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Re: trackbike [Re: kevin roberts] #721619 01/10/18 11:57 am
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Hillbilly bike Online Content
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I set it back to 37 degrees based on the assumption the MAP piston design gives a faster burn rate and previously it was over advanced .....You know, the combustion must be complete by 16 degrees ATDC for best power..The best the 32MM Amals ran was 120 mph with a stock head..I never jetted them on the dyno..I believe the #280 main jets were too rich....After I had the head massaged by Rob Hall and he recommended the Mikuni 34MM TM's, the bike went on the dyno for about two hours where only the jetting was changed...A total of 8 runs...Then the bike ran 125 at Ohio, 127 in Maine and with a few inches chopped off the exhaust pipes three inches, changed cam timing and different gearing and fuel tank ran 133 at Maine..no other tuning was done,


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
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Re: trackbike [Re: kevin roberts] #721623 01/10/18 1:15 pm
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you know, i did fifty airstrip runs picking needle jets, needles, main jets, and ignition timing on my morgo to get 117 mph.

which gods do you sacrifice to?


every day you do not take a chance is a day of your life that you will never get back.
Re: trackbike [Re: kevin roberts] #721625 01/10/18 1:36 pm
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Originally Posted by kevin roberts
you know, i did fifty airstrip runs picking needle jets, needles, main jets, and ignition timing on my morgo to get 117 mph.

which gods do you sacrifice to?


LOL...Superflow Dyno god...........The Mikuni 34MM flat slides come with #280 mains I believe.....I asked here if anyone had jetting clues...Pushrod Tom said TM's on his BSA use 210-240 jets depending on conditions...I showed up at the dyno with 210-250 main jets....the first run with the stock jetting was far too rich but none of that "8 stroking" guys often mention...I looked at the dyno operator and said " how about 220's ?. (he has years of experience running bikes and sleds on his dyno.) Ran the bike with 220's... power dropped slightly with 210's or 230's.....Ohio and the first trip to Maine was 220's..I changed the jets to 230's for the "worlds fastest 650 Triumph stock frame" at Maine last year before the racing figuring the loading at higher speeds might be better with a slightly richer mixture....
I also believe the guy who rides my bike is one of the best LSR riders out there...At 133 mph he's posting like a race horse jockey (full weight on his legs ,his ass slightly lifted off the seat) to get his back in the best profile for least air drag...


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: trackbike [Re: kevin roberts] #721626 01/10/18 1:55 pm
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i refuse to believe that your bike is fast because of your rider. that's just got to be b ullshit. he can't be that good.

can he?

but this whole butt-up-in-the-air thing is weird, anyway. the bonneville people swear by it, but they can't agree whether it's because of the slipstream closure past the rider's ass or whether it's because of the air running between his legs. and who can afford a wind tunnel to find out? youtube has almost nothing useful with wind tunnel stuff.

but i'm reinforcing the footpegs on my machine anyway so i won't be afraid to stand up and fart my way through the lights, too.


every day you do not take a chance is a day of your life that you will never get back.
Re: trackbike [Re: kevin roberts] #721635 01/10/18 5:03 pm
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Hillbilly bike Online Content
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I have to give him some credit.....There's no way an engine built by a retired electrician who hand cut piston valve reliefs while the piston was still in the engine and honed the cylinders holding them between my legs using a hand held drill could make enough power.........Right? wink


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: trackbike [Re: Hillbilly bike] #721656 01/10/18 9:14 pm
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Originally Posted by Hillbilly bike
I have to give him some credit.....There's no way an engine built by a retired electrician who hand cut piston valve reliefs while the piston was still in the engine and honed the cylinders holding them between my legs using a hand held drill could make enough power.........Right? wink


Burt Munro didn’t have those luxuries haha


beerchug
Re: trackbike [Re: kevin roberts] #764993 02/09/19 9:49 pm
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lift is empty so the trackbike stuff is getting laid out, looking for what i don't have. forks first:

[Linked Image]

i looked and looked, and said, what did i do with the shuttle valve restrictors? looked all over the shop, couldn't find them. so i ordered new ones, bolts too. one of these days i'll clean up and assemble a whole nother motorcycle from all the stuff i've lost in here.

the rest of the machine is mostly there:

[Linked Image]

don't think i need anything structural. just steering stem and wheel bearings, i think. cables too, unless i have some kicking around with the shuttle valve restrictors.


every day you do not take a chance is a day of your life that you will never get back.
Re: trackbike [Re: kevin roberts] #767055 03/03/19 8:40 pm
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Big Al Offline
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FYI, I raced a T140 in the Production class for 10 yr with AHRMA with a kicker. The couple times I was asked about it, I said because I couldn't push start it.
Never a problem. Yes ,a bungee loop or inner tube rubber band stay to secure it against the frame.

Last edited by Big Al; 03/03/19 8:41 pm.
Re: trackbike [Re: kevin roberts] #767063 03/03/19 9:35 pm
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got to put stuff together for a roller pretty soon. it might be push-start machine, as i'm not going nuts on the tuning. my LSR T120 won't push start at all.


every day you do not take a chance is a day of your life that you will never get back.
Re: trackbike [Re: kevin roberts] #767301 03/06/19 12:20 am
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As an alternative, I used on my Sportsman 750 with 11.5 pistons, a really neat little fix I got from another racer--he machined the protruding end of the kickstarter shaft into an 11/16 Hex (if memory serves me accurately), and then welded a black impact socket onto the bottom end of the kickstarter. Just plug it onto the shaft, kick start it, then reach down and pull it off. 1000 time better than leaving the nut off the pin and trying to pull the piin out after you start it, and actually also better than starting on rollers too.

That bike would not easily bump start and it was touch and go on rollers, if you could find them, the lawn mower engine-powered rollers were best, better than the electric ones which often wouldn't spin fast enough or hard enough. It takes a certain technique, shall we say, to kick start something with that kind of compression, but it kick started quite well once understood. FWIW.

But if you can get away with leaving the kicker on (remember, this is a safety rule), and you don't mind hitting it with your leg on the bike, well, that is even easier.

Re: trackbike [Re: kevin roberts] #767309 03/06/19 2:18 am
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i'd rather keep the kickstart, just because it's vastly more convenient to start a machine that kicks than one that doesn't. i intend to run this thing around the local track day circuits, and so starting it away from the trailer is a must. your idea of a quick-detach lever is one that i might copy.

i had to remove the kickstart from my LSR machine because of clearance issues with the shift lever, which was a drag. it was an easy kicker, even with fixed timing, but wouldn't bump start at all. now i use an electric hand-held on that. but the more junk you have to cart around from pits to the starting line, the more trouble it all is. the solution to that problem wasn't elegant, but worked very well:

[Linked Image]

i've got to take the jugs for that bike to the machine shop tomorrow, but when i get back i'll start bolting the trackbike frame together and see about the forks.


every day you do not take a chance is a day of your life that you will never get back.
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