Better to have re-phased and lost than never to have re-phased at all

[scabber]

If you could explain how you static balance the crank web. How you do the process a picture would help but not necessary. In the other thread you were going to do the 85% factor. Looking to buy one of your re-phased cams with a Shell #1 grind. What would that cost. I like the way you do your cams. Thanks for bringing up this subject.

 

[650Skull]

The crank is welded so essentially it is a one piece after the re-phase.

Only if you want it to be.................... Not a necessity in normal use, in a racing situation or if the motor is going to be thrashed.........Yes

A welded crank is a wasted crank.

 

[imworks]

Yaaaa, raced and thrashed, that's the whole point isn't it????
Certainy didn't throw 10k into this thing to baby it around

 

[650Skull]

Give me a bell in a couple of years when cranks are scarce.

My retirement fund

 

[mrriggs]

If you could explain how you static balance the crank web. How you do the process a picture would help but not necessary.

Pictures definitely help. This gave me a good excuse to finally check the factory balance factor.

The first thing I did was bolt a top case to my drill press table and set half of a crank in it.

The table was tilted so that the rod could hang straight down with the crank throw perpendicular. Weight was added to the end of the rod until the crank was balanced (wouldn't fall either way when nudged).

I weighed the weight added to the rod, 180.1 grams.

Then weighed the small end of the rod, 94 grams.

Finally I weighed a complete piston assembly, 386.3 grams.

So the total reciprocating weight of a stock motor is rod end plus piston, 94 + 386.3 = 480.3.

Our "bob weight" is rod end plus added weight, 94 + 180.1 = 274.1.

The balance factor is bob weight divided by reciprocating weight, 274.1 / 480.3 = 57%.

When balancing a crank you do the same thing, only in the opposite order. Weigh the parts, calculate bob weight, then add or remove material from the crank until it's balanced.

To balance each web you would mount them between centers and hang half of the calculated bob weight. Of course, you would need to add the weight of the big rod end, bearing, shims, and rod pin to your initial bob weight calculation since they will not be hanging there.

 

[mrriggs]

A welded crank is a wasted crank.

I haven't tried it yet myself, but I have been told that welded cranks can be disassembled the same way as a non welded crank. You just press them apart. The weld has little penetration so it gives way easily to a hydraulic press.

 

[scabber]

Those pictures helped tremendously. Thanks for showing and explaining the process. For a Re-phased 277 street motor that will probably never see more than 75000 RPM. In your opinion is the welding the crank necessary or just an added safety factor for those who push the limits of the motor and race or just beat the hell out of them in general?

 

[Punkskalar]

what a total crock of shit. Maybe the Biggest crock of shit I've read here so far.

This guy chimes in on every single rephase thread - take it with a grain of salt Come ride on of mine - seriously, I welcome anyone who would like to try one out to come ride one of my bikes

I know they work without it, Hugh has done dozens, but shouldn't the crank really be rebalanced to eliminate this vibration and take full advantage of the rephase? You are basically rephasing a crank that was balanced to be a 360 degree motor.

Dozens? We've done probably 1,000 or more cranks and cams, and built about 45 Complete Engines - with great success in the 277 Mod

Perhaps you missed this thread.

http://www.xs650.com/forum/showthread.php?t=19680&highlight=wagging

Dynamic balancing an XS crank is unnecessary. If you static balanced each crank web when it is disassembled then you will achieve a better balance than if it were dynamic balanced as a whole. This is one advantage of assembled cranks. One piece cranks have to be dynamically balanced because there is no way to isolate each plane for static balancing.

We sent out 5 cranks to be "perfectly" balanced when we started doing this - 3 of them came back completely untouched. So we've not been worrying with it for a street machine. For a full on race 24 hour endurance machine, maybe the extra 1-2% would help. But my personal engines are all as per OEM balance and run great.

I had the same experience as Mr Riggs - kinda. I had a Freshly Rebuilt 750cc engine (stock 360 crank/cam) and just couldn't bring myself to not run it. I ran it for about a month before I HAD to tear it down and rebuild it as a 277 Once you've rephased, it's hard to go back.


In my experience, ALL XS650 cranks should be welded. They are a dime a dozen on Ebay and I've never had a welded crank fail. I have had non-welded cranks come apart though.

Keep up the discussion folks, thats what I love about the XS650 Community

 

[RCGRT]

Wow, there is so much info on this forum about the "Rephase" it would almost be nice for it to have it's own place with-in the forum...

Excellent write up Mr.Riggs! I'm currently rebuilding mine, 277 rephase, and it's so nice to hear more and more talk about how much they like it!

Not to highjack the thread, but to all those more knowledgeable than me, could you drill and pin the flywheels to the crank pins? Instead of welding? I realize the pins are probably very hard, and one of the flywheels has gear teeth in the area a "pin" would have to intersect, but still...is it a possibility?

 

[GreasyC]

Pictures definitely help. This gave me a good excuse to finally check the factory balance factor.

...

The balance factor is bob weight divided by reciprocating weight, 274.1 / 480.3 = 57%.

Wow if that's right it's no wonder they shake so bad stock. A crank for the stock engine arrangement should be 70% or even more. Would also be good news for the rephase since that number would actually be closer to correct for a rephased bike than a stock one.

 

[Okie]

Dozens? We've done probably 1,000 or more cranks and cams, and built about 45 Complete Engines - with great success in the 277 Mod

I appologize for that remark, I should have known better. I think everyone on here realizes the quantity and quality of work you do for the XS community.

 

[Tomterrific]

Hi Mr. Riggs,

Interesting observation. i have ridden a BMW 900R and was surprized at the troubling vibration at the footpegs. I had traded off from my old Triumph so it isn't that I don't know what vibration is.

Both the BMW and the rephase suffer from rocking couple vibration. A parallel twin will suffer the most because the cylinders are so far apart.

I think the 360° crank gives a single vibration but the vibration doubles in rocking couple. It's difficult for me to visualize this so i may be wrong.

Check old threads about my lead weighted bars. I'm still happy with how nice the vibration is at the grips. I'd like to get the vibration softer at my feet now.

Tom

 

[Jack]

Hi Mr. Riggs,

Interesting observation. i have ridden a BMW 900R and was surprized at the troubling vibration at the footpegs. I had traded off from my old Triumph so it isn't that I don't know what vibration is.

Both the BMW and the rephase suffer from rocking couple vibration. A parallel twin will suffer the most because the cylinders are so far apart.

I think the 360° crank gives a single vibration but the vibration doubles in rocking couple. It's difficult for me to visualize this so i may be wrong.

Check old threads about my lead weighted bars. I'm still happy with how nice the vibration is at the grips. I'd like to get the vibration softer at my feet now.

Tom

Tom , I have a "76" R/90S that's been punched out to 1000 that exhibits very little to no vibrations with the exception of around 5000 RPMs then feathers off due to the lightening of fly wheel without re-blancing. The inherited rocking motion of "R" is more tolerant than the vibrations of the XS. Replacement of the overly weighted W/P's with tool steel pins in most cases will eliminate those vibrations of the "R's".

 

[Tomterrific]

Hi Jack,

The BMW's have the rods closer together also so I know the rocking couple is not as amplified. I have hear of guys changing vibration in BMWs and other bikes with component change (mostly pistons). I was just surprised the BMW had any vibration. Also I must be sensitive to footpeg vibration. With the heavy boots I like to wear I'm surprised I feel anything!

I've heard the R/90 is one of the best shakers in the BMW line. I haven't ridden this bike lately but if my buddy talks me into working on it I'll take it for a spin and report what I think.

Tom

 

[5twins]

Yes, on the old BMW twins, the bigger the displacement, the more they vibrate. The 750s are smoother than the 900s, the 600s are smoother than the 750s, etc.

 

[mrriggs]

I rechecked the balance factor of this crank last night. When I did it before, it was spinning on crusty old bearings so it wasn't as accurate as it could be. This time it was completely disassembled and I used a different method that pretty much eliminates friction.

I just happened to have a surface-ground steel plate sitting on my bench so I leveled it by stacking sheets of paper under the low side. I slid a shaft through the pin hole of a crank web and hung bearings and shims on it until it would sit level on the plate. If off by only a couple of grams, the web would roll towards the heavy side.

I turned the web around to double check that the plate was level.

After finding balance the bob weight is measured.

Add the bob weights from two webs (803.5), subtract the rotating weight (500.1), then divide the reciprocating weight (480.3); (803.5-500.1)/480.3 = 63.2%.

I calculate the "perfect" balance factor for a 1.76 rod/stroke ratio is 64%, so the factory setup is surprisingly close. Perfect in this case means it will transmit the lowest peak force to the crank bearings, not that it will feel the smoothest. The perfect balance factor is determined solely by the rod/stroke ratio. What balance factor "feels" the smoothest is determined more by chassis design and rider perception.

 

[jetmechmarty]

I rode someone else's rephase. I should do it again. I didn't think it was my cup of tea. I was fond of it at high rpm, but preferred my 360 on the low end. Where the 360 got buzzy, the 277 smoothed out. That's how I remember it. The 277 loves to run wide open.

Posted via Mobile

 

[sonicarb13]

Hi Mr. Riggs,

Interesting observation. i have ridden a BMW 900R and was surprized at the troubling vibration at the footpegs. I had traded off from my old Triumph so it isn't that I don't know what vibration is.

Both the BMW and the rephase suffer from rocking couple vibration. A parallel twin will suffer the most because the cylinders are so far apart.

I think the 360° crank gives a single vibration but the vibration doubles in rocking couple. It's difficult for me to visualize this so i may be wrong.

Check old threads about my lead weighted bars. I'm still happy with how nice the vibration is at the grips. I'd like to get the vibration softer at my feet now.

Tom

Do you mean a F800R? I have a 2011 and have almost 20,000 miles on her. It does vibrate more than I had hoped. They have a weight attatched to the crank to try and offset the vibration but at 75 to 85 its about the same as riding my rigid. HA

 

[dps650rider]

I rode someone else's rephase. I should do it again. I didn't think it was my cup of tea. I was fond of it at high rpm, but preferred my 360 on the low end. Where the 360 got buzzy, the 277 smoothed out. That's how I remember it. The 277 loves to run wide open.

Posted via Mobile

I have found the same thing with my rephase, not as nice at low RPM but better when the RPM's are up. One of the things that hurts the low end with the rephase is driveline slack caused by the chain. With the stock engine I could lug it to a lower RPM before it would be a problem than I could with the 277.

That was one of my motivations for converting to a belt drive. Since I did that I have regained some of the low RPM range and removed another source of vibration, the whipping chain.

Here is what I want to try next in my quest for a smoother XS: http://www.vibranator.com/product_p/s05-b01-r04-n02-m02-t125.htm

 

[deadchef]

That was one of my motivations for converting to a belt drive. Since I did that I have regained some of the low RPM range and removed another source of vibration, the whipping chain.

are you saying you have a belt driven xs650? i'd like to see that!