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Discussion Starter · #1 ·
Apologies in advance if this gets a bit disjointed. The pics are scattered all over multiple drives and files and hard to organize. A couple of you expressed interest in my Bonneville racing TR25W, so here's a little taste of it.

Early on, just starting to envision what I wanted to build and how I wanted it to work. Working with stuff laying around in the scrap piles as much as possible, LOL.
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Had to finish up this Sporty chop before I could start actually building the race bike. (Required on topic content.)

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More in the next post.
 

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Discussion Starter · #2 ·
After getting the Sporty out of the way,
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Made up a quick sketch as a guide to the plan.

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I started cutting, bending, and welding to make something to support the engine and myself as we raced toward our demise across the salt.

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The backbone and center downtube are pieces of a 5" semi truck driveshaft, fuel in the backbone and oil in the downtube. Seemed like the way to go given the materials on hand.

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Discussion Starter · #4 ·
Modified some sprockets to get an assortment of ratios and made a hub adapter to fit them to the rear wheel.
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I bought an old, pre-rotted van as a racing support vehicle, loaded up and headed to the salt. The engine had never started before unloading at Bonneville, but a couple of hours of tweaking on it and it fired right up and sounded strong.

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The first time it moved under its own power. I was pleasantly surprised at how well it actually worked!

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The mandatory "glamor shot" of the team bikes, before the mayhem began. The green one was Tucker's ride. It ran in stock frame class, I was running special construction.

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Discussion Starter · #5 ·
On the line, ready to launch for my first pass. Plan was to make it an easy shake down and break in pass just to make sure everything was right.

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What is it they say about plans??? The course is a 5 mile strip, 2 miles from the start line to the start of the timed mile. I feathered it easy for about the first 1 1/2 miles and it was feeling really strong. I abandoned the plan and wicked it up and it pulled strong into the trap. About 1/2 way through, I realized that the noise had stopped, and then wondered why I was going sideways! Pulled the clutch and it straightened back out, but the engine had seized. Rookie mistake. Put a fork in it, it's done.

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We didn't come all this way to just quit. I had a spare piston, but no spare jugs, and I had just successfully welded pistonium to the cast iron cylinder liner. Went to Wendover and found some muriatic acid at the hardware store. Boiled the aluminum out of the liner, and then had to do some precision machining (Bonneville style) to smooth out the scars in the cylinder from the rings.

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Yes, really.

It actually did run and make a couple of full passes after reassembly. Enough to qualify and back up the record for the class (which was open, so all that was required was to complete passes). We won't discuss the pathetic speeds, but it was still a record. We had gone to Bonneville and made passes. Mission accomplished. Much fun had.

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Well, your bike deserves to hold the record for something. I mean, uh ... I like the color, and ...

Cool. I'm definitely still interested, sick soul that I am. You mentioned big modifications inside the engine, didn't you? Want to know more about those, unless you decline to give away secrets to the legions of hypercompetitive rivals and copycats who are building LSR TR25s. Thanks for the pics.
 

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Discussion Starter · #10 ·
Well, your bike deserves to hold the record for something. I mean, uh ... I like the color, and ...

Cool. I'm definitely still interested, sick soul that I am. You mentioned big modifications inside the engine, didn't you? Want to know more about those, unless you decline to give away secrets to the legions of hypercompetitive rivals and copycats who are building LSR TR25s. Thanks for the pics.
Well, it wasn't built to any standard of beauty. Pure form = function, factoring in the available materials to keep costs down. The internal engine stuff is all pretty much standard racing fare, titanium valves and spring retainers/keepers, stiff springs, sludge trap elimination, welded and balanced crank assy, Carrillo rod, custom stock bore 14:1 compression pistons from EV, careful cam selection and timing, oiling modifications, total loss electrical system to eliminate drag from the alternator, trying various carbs to find what worked best, yada yada yada. Mostly trying to optimize the engine to repeatedly run 3 miles at over 10,000 RPM. I kept getting seizures, and when I would take the engine apart the piston would be literally dripping with oil and still wiped out. I eventually (after a few years of fighting it) got it to run reliably without locking up by turning the piston down on the lathe to get .010 cylinder wall clearance and opening up the rings gaps to .040. (Couldn't bore the cylinder larger without going over class displacement limit.)
 

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I hope I gave no offense. Plenty of competition (and other) bikes look ... not that elegant under their slick sleek bodywork.

Sludge trap elimination? Say more if your patience allows.
 

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Great Fun
What sort of speeds were you hoping for?
 

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Discussion Starter · #14 ·
I hope I gave no offense. Plenty of competition (and other) bikes look ... not that elegant under their slick sleek bodywork.

Sludge trap elimination? Say more if your patience allows.
The crank assemblies in these engines are a forged/machined crank with flywheels bolted around it on both sides of the rod journal. The oil passage to the rod is drilled such that it goes through the bolted on weight. The sludge trap is a cavity machined into the inside of the weight to collect any debris. Filling the cavity to eliminate it, and making a smaller passage for the oil to flow through improves reliable oiling to the rod. Any gap between the weight and the crank will result in loss of oil pressure to the rod as well, and high revs can cause the weights to come loose, so welding the weights after eliminating the trap, and then carefully balancing the assembly, addresses these possible issues.
 

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Hello; more than 10000RPM? man I broken a T140 crank that seems previous owner put it with more than 8000RPM
and is a road bike...
The frame that you made is not too heavy for that engine? or is lighter than the other frame that you showed?
Did you found what was the seizing problem? the cause I mean.
Is it possible to fit a T140 camshafts in this BSA/Triumph engine?

Thanks
 

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WB, I never said thanks for your explanation about eliminating the trap. (In fact, thanks for this swell thread.)

If it isn't a hopelessly stupid question: What do you fill the sludge trap cavity with? Did you turn a plug, press it in, tack it around the visible end, and cross-drill it, using the existing crankhole as a pilot? If (somewhat) so, what material for the plug?

Reverb's post reminded me: You mentioned careful selection of cams. Are many racing cams available for your engine? Will a B50 cam fit, with or w/o modifications? Can/do you buy appropriately dimensioned blanks and make your own profiles?
 
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