Landracing Forum
Bonneville Salt Flats Discussion => Build Diaries => Topic started by: Bruin on March 15, 2010, 02:27:43 AM
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We ran four bikes in '09, plan to do the same in '10. Ed got a record on his Trump 250, Harry made some feeler runs on his Suki 250, Tucker bettered her speed but her Trump 250 crapped out before she could back it up. I ran better than expected on a stock engine '82 XR 500 at just under 102 mph then blew the engine. But I just dusted them off and the prep for '10 has begun!
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In '09 my '82 Honda XR 500cc engine failed on the last run of the last day at about 100mph. KS finally warmed up enough for me to venture into the garage and take a look-see. It seems the piston siezed, the pin that holds it to the rod broke free of it and tore up the lower cylinder and beat the bottom of the piston into an unrecognizable mass. The valves smacked the top of the piston as well. Pin=trashed, Piston=trashed, Cylinder=trashed. Valves and rod need further assessment. If you don't break it, you aren't trying. I tried. ~Brian
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Do you think it seized from running lean or did it overheat? Do you run an oil cooler?
What will you do different with the engine rebuild?
Regardless, it sounds like you had fun and are making plans to return.
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Had a ton of fun and will be back. The plug was not reading particularly lean. The engine did not radiate heat like it was cooking though I do house it behind a wind cowling. No obvious symptoms beyond running it above redline and pegging it. No oil cooler... yet. An oil cooler, no cowling, and maybe a little two stroke oil in the gas are under consideration.
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Bruin,
It has been many years since I ran bikes... But love the old Honda "Thumpers".... you SHOULD run as big an oil cooler as you can for the extra oil capacity and the cooling. You should also make sure that you can get some forced AIR to cool the cylinder and head. If you keep a cowl or fairing,, OK,, just duct some air to that area.
Good Luck,
Charles
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doesnt look like the piston stuck bad enough to break the wrist pin out of the piston... the underside or the piston definately doesnt show enough heat to melt i think you siezed the wristpin.... it usually happens when the wrist pin is too tight on a lsr motor.... the piston swells due to heat, seizes the pin, then cracks the piston.... in this case it looks like the wrist pin area of the piston broke... any other piston srapnell in the case we can look at?
you wann see a stuck piston go ahead and add some oil to your gas..!...lolololol.... go ahead and mix her really slippery at lets see something like 20 to 1.....lololo.... let us know how that works for ya...
yours in sport
Kent
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I would not put any two stroke oil in the gas of that XR 500....
Just get an oil cooler and air flow to the head and cylinder areas.
Like Kent said. you could loosen the tolerances a bit on the wrist pin.
Keep us posted.
Charles
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Thanks for the tips. I'l ditch the cowling and hold the fuel oil. Not sure how to rig an oil cooler on a wet sump. I'l have to look it up. The wrist pin itself didn't look scortched but I have not cracked the case yet to look at the debrie. The piston fell out of the cylinder easy enough and there wasn't the kind of galling you see when a cylinder siezes up good. Clues point to the pin as you said. However, the engine was run completely old stock with worn everything. Tolerences were loose, even smoked a bit.
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Bruin,
I am not sure, but I think the Honda XR600's and XL's as well may have had an external remote oil cooler,,, you can see how they where plumbed in and use one of them.
I am not sure with the wet clutches if you can use Snthetic Oil ? That may help too. I just can't recall if the older Honda wet clutch would be OK with new synthetics ??
Charles
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You could run a Barrnett clutch with a synthetic oil. Talk to some of the old desert racers that ran XRs, they used to run them wide open across the flats for miles.
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We had lots of wrist pin problems at first with our Turbo/Kaw. due to heat..........solve the problem with the best oil for racing....."old School" BEAN OIL......hard to find.....better than Synthetic and will work fine with a Barnett clutch...........bean oil can make for a dirty engine and will not hold water....so you have to drain it out when the engine is still hot..........but it will lube under extreme heat......put some of the new
fancy oils in a frying pan on the stove, turn on the heat and see where the oil run to......the sides......
use bean oil, it stays on the heat...................Hey, but then I am at 73 "Old School" myself so what do I know!!!!!!!!!!!!
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The picture shows a partial seizure on the Triumph gudgeon pin. I pulled the engine down this winter. The seizure was between the pin and the small end rod bearing.
I am one lucky dude. A full seizure with everything breaking apart would cost big $. Barrels cost $1,465, cases cost $4,265, a crank is $891, etc.
South Bay Triumph in Lomitas, Calif. has a lot of experience with land speed. They sold me a set of pistons and they strongly recommended that the pistons and pins be coated, and they did this. It is a teflon coating, as I recall. If you call them, ask for Matt or Carlos. They know the details.
The new triumphs have oil radiators and two oil pumps. One pump sqiurts oil directly under the pistons to cool them, like a Suzuki. I was running a good quality oil, so lack of lube was not a problem. The pistons have some minor scuffing with the classic pattern one gets when running a cold engine hard. The pistons heat up and expand faster than the cylinder expands.
Drag racers run cold engines very hard. Maybe one of them on this website will know about this problem.
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I've heard about coatings but our budget is tight. You wanna see a bad wrist pin... this is the suspected culprit.
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I've heard about coatings but our budget is tight. You wanna see a bad wrist pin... this is the suspected culprit.
Wimp, that'll buff right out.
Time to tear into the spare engine and start getting it ready.
When do we get to see what's going on inside Tucker's 250?
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Ed, what is the stroke and rod length on the Honda? Were you using the Honda piston or a forged one?
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Bak189 is right. Good ol' Castrol R40 (or Oilzall, more readily available) will keep an engine alive a lot better than regular motor oil. And you definitely need an airflow across the engine. I run an old Weslake in my sidecar. It has about as many fins as a small goldfish. I run Oilzall, an extra .0015 clearance on the piston and a lot of air over the engine. I have two big scoops and deflectors to make sure. It works just fine.
(http://img183.imageshack.us/img183/737/img026h.jpg)
By weslake (http://profile.imageshack.us/user/weslake) at 2009-09-19]
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Bruin here, concerning the Honda rod stroke and length, I don't have the manual in front of me but we ran the engine 100% stock. So whatever the factory put in is what we ran. Thanks for the oil tip.
Ed, Tuckers 250 is waiting line, I'm trying to time the BSA Lightning, get clutch plates on the B-50 and get her pit bike working. But I hope to pull her head by this weekend.
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Gotta love the old parts bin. I found a spare piston and cylinder in the pile that might make my repair affordable. If the wrist end of the crank isn't brutalized too much all I need to do is muck out the case. Maybe I can just reverse my wind shedding cowling and make it into a wind gathering scoop? LOL Where does one find those fancy oils?
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I think you'd be wise to install a piston oiler. Many of the V-twin Hondas have them, to keep the bottom side of the piston crown cooled down. The wrist pin was lubed by the oil dropped off the ribs, but if the crown temp is high enough to vaporize the oil, there will be no lube on the wrist pin.
The oil squirter cures that AND prevents detonation. Mine are just small metal tubes with a tiny jet sized orifice, below the bottom of the cylinder liner....hits the bottom of the crown at BDC of the stroke.
Regards, JimL
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The Triumph has a similar piston pin problem. Fortunately it was a partial seizure. The various things I will do to prevent it from happening again are as follows. 1) teflon coated piston pin 2) a bronze bushing on the rod small end bearing (dissimilar metals) 3) honing the bronze bushing to exactly the correct racing clearance. This is a little bit more than the standard clearance.
The Triumph has oil squirters under the pistons and they do help. The extra oil probably kept the partial pin seizure from being a complete disaster.
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Oooo, the squirter sounds interesting. Our team has a couple TR25s that might benefit as well as my Honda. How expensive and how involved are they to install? Should I just google "Triumph/Honda Piston squirter" or might you have a reliable source you can recommend? Thanks for the tips.
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I'll take a pic of one of mine, this weekend, and put it on here. It's just a small metal tube off of an oil line (tube is about 1/8", end smashed shut, top drilled with a hole about .020"). I'm going to rework mine, because they were originally mounted in the primary drive covers, with the tube sticking through a small hole drilled in the side of the main bearing web in the crankcase.
I've made my own primary cover, so I have to change the oiler setup.
More to come,
JimL
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Here is a piece of advice I got from another site. Whatcha think?
"Drill hole in rocker cover near cam, right side,weld nut in cover,tap tread for oil line screw. Oil line going to clutch cover,drill and tap where oil pressure coming from oil pump in cover. Feeding more oil to the head,that's the way."
I wish he had a picture...
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The Triumph came from the factory with them installed. They did the smart thinking, not me. Tonight I will post something about the pin problem on the team Go Dog Go build diary.
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I needed to clear the on-deck circle before I could settle into what promises to be extensive rebuilds of the Bonneville racers. But I can report progress has been made. The '70 Triumph B-50 is thumping to beat the band and the '66 BSA Lightning is cracking thunder. Now the real work begins...
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Great looking British bikes. :cheers:
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Great looking BSA.......I like the oil-filter........I don't like the carbs........
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Finally got around to swapping out the toasted engine for the spare eBay special. The only problem is that the team's Honda mechanic felt that the spare's connecting rod was a little loose on the crank for stressed running. We'll fire it up and see how much it rattles. I had replaced the old XR engine's reeds with a duckbill collar to help it breath but the spare's head is an XL model built without reeds as part of the intake so maybe it will flow better.
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The new-old eBay engine was leaking oil like an uncapped sea well. It was hard to tell if it was the gasket, the bolt hole, or a crack. I dusted it with flour and looked for the wet spot. Bingo, it was a hairline crack. It was bigger on the inside than outside. I cut a groove into the crack with a dremil tool and patched it with JB Weld.
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JB weld is good, got some on my cases.
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When we (Mostly Ed) constructed the bike the accent was on strength, simplicity, and git-er-done. Now that I have time to revisit I am trying to shave a few pounds off it. The rear fender was a large piece of steel that served as fender, tank support and chain guard. Very effective but weighty. I replaced it with a small steel tank brace, a minimum plastic fender and an aluminum chain guard. (All that is enclosed in a rear streamline fairing.)
The enclosed chain guard-tensioner was sandwiched in steel so I cut some panels out of it and used some balistic tough polycarbinate for an adjustment monitor window on the inner-back side. (The front, leg side, has a steel screen.)
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I pulled the head off Tucker's LSR, a '70 Triumph 250. It actually looked pretty good. I did my first valve lap job with a spring compressor I made from an old C-clamp and a 1" socket. Not fancy or fine but it worked. There was a learning curve, keeping the collar halves in place during installation with a little grease as glue helped. Anyway her engine is buttoned up now and I can get back to the 500 thumper, the Big Red One.
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I boxed and weighed everything I trimmed off my 500 APS . The bike is now 22 lbs lighter.
I built a new chest bolster for it, compared to the nard busting, sternum cracking 1/4" padded original, 3 inches of foam is like laying on a cloud.
My wife struggles mightly to kickstart her 250 MPG with its 12:1 compression so Ed found her a through the spark plug compression release gadget.
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My XR 500 suffered a catastrophic seizure last year due to an engine cowling/fairing that was just a bit too efficient. I cannibalized the cowling to let air get to the air cooled engine and thought I might go one better. I made some air scoops that I just might attach if the ambient temperature starts getting too deserty.
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Salt clogging the fins can be an issue, too.
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Indeed, I have seen the salt clog fins and turn into concrete. I will be running the same front fender as you see in my ID picture, worked pretty good last year.
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When the big stuff is done you turn to the little things to kill time untill race day.
I hung a small leather tool bag on the lower part of rear fender to carry kickstand zip ties, snips and goggle wipes.
Rigged an easy on/off spring to insure the kickstart arm stays folded in.
Zipped the wire harness and applied a hose clamp so that the weight of the throat and filter doesn't hang on the spigot stlye carburator manifold.
Made an alternate front fender. The original steel one is more aerodynamic with ears that shield the fork tubes but the fiberglass alternate saves 8 lbs according to the bathroom scale. (That seems a heavy read.) I plan to run both and compare times.
Race day better get here soon before I do something really foolish. See ya at BUBs Bonneville play day!