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Presidio High School Knucklehead Special

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Pa

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Post Wed May 21, 2008 3:28 pm

Re: Presidio High School Knucklehead Special

Sometimes those gremlins are difficult to locate. Can't wait to see the magazine photos and story. Howdy and deep admiration to your students Randal. With regret....I don't want to hear any of the students Mexico visit stories. I have been trying to forget my younger days for years now. Those yarns would just bring those memories back to me. Pop always said....sew those wild oats while your young son. The tamed ripened fruit gets heavy as you age :wink: Pa
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Fri May 30, 2008 11:21 am

Re: Presidio High School Knucklehead Special

Howdy Folks,

I've been working with the Knucklehead Special over the last week or so when I've had time. We are finishing up the school year, today's the last day, and I've been giving final exams and getting the students to clean up the shop. In addition to the checks I've mentioned in my earlier post, I've drilled a couple of holes in the interior of the right-side gas cap to improve venting; when I blow through it there is very little restriction.

I rode the bike around town last Monday in the morning when the temperature was in the 80's. It ran fine in town, so I took it out to Fort Leaton State Historic Site, 3 miles from town. Within sight of the fort, running 60 mph in 4th, it started cutting out. When I shut the throttle, slowed, and down-shifted, it picked up and started running again. I pulled into the fort's parking lot and it sat there and idled as nice as anything. I rode back into town and then around town before riding back out to the fort; ran beautifully. When I returned to the school and shut it down in front of the shop, I neglected to turn off the petcock while I was unlocking the door. Upon returning to the bike I found it was dribbling gas out of the CV Keihin's over-flow tube, something I've not previously had trouble with.

The motor, when it cuts out and loses power, acts exactly like it does when I pull away having forgotten to turn the petcock on, like it is running out of gas. Today I put the bike on the stand and pulled the floatbowl. I reasoned that, if the float was sometimes sticking open, then it might also be sticking closed. I found nothing obviously amiss, the float raises and lowers without binding and there is a good flow of fuel when open and none when closed. We set the float level as per the H-D service manual when we went through the carb and I have doubled checked it. The petcock is a Pingel hi-flow item. I took the bike out and ran it the 3 miles between town and Fort Leaton four times this morning. It started with two priming kicks, switch on, and one kick to crank, as it almost always does. It ran great the first three trips, then on the fourth trip it started acting like it was running out of gas at 60 - 65 in top gear again. If I shut the throttle and slow down it will pick up and start running. Loosening the gas cap on the left-side tank when this happens has no effect.

Any ideas? Should I maybe set the float higher the manual recommends? I don't have any experience with these CV Keihins, but lots of people like them. Suggestions...

--- Randall
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john k. endrizzi

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Posts: 726

Joined: Thu Dec 09, 1999 1:01 am

Location: nekoosa,wisconsin,usa

Post Fri May 30, 2008 12:10 pm

Re: Presidio High School Knucklehead Special

Randall<
You didn't reply to my answer ( link on Iron Motors Tech ). I am struggling with the identical problem. Our motors share the very same symptoms. I'm also running a Kehin CV. It was suggested that maybe I'm boiling the gas in the fuel supply line. I rather doubt that, but I'm taking a break from the re-routing task as I write this. When I took my carb off the intake manifold I noticed that it was a few degrees out of plumb. This led me to believe that maybe the bowl is running dry because of the angle. I installed a press on flange on the carb ( to replace the compliance fitting that is used with these carbs) There are a couple of other tasks left before I test ride. Please keep us posted and I'll do the same. BTW Now that school is over why not think of a cross country ride. Knucklehead Company M/C is having it's 6th Knucklehead Reunion at the S&S 50th Anniversary celebration . You would be likely to win the honor of long distance rider . ( Plumber is farther out........ but he has been strangely silent about attending ?)
JKE
Call on God, but row away from the rocks.
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Fri May 30, 2008 12:56 pm

Re: Presidio High School Knucklehead Special

Hey John,

I have been following your posts with interest and I check your Iron Motors Tech site pretty much daily; there is always good stuff there. I double checked the routing on the fuel line and it is in clear air between the heads, only making contact at one point with the overhead oil supply line. I suppose I could rig a wire keeper to separate it even from that, but the motors not running all that hot and I've had the problem occur even when the motor hadn't fully warmed up. I had no problems at all during the first 1,000 miles. As with your description, it only occurs when running at cruising speed or a little better in top gear. I am fairly certain it is a fuel problem. I've run into bad coils before, and they always fail , say, 20 minutes after the ignition is turned on, you lose spark to both plugs, and don't get it back until the coil has cooled down. This acts like the machine is running out of gas.

As I said, I have no experience with Keihin CV carbs, but I've had a lot of experience with Bing CVs on air-cooled BMW Boxers; as long as there was no hole in the slide diaphragm they were very reliable and trouble free. If there was a bad diaphragm it was immediately obvious. My friend, Ernest Rodriguez, who now owns my old bike shop, has worked on Keihin CVs a lot, and says they are pretty much cut and dried; if everything is in place they work. As far as ease of starting, power, smoothness, and nice idle go, its a great carb as fitted on the Knuckle. There has got to be something simple that I am missing...

I'd love to attend the Knucklehead Reunion; I was stationed at Chanute Air Force Base in Rantoul,IL, in 1977 and rode up into Wisconsin; beautiful country. But, its a long way from West Texas, gas is $4 a gallon, and I'm teaching Driver Education and a welded steel sculpture class in our summer school during June; maybe another year.

I will continue to follow your posts on the diagnostics you are running and will keep you posted on what I come up with. Thanks for your interest.

--- Randall
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Wed Jun 04, 2008 2:07 pm

Re: Presidio High School Knucklehead Special

Howdy Folks,

We ran the darling students out the door Friday for the end of the 2007-2008 school year, and graduated 71 Seniors on Saturday night. Most of my students are going on to welding or mechanics programs at Odessa College or Texas State Technical College in Sweetwater. Pipeline welders are making $55 - $90 an hour in the oil patch right now and they want to get in on that action! I've got a week before summer school starts.

I took some time yesterday and pulled the CV Keihin off the Knuckle. The problem seems to be fuel starvation in top gear at 65 mph and up. I did not experience the problem during the first 1,000 miles, but I was keeping the speed under 65. I rechecked the float level on the carb; it measured .730" from the bottom of the float to the gasket flange on the carb body with the floatbowl removed and the carb held up-side-down, just as it had when we installed the overhaul kit. The H-D service manual calls for a measurement of .730 - .725". I reasoned that maybe the fuel consumption in 4th at speeds over 65 mph was outstripping the floatbowl's refill rate at that level, so I bent the float tab to set the float measurement at .720". I checked the overflow tube after I reassembled the carb and there was no leakage, so I fired the bike up and rode the 20 miles home, running between 55 and 65 mph because it was very hot. The bike ran great, smooth and plenty of power and no missing. I got up this morning while it was in the 70's and ran up and down the canyon through the Chinati Mountains, hitting 70 and 75 in bursts and taking some of the grades pretty aggressively, putting 20 miles on the clock. The bike ran real strong with no repeats of the missing and cutting out. I am hoping that the problem is solved. I'll take the bike out again in the morning and do a shutdown test to see what the sparkplug color looks like.

--- Randall
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john k. endrizzi

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Joined: Thu Dec 09, 1999 1:01 am

Location: nekoosa,wisconsin,usa

Post Thu Jun 05, 2008 8:38 am

Re: Presidio High School Knucklehead Special

Randall,
Thanks for the update. Certainly not to be arguementive but .005 seems like a very minimal change. On the other hand there is only .005 spread in the factory tolerance. I'm anxious to hear what further trials show.
JKE
Call on God, but row away from the rocks.
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Thu Jun 05, 2008 1:45 pm

Re: Presidio High School Knucklehead Special

Hey John,

I started with the float at .730" and went to .720" so the change was .010", but I agree, it doesn't seem like much. On the other hand the cutting out and dieing hasn't repeated so...? I rode 10 miles this morning early in the cool at between 60 and 70 mph and killed the motor, pulled the clutch and coasted to a stop, then pulled the sparkplugs to have a look at the electrode color. This method of tuning does not work well with electronic ignitions, but I've had good results when running a points ignition such as the Knuckle is fitted with. The bike ran well but I experienced some hesitation and roughness at steady throttle. Both plugs were gray, so too lean. I was running rich with a 180 main jet and had changed to a 170. I have an aftermarket slide and needle installed. The needle has 5 slots to adjust how far into the main jet it extends and I have the E-clip in the 3rd slot from the top. I'll raise it a slot or two this evening and repeat my shut-down test in the morning. If I can't get a nice brown color by adjusting the needle height I'll go back to the 180 jet. This is an 80 c.i. engine; are any of the rest of you running CV Keihins on Knuckles besides John on his 93 c.i.? If so, what size jets are you running? I have a round 7" K&N air filter fitted and a stock 2-into-1 header with a Panhead rigid-frame cigar muffler.

--- Randall
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panacea

Posts: 121

Joined: Thu Apr 12, 2007 8:22 pm

Location: Mpls. area

Post Thu Jun 05, 2008 4:19 pm

Re: Presidio High School Knucklehead Special

Randal, My 84" pan is starting and running great with a 45 pilot and a 175 main. My idle screw is 2 1/2 turns out and my "yost" power tube blue needle is set with the "c" clip in the fourth groove from the top. The plugs are running a bit dark but thats where she runs the best. I also found that starting is easiest when give a squirt from the accelerator pump with two key off kicks, then half choke and she starts on one kick. I'm running a screamin' eagle air filter with Paughco two into one with a 1- 7/8" holesawed out cigar muffler. Mike
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Chris Haynes

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Location: Los Angeles, CA

Post Thu Jun 05, 2008 4:27 pm

Re: Presidio High School Knucklehead Special

I have this same problem on my '95 Ultra Classic. Runs fine at legal highway speeds but when pushed hard it starts starving for fuel. The dyno guy tells me it is because I replaced my stock fuel valve with a pingel. He sez that the H-D Keihin's need a vented fuel valve. I don't know exactly what that is yet,but I am invesiigating.
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BrentCross@Bronko's

Posts: 88

Joined: Thu Feb 01, 2007 8:20 pm

Post Fri Jun 06, 2008 5:02 am

Re: Presidio High School Knucklehead Special

Sounds like a crock of $%#@ to me. I have replaced the notoriously bad HD vacuum petcocks for years with Pingels (top quality pieces I might add) and never, ever had a issue. Now if your tanks are not venting properly that is another issue but I would certainly not be blaming the petcock.
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john k. endrizzi

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Posts: 726

Joined: Thu Dec 09, 1999 1:01 am

Location: nekoosa,wisconsin,usa

Post Wed Jun 11, 2008 5:34 am

Re: Presidio High School Knucklehead Special

How about it Randall ? Have you had your Knuckle out for a longer test of your float level change? I'm anxiously awaiting your final take .
JKE
Call on God, but row away from the rocks.
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Wed Jun 11, 2008 8:04 am

Re: Presidio High School Knucklehead Special

Howdy John,

I reset the E-clip on the slide needle two slots lower and did another shut-down test. The plugs were a very light tan, so I think I need a 175 main jet such as Mike is running. The bike was running very rough at steady throttle, and when I pulled the slide yesterday morning I found that I'd pinched and perforated the edge of the diaphragm; that's what I get for trying to change the E-clip setting without taking the carb off the bike. We had installed a Japanese-made V-Twin Mfg. tuning kit and I'm not real pleased with the quality of the rubber bits; they swell when exposed to gasoline. I called up Barnett H-D in El Paso and ordered a couple of OEM diaphragms and floatbowl gaskets, as well as a 175 main jet. I'm running a 48 pilot jet and have the mixture screw 2 1/2 turns open. Thanks, Mike, for your response, I know I'm in the ballpark anyway. The parts should be here tomorrow or the next day and I'll post my results as soon as I have a chance to install them and run the bike down the road some more.

All of West Texas is suffering under a heat wave and temperatures in Presidio have been breaking 110 F. We have had a few afternoon thunderstorms which can drop temps by 30 degrees in a matter of minutes. The Chihuahuan Desert gets most of its annual rainfall in the form of summer thunderstorms, so I hope it keeps up. In the meantime, I'm restricting my Knucklehead riding to the early morning hours. My 2002 Victory V92C Classic Cruiser is apparently impervious to the heat, even when pulling a steel Ural military sidecar down the road at speed; it has oil-cooled SOHC 4-valve heads with a 3" x 10" oil cooler and air-cooled nikasil-plated cylinders with oil jets spraying the underside of the slipper pistons. Excellent bike! In my opinion, the best all-around American heavy cruiser offered in years; too bad Victory has abandoned the model in favor of more "Kustom" styling.

Later --- Randall
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gin

Posts: 171

Joined: Fri Jan 16, 2004 1:01 am

Location: vero beach FL.USA

Post Mon Jun 23, 2008 3:30 pm

Re: Presidio High School Knucklehead Special

Any iron motor needs a lot more then .002 piston clearance no matter what,.005 is more like it.
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Tue Jun 24, 2008 7:59 am

Re: Presidio High School Knucklehead Special

Howdy Gin,

I don't know you or what your experience is, but thanks for offering an opinion. I owned and operated an independent motorcycle shop specializing in H-D, British, and European motorcycles from 1980 to 1994, so we worked mostly on iron-cylindered machines. We did all engine building and machine work in-house. I was trained as a machinest at St. Phillip's College in San Antonio by instructors who had learned their trade as Army machinests during WWII on iron-cylindered machines, and I did most of the machine work, including cylinder boring, myself. How I fitted the piston depended on the intended use; for iron-head Sportsters that were going to be hot-rodded around town and used forged pistons I fitted them at .004 - .006" clearance, depending on how much restraint I felt like I could trust the owner to show during break-in. For Big Twins that were primarily road machines where maximum engine longivity was desired (and if I trusted the owner to follow my break-in instructions) I fitted cast pistons at .002 - .003" clearance. Even in the desert heat of West Texas these motors did fine if carefully broken in. Average top end life for Knuckles, Pans, and Shovels set up this way ran from 20,000 to 30,000 miles.

I now teach metal trades and mechanics at Presidio High School and we have a good boring bar in the shop, but for ths engine I wanted to use the silicone-carbide embedding process offered by Bore-Tech in Ohio to get maximum life out of my very expensive MBS cylinders. When I talked to Bill Moeller at Bore-Tech about the job and suggested .002" clearance, he seemed to think that would be fine. I took the added precaution of having Bore-Tech teflon-coat the piston skirts and ceramic-coat the crowns as per late H-D practice. So far, with over 1,000 miles on the mill, and despite unusally high temps here in the Big Bend, I've had no signs of piston seisure and no blue smoke out the pipe, so I'm pretty happy with the set up. Of course, results may vary, so do what seems best to you.

My carb parts finally arrived from Barnett H-D last Friday and I put the carb back together yesterday morning. When I went to start the bike I found the scarcely 3-month old 12N5.5A-3B battery was dead as a door nail. I hooked up my trickle charger but the battery would not accept a charge, even after spending all night on the charger. Has a faulty battery possibly been the source of the missing and cutting out I've been experiencing? I'm going to see if I can find a suitable replacement at one of the auto parts stores in Presidio today. I think Auto Zone carries a 12V gel cell battery that might fit in my OEM oil bag.

I also ordered and recieved a Quick Start 2000 electronic ignition kit to replace my points and condensor. I think I'm going to finish jetting the carb before I install it as I've found that I cant't get reliable color readings from the plugs on electronicly fired bikes; the carb can be so rich that there's all kinds of black smoke coming out the pipe and the plugs still come out gray or white. I've run points for years with acceptable performance, but you do have to adjust amd mess with them from time to time and condensors sometime go bad; I'm after maximum reliability. I installed lots of Boyer-Branson electronic ignitions on Brit bikes when I was in the business, and you just set them once and forgot about them. All I've got to do is remember to lube the advance unit occasionally. I'll let y'all know how it comes out.

Do any of you have experience with gell cell batteries or the Quick Start 2000 unit?

--- Randall
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BrentCross@Bronko's

Posts: 88

Joined: Thu Feb 01, 2007 8:20 pm

Post Tue Jun 24, 2008 10:22 am

Re: Presidio High School Knucklehead Special

Hi Randall:

I have run a Yuasa Factory Sealed battery (BCI group #YTX5L-BS) for years in my kick start rigid frames (even solidly mounted) with never an issue. The stock application is for a dirt bike so they are built to take the abuse. They are 4 3/8" long, 2 3/4" wide, and 4 1/4" tall. They fit nicely into the 6v cavity in oem rigid oil tanks and because they are factory sealed you never have to worry about checking fluid levels - just put it in and forget it.

I love the Mallory distributor (with electronic pickup) for all generator bottom end HDs. They are just like the Boyer units in Brit bikes - install, set the timing, forget about it. There is a new version totally solid state but the old version with automotive style mechanical advance is still available and these are the ones that I have always used. They are billet, but they work so good I don't mind that they don't look "factory".

Brent
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bobphd

Posts: 89

Joined: Sun Mar 28, 2004 1:01 am

Location: Wisconsin USA

Post Tue Jun 24, 2008 10:53 am

Re: Presidio High School Knucklehead Special

Regarding gel cell sealed batteries. I had a 12 volt gell sealed battery in my 47 custom with a cycle electric 12 volt generator with the built in regulator. The battery only lasted about 3 months with about 6000 miles on it. Went back to the lead acid. I had a 6 volt gel in my stock 40 with the stock 3 brush and relay. It lasted about 1 week and I got a warranty replacement that lasted a month with only about 2,000 miles on before it EXPLODED in the oil bag going down the highway at 65 mph. I think that these batterys are very sensitive as to how they are charged and not compatable with vintage motorcycles. I contacted the guy on ebay who is selling these and told him these batterys do not work in 6 volt 3 brushes that are ridden but he is still selling them for this purpose.
Bob
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Wed Jun 25, 2008 11:22 am

Re: Presidio High School Knucklehead Special

Howdy Folks,

Brent and Bob, thanks for replying. I found a small dirt bike lead-acid battery at Auto Zone that fit the battery box and installed it this morning. I replaced the perforated vacuum diaphragm on the CV Keihin and replaced the V-Twin tuner's kit main jet, tube, slide spring, and slide needle with OEM parts, running a 180 main jet. The bike cranked right up and I rode the 20 miles into town with nary a hiccup or bobble, nice and smooth, plenty of power, running between 60 - 65 mph. I pulled the plugs and they are a nice even tan color.

So, what was causing the cutting out, missing, and dieing at speed? I think the rough running I experienced just prior to doing the above was cased by the 170 main jet being too lean and the damaged diaphragm. Raising the float level by .010" seemed to help, prior to all that, but what if the real problem derived from the battery failing and I was getting a weak spark in top gear under load? Well, the bike ran great this morning, so I guess I'll keep riding it and see what happens next. Fun with old iron! I'll keep y'all posted...

--- Randall
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woody

Posts: 502

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Wed Jun 25, 2008 6:32 pm

Re: Presidio High School Knucklehead Special

Randall, I have had a low battery condition cause cutting out and backfiring many times. At present I use an Odyssey PC 545 battery in my UL. It is an AGM battery rather than a gel cell. I have an aftermarket oil tank that is configured for the 6V battery. The Odyssey battery can be mounted in any orientation and I was able to stuff it in standing on end. I don't know if my tank has exactly the same dimensions for the battery as a stock tank and the battery was a tight fit in mine, but it works very well. My Cycle Electric generator keeps it up just fine, and last winter I hooked up my Battery Tender to it after sitting for nearly 3 years without being charged and it went from charge to maintenance after less than 5 min.
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Randall

Posts: 62

Joined: Wed Oct 24, 2007 1:29 pm

Location: Texas' Big Bend country

Post Thu Jun 26, 2008 4:19 pm

Re: Presidio High School Knucklehead Special

Hey Woody,

That sounds interesting. How much does the Odyssey battery cost, more or less, and where may they be purchased? I'm running a Cycle Electric 12 V generator with built-in regulator and reduced charging rate for small batteries.

--- Randall
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woody

Posts: 502

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Thu Jun 26, 2008 5:48 pm

Re: Presidio High School Knucklehead Special

It was around $100 and should be available from most battery dealers. I got mine from Pacific Power Batteries. I have the high rate Cycle Electric regulator. They may make smaller batteries, but I went with the largest one I could stuff in the hole just to see if I could do it.
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