HammerHead1st's Rat Rod??

[TopCatGr58]

Hey Hammer,

You haven't posted any tech requests yet, but I caught your report about solving your low end miss with double insulating the spark plug wires with electrical tape.

I've reread your posts, and checked your Avatar, but can't tell what other mods you may have done to the INTAKE?

You tried a WOT run, but only got to 85mph, what rpm was your max that you could attain? Does it have the stock airbox, or Indy filters? Unless you've swapped out the mains, it shouldn't be running that lean to starve at speed? These machines will run fairly well at varying levels of leanness!

So...if you DO have Indy filters, take them off for a quick test run to see IF you can get the rpms and speed up beyond 85? Some aftermarket "frugal" indy filters have a prominent lip that interferes with the airflow thru the inlet side and chokes the engines down preventing the vacuum slide from rising properly, etc.!

I'll go back and review what year it is, and then "we" can suggest other things to check to get you "up to speed"!

Okay, 79 Standard. You have stated that you've done the carbs twice so far. The standard petcock is vacuum actuated. Have you checked the vacuum lines going to it for cracks and leaks which could prevent adequate fuel flow at higher speeds? I don't remember but I think it has a PRIME setting, might try that?

Have you verified that the upper carb VENT T's and the tubes and the airbox(if you have one) are all open and freely flowing AIR, if blocked by crud, can cause carbs to puke, etc.!

Did you verify that the vacuum slides rubber diaphragms didn't have any pinholes, and they were sliding freely, and that the would stay UP when pushed up by hand and finger placed over the top arced intake port on the carb? When you were in the carbs, did you remove the main jet, AND the main nozzle that the jet was screwed into and soaked/cleaned the little aeration ports in it?

Also, now that the plug wires are fixed, have you checked the timing with a light? Does the vacuum advance module pull the timing plate around when suction applied, and does it HOLD when you block off the tube?
T.C.

[Hammerhead1st]

Sorry for the delay!!!

Past few days have been absolutely NUTS!!

A few answers for you to ponder...

Carbs were done by a certified mechanic friend of mine as I watched. He stripped em clean, then cleaned em up, then put em back together. He did a great job.

Vaccuum lines are all clear and solid, no cracks or wear.

Timing advances with rpms as it should, have not yet checked timing by light.

petcocks were cleaned totally and operate normally.

Carb T's are in ok shape, not the greatest, but DO flow freely.Floats look ok and are set to JUST under flood level.

Diaphrams and sliders all work properly and operate by hand.

Air filter is stock in a stock box.

Just recently (this morning), I replaced the plug wires in the coils.Did a 200 mile run Sunday and the top end just wouldnt come to life for me. I have gotten her up over 100 now but anything over 5 grand causes a miss in one cylinder. I plan to diagnose which one tonight after work. Rode it to work today with new 7mm resistor silicone wires and it ran like crap and sputtered all the way here. Thinking I may need to get some Accel HP superhot wires with solid cores to make the bad skip man go away.

BTW...had a friend help me sync the carbs with some fishing line and water...LOL...was funny and redneck but it worked. Now all the mix screws are 1 1.2 out as it should be.Idles at 1 grand with a slight lobe...like a Harley choking on good gas...heh heh heh

SOOOO...will letcha know what I find with the top end miss...thanks for the tips!!

[Hammerhead1st]

So I talkted to a Kawi dealer here

and discovered WHY the tech tip on changing plug wires specifies no resistance plug wire.

Called Napa here in town, they have some set aside for me when I get out of work...at .39 cents per foot. SWEET!!! Already did the hard part with the coils, so throwing some 7mm solid copper core wire into them will be a snap. Lots of silicone left over and duct/black tape too! Will post a new reply here when I have it done.

[TopCatGr58]

Hey Hammer,

Have you checked the resistance in the ignition coils, should be about 15Kohm one plug end to the other, and the Primaries should be ~1.5 ohms? Also, check the plug caps, should be 5k or less, they have been known to corrode and generate very high resistances or even no continuity! Ijust would hate to see you putting this much work into BAD coils! IF they do measure out bad, then high power replacements are availabe fairly cheaply, see the Mods tech tips, MikesXS coils tip!

You mentioned in your Member's Forum thread that you can't get it above 5k rpm before it misses. Along with the vacuum advance module...btw you do have the vacuum adv. hose plugged into the #2 carb BODY metal port, NOT the #2 carb intake manifold synch port? Back to timing, with the engine off, timing cover off, can you easily slide the timing plate around, do the cent. adv. weights rotate easily?? They may be sticking and you may not be getting enough advance!?

Also, okay, stock airbox/filter. The airbox has a SNORKEL, sometimes critters like to get in there and make nests, etc., or it can get kinked restricting total air flow into box, you'll want to check it!

Don't know what you mean by fuel levels set to just below flood level?? They should be set to ~25.7mm above the gasket mating surface on the 78-79 series bikes.

No aspersions to your mechanic friend, but did he take out the brass main jet nozzle up thru the body of the carbs and soak and clean them, verifying the little aeration holes in them were clean and open? Also, did he use a "KIT", or did you just put back the same jets that were already in it? Did you look to see a size stamp on the mains...should have been 137.5 or possibly larger! And there should have been a screw cap for the PILOT jet tower.

Later,
T.C.

[Axel]

Plug Cap Resistance

Is the resistance for the plug caps on a XJ 5k as well ?

[TopCatGr58]

Hey Axel,

Jerry may be able to better answer that one, but I've found from 5K to 8K on mine, 81SH, but just recently replaced with NON-resistor types!
T.C.

[Axel]

spark plug caps

Hey
I tested one and it was 6000ohms. Why did you go non -resistor ? Resistor plugs ?
Alex

[Hammerhead1st]

Ok...

For the resistance question...

You asked why resistance versus non-resistance. According to the Kawi dealer here in town, older bikes and therefore older coils were made to work with low/no resistance wires, and the caps only put out 5k ohms. TRUST me, the difference is amazing...

TopCat...

Will triple check vaccuum lines after work, I get out at noon. Timing plate does move freely. Was one of the first things I checked after I got the bike...didn't want to go crashing things together on the first fire-up ya know?

Carb floats are set AROUND 25mm but not exact, mostly eyeballed due to the lack of any REAL measuring devices at the time. Mistakenly set them at 29 and ended up with a gas flood under the bike...

Airbox snorkel is clear, as are the little individual snorkels inside the box. FIlter is nasty yucky but cleaned it out the best I could.

When my mechanic friend did the carbs, there was no money for a kit or ANYTHING...so he looked them over as a favor to me. He had everything out of them that would come out, checked seats, etc, blew them out and checked the little holes, showing me things here and there for future reference, like..."if this is plugged you're dead in the water", etc. He's VERY anal...so I never questioned it.

Will be checking coil resistance later today, my friend is bringing me his digital mutli, I have an OLD analog model that's just not precise anymore.

Thanks for all the awesome info, man...It's VERY appreciated, and You'll be getting updates as I progress.

...put in new plug wires Wed...7mm solid core with the original boots. Fired her up, and she ran like a bear. Sounded GREAT..still has the 5grand skip. Started it this morning after last nights rainstorm, and it ran like CRAP...two cyls firing intermittently. HO-HUM...

[TopCatGr58]

Re: spark plug caps

Originally posted by Axel
Hey
I tested one and it was 6000ohms. Why did you go non -resistor ? Resistor plugs ?
Alex

Give me Fuel, Give me Fire, Give me That(power) which I desire!

I didn't care about radio noise, and wanted ALL of the power going to the plugs, especially since the spark has to travel thru one wire, plug, ENGINE, back thru other plug, wire, and back to coil, wanted as little resistance as possible.

Hey Hammer,

You said your OEM filter was very gunky! Have you tried taking it out and just running the airbox for a test to see if you can get it up over 5 k without any missing?

Also, sounds like the carbs are in pretty good shape, so you may need to turn your attention to the PU coil wires, but also interested in your coil ohm readings. Check your power connectors to the ignition coils, sounds like they are either rubbed bare and possibly intermittently grounding, moreso when wet!?!? The vibrations at the higher rpms could also possibly cause the wire to touch the frame and ground out cutting power to the coil or stopping the 'trigger' signal??
T.C.

[Shuriken]

So my question is for those who have changed the plug wires is, what is the resistance measured through the wires and the cap altogether in comparison to stock?

Ben

[TopCatGr58]

Hey Ben,

Solid core wire has essentially no resistance at these lengths, so with 5K caps, you should be reading about 25Kohms vs. the coils 15k ohms alone!
T.C.