Harley-Davidson 1954 900cc KHK improvements for Speed Week 2014, APS VBF

[thefrenchowl]

Hi all,

I lurk quite a bit here but haven't posted om my progress (or lack of it depending on your view point!!!) since 2011, a long time... My original build diary can be read here:

http://www.landracing.com/forum/index.php/topic,8744.0.html

Once the bike and meself were back in GB, it was obvious there was some unfinished business and the Salt Fever kicked in...

It has involved inputs from Lady Bad Luck, Lady Luck and some of my closest friends and maybe it is time to set the record straight before we make another attempt in 2014 at these elusive records...

I used to write a lot on the XLForum where there's a nice crowd of ironhead Sportster nutters. One of them, Joe, aka "DrDick", offered his services for Speed Week 2013, promply followed by his brother Mark, aka "model H".

On my side of the pond in Great Britain, another friend, Richard, learned I was coming over again and said he'd come as well... Then his friend Graham at the antipodes in Australia, well known here as "Graham in Aus", followed suit so it was that the 5 of us converged from all over the world and met on the Salt Flats last August.

Joe started a thread on the XLForum where you can read what actually happened in real time on Speed Week:



http://xlforum.net/vbportal/forums/showthread.php?t=1666561

The outshot was, that after 8 runs, 5 good'uns, 3 aborted, our luck ran out and we ended up with no compression on the back cylinder and a crank slightly out of shape. So nothing really broke, no record still and no way to get more runs in 2013...

Back again in GB, I set a few goals for next year...

1) Better aero so the threshold between proper drive and wheel slip can be pushed further up the mph scale (we attained 121.775mph with a 135mph gearing and rpm...) On my best 121.775 run, I entered the 2nd mile at 118mph and it took a whole mile to get to 123 and a bit, it was just constant wheel spin whatever I did with the throttle...

Looked around on the net for various better fairings... really wanted a fully enclosed Harley alloy XRTT type as seen at Daytona in 1973/74 but prices of replicas are pretty steep in the USA, plus postage and customs to get it in GB...

So settle for the next best thing, and the one that probably inspired the Wixom Brothers that did the XRTT one, a red replica of the 1960 Peel Mountain Mile... The whole lot in 2 parts plus perspex screen for about $200.00. But no fittings or brackets...





Found a lady's bicycle at the breakers to pinch some lightweight tubing for all the new brackets... Then a few 1/4 turn Dzus kits on ebay

2) Better way to put power down on the Salt Flats, so installed the old shocks for a better ride on the salt and dumped the rigid struts on the shelves...





Sounds easy? It never is... Half the rear of the bike was hung off these rigid struts, so a multitude of other brackets to be done, some of them, like for the oil tank, pretty essential, not done yet!!!

That's it for today, see you at the next instalment...

Cheers from Patrick

[wobblywalrus]

Hi Patrick.  It is nice to see you are still in the game.

My bike was getting what I thought was wheel spin in the speed ranges you were running.  It was the clutch slipping just a little bit under peak power loads.  This showed up on the dyno runs as a culy-Q torque curve line at high rpm.  Some kevlar plates and stronger springs cured it and up to the 140 mph maximum I have been there have been no signs of either wheel spin or clutch slipping.  The bike hooks up and goes straight.

The shocks I use are some ones made in Australia with adjustable damping and spring preload.  The lightest damping setting resembles worn old shocks.  That was what I used for my first run with them and it was a day with rough salt.  The chassis bounced around a lot.  A rigid rear end would have been better, I thought.  The damping setting was increased to the maximum.  The rear end acted great during that second run.  The benefits of suspension were evident.  In summary, I learned that funky suspension is worse than none and good suspension is better than not having it.  It might be a good idea to check those old shocks to make sure they work.

That fairing looks great. - Bo   

[Stainless1]

10% slip at those speeds is a lot... I agree you should look at the clutch... I would also figure out how to add some weight.  Weight = Traction

[thefrenchowl]

Seems to be a concensus!!! I'll have another look at the clutch...

More brackets... carb:



Exhausts plus megaphones I had in the rafters for over 20 years...





Up to that stage, engine was left untouched... Started dismantling to check the rear cylinder... Nice blow torch effect...





Cylinder, valves and piston are not damaged, guess either a bolt got loose or a localized hot point did that. Certainly not lean with about 3/4 of a litre of methanol per mile...



Haven't decided what to do next, repair or find other heads... Most of the ones on eBay are cracked beyond the joke...

Bye, Patrick

[thefrenchowl]

Hi, speed freaks...

After a long conversation the other day with my old friend Neil, also in GB, he accepted to lend me a pair of K model billet heads he found some 20 years ago in Holland... They arrived today in the post, big, brashy and chunky... A bit of work needed to bring them up to specs, twin spark an'all, but the nice thing is they are about 3/4" thick at the minimum, we're on a winner here.

Plus we'll repair the sand cast OEM set, so spare parts as well...









Bye for now, Patrick

[bak189]

Anytime you think you are having clutch slipping problems.....................contact Barnett Tool and Eng. in Ventura, CA. USA................They have plates and complete clutches for new and OLD bikes....many combinations for Harley...new and old..........................

[Briz]

Wow! thats a right result Patrick! You wont break those!
Looks like one has had some shrapnel rattling around in there.

[wobblywalrus]

The denser billet will conduct heat better and it will be less susceptible to hot spots.  What sort of pistons are you using, cast, hypereutectic cast, or forged?

[thefrenchowl]

wobblywalrus:  What sort of pistons are you using, cast, hypereutectic cast, or forged?

The only sort you can find for a K model, cast alloy with a dose of silicium, sand/glass to you and me...

They don't look bad at all considering  ...



Patrick

[wobblywalrus]

The undersides of the piston can discolor due to oxidized oil.  Black is a sign of a lot of heat, brown less so, and no burnt oil means the crowns are cool.  Are there places under the crowns that are black or brown?

[thefrenchowl]

Can't hide nothing from you, my friend!!!

Yes, the front is OK but the back is a bit darker from burnt oil underneath... But no sign of really hot or start of collapsing.

I will up the carb jetting (again... ) and drill the oil hole in the cylinder bigger.

Was also thinking of reducing slightly the diameter of the flywheels, say 40 thou, to let more oil pass the scavenge scrapper (which is just between crank and gearbox cavities) and land in the rear cylinder...



These are pistons that have also about 3000 miles of road use, so not too sure if it's all Bonneville or if some is the road as well (I was, no joke..., doing flat out rides at 80mph average for a few hundred miles of GB highways with that bike, NA with twin carbs. Stopping every 60 miles or so due to Sportster small CH tank, but still, had guys in car and modern Harley TCs trying to follow me to no avail... 375lbs all in with gas and oil... Vintage, what vintage???)



Patrick

[wobblywalrus]

The rear seems to be running hot.  Look at the center electrodes of your plugs.  Part of the electrode towards the tip should be cleaner and shinier than the rest of the electrode.  Does the shinier area extend down further from the tip on the rear plug?

[thefrenchowl]

Hi wobblywalrus,



That's the spark plug nearest the disaster in the rear head. Center electrode is whitish, which I take as OK. It's not protuding by much over the ceramic insulation, so hard to gauge if different color away from edge.

Outer ring is about the same dark grey color as the rest of the combustion deposits elsewhere in the head... Earth electrode in between both colors...

These are racing NGKs, number 10 or 11, 3/4 reach with SS spacers on the outside, there's only 1/2 thread depth on the street K/KH head

Patrick

Patrick

[Briz]

The rear seems to be running hot.  Look at the center electrodes of your plugs.  Part of the electrode towards the tip should be cleaner and shinier than the rest of the electrode.  Does the shinier area extend down further from the tip on the rear plug?

HD rear cylinders always run hot!

[wobblywalrus]

I know, Briz.  What I am showing Patrick how to do is to cool it down a little without hurting performance.  Most of my experience is with the center cylinders on Jap triples, the inner cylinders on Jap fours, and the hotter running cylinders on other motors.  My figuring is the principles are the same.

Tonight I will look in my used plugs box and see if I can take a picture of the ring I am talking about.  It tells about the spark advance, at least on gasoline powered engines.  The rings should be the same distances down the center electrodes on both plugs if the spark leads are the same for both jugs.  A ring that is further down one electrode than the other indicates the timing is advanced in that cylinder.  That is something to check for and it is not uncommon.

The next thing to check is to put the pistons and cylinders back on and to check the deck heights on each cylinder at TDC.  A piston that projects up further than the other can cause problems.  This is also a good time to measure the bores and how far the pistons are from the decks at BDC.  The eroded head is reconstructed with modeling clay and all four heads are cc'ed, the head gaskets are measured and the static compression ratio is calculated for both cylinders with the old and new heads.  The measured compression ratio should not be higher for the back cylinder.

The measured ratios can be a real "eye opener" a lot of the time.

The last thing is to verify there are no air leaks in the plumbing, or constrictions, to the hot jug or other things that cause it to run leaner than the cooler one.  This does not apply here, but it is good to remember on two carb bikes with one carb in the back is the rear one can be sucking hotter air than the front one.  It is not unusual to have slightly different jetting on the front and rear carbs. 

At this stage any problems are corrected, and if needed, and I richen the mixture to the hot cyl and lower its compression until it cools down.  This is what I do, it seems to work, and I am no fancy engine tuner.  Tell me if I am wrong on anything or if there is a better way.