, Haynes, Factory supplemental. I think I have every manual made for all my bikes. I will look that stuff up. I can probably do most of it that way now instead of bugging everyone with questions and only pop in as I have a few that I cannot figure out. I need to learn to decode these things. They are confusing at best :?

I just rinse off my floats in gas. I can't imagine needing anything else to clean them off. They can't be that bad?

That's what I'll do then They are pretty crappy looking.


Sorry about all the confusion Keith. I know I tend to jump around a lot at times and lose people. Sometimes I think out loud and confuse people. I'll try to just ask very specific and less broad questions from now on. I appreciate all the info.

As soon as I get the parts in and get these back together I will bench sync them as well as set the floats. Then when my carbtune gets here I'll sync them up. Here is hoping all goes well 8-[

 

[KEITH KRAUSE]

Sorry Mark about the confusion. I try to help so many members that I can get mixed up sometimes.
Suzuki describes it as "tappet clearance". When your cam lobe is in a certain position, there needs to be a range of clearance between the lobe and the shim above the valve. Different size shims are available to adjust this clearance. Too tight, and the valve can burn, too loose and the valve wear will accelerate and be noisy. You can generally hear the "ticking and clicking" going on in that area if the clearances are too wide. To do the most accurate vacuum synch, these need to be adjusted correctly. Basic maintenance.

 

[Hoomgar]

The apologies are mine Keith

I do it to everyone, don't feel bad


Anyway, my engine seems really tight and quiet for an old GS. My other bike was alot louder in the engine at idle than this one is. None of the traditional rattle and knock I was used to. I am going to let it go. When I ever get another ride going I will tear this one apart. until then it's just about getting the carbs on and as good as I can and go with it.

I already am stocking up on all the needed gaskets and stuff for that work in the future.

I hope when I get home my o-rings at least are there so i can start on this.

 

[KEITH KRAUSE]

Good luck on the carbs. If anything hangs you up, give a yell.
I gave you my jetting suggestions. Remember to seat the pilot fuel screws only lightly when you adjust them.
Now might be a good time to replace the throttle return spring with something a little lighter, if you think it's too hard on the wrist. I do.

 

[Hoomgar]

Good luck on the carbs. If anything hangs you up, give a yell.
I gave you my jetting suggestions. Remember to seat the pilot fuel screws only lightly when you adjust them.
Now might be a good time to replace the throttle return spring with something a little lighter, if you think it's too hard on the wrist. I do.

Yes I do. It is bad for longer trips. Where do I get something like that? A lighter spring would be nice.

 

[KEITH KRAUSE]

Good luck on the carbs. If anything hangs you up, give a yell.
I gave you my jetting suggestions. Remember to seat the pilot fuel screws only lightly when you adjust them.
Now might be a good time to replace the throttle return spring with something a little lighter, if you think it's too hard on the wrist. I do.

Yes I do. It is bad for longer trips. Where do I get something like that? A lighter spring would be nice.

Hardware store has lots of springs. You can find one that's lighter but still has plenty of "snap back" in it. Just don't get one that's so short, it tries to spread at wide open throttle.
You can easily find one that's very close to the same length but lighter. Springs are rated by their strength, a numbering system I believe. Take yours in with you if you're not sure what you need. Any knowledgeable hardware guy can help you. Buy a couple at different strengths if you want to choose the best feeling. They're cheap.

 

[Hoomgar]

Thx Keith. I have some good news too. I spoke with Joe and our valves for my project bike are being made. No one and I mean no one had them in stock. Orient Express is making them for us. But that means it will be really tight to impossible to have that bike ready in time for the PA ride. No surprize there huh? That's why I bought this here bike.

I told Joe about this bike last night and he is still the same friend I always knew he was. Let's just say that he is going to take care of me on this one (the project bike) as far as the money is concerned. He hates that it went this long and will most likely scrub off the rest of what I owe him if I know Joe. He said "don't worry about paying me for this". That's how he has always been. Kind of hard to stay mad about anything when you talk to him. He is such a nice guy, really.

Plus! He is going to give me a slug of assorted sized Mikuni jets for this here bike to get it sorted. He said to come get them tonight and no charge

What main do you think I should start with given that I can use anything now? Were talking Mikuni jet's now to go with the Mikuni needles I have in it.

I was thinking like this. I know the 132.5's that were in it were rich. The 118's in the other set of carbs were lean. So maybe start with a 125 or a 127. something? What do you think?

 

[KEITH KRAUSE]

I would try 130 mains as I said earlier. I didn't see anything in your posts to think the 132.5 mains were too rich. But I would personally try the 130 mains since you can get 'em. As long as you're sure the pods are K&N's. In fact, all my suggestions depend on the pods being true K&N's.
Put the e-clip in the bottom position (5th) on the jet needles. Your 1/3 throttle reads were too lean. The richer #4 read is hopefully due to a poor
synch, high float level, or worn needle jet o-ring...that should be good if you do all the carb work right.
Now that I know you don't have a DJ kit, I almost forgot to add: you most likely will need 17.5 pilot jets. You can try pilot fuel screw adjustments out to 3 1/2 to 4 turns if you want first. If the results are not good, go to the 17.5. Take your pilot jet with you and buy the correct length. There are two types..one like yours, and a shorter one. Adjust side air screws for highest rpm's.
Vacuum synch the carbs.
That should get you going. If the 1/3 throttle reads remain too lean, you'll have to go with a DJ kit to avoid lean mixture/overheating. Remember, you spend the most time on the needle circuit, so get it right.

 

[Hoomgar]

Thx again Keith. I have got you confused still though and I wish now I had never mentioned the other carbs because it has screwed up this thread. The lean reads were from the "other" set of carbs that we are not working with here. The set were woring with had the needles in the 4th posistion and was seemingly a bit rich? So maybe middle position for starters or leave them in four with smaller mains?

I didn't get a set of 130 mains last night. I got a set of 125's and 128's

The 125's are Mikuni but the 128's are some other make that started with "K" I think but can't remember? They have smaller heads and a slightly differant thread pitch but screw in just the same and will work fine with my needles I was told.

So:

Should I start with the 125's?
The 128's?
The 132.5's that were in it?
Or look for some 130's?

 

[KEITH KRAUSE]

Mark, sorry if any of this confusion is my doing. Why would you show me plug reads of carbs that we're NOT trying to re-jet? :? :lol: I give!
Tell me what mods and brand names of the mods the bike has that these carbs are going on.
If you had rich readings with the jet needle clip in the 4th position (from the top), that's interesting... considering you have K&N pods (?) on this bike and the 3rd position is the factory setting. There's no way a pod filtered bike runs right or gets passing plug reads with the stock needle setting. Seems odd.
I wouldn't use the 128 mains. You don't know how their flow rating is determined.
Give me the mod info again any plug read info you've gotten.
Give me the # size on the jet needles too. Should be: 5DL36.

 

[Hoomgar]

I am going to get back to you with the answers to those questions Keith. Since I didn't have the carb rebuild kit yet anyway (I want to use the new float needles and seats, the old ones have noticable wear rings in them) so I spent the weekend sorting some other things that needed/I wanted done.

I repainted my header and can with some high heat ceramic paint and let it cure then redid it again. Hopefully it will last the season. I repacked my baffle using a steel wool idea that first timer mentioned. It is reinstalled now.

I cleaned out the motor completely of all gas contaminated oil and resealed the oil pan with a new gasket. New oil filter. Fresh oil.

I pulled, examined and reinstalled the clutch.

Pulled and cleaned the front sprocket cover a bit.

I am ready to resume carb work now.

 

[KEITH KRAUSE]

Ok. Standing by. I hope that steel wool substituted for regular packing doesn't rob you of a little power. Jetting can be funny enough without home repairs.

 

[Hoomgar]

OK I have everything now for the rebuild of the carbs. The kits came in today and I have the o-rings.

I checked the needles. They are Mikuni 5DL36

 

[Hoomgar]

The carbs are completely rebuilt now.

The floats are all set at 24mm and level.

The pilot fuel and the air adjustment screws are all set at 1.5 turns out after seating.

The K&N's are cleaned and oiled using the K&N recharger kit.

A new much lighter throttle return spring has been installed.

The carbs are back in the bike with filters installed.

The throttle and return cables are connected and adjusted correctly by the manual.

Now all I need is my carb sync tools to come in and I am set.

I have two nights left to play with this before the ride.

*sigh* Here is to hoping I can actually pull it off.

 

[KEITH KRAUSE]

Sounds good.
I assume you did a careful bench synch per my info? It's very important to make the vacuum synch go easier, especially if you haven't synched before.
The fully opened position is important too and wouldn't be adjusted accurately during the vacuum synch. This part of the synch can only be done by eye. If the slide(s) are opening too far, strange things can happen like backing off the throttle a little from wide open, can actually INCREASE the acceleration. Just want to be sure you did it right.
Manifold o-rings replaced, greased and torqued correctly?
Hope the throttle spring you put in isn't TOO light.
Remember to remove the two floatbowl vent lines and leave the nipples open.
Remember to turn up the idle adjuster knob enough so the bike will start initally.
When it's warmed up, fine tune the side air screws before the synch.
Use two large fans, don't over-heat.
Be sure the vacuum tool adapter tubes are installed snugly to avoid leaks.
Always adjust the initial higher mercury vacuum level(s) DOWN to match the lower levels. Don't over-tighten the holder nuts for the throttle valve adjuster screws.
Double check your settings.
What am I worrying about? It's your bike! :lol:
Hopefully, I covered everything here or before. Hope it goes well and the jetting works. It can be a small miracle to get the jetting right the first try.
As for the re-jetting, what about the info I asked for? I still think the 130 main is a good choice, but I need the info to guess the needle position. The mains and pilots are easy to change by just removing the bowls if you like. But changes to the needles require the carbs be removed, disassembled and then re-bench and vacuum synched. So I'd like to guess then right if possible. Will need any plug reads you had at 1/3 throttle too, if you can supply them. If not, I'll just guess based on other 78/79 1000's with similar mods.

 

[Hoomgar]

Sounds good.
I assume you did a careful bench synch per my info? It's very important to make the vacuum synch go easier, especially if you haven't synched before.
The fully opened position is important too and wouldn't be adjusted accurately during the vacuum synch. This part of the synch can only be done by eye. If the slide(s) are opening too far, strange things can happen like backing off the throttle a little from wide open, can actually INCREASE the acceleration. Just want to be sure you did it right.

Sorry Keith, I forgot to mention that. I did it by the book buddy. The fully open is about .5 to .6mm and that was done after the fully closed adjustments. It?s looking good.

Manifold o-rings replaced, greased and torqued correctly?

O-rings will need replaced sometime but were intact enough to reuse this time. I used the hi-temp grease (axle) on then and wiped off the excess before bolting them up. I replaced the bolts with allen heads and they are torqued down as you said.

Hope the throttle spring you put in isn't TOO light.

It is to light for sure. LOL! Why does this matter? It will close on it?s own but just barely. I like it. For once I won?t have a sore wrist after riding. Must it be heavier?

Remember to remove the two floatbowl vent lines and leave the nipples open.

The ones that are on the same plain as the fuel intake right? Why must these be removed? I just want to understand.

Remember to turn up the idle adjuster knob enough so the bike will start initally.
When it's warmed up, fine tune the side air screws before the synch.

What is involved there? Just turning in and out until it runs right or what? Is this the highest idle adjustment I have seen you talk about?

And what about the pilot jet? I have both needles set to 1.5 turns out from seated fully in right now.

Use two large fans, don't over-heat.

10-4 :wink:

Be sure the vacuum tool adapter tubes are installed snugly to avoid leaks.
Always adjust the initial higher mercury vacuum level(s) DOWN to match the lower levels. Don't over-tighten the holder nuts for the throttle valve adjuster screws.
Double check your settings.
What am I worrying about? It's your bike! :lol:

Will do. You worry because you care Keith

Hopefully, I covered everything here or before. Hope it goes well and the jetting works. It can be a small miracle to get the jetting right the first try.

I am hoping and praying Keith.

"KEITH KRAUSE"]As for the re-jetting, what about the info I asked for? I still think the 130 main is a good choice, but I need the info to guess the needle position. The mains and pilots are easy to change by just removing the bowls if you like. But changes to the needles require the carbs be removed, disassembled and then re-bench and vacuum synched. So I'd like to guess then right if possible. Will need any plug reads you had at 1/3 throttle too, if you can supply them. If not, I'll just guess based on other 78/79 1000's with similar mods.

I answered your question about the needle above? As for the jets? I didn?t find a set of 130?s. So I am using the 125?s. I am also using the pilot jets that were in it not the ones that came with the rebuild kit per your suggestion. The pilot jet has a "15" on it. The main needles are 5DL36 and it looks to all be Mikuni parts. I put the needles on the 4th slot down from the top.

We?ll see how this does. It was running rich with the 132.5?s in it while setup this way and the 118 mains were lean so I am hoping the 125?s will dial right in for me. Maybe I will have the miracle of hitting it on the first try :lol:

I have the Morgan Carbtune and the Colortune coming so I hope to get it right. I am the one who should be worried but I am not because I have you Keith


I sure hope my manometer is there when I get home tonight.


Keith, as always, your help and advice are proving invaluable and I thank you for your time. You don't have to take time out of your busy life schedule to be providing free tech support for me but you choose to do so and I am appreciative of that.

I am trying to follow you to the T and report back as much info as possible. Rest assured, if I can eventually master this (or get close to doing so) I will be able to help answer some of the questions in the future instead of being the one asking them.

Rock on!

 

[KEITH KRAUSE]

Hi Mark. To answer your latest questions (I think I have them all covered here)...
Don't install a spring that's so light that the pulley won't snap back quickly. The throttle should return smoothly even when the bars are fully turned to one side or the other. The throttle will not return with as much snap when the bars are turned, but it must still return smoothly. Be sure the cables are routed correctly too. I insist on my throttle returning smoothly. My lighter spring helps out my wrist without creating a slow to return/hanging up problem. I'd hate to think I suggested something that caused an accident. There is such a thing on these dual cable pulleys as too light of a spring. Be careful.
On pod filtered bikes, remove the two float bowl vent lines. One line is connected at carb #4 and the other at carb #2. This is a jetting requirement from the DJ jet kit and others. Fuel starvation will result if you keep them on. On pod filtered bikes, crosswinds and even just normal wind turbulence will create a vortex in the vent tubes. This will compromise proper venting and the jets simply cannot draw fuel easily. Removing them also minimizes resistance to proper venting. I've tested for this and it effects the bike greatly, especially noticable at steady speeds. Feels like a lean condition, because it is. People drive themselves nuts trying to re-jet for this and wonder why they can't get rid of the problem. Just be careful when washing the bike to avoid water into the open nipples.
Yes. The side air screws are to be adjusted using the "highest rpm method".
The pilot jet re-jet question is a good one, and the change necessary varies bike to bike. I think I previously warned you that you may have to go up to a 17.5, especially with a stock jet needle. But you can certainly try using the stock #15 and make richer adjustments to the pilot fuel screws underneath. If you still have lean problems by the time the pilot fuel screws are out to 3 1/2 to 4 turns, then you'll have to go with the larger pilot jets. At least they can be accessed easily by removing the bowls.
Just to stop any possible confusion, when I speak of "needles", I mean the jet needles, not the pilot or side air screws.
As for your jet needle e-clip position, USING THE STOCK NEEDLES with K&N's and a GOOD FLOWING pipe, I've always set the needle at the bottom position. The stock Mikuni needles aren't tapered enough for good results by just raising them one position. From my experience, the stock needles may not be rich enough even then. That's why I always suggest the DJ kit with their better flowing needles. Hopefully you'll be lucky to make the stock needles work, but I really doubt the bikes mixture will be correct with the needles at the 4th position. If you decide to change them, remember to re-bench synch. Why exactly do you think the 4th position will work? Plug reads? Performance?
Talk to you later. Keith.

 

[Hoomgar]

Hi Mark. To answer your latest questions (I think I have them all covered here)...
Don't install a spring that's so light that the pulley won't snap back quickly. The throttle should return smoothly even when the bars are fully turned to one side or the other. The throttle will not return with as much snap when the bars are turned, but it must still return smoothly. Be sure the cables are routed correctly too. I insist on my throttle returning smoothly. My lighter spring helps out my wrist without creating a slow to return/hanging up problem. I'd hate to think I suggested something that caused an accident. There is such a thing on these dual cable pulleys as too light of a spring. Be careful.

I'll be careful and adjust as needed. I don't see this being an issue for me.

Just be careful when washing the bike to avoid water into the open nipples.

Wait, are you saying they never go back on then? I remove them and leave them off permanantly?

Yes. The side air screws are to be adjusted using the "highest rpm method".
The pilot jet re-jet question is a good one, and the change necessary varies bike to bike. I think I previously warned you that you may have to go up to a 17.5, especially with a stock jet needle. But you can certainly try using the stock #15 and make richer adjustments to the pilot fuel screws underneath. If you still have lean problems by the time the pilot fuel screws are out to 3 1/2 to 4 turns, then you'll have to go with the larger pilot jets. At least they can be accessed easily by removing the bowls.

Oh boy, this doesn't sound fun. I thought you told me to use the rejected pilot jet that was in the carbs and not the ones that came in the stock rebuild kit? I missed that larger jet recommendation. Sorry. I didn't ask for any but I know Joe has them so getting them wont be an issue. I have no idea what to do with the pilot screw then or what I am even looking for?

Just to stop any possible confusion, when I speak of "needles", I mean the jet needles, not the pilot or side air screws.
As for your jet needle e-clip position, USING THE STOCK NEEDLES with K&N's and a GOOD FLOWING pipe, I've always set the needle at the bottom position. The stock Mikuni needles aren't tapered enough for good results by just raising them one position. From my experience, the stock needles may not be rich enough even then. That's why I always suggest the DJ kit with their better flowing needles. Hopefully you'll be lucky to make the stock needles work, but I really doubt the bikes mixture will be correct with the needles at the 4th position. If you decide to change them, remember to re-bench synch. Why exactly do you think the 4th position will work? Plug reads? Performance?
Talk to you later. Keith.

Got ya on the needles. What makes me think it? Nothing, it was a guess based on the fact that it was running rich with them in that posiiton with the 132.5 mains. I am using shotgun trouble shooting here. I sure hope I come close :|

No problem taking them out and moving that down though if needed.

 

[Hoomgar]

Well I don't know how it's possible to get them this close on the first whack but here it is...

My manometer and colortune still have not arrived. I am afraid they will not be here in time for me to use them before the ride. So tonight I figure, well I have to get this running and right now! The ride is Saturday and I must have a running GS for it.

So I pop a new high volume Emgo paper fuel filter on it and put the tank on after putting the tops of the carbs on. I fuel it up and after a crack or two, pop pop vrooom!

OK so it isn't really smooth? I shut it down. I turned each of the pilot screws out 1/4 more turn. Then I turned out each of the air screws one half turn. Try again, much better. Turn each air screw out another half turn. Try again, hmmm... seems to have smoothed out greatly?

OK so curiosity got the best of me. On with the seat, jacket and helmet.
Off I go. It runs incredibly well! It isn't pulling as hard as it could but it is no way near to being bad. It idles nice now that I took it for a burn. It revs smoothly and quickly. No pops or crackles. No sputtering. And no flat spots that I could perceive on this run.

I didn't really have the road to test well but she went straight to redline in 1, 2, 3 and 4 and I had to leave off in 5th but I think it was all there.

It seems really smooth and doesn't vibrate at all.

Is it possible I got it this close on the first try like that with only a bench sync and the baseline screw adjustments?

Keith, I took a plug read as best I could for you. I cannot guarantee these were at a steady 1/3 throttle but I tried. Most likely a 1/4 to 1/3 throttle most of the time with some shifting and variances due to traffic. But it was a good 5 mile run. Read below then...

I hope you can see the color right? They are not bad at all! The 1 and 4 look almost perfect and the 2 and 3 look good too but are just a bit lean compared to 1 and 4. But not lean at all according to the color chart. I need to tweak it a bit from here. What should I be trying next? Given that I don't have my carb sync tools yet?

The throttle spring is decidedly way to light. I need to get a stronger spring.

The baffle packing worked awesome! I am going to update that thread.