Low secondary resistance on coils

[Anonymous]

From the caps. 1 to 4 and 2 to 3.

1-4 shows 23.3k Ohms and 2-3 shows 23.5k Ohms.

[cmroche]

The coils on your bike work very much like a transformer in all practical electronic applications.

A coil with an equal number of windings on both sides causes the input and output voltages (primary is input, secondary is output) to be equal... if you reduce the number of windings on the output side you reduce the output voltage on that side, and logically if you increase it, you increase the output voltage (bearing in mind that power has to always be equal, so amperage if the factor here that compensates for that).

This is why your secondary resistance is higher, more windings in the coil cause for greater resistance from more wire being used in the coil than the primary, so your output voltage is actually measured as (primary voltage ~12v * secondary resistance / primary resistance). (This of course assumes the same type of wire material and guage on both ends, and though may not be pratical for actual output voltage it none the less proves my point)

Now if your secondary coils are shorting, you end up with a lower output voltage, meaning your spark becomes less blue and fat (amperage can increase too, be careful and don't shock yourself, could be fatal).

[scotty]

I dont believe that he gets improper resistance at the secondary side of BOTH COILS

I guess i should say i believe it buts something is wrong that is common to both coils but i dont know what. Both coils do not go bad at the same time with exactly the same secondary resistance.

8O i theeeenk!!!!!!!!! 8O

[Anonymous]

Just to add some extra data here, the coils are completely unplugged, but are still grounded via the chassis brackets.

THEEENK GUYS!! :P

Thanks!!

[Billy Ricks]

If they are aftermarket coils like Accel or Dyna your reading is fine.

[Anonymous]

I wish!

They are old beige-coloured stockers.

[Billy Ricks]

I don't think the coils are the problem at all. You're not that much off the readings you are supposed to get. If you decide to replace them jusst go with GSXR, Bandit, or Kat coils off Ebay. The newer the better.

Keep working the carb settings. As Keith suggested, make sure the spacers are stacked right on the needles.

[cmroche]

23k doesn't seem bad though for secondary resistance... GS1000 bikes use anything from 11k - 35k depending on the model of the bike so to me it doesn't seem like a short if they are reading 23k.

[Anonymous]

Ok... back on carb track.

I've taken them apart and compared some things with my spare carb set. My spare set indeed has the little plastic spacers. I'll be moving those over.

1st) my current set has the needle one notch from the bottom. Should I leave it here and just use the spacers properly? This should raise it a tad, right?

2nd) When comparing the needles with my spares, it looks like my current needles are pretty fat. The markings are 5F21. My spares say 5DL36. Should I swap or keep the larger ones?

3rd) My current pilots are 27.5s. My spares have 15s in them. Should I stay with 27.5s?

Ok, enough questions for now!

Thanks again!

[Billy Ricks]

Keith Krause would be your best bet with your questions on jetting. Just be aware the jet needles and needle jets have to be compatible.

[KEITH KRAUSE]

First of all, I have to say your carbs may have been jetted by a fool.
They were missing the jet needle plastic spacers.
A 27.5 pilot jet would fuel the Queen Mary. The 107.5 mains you have are very lean for your mods. As for your jet needles, I believe you should have the 5DL36 for the '77. What bothers me about all this is I have to wonder what else may be changed incorrectly?? The needle jets may be wrong. The float levels screwed up, though that is fixable. You could see differences in the pilot fuel screw design. There could be even more "changes". It seems your spares have all the correct stock parts and may be the wiser choice? I can't say without seeing the two carb banks, but I wonder if you should transfer all the new o-rings to the spares? I just don't trust what other things may have been done to these carbs. If you must stick with these carbs, I suggest using the needle jets from the spares too. Also, double check that the pilot fuel screws are the sharp tipped design and the tips are all in good condition. Check throttle slides, side air screws, etc. Check for any other missing parts.
Reading back, you said you would check/adjust valve clearances. Just be aware this should be done, along with correct ignition timing and point dwell setting/advancer action check and side air screw "highest rpm setting", BEFORE the vacuum synch, which also must be done to get accurate performance/plug tests.
As for your latest jetting questions, I would try the stock 5DL36 needles in the highest position. So put the e-clip in the bottom groove. Be sure the stock plastic spacers are replaced as I said earlier. If you had K&N's, this needle set up would probably still be too lean, but I think it will work with your Emgo's. If still lean, jet kit time. If the Emgo's run even richer than I think, then we'll lower the needle some. Depends on the performance/plug reads you get.
Your 15 pilot jets should be given a chance to work with the help of pilot fuel screw (underneath) adjustments. Start testing them at 1 1/2 turns out or close to that. If you can't get the mixture correct by the time these screws are 3 turns out, then go with a 17.5 pilot jet.
As for the main jet choice, I'm guessing 125's. That's only a guess of course. Jetting can take a few tries. I'm actually a big jet kit fan instead of trying the stock needle and buying seperate jets. But with the Emgo's you have a better chance of making the stock needle work.

[Anonymous]

A 27.5 pilot jet would fuel the Queen Mary.

Hahah... I figured that a 83% increase on the pilot seemed odd when compared to a 7.5% on the mains!

With regards to the spacers on the needle (plus the round plate & spring)... it looks like they were only introduced in 78! Perharps after some problems??

Take a look at this fiche from 77:

http://tinyurl.com/7b7uv

And now from 78:

http://tinyurl.com/c6npk

Strange... anyhow...

I will give your suggestions a try this week. Hopefully tonight. Should I be able to continue using the 107.5 jets with their "pipes" (what are those thing called??)

I'll try sticking with my current carbs as I put a lot of effort into cleaning them . If this still doesn't work, these new carbs will be my winter project The float levels in my current set were reset by myself to 26mm using new valves and seats.

I've checked the tips and they are good in the current and new sets.

I do have spot-on timing right now, done with a timing light. I also tried the "highest-rpm" air-screw setting, but it would never modify the RPM when I turned it.

Thanks so much Keith for your assistance so far. Your commitment to the GS community is to be commended! 8)

[KEITH KRAUSE]

I'm not sure what you mean by "pipes" regarding the main jets, but the 107.5 mains are way too small for your mods.
As for trying to set the side air screws, they won't respond normally with those huge pilot jets in there.
As for those two carb parts pics, they both say 77-79. I don't know what to say about them. I haven't worked on the VM carbs with no spacers/plate/spring, etc. I can tell you that if earlier carbs came without the plastic spacers and spring and brass plate, those jet needles would wear very quickly from vibration. The plastic spacers stop metal to metal contact and the plate and spring keep the needle under a light tension so it doesn't shake and rotate around.
The earlier design is inferior and I would use the newer carbs. I can't be absolutely certain if you can swap the plastic spacers onto the earlier jet needle without causing an unknown jetting problem. I'm just saying there could be differences and I would be cautious.
I'm not sure what your plan is but I think I wouldn't transfer just the plastic spacers over...I would transfer the entire throttle arm/thin brass plate/spacers/spring/jet needle/slide over as a unit. To go further, I'd clean up and rebuild the spare carbs and use them. But I know you've decided against that. I just hope this "problem" doesn't create a jetting headache. It's hard for me to say anything 100% without being able to check and compare every part.

[Anonymous]

Agreed on the slides and needles, the earlier ones are not compatible with the springs and plates, so I will have to transfer the whole assembly over.

I'm hesistant to use/clean the new carbs because they are extremely nasty. It looks like molasses in there... Plus, I really can't stand that carb dip biohazard anymore. I just dipped a carb last weekend and the stench lingers for a week at least.

The plan right now is to:

• Replace all of my jets with the #15s.
  Replace the slides, needles and linkages from spares
  Move the needles to the bottom clip
  Install plastic spacers (large bit on top)
  Double check float height a confirm "floatiness" of said floats (swap from spares if required)
  Set pilot screw to 1 1/2 turns out

I'll let you know how it goes.

Thanks again!

[KEITH KRAUSE]

OK. Hope the slide assemblies work correctly in the other carbs.
I feel funny making suggestions when I can't see the parts myself. All I can say is that I'd look hard at all the parts being swapped. The length of the slides, etc. I guess you know what I mean. So easy to not notice something. If at all possible, I'd use the better slide assemblies though.
Be sure to keep the 5DL36 jet needles with the needle jets they are designed to move through. Very important.
Also, set the side air screws to 1 3/4 turns out for starters.
Don't forget the mains.
You'll also need to bench synch the slides. I'm not sure if you know how?
I made a detailed post on how to at Hoomgars topic about re-jetting his GS1000/bad fuel economy? The only difference in procedure is your 750 carbs I believe should be synched starting with the #3 carb. I'm too stupid to know how to provide the link, but you can search if you need it or someone here may help? If it's easy, I'd like to know how to do that by the way.
After the bench synch, which is really done to make the vacuum tool synch quicker/easier, you'll need to get the carbs vacuum tool synched. It's easy to learn and a Motion Pro tool is about $40. The Morgan Carb tool is more money, but easier to use because it doesn't get condensation gaps mixed with the mercury (a problem for some). Some people live with their bench synch but I don't recommend doing so. The tool and its effects on tuning are more than worth the money and time taken to learn how.