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MAP parts and digital scale #798055 02/10/20 7:48 pm
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This may not be the correct forum for this question but since it's in regard to Triumphs and their parts I'm asking it here:

I just received a very nice MAP billet offset crank, H beam 4340 rods and nikasil cylinder kit and would like to weigh and compare wts. between themselves and also stock parts. The crank comes dynamically balanced at 52% based on 585 gram bob weights per MAP, which means if I can accurately weigh my parts then I can back calculate and determine the factor per my wts. Since Falicon went out of business MAP can no longer have your crank balanced to your rods and pistons before shipping out, which I believe was the case in the past.

So the question is, who makes a good digital parts scale in around the $200 or so price range? I went on Amazon and got caught up in all the reviews and gave up but I do like the better reviews of Ohaus and would think that 0.1 gram accuracy acceptable although 0.01 gram is also available in same basic price range. Any thoughts and thank you...Mark

PS...I have an Ohaus 3 beam scale but a digital for rod end to end balancing would be much more convenient and smaller.

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Re: MAP parts and digital scale [Re: MarksterTT] #798060 02/10/20 9:07 pm
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Is 0.01 gram a bit overboard? Carrillo Pro-H rods are only matched to +/- 1 gram.
USPS has an 25 lb. electronic scale, resolution to 1 gram for $35.

Re: MAP parts and digital scale [Re: DMadigan] #798080 02/11/20 3:30 am
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Thanks David, yes 0.01 gram would definitely be overboard. I'm just skeptical that I might not get the repeatable accuracy from a $35 unit...I'll check it out, thanks...Mark

Re: MAP parts and digital scale [Re: MarksterTT] #798089 02/11/20 5:31 am
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For what it's worth, I've balanced many engines using an inexpensive scale. Most of the digital scales I've seen are self zeroing when you power them up, so as long as the load cell in it is functional it should provide adequate results.

My full time job is dealing with instrumentation/calibration in a test lab and every time I've checked my cheap scale it is accurate.

Re: MAP parts and digital scale [Re: MarksterTT] #798119 02/11/20 6:39 pm
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Hi Mark, I have a $40 scale. Very accurate. I also have calibration weight set. + one more lager weights as it takes that for calibration. You MUST calibrate for accuracy for this job.
All made in China. Uncanny how accurate it is.
Online manual will show calibration weight for scale you buy.
Large platform is important to fit piston on. Rod checker jig can be made with bead chain. Look at eBay or online rod jigs. My scale is packed away. I’ll get it out tonight.
Don


1973 Tiger 750
Re: MAP parts and digital scale [Re: MarksterTT] #798128 02/11/20 8:28 pm
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mark, are you using MAP's 76 degree cams?


every day you do not take a chance is a day of your life that you will never get back.
Re: MAP parts and digital scale [Re: MarksterTT] #798160 02/12/20 6:42 am
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Hi Mark, My scale is Triton T2 550g X 0.1g capacity. You need 2) 200g calibration weights to calibrate. I also have American Weigh Scales Calibration Weight Kit
WGHTKIT, Class M2. A bunch of weights & storage box, tweezers. The tiny weights are bits of sheet metal with g amount stamped on them.

If your rods or pistons are too heavy you'll need larger scale. I found this one worked for all my needs.

The original batteries like to leak. I'd toss them & get good batteries.

I emailed you photos of my kit. In real life I run rod nuts down to the installed position. My rod scale has precission bearings. I have adaptor to weight with or without bearing shells. I'll also email the Triumph factory balance sheet for racing. It has formula for balance so you can run numbers to determine factor from your actual component weights. You'll be quite accurate since MAP stated to bob weight. Photos should come through by morning. The rod jig & scale must be level both ways & acclimated to room temperature for best accuracy. My jig has 3 screw feet for leveling. I use a machinists level. Again I would make ball chain hanger next time to hold rods.

Rod weight can be looked at 2 ways. Total or ends made even. I feel both ends of rod made even side to side is best way. Of course big end + small end is total. But some rods sold as weight matched can have light big end, heavy small end for a total, but I don't like that. Small end can be added to piston for a total, but at the speed shop we made every part match in its own right.

Spent most of a day at Rabers weighing used rods & pistons.... What a crap shoot. No wonder some motors shake so bad. Easy to stack tolerance such to where left to right was 6 to even 10g difference. Luck of the draw. Same with dynamic. Some are good, others horrible. I feel factor was correct & the workers did a decent job on the static balance. So the smoother motors are the stacking of tolerances in the best way. Weighing Emgo & Harris pistons was a big surprise. They are very close. Nearly perfect in the examples we tested. Diameters were spot on also. Who knows who makes them, but they run close tolerances.

Don


1973 Tiger 750
Re: MAP parts and digital scale [Re: MarksterTT] #798162 02/12/20 10:07 am
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I have an Ohas triple beam scale. Never needs batteries,lol.


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: MAP parts and digital scale [Re: MarksterTT] #798212 02/12/20 10:42 pm
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I use paint mixing scales, they go up to 500g.


'74 T140V,'83 XR1000, C&J FLATTRACKER T140,
Re: MAP parts and digital scale [Re: MarksterTT] #798243 02/13/20 4:56 pm
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Thanks mondtster and Don, I guess I'll look at some cheaper units and thanks for the pictures and instructions Don

Kevin, yes the MAP offset 1066's (similar to Mega 1065) why do you ask?

Hillbilly, for the same reason as you I have an Ohaus triple beam but for some things it would be nice to have a small digital, less fiddily?

wilksville, I don't know what a paint mixer scale looks like but if it works...then it works

Re: MAP parts and digital scale [Re: MarksterTT] #798253 02/13/20 7:08 pm
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Any scale that has range & accuracy needed would work so long as you can set rod to 90deg of scale bed. That's where digital is nice. The bed movement is so tiny it doesn't effect rod angle.

I got my weights & scale on eBay. Under $80 for all including shipping. Playing around with the weights are quite accurate. You put on .2g it reads .2g. Very repeatable.

Piston weights repeatable. Rod weights no as repeatable. My fulcrum is not perfect. That's where it looks like bead chain fulcrum might work better. Mine I do several measurements & average it. Small end is more the problem. .3g is variation from zero so I guess 1.5g + or -. Working the average I feel .1g tolerance is what I can measure with small end. Since small end + big end = overall you can use overall for an audit of sorts.

I'd have to check notes, but as I recall '69 Bonnie 7.1 pistons were way lighter. But wrist pin heavier. LF Harris rods heavier, mostly at big end. Doing math, factor came to 87%. So crank balance was needed. Factory spec is 85% in manual. They took a lot of metal off right pork chop & drilled 1 large & 3 small holes in flywheel. Has the light flywheel from factory. Just was riding with John yesterday. That motor turned out really good. Very smooth 60-70.mph. Higher rpm vibration starts again. We never ride faster unless to pass a car.
Don


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Re: MAP parts and digital scale [Re: MarksterTT] #798290 02/14/20 1:30 pm
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Absolute accuracy when weighing isn't important with these engines. Repeatability however is. A 1g resolution is adequate.
Who cares if your balance weights are a few grams more or less, when there's no objective optimum balance factor anyway.
Lets get real about these things, no matter what you do these engines are out of balance, and unless you balance then dynamically you don't know if your pistons and rods with their 0,1 gram accuracy will improve on any rocking couples. One of the sweetest Bonnies I owned had different connecting rods for years. I didn't know better when I built it at 20. I installed a matched set later, with pistons matched to suit, and the engine vibrated more. Luck of the draw first time, but I learned something the second time.
I do match rods and pistons to this day though, but only to avoid any adding up of forces if the heavier goes to the wrong side and vice versa.
I don't expect miracles, and I never get them, but sometimes happen to build something nice enough to ride.

This is MY opinion and I don't get offended if anyone thinks differently!

SR

Last edited by Stein Roger; 02/14/20 1:32 pm.
Re: MAP parts and digital scale [Re: MarksterTT] #798299 02/14/20 4:25 pm
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Quote
Lets get real about these things, no matter what you do these engines are out of balance, and unless you balance then dynamically you don't know if your pistons and rods with their 0,1 gram accuracy will improve on any rocking couples.


Engineers tell us that you cannot "balance" a single or a vertical twin. I say again, "You cannot "balance" a single or a vertical twin!" What you can do is move the rpm range where you hope your going to feel less vibration. Simply stated the process of using a balance factor is to change the up and down forces to front to back. It is felt that most people are less irritated by a fore and aft motion. Then the actual factor takes into consideration how the rolling chassis is going to deal with different frequencies of sympathetic resonance. Mounted in a stock frame an acceptably smooth T140 balanced at 74% when mounted in a Rickman Road Race frame will vibrate so bad you cannot hold onto the handle bars at 7,000 rpm. No tach needed, hands will vibrate off of grips.

Change your rolling chassis can change the resonant frequencies. Something a simple as a loose engine mount bolt that is loose or a side stand mounting lug touching the engine can cause the engine to seem to vibrate. Changing the top motor mount can move an irritating vibration to an rpm range that you don't use that often.

You can, through trial and error, come up with a factor that will be smoother to suite your riding style. Is that factor universal? Will you be happy with the factor used by road racer, Tim Joyce? Or the one for that guy, let's call him Casper Milktoast, who never takes his Bonneville over 2500 rpm?

Triumph recommended balance factors were not finalized with a factor calculated on a slide rule, but by real people actually riding the bikes. It reflects the opinions of which factor is most pleasing and is an average of the opinions. It reflects what they believe how the end customer will be using the bike.

What you can do, using electronic balancing equipment, check, and correct any vibration caused by a rocking couple. Typically this will please both Casper and Tim.

Do you have to balance the rods and pistons to a gram to attain this. Well the balance shop I got the best results from, now retired, would use the balance factor I requested (some thing that is important to me), and use the different big end rod weights to help correct the imbalance in the side to side weight of the flywheel. I got tired of people balancing rods with a belt (linisher) sander with 80 grit abrasive to the point where I would have to throw them away.


Re: MAP parts and digital scale [Re: MarksterTT] #798334 02/15/20 12:18 am
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...in my case I do not know if this bike is at 74% of balance factor but the bores are at .040 and I am thinking to go to .060. My question is if that change (a distance from STD condition) put more vibration in the same rpms. If so, how do most do when not tearing apart all the engine only the top part and change the pistons, rings etc?

Thanks

Re: MAP parts and digital scale [Re: MarksterTT] #798345 02/15/20 1:43 am
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Reverb,
First let me say I have the highest regard for you just for being able to keep these old turds alive while living on the dark side of the moon. For them to be your primary source of transportation, must mean you are a bit nuts. I have changed pistons and rings many times. I've had the 72 for 35 years and I think I'm at .060 over. I've had the 68 for 16 years and I'm at .040 over. I have heard about "balance" but never understood what it was all about or that it was changeable. Both my bikes are all day riders at 70 to 80 MPH or more. I have never noticed any change after a top end rebuild.
The problem with the internet is that it exposes you to fears and concerns you never knew existed.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
Re: MAP parts and digital scale [Re: MarksterTT] #798346 02/15/20 1:58 am
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1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
Re: MAP parts and digital scale [Re: Stein Roger] #798361 02/15/20 5:30 am
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Originally Posted by Stein Roger
Absolute accuracy when weighing isn't important with these engines. Repeatability however is. A 1g resolution is adequate.
Who cares if your balance weights are a few grams more or less, when there's no objective optimum balance factor anyway.
Lets get real about these things, no matter what you do these engines are out of balance, and unless you balance then dynamically you don't know if your pistons and rods with their 0,1 gram accuracy will improve on any rocking couples. One of the sweetest Bonnies I owned had different connecting rods for years. I didn't know better when I built it at 20. I installed a matched set later, with pistons matched to suit, and the engine vibrated more. Luck of the draw first time, but I learned something the second time.
I do match rods and pistons to this day though, but only to avoid any adding up of forces if the heavier goes to the wrong side and vice versa.
I don't expect miracles, and I never get them, but sometimes happen to build something nice enough to ride.

This is MY opinion and I don't get offended if anyone thinks differently!

SR


I appreciate all opinions so no worries, I'm not obsessing on the accuracy but definitely repeatability. Just to clarify though, I'm talking about a billet dynamically balanced crank at a factor of 52% using 585 gram bob weights, done by the manufacturer, so I figure that their equipment was probably pretty accurate so I want my actual parts to be as close to identical side to side. Hence the search for a little scale and a rod weighing jig. Once I can determine which direction the BF moved with my wts., then if need be I can later rebalance to a different factor until I'm either happy or frustrated.

Re: MAP parts and digital scale [Re: reverb] #798363 02/15/20 5:49 am
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Originally Posted by reverb
...in my case I do not know if this bike is at 74% of balance factor but the bores are at .040 and I am thinking to go to .060. My question is if that change (a distance from STD condition) put more vibration in the same rpms. If so, how do most do when not tearing apart all the engine only the top part and change the pistons, rings etc?

Thanks

I think most of us have replaced pistons/rings without ever rebalancing, in most cases you really won't notice a difference if your close to similar wts...I think the biggest change from a dynamic rebalance would be evidenced if you had a bad rocking couple from a side to side imbalance but you'd never now unless you tore it down and did the balancing. I'd put it together as is with your new pistons/rings and a good bore and hone with a torque plate if possible.

Re: MAP parts and digital scale [Re: John Healy] #798366 02/15/20 6:03 am
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Originally Posted by John Healy
Quote
Lets get real about these things, no matter what you do these engines are out of balance, and unless you balance then dynamically you don't know if your pistons and rods with their 0,1 gram accuracy will improve on any rocking couples.


Engineers tell us that you cannot "balance" a single or a vertical twin. I say again, "You cannot "balance" a single or a vertical twin!" What you can do is move the rpm range where you hope your going to feel less vibration. Simply stated the process of using a balance factor is to change the up and down forces to front to back. It is felt that most people are less irritated by a fore and aft motion. Then the actual factor takes into consideration how the rolling chassis is going to deal with different frequencies of sympathetic resonance. Mounted in a stock frame an acceptably smooth T140 balanced at 74% when mounted in a Rickman Road Race frame will vibrate so bad you cannot hold onto the handle bars at 7,000 rpm. No tach needed, hands will vibrate off of grips.

Change your rolling chassis can change the resonant frequencies. Something a simple as a loose engine mount bolt that is loose or a side stand mounting lug touching the engine can cause the engine to seem to vibrate. Changing the top motor mount can move an irritating vibration to an rpm range that you don't use that often.

You can, through trial and error, come up with a factor that will be smoother to suite your riding style. Is that factor universal? Will you be happy with the factor used by road racer, Tim Joyce? Or the one for that guy, let's call him Casper Milktoast, who never takes his Bonneville over 2500 rpm?

Triumph recommended balance factors were not finalized with a factor calculated on a slide rule, but by real people actually riding the bikes. It reflects the opinions of which factor is most pleasing and is an average of the opinions. It reflects what they believe how the end customer will be using the bike.

What you can do, using electronic balancing equipment, check, and correct any vibration caused by a rocking couple. Typically this will please both Casper and Tim.

Do you have to balance the rods and pistons to a gram to attain this. Well the balance shop I got the best results from, now retired, would use the balance factor I requested (some thing that is important to me), and use the different big end rod weights to help correct the imbalance in the side to side weight of the flywheel. I got tired of people balancing rods with a belt (linisher) sander with 80 grit abrasive to the point where I would have to throw them away.



Thanks for your response John, point taken. In my case I'm starting with MAP's pistons and steel rods and they're within a couple tenths of a gram of each other respectively so I don't want or expect to remove any wt. from either and the crank came dynamically balanced to a specific factor and bob wts. but I have no idea how this will work out with the C&J frame with it's design and materials etc. Mark

Re: MAP parts and digital scale [Re: MarksterTT] #798371 02/15/20 10:10 am
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Originally Posted by MarksterTT
Originally Posted by reverb
...in my case I do not know if this bike is at 74% of balance factor but the bores are at .040 and I am thinking to go to .060. My question is if that change (a distance from STD condition) put more vibration in the same rpms. If so, how do most do when not tearing apart all the engine only the top part and change the pistons, rings etc?

Thanks

I think most of us have replaced pistons/rings without ever rebalancing, in most cases you really won't notice a difference if your close to similar wts...I think the biggest change from a dynamic rebalance would be evidenced if you had a bad rocking couple from a side to side imbalance but you'd never now unless you tore it down and did the balancing. I'd put it together as is with your new pistons/rings and a good bore and hone with a torque plate if possible.

I think you're right.
Over the years I've collected a number of pistons, mainly from Triumph 650 twins or triples, and I've worked on a good few engines were I've weighed the pistons. Sometimes the weight difference in a pair from the same engine will differ as much as 5 grams. However, between different sets and sizes it can vary much more, over 20 grams has been seen The net effect of fitting a set of heavier pistons in your engine would likely be moving the vibrations up or down the scale, but is something I've never heard much about after people have had their cylinders re-bored.
On a T140/TR7 there's a big weight difference between 7.9 and 8.6 compression pistons but it's never discussed.
The worst variation I've seen in a set of pistons, was in a set of triple pistons that came with a BSA R3 engine I have. The +.020" pistons varied 14 grams. It's anyone's guess how that would have affected a triple, but on a twin it would likely have set up a serious rocking couple.
I have no doubts that a proper dynamic balancing job would improve immeasurably on perceived vibration, but it's too expensive to consider for me, with shipping and customs and all.
I wouldn't go on any long distance haul on a twin these days anyway, though I may possibly come to reconsider when I restore my first Triumph, a 1958 T110.

SR

Re: MAP parts and digital scale [Re: Stein Roger] #798394 02/15/20 7:09 pm
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Originally Posted by Stein Roger
Originally Posted by MarksterTT
[quote=reverb]...in my case I do not know if this bike is at 74% of balance factor but the bores are at .040 and I am thinking to go to .060. My question is if that change (a distance from STD condition) put more vibration in the same rpms. If so, how do most do when not tearing apart all the engine only the top part and change the pistons, rings etc?

Thanks


I have no doubts that a proper dynamic balancing job would improve immeasurably on perceived vibration, but it's too expensive to consider for me, with shipping and customs and all.
I wouldn't go on any long distance haul on a twin these days anyway, though I may possibly come to reconsider when I restore my first Triumph, a 1958 T110.

SR


I'll be looking forward to seeing this bike restored. In Ivory and in Black, of course.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: MAP parts and digital scale [Re: MarksterTT] #798411 02/15/20 10:04 pm
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Just to put it out there, balancing a triple or a 76° Triumph crankshaft is a different discussion.

Over the past near 100 years, It is has become the norm to bore a bike oversize without "quote" balancing, or re-balancing the engine. What peaked my interest in balancing, beside all of the articles I was reading in bike, and hot rod, magazines was this thing that become to be called dynamic balancing where they corrected any imbalance from one side of the flywheel to the other. I think a lot of people have come to feel that this is where you get the most "bang for the buck."

So this trend of having flywheels "balanced", for me, created a love hate relationship with people who balance vertical twin, and single, flywheels. Most have never done one before and believe you are nuts when you ask for a percentage like 85%. When they lack experience they often rely on information distributed by a mid-western supplier of balance percentages for British and American bikes known only to the author and his committee or deity. I have had perfectly good parts ruined because many of them have no idea how to remove weight from parts in a workmanship manner. I look at the time bomb flywheels with so many holes drilled into the cast iron that it could pass as Swiss cheese. Typically balance holes should 3/8" dia. x 1/2" deep and 3/4" apart. Cast iron flywheels have been known to come apart.

Some of these people doing balancing are so full of themselves, and their black magic, they believe that the factor they used for Ricky Racer is going to be great for your street machine, or when you ask for 85% they give you the "bobble head." Yes, yes I understand and then balance your crank to 65%.

To this end I have bought all of the kit to static balance the crankshaft to the factor I choose. I attach the weights I choose to the crankshaft and have them only remove any imbalance side to side. The other thing I have been doing is reverse engineering the original balance factor, and work from their to decide on if I am going to raise, or lower the factor.

I build, and re-furbish, quite a few Vincent flywheels. There are two of what I call committees who want me to use their balance factor. One is 46% which comes from writing's of Phil Irving and the other is 52% which is closer to what you would balance a Harley of the same era.

Both claim the Vincent engine is absolutely the smoothest using their factor. The 52% committee is adamant about their percentage, yet more people ask for 46%. Now don't compare a Vincent with your other British bike. It is an engine that delivers its torque at low rpm, there is no frame as such and it is a 50° V-twin. There still seems to be a little black magic involved. Is it smoother because my committee says it smoother, or is it because it is really smoother?

Just thinking out load.


Re: MAP parts and digital scale [Re: MarksterTT] #798418 02/15/20 11:25 pm
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Its good to see John thinking,

I remember learning a new word at the Inverness Tech , Scantlings, which does not seem to be recognized by the spell checker, . Our lecturer was from the Black Country , Mr Briggs IIRC. He described Scantlings as the non rotational parts in an engine, such as pistons, rockers , push rods and tappets/cam followers. The mass of these items is considered to be a negative factor when considering efficiency and balance in the case of pistons particularly. I think parasitic losses was another phrase he used. A simple thought experiment on mercury filled lead pistons versus balsa wood pistons illustrated the point well.

Last edited by gavin eisler; 02/16/20 1:30 am. Reason: Remembered the name of tthe lecturer, Andy Briggs.

71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: MAP parts and digital scale [Re: MarksterTT] #798419 02/15/20 11:29 pm
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TR7RVMan Offline
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Hi Guys, I fully get singles & our twins cannot be fully balance. I think there is a big point to this discussion for us that like to ride long distances.

However, there’s a huge dramatic difference between bikes of same year, properly assembled with correct brackets & all parts properly tightened etc.

I’ve ridden shakers that numb the hands & feet & burn your bum in less than 50 miles.

All I’m after is smooth as possible for long easy rides generally no faster than 63-65 mph.

I get the reverse engineering.

The ‘69 Bonnie was horrible. Had .020 over pistons, using oil. Had rattle. Left small end bush loose rod. So needed bore & rods. Old parts were close L to R. So it seemed dynamic of crank was out.

After dynamic it’s no problem all day rides.

200 miles is nothing for us. We actually ride these things. No support truck, often no cell service.

200 miles on a shaker is pure torture!

For some splitting hairs does matter. It does to me, smoother just makes these old bikes more fun.

Revco Long Beach gives you balance sheet with weights, balance factor you requested. Bob weight, weight is on the sheet.
Of course I audited weights that I could. Our numbers matched. What I don’t know is if he actually used bob weight he says. Talking to him on phone he is very straight forward with no nonsense. I think he does what his sheet showed. Whatever, the results made a pleasant riding bike.
Don


1973 Tiger 750
Re: MAP parts and digital scale [Re: HawaiianTiger] #798444 02/16/20 10:16 am
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Stein Roger Offline
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Originally Posted by HawaiianTiger

I'll be looking forward to seeing this bike restored. In Ivory and in Black, of course.
Cheers,
Bill

As do I Bill.
When I bought it at 18, it was Ivory and Black and in pretty good shape too. Apart from some patina it was a complete and nice bike with a new exhaust.
I promptly discarded the Nacelle and the front fender and painted it Signal Red!! facepalm Rode it like the idiot I was and broke the gearbox due to a sticky clutch.
Sold it, and it was lost, happened to find it by chance, and now have many of the original bits, plus the correct fenders.
It's really too painful to talk about, but it's the one bike I will restore. beerchug
It's also one I'd consider having the crank dynamically balanced on, if I can find someone I trust to do it.

To the OP; sorry for the thread drift!

SR

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