Landracing Forum
Tech Information => Technical Discussion => Topic started by: racer x on August 03, 2009, 12:01:35 AM
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Hello all
I have bin tuning my bike with the seat of the pants method.Or the old plug chop method. Then a year of trial and error racing the mile at Maxton. Then drag racing the 1/4 mile . All with OK results. Now I have enough stuff to adjust that I need help .
I have an assortment of carb jets and filter or velocity stacks.
Plus three exhaust systems with five different levels of back pressure .
A custom made ignition system that I can adjust the timing along 30 points
I have adjustable cam sprockets
different gears for the back wheel and two different tire sizes.
And I can use a 1 pint fuel tank on the dyno to test different octane fuels.
I have the bike running better than ever but want to be sure it is set up as well as it can be. So I have scheduled a day at the dyno . Dose anyone have any general advice for going to the dyno . I will figure out the bike part . But just want to get the most from my time. Thanks
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Try to tune for right after the shifts and what you think you can PULL in the last gear!!!!!!!!!!!111
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Lots of people break parts at the 2-3 mile point on the course, if they dyno can sustain a load, hold the engine under full load long enough to determine if you have a safe tune down track after some heat has built up. A tune that is safe in a 20 second dyno pull might melt your pistons at the 3.
Larry
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I only have to run a mile but I get your point . I will leave the load on the bike for the time it takes to run the mile . maybe a couple seconds more for safety .
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A lot of good information in "Dyno Testing and Tuning" by Harold Betes and Bill Hancock. ISBN 978-1-932494-49-5.
I found it well worth the purchase, have and continue to learn a lot from it.
Ed Purinton
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Сool!!! :-D
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I'm sure I don't have to say it but just in case.
Since you have all day only make one change at a time. After the change I'd make two pulls. First a full run through the gears at wide open throttle in each gear and chop the throttle at max RPMs. Second run, on the same setup, would be a slow run up through the gears and a hard roll-on in top gear to max RPMs.
After the runs check the top gear peak HP and torque locations (rpm range) on of each run sheets. If there are big differences in the peak HP (more than 5 HP) between the runs you might want to start looking at the cam timing.
My two cents worth...cam timing, ignition timing are going to be where you can pickup or loose noticeable amounts of HP and torque.
Depending on the induction system (blow through or draw and Injection or carb) exhaust would be the last thing I'll deal with. As far as the rear wheel unless there's a substantial weight difference or circumference difference I'd leave that till last on the list.
Let us know how the tuning turns out.
Buzz
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My Hinckley Triumph Bonneville has a worn cam chain. The cam trails several degrees behind where it should be. Usually I wind the engine tight in each gear and I shift at high rpm. I rode on the big white dyno a few weeks ago. I rode real conservative so I would save the cam chain. As little time as possible at full chat. At the 2.5 mile mark I was halfway to max rpm in top gear and at half throttle. Then I got down on the tank and wound it tight. At the 3 mile mark I was at top speed.
The bike worked really well. Better than ever. Is this to be expected for a lagging cam? Is a lagging cam a good thing for top end power?
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an "all gear" dyno pass is only for impressing your buddies with bigger numbers...... "roll ons" are used by people who know how to tune....
kent
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Kent,
The "all gear" method can be a tuning tool also. Lots of good information on that run sheet that can be very beneficial with proper interpertation.
The two run method "all gear" and roll-on can be used together to not only setup and tune the engine but also look at potential issues with the lower end, tranny and the drive train that might not, yet, be obvious or evident to the naked eye.
If the bike is tested properly every spike and dip on the sheet will tell you something about the engine and drive train.
Buzz
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The dyno really helps us and we are only using it for a small number of the things it can do. It is time for me to order the dyno tuning book and sit by the fire for some winter reading.
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Does anyone have experience with changing the cam timing on a modern Hinckley Bonneville? Dyno time is expensive here, and I was going to try standard timing and either advanced or retarded. If changing the timing in one direction obviously does not work I do not want to try it. The actual method to change the cam timing puzzles me. On the old Triumphs I would juggle around the timing gears and the locations of the keys on the gears. How is this done on the new ones?
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My Hinckley Triumph Bonneville has a worn cam chain. The cam trails several degrees behind where it should be. Usually I wind the engine tight in each gear and I shift at high rpm. I rode on the big white dyno a few weeks ago. I rode real conservative so I would save the cam chain. As little time as possible at full chat. At the 2.5 mile mark I was halfway to max rpm in top gear and at half throttle. Then I got down on the tank and wound it tight. At the 3 mile mark I was at top speed.
The bike worked really well. Better than ever. Is this to be expected for a lagging cam? Is a lagging cam a good thing for top end power?
Ooooh yeah! Cylinder continues to fill even when the piston is starting up the bore. This has to do with the ram effect of the manifold.
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Thanks Rob. Here is my plan. Does it make sense?
I will have the engine apart this winter. I will check valve head to piston crown clearance with play dough with both cams timed as per the manual. Then I will check the clearance with one or both of the cams lagging one tooth on the upper cam sprocket. Assuming the valves do not hit the pistons, I will dyno with the cams set as per the manual. Then with one or both cams lagging. Is it best if the intake cam lags, or if both lag? Top end power is the goal.
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Wobbly,
I'm not familiar with the Hinckley engine. Is it an overhead valve engine with the cams driven by chain and sprocket? It's kinda sounds like it when you talk about moving the sprocket back one tooth. Anyway....depending on how the sprockets mount to the cams you might be able to buy a set of adjustable cam sprockets or modify your cam sprockets by slotting the mounting holes.
Good luck,
Buzz
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wobbly insted of running 1/2 throttle to the 2 1/2 you would go faster if you ran balls-out to the 2 ----you are timed from the 1 to the 2 and again from the 2 to the 3 not at the finish line---your speed is the average time between the 1 and 2 or the 2 and 3 --run balls out to the 2 then turn off if you want to save your motor and you will run faster willie buchta
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wobbly insted of running 1/2 throttle to the 2 1/2 you would go faster if you ran balls-out to the 2 ----you are timed from the 1 to the 2 and again from the 2 to the 3 not at the finish line---your speed is the average time between the 1 and 2 or the 2 and 3 --run balls out to the 2 then turn off if you want to save your motor and you will run faster willie buchta
Actually all runs are the speed of the timed mile so your best bet is either be at full speed at the 1 for courses that have timing from the 1 -2 (speedweek short courses only) or the 2 and run full speed for the entire mile. You will get the best time if you only gain about 1 mph in the mile.
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Math isn't my strong subject and I was in error when I wrote my earlier post. There is a mile in the middle of the 5 mile course that has lots of flags at the beginning and lots of flags at the end. It is right in front of the pits at the BUB trials. I try to go as fast as I can through that mile. I drew the course out on a piece of paper this evening and remembered what I did. I was in top gear at half throttle at Mile 1. I cruised to Mile 1.5, then I got down and pulled the throttle all the way back. I was going as fast as I can at Mile 2 and I held it till just past Mile 3. Then I gradually slowed down.
Do they time me between Mile 1 and 2 at BUB? They only print one average speed on my timing slip.
Buzz, the Hinckley Bonneville has a chain between the crank sprocket and an idler gear between and below the camshafts. The idler gear drives gears on both cams. It's a unique arrangement. Parts for this thing cost a lot of $$. I am hesitant try anything inside the engine unless a better engine builder than myself has done it and knows that it will work.
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The last few weeks I have been fixated with changing my cam timing and running various combinations intake and exhaust cam timing on the dyno to see which one makes the best power. I got out all of my old tuning books and did some internet research. I went to Borders bookstore, bought lattes, and read some of the tuning books they have. What I learned might be of interest to others.
Cam timing, intake tract characteristics, and exhaust characteristics are all related to each other. To evaluate cam timing, I need to do some serious dyno work to tune my intake and exhaust to work with the cam I have. That will be my baseline for torque and horsepower. Next, I change the cam timing and retune the intake and exhaust to work with that combination. Only after all of that work, I will be able to make a comparison. This dyno time is way beyond the budget of this team. No oil well in my backyard. Now it is time for Walrus Plan B.
Plan B is to buy cams for racing from someone who knows what they are doing. I will ask them for timing numbers so I can degree the cams in to their settings on my bike. I will ask them for info about their intake and exhaust, such as velocity stack length, exhaust header diameter, length, cone dimensions, etc. I will duplicate their setup. Then, I will use the dyno to set the ignition advance and fuel mixture. Lastly, I will work on riding the beast.
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WW, at the Bub you only get timing through the marked mile, no quarter speeds or multiple mile speeds. But it sounds like you did it right.... max speed for the timed mile. :-D
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didnt know you were talking about BUB willie buchta