Rephasing the cam shaft.

[srinath]

So I turned my crank into a 277. So my cam has to go from the 180 degree it is now to 138.5.
So Here is my thought and I know someone here has done it or similar.
Measure the ID and find/make an aluminum slug to fit in there tight. Steel also can be used, but aluminum is better if you want to remove the slug later. Plus it will take heat away from the wall and prevent it from getting over burnt in 1 spot. Also a bolt running the length of the cam shaft can be used, that is good to keep it aligned when re fitting in the head. Anyway on to the next step.

Turn the stock cam in a lathe and make a scratch where you want to cut.
Use a degree wheel and make a scratch on either side of the cut line. That is where the cam shaft will have to end up so as to rephase it.

Put it back in the lathe, cut @ the line and its preferable to have a V shaped cut instead of an | shaped cut, cos weld needs a space to fill. Also its better to do the opposite sides right back to back, first like - the it becomes a + then becomes a x+ etc etc. Anyway a good tig welder will get it sorted out perfect.

Then bolt it back together, or put the slug in and press it back with the marks lined up.
Then bolt it back in the head. Weld up the trench.
Check for run out. My guess, dependign on how tight the slug is and how good all the rest is, it should be in spec.

Anyone have any experience doing this. Did you end up with a good result. What needs to be changed in this.

Thanks in advance.

Cool.
Srinath.

 

[Punkskalar]

I've found the the camshaft halves do not like to be press fit. The cast will crack about 50% of the time. Im not telling all my secrets, but I'll tell you what NOT to do

And remember the camshaft will have to stay hollow if you are planning to run Pamcopete ignition.

 

[Patches]

Being that the cam shaft is hollow, I think the aluminium slug for the inside is a great idea. I wouldn't make it a insanely tight fit for fear of cracking something like Punkskalar mentioned but it seems like you are on the right track and aluminium is super soft any way. I would just be very careful that you don't get that aluminium slug stuck in there when doing the welding. Maybe some really heavy duty tacks and then remove the slug, and be sure not to try and weld it up all at one time for fear of warpage/heat distortion. I'm definitely going to keep an eye on this thread and please be sure to update us of your progress!

 

[mrriggs]

I'm happy to share all of my secrets. Here is how I do it.

Drill two 3-hole patterns 41.54° apart. I use a mill and index head, but the same could be done with a drill press and 26-tooth gear or sprocket to direct index it.

Then cut it in half right through the center of the sprocket hub.

Three precision dowel pins are used to key the two halves. Not only do they take all of the guess work out of indexing the cam but they also maintain the perfect spacing and alignment of the two halves.

I built a jig to cross drill the flanges so they can be bolted back together. The jig was just to speed up production, not necessary for a one-off.

With high grade bolts, this alone is a SOLID setup. Add to it the tight interference fit sprocket, which acts as a sleeve, and this setup is bullet proof. You are splicing it at the thickest, strongest, least stressed part of the cam. Plus, the sprocket drives both halves of the cam directly so no force is being tranfered through the splice.

The last picture is just a demo on a junk cam. To assemble it, I slide all-thread through the center of the two halves, align them, slide in the dowel pins, then tighten it down so everyting is tight and square. Then I heat up the sprocket and drop it on the cam, lining up the marks I made on it before pressing it off. Once everything cools, I Loc-Tite the cross bolts and torque them down. I put the bolts in last so that the Loc-Tite is not compromised by the heat from the sprocket. The last step, of course, is to remove the all thread.

 

[hotdog]

Srinath, I have purchased one of MrRiggs cams, have not installed it yet but am more than happy with the product I received. Just buy one from MrRiggs or Punkskalar - they have done the R&D & know what works well & what does not.
If you decide to do it yourself take your time as you don't want to make too many mistakes as it will start to cost $$$

Cheers.

 

[650Skull]

Wow That's nice mrriggs. On-ya for sharing,. this looks to be a great set up. I would defiantly buy this type of set up

I think this is what forums are about, (sharing ), and if you can make some money out of it well and good. I have noticed a couple of threads have got to commercial driven and in the garage instead of the shop where they belong

 

[paul45]

I agree both mrriggs and punkskalar definitly have the experience but it looks to me that you are on the right track and have the equipment and know how to get the job done Go for it! and if it breaks wtf both of these guys can hook you up with a new one

 

[nj1639]

Now if someone could come up with a rephase for the stock TCI........
2 rare earth magnets in the rotor?

 

[650Skull]

run another pick up on the stator at the 277 mark

 

[xjwmx]

Either an extra pair of magnets or an extra pickup might work - if one cyl is still on the exhaust stroke when the other is supposed to fire, like with stock. Otherwise, would take two independent tcis.

 

[mrriggs]

A waste spark ignition driven off of the cam works (that's how I'm running mine) but a waste spark ignition driven off of the crank will not work. The ignition will fire four times per cycle, twice per crank revolution. Even if you had a module that could properly set the dwell for that (I doubt the factory TCI can), one of those four firing events comes at about 98 degrees before top dead center on the left cylinder. While compression is low at that point, you still run the risk of pre-igniting the mixture.

 

[650Skull]

Of course 2:1 ratio

 

[Patches]

Wow That's nice mrriggs. On-ya for sharing,. this looks to be a great set up. I would defiantly buy this type of set up

I think this is what forums are about, (sharing ), and if you can make some money out of it well and good. I have noticed a couple of threads have got to commercial driven and in the garage instead of the shop where they belong

Didn't everyone learn in 2nd grade that "sharing is caring."

Mr. Riggs-
It looks like a great little set-up you have going on there. I never would have approached it that way. I can appreciate the ingenuity behind what you have done. I'm sure if somebody wanted they could copy your process, but the question is why. Especially doing all of that work for just one. Personally I would think they are better off sending it to you considering the amount of set-up work involved. At the same rate if somebody is wanting to do it for themselves just to see if they can, I can appreciate that too.

To the OP, keep us up to date on how you do yours. I've definitely got my eye on this thread! Great info so far.

 

[650Skull]

Didn't everyone learn in 2nd grade that "sharing is caring.

Not every one, some want to buy off them so will only tell you if you do something wrong. But that's ok.

 

[mrriggs]

Not every one, some want to buy off them so will only tell you if you do something wrong. But that's ok.

Hey, be fair. That is his livelihood, where it's just a hobby for me. Besides, it was his detailed build thread on the 4x4 forum that inspired me to tackle my own re-phase. Without his efforts you would have had zero replies to this thread.

 

[rwingsfan]

You are right, it is ok. The person you are talking about gives tons of advice on many different subjects discussed here and yet you diss him because he does not want to divulge a few of his secrets? Mr Riggs has it right, it is his business and really does not have to "share" any of his process, but regularly does. I have had great dealings with both Mr Riggs and Punkskalar and they both know their stuff, but as far as "sharing" goes neither is obligated to share anything, especially things that directly affect their business.

Not every one, some want to buy off them so will only tell you if you do something wrong. But that's ok.

 

[650Skull]

Hey, be fair. That is his livelihood, .

Yes you are right. And a good help he has been as well.

Punkskalar, I admire the dedication put into the welded Cam. It is something a few have tried and not mastered. It is skill that cannot be taught, you have to have it before hand and if it was easy it would have been done before. I guess that is why i thought it wouldn't matter if you told people how to.

 

[srinath]

Mriggs That is awesome, just bucking awesome.
So in the interest of reinventing the wheel, how about turning the round dowel slots into V shaped after the drill and cut step, with a V shaped end mill and dropping a square key instead of round ... muhahahaha ... hhahahaha ...

Anyway cam shafts are about precision not to carry any real load. I cut a savage FE with a 9 degree rake and fitted a KX250/500 forks set on it and that thing did carry tons of load, and it handled better and let the bike accelerate better than a stock POS savage, Dont laugh and call me a liar ... That's the difference between a 21 inch aluminum dirt bike wheel and a 18 inch street bike steel wheel. My wheel spins ~30-35% slower at any speed, and it weighs maybe 75%, since Moment of inertia depends on square of rpm and on the mass, it is like it has ~40% of the rotational kinetic energy of the stock front wheel. Hence accelerates quicker. But of course the change in direction involves the radius of gyration in addition to the rotational kinetic energy, so that was only ~60% less. Pics are here - https://picasaweb.google.com/srinath.the.man/ChopperBike#. I eventually turned the front end around, the disc came to the right and the brakes went in front of the fork leg. It handled better that way, however the guy that bought it from me said he flipped it back cos he likes that feel better ...

I am seriously going to make it myself, besides I suspect my crank is rephased the other way compared to the ones punkskalar makes.
I got 2 cams I can get a couple more if I screw up, no worries.

BTW I am also going to use a virago 920/750 electronic ignition and the virago's crank triggers and make a custom magnet basket and put the monster strength neodymium magnets in it. Now if that doesn't scare you ... I dont know what will.

Cool.
Srinath.

 

[Punkskalar]

I appreciate everyone's support, as always... Mr.Riggs does some really nice work as well, and seeing as how I've used his products before, I have nothing but good things to say about his work.

If I've offended some, I'm sorry, but I gotta keep a few for myself to enjoy every now and then


Srinath, If you need help, drop on into the shop. I'll be glad to help you rephase the cam either direction. We can even try a new method if you wanna give it a shot... I'm game for all of it!

 

[srinath]

Now if someone could come up with a rephase for the stock TCI........
2 rare earth magnets in the rotor?

OK you cant do it with 1 stock TCI, but 2 stock tci's can be made to work, especially with a second pickup.
However there is an easier way, virago 750/920/500/535 (anything but a 1100/1000, though I can ge that part also to work, just more hassle) triggers, ignitor and coils. Done.

The 1100/1000 uses vacuum as well, now vacuum retards with increasing vacuum which the dwell based system advances. AKA vacuum needs to be thrown out, its just there to clear emissions. Anyway, there is a dozen other bikes that would let you use their trigger/TCI/Coils, just have to fit and find out. I think a custom basket, a set of flat curve neo's and a stator like a banshee and virago triggers are just the ticket.

You also can use very likely the virago triggers and the xs everything else, but the magnet in the rotor has to have a nice steel flat plate glued on cos the virago coils need a metal, not a magnet. I have to check though.

Cool.
Srinath.