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Roebling Road 2020
#799216 02/24/20 1:00 pm
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Work almost got the better of my racing plans but finally was able to leave for the 5 hour drive to Savannah Friday afternoon. That meant missing Friday practice after almost 5 months off the track. Not an ideal way to start the season. Saturday morning temps were in the high 20's and I elected to skip the first practice session. By the time second session came around, it was in the low 40's so seeing as it would be my only chance to refamiliarize myself with the track, I got the Triumph started and headed out. Now, over the winter, I had some work done - a new dual plug head with some extensive porting. Made an almost 10% power bump on the dyno. So- I was anxious to see what it felt like on the track. It didn't disappoint, until on the second lap it dropped a cylinder at about 6500 rpm in 3rd to the sound of shattered aluminum. Coasted into the pit feeling shattered myself. An autopsy this week will most likely point to a total engine strip. Hopefully that head can be salvaged. Dropping a screwdriver into the plug holes showed a bottomless pit on the right side. First guess is that I had jetted on the smallish side and with the cold air (density) it got too lean.
The B 50 did good though. I got through the production lightweight pack and wound up on Alex McClain's tail for a few laps. Chasing a really good rider is the best schooling there is. Sunday, The B50 was kind of hard to start so I switched out the battery for a fully charged one. All good. Just leaving the pit for the warm up lap and it quit. A battery lead had come off and I couldn't get it back on in time so that was that. The officials agreed to let me run in heavyweight though.
Gridded for that race - I'm used to a multiple wave start, this was a single wave start - the pack left and I was on the start in neutral. SH*T....Nothing to do but try to make up time. The B50 isn't all that powerful but it seems to be able to carry a lot of corner speed and I was able to pick off the 3 back riders in the corners. The guy in second was on an RD 350 Yamaha. He out pulled me on the straight but I made up in the corners We had a good race for a couple of laps, I couldn't get by him until he went a little wide in a left, I think turn 7 and I dove inside of him and proceeded to further test the limits of the BSA. Didn't find them. Incredible. What a fun bike! Anyway, was able to hold him off and take 2nd to a 750 Triumph.
Good weekend spent with friends. Hopefully Semper Gumby chimes in.

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Re: Roebling Road 2020
Mike Baker #799231 02/24/20 5:26 pm
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Sorry to hear about that engine noise, that has to be so frustrating. I have no idea what your background is, so please don’t take offence to this.... You mentioned a new duel plug head with extensive porting. From that I assume the previous head was single plug? The reason I ask is I converted a cylinder head ( from a lesser brand) to duel plug. This one is just destined for street use, but I had several conversations with a couple of folks who race that have done the same mod on the same engine as mine ( antiquated hemi combustion chamber). Their dyno time showed that the advance had to be cranked wayyy back, because now you’re dealing with 2 flame fronts. I installed a programable ignition system along with an A/F gauge and wide band sensor to make it a little easier to dial in. I’m certainly no expert on the subject and a search of the inter webs didn’t reveal much discussion on the subject. Totally off topic, but in 2002 Honda had a duel plug system that controlled timing on each plug independently. It will be interesting to see what you find in there and hopefully there is enough left to tell you exactly what transpired.

Re: Roebling Road 2020
Mike Baker #799234 02/24/20 6:12 pm
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Great write up.
Could feel the cold bite my nostrils.


1970 T120R
1970 Commando
Re: Roebling Road 2020
Mike Baker #799276 02/25/20 3:18 am
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Got the top end off tonight. There is no piston on the right side. Nothing. It's in a thousand pieces in the sump. Only a steel rod and battered wrist pin. Never seen anything like it. The top of the rod shows it took a lot of heat. Didn't seem to be an intake leak. The Left side looks fine. Under piston and pin are completely normal. Doubt I'll find any clues in the pile of aluminum. But the top of the rod is saying something.

Last edited by Mike Baker; 02/25/20 3:19 am.
Re: Roebling Road 2020
Mike Baker #799308 02/25/20 1:12 pm
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Mike, Thanks for the report. My spectator budget was spent for California this year. I'm sure there will be some extensive head scratching with the motor. PRT
PS I can feel your pain!

Re: Roebling Road 2020
Mike Baker #799309 02/25/20 1:29 pm
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Mike,

Sorry to hear about your blown motor. I did the same thing with my B50 race bike that I had bought from a racer in Georgia who sold it to me as "ready to race". It took me lots of towing it up and down my Mom's 1/2 mile driveway before I could even get it started. I imported it into Nova Scotia, about 15 years ago, and started racing it at Shubenacadie. First time out I blew the motor, the Carrillo rod yanked the bottom out of the piston and drove the rod thru the barrel, but luckily not thru the cases. I could not identify the piston, but I believe it to have been a cast one not suitable for racing the long stroke motor.

I did race it in AHRMA at Miller in 2009 thru about 2011 in "Sportsman" class, but never got good enough to finish better than mid-pack with a best of 3rd place at Sandia (last AHRMA race at Sandia). I considered converting the bike to "Historic Production" but it was too heavily modified to do so - - aluminum rims, CNC top triple with no handlebar mounts, carb too big, exhaust too big, etc. I note in the newest AHRMA rulebook that I have (2016) that even the fenders and seat must be OEM.

So how strict are they about things like OEM mufflers, fenders, seats, etc.? Can you run a 32mm AMAL (or Mikuni), as the MX B50's used the 32mm AMAL? Do you run the original box muffler or can you use a more standard smaller unit like the unobtainable MX style? I still miss the thrill of road racing.

Tom


Life's uncertain - go fast now!
Re: Roebling Road 2020
Mike Baker #799618 02/29/20 12:34 pm
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Hey Tom
Things seem to be fairly relaxed regarding the rules. I don't have a front fender and nobody has said anything. Very few bikes have stock mufflers although most have stock pipes. I have a Cone muffler on a stock pipe, seat is stock, I have rearsets and a 32mm AMAL. The bike is a MX, they came with a 32. According to the man who owns the bike, the motor has never been apart.
Looking at the 650 critically now that I'm beyond the stage of denial, It suffered a classic 4 point seizure. The evidence is clear. The question is why. I took apart the carb and cleaned everything last night and all looked good there. Both petcocks on the tank flowed well. The only thing I can come up with is perhaps the fuel line got kinked somehow. It has happened in the past with that soft blue line if everything isn't routed properly. I have 1 line each tap to each carb. Time will be spent assuring flow when this gets back together. All this said, I'm still amazed that the piston completely disintegrated as it did.

Re: Roebling Road 2020
Mike Baker #799619 02/29/20 12:38 pm
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And PRT- I'm planning on being at New Jersey this year. Hopefully there's enough left in your budget for that!

Re: Roebling Road 2020
Mike Baker #799820 03/02/20 2:43 pm
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Yep I’m here: the lone survivor in the Classic 60’s 650 class.

The bike is in the shed. I’ve got video of Mike on the back curves. And some nice pics. This time the bike just ran and ran. Sometimes the turtle wins. I just did general stuff like make sure there was oil in the right places inside the motor and tank. I have rear sets on the bike now and the riding position was completely alien to me.

The slash pipes and rear sets kept me from dragging anything. My one issue was the clutch slipping a bit coming on to the main straight. So there is a Bob Newby in a box on the floor. The west coast oil tank had another hairline crack around the mounting bung on the back. Pig mat kept the seep at bay. I’m going to come up with a different mounting system since the warranty on this Faulty design has long since expired.

And the oil cap leaks. WTF?! Beno suggested welding a screw top on it which I think I’m going to do unless somebody has a solution to twist on BSA Oil cap leaking?!

Thanks to Mike who brought a small electric heater for me in the UHaul. Friday and Saturday morning was 29’F.

I got to some familiar faces again: Great to see Tom Sanders!!

Super weekend.

Last edited by Semper Gumby; 03/02/20 2:49 pm.

"Don't trust your eyes if your imagination is out of focus." - Mark Twain
Re: Roebling Road 2020
Semper Gumby #799825 03/02/20 3:24 pm
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oil cap: a rubber expando plug from the car or marine industry?

Re: Roebling Road 2020
bodine031 #799831 03/02/20 4:47 pm
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Originally Posted by bodine031
oil cap: a rubber expando plug from the car or marine industry?


Got link? I like this idea. With a wing nut in the center?

I really good at safety wiring just about anything now because of this obsession.

You mean something like this??

https://www.amazon.com/Spectre-Perf...mp;psc=1&refRID=QA9KR14WV2FPM0920Y63

home depot!!!

. https://www.homedepot.com/p/Oatey-1-1-2-in-Gripper-Plastic-Mechanical-Test-Plug-33400/100342630


Last edited by Semper Gumby; 03/02/20 5:12 pm.

"Don't trust your eyes if your imagination is out of focus." - Mark Twain
Re: Roebling Road 2020
Mike Baker #799840 03/02/20 6:46 pm
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1970 T120R
1970 Commando
Re: Roebling Road 2020
Hugh Jorgen #799860 03/02/20 10:25 pm
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Got the gripper from Home Depot but I ordered your plug Hugh. It looks like it has a lower height and since the thing already sticks into my leg I may want a lower profile option.


"Don't trust your eyes if your imagination is out of focus." - Mark Twain
Re: Roebling Road 2020
Mike Baker #799906 03/03/20 12:28 pm
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Gumpy, Keeper of the BSA A-65 at AHRMA!! PRT

Re: Roebling Road 2020
Semper Gumby #799914 03/03/20 3:35 pm
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Originally Posted by Semper Gumby
... I ordered your plug Hugh. It looks like it has a lower height and since the thing already sticks into my leg I may want a lower profile option.
A bilge plug on a BSA.
Say no more. smile


1970 T120R
1970 Commando
Re: Roebling Road 2020
Hugh Jorgen #799922 03/03/20 4:07 pm
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Originally Posted by Hugh Jorgen
Originally Posted by Semper Gumby
... I ordered your plug Hugh. It looks like it has a lower height and since the thing already sticks into my leg I may want a lower profile option.
A bilge plug on a BSA.
Say no more. smile


Hey if it works and look - it’s already got a hole on the end of the lever for Safety Wire. WOOT! Where are my pliers?

Last edited by Semper Gumby; 03/03/20 4:07 pm.

"Don't trust your eyes if your imagination is out of focus." - Mark Twain
Re: Roebling Road 2020
Semper Gumby #799926 03/03/20 4:54 pm
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My local Boathouse Marine has them with the wingding. Rubber freeze plugs automotive with nut to tighten

Re: Roebling Road 2020
Mike Baker #799951 03/03/20 7:57 pm
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Mike, you were using MAP pistons? They are the newest ones with a different alloy? Probably detonation related......I had a 4 corner seizure on a MAP piston on my dual Triumph engine LSR bike but it didn,t stick so bad the piston pin broke loose. Likely case was slightly out of spec race fuel....


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: Roebling Road 2020
Mike Baker #800014 03/04/20 11:19 am
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I'm not going to name the piston here until I have a chance to speak to XXXX. You're right in that there was a detonation event. The cause is not clear to me, though. I've been using 100LL avgas for 3 years in this bike with no issues other than some lead deposits. One of the reasons I use it is it's supposed "shelf life". I never researched that for myself and will do that before using it again. But.... the left side was perfect when the right side went. So fuel? I might put fuel towards the bottom of the list.
What still amazes me is the total deconstruction of the piston. The amount of powder consistency aluminum that I'm cleaning out is incredible. Like it came apart on a molecular level.

Re: Roebling Road 2020
Mike Baker #800016 03/04/20 12:16 pm
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Generally speaking,pistons can tolerate some detonation,forged better than cast..You might want to read Kevin Cameron's recent article on racing fuel and aviation fuel and how it changes when stored..


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: Roebling Road 2020
Mike Baker #800018 03/04/20 1:59 pm
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If the one piston that came apart did not have enough clearance between top of piston and the combustion chamber the piston may have be " kissing" the head at high rpm due to the flex in the crankshaft. When a piston 'kisses" the head it generates a tremendous amount of heat much like how a nail head gets hot when you drive it in with a hammer. This heat can lead to detonation and cause the piston to expand more than normal leading to seizure. It may be hard to tell if the piston was hitting the head after the piston came apart but I would check it out.

Re: Roebling Road 2020
Mike Baker #800077 03/05/20 2:07 am
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These pistons are (were) billet. In a sense cast but certainly not forged. They may be suitable for street use but I won't put them back in a race bike.
Keith, You could be on to something. When assembling this motor, I had almost no clearance intake valve to piston on both sides. I had 60 thou removed from the valve pocket and the good side still showed the valve made minor contact there. So I cannot rule out crank flex. And if the case deck isn't parallel to the crank by another couple thou...... Stacking up a few here and a few there and all of the sudden everything's out of kilter.

I couldn't find the KC article you mentioned, Tony. Do you have a link?

I'm going to race at Kershaw next month. I have a good running 71 motor that doesn't see much use anymore. Stock compression with a T140 intake cam. It'll keep me on the track until I can spend the time it takes to make the race motor right. It may also force me to ride better which isn't all bad.

Re: Roebling Road 2020
Mike Baker #800109 03/05/20 1:16 pm
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Mike, the Cameron article is in the latest issue of Vintage Bike. If your pistons are the hypereutechic alloy,they are very good but are more likely to shatter from detonation or physical contact compared to forged pistons


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: Roebling Road 2020
Mike Baker #800155 03/05/20 8:52 pm
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VB Vol.2017 #1 Feb.7,2020

Re: Roebling Road 2020
Mike Baker #800616 03/10/20 10:58 am
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VB arrived in the mail over the weekend. The fuel was left over from Barber, 5 months ago. I'll bet it'll work great in the lawnmower this spring.
Motor swap this week.....

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