Repair of damaged engine KTM sx-f 350 - when to failure oil pumps. Stroke loss 0.15 mm after grinding. The camshafts are after grinding still hard. . . . for more interesting videos click ,, HERE " / @paulxchannel
Now I find the making of your equipment, absolutely amazing. BUT.... I would in no way consider that repaired, but rather, damaged even further. You changed: smaller lift, shorter duration, ramp rate, overlap and possibly the LSA. You also removed any hardening or nitriding done to lobes.
This is proper old school engineering. I think a lot of these armchair engineers don't realise that this is the way things were done back in the day .. know how and skill
It's great to realize that this level of repair work is still being done. Planned obsolescence and part-swappers are mostly what you see nowadays. I don't think I've met a true old school mechanic in 20 years let alone an engine machining and rebuilding. I guess it's still being done in certain cases but they're becoming harder and harder to come by.
BRILLIANT WORK... gave me a bunch of ideas.... watched another video where they made a blank to trace the profile from a good unit and it rode on something that would act as a stop against the wheel to get an exact profile.
I recently repaired a cyl head off a RMZ450 that had run a cam bearing and I got the damaged cam bearing bored out slightly then made a pair of small split bearing shells and fitted then with an interferance fit and it worked. I am also forging my own conrods for a Yamaha HL 500 replica at the moment and they have come up really well and are ready for heat treatment
that's really cool! What application did you get the bearing shells from? I've wanted to do this kind of stuff but finding what sizes factory bearing shells are on various applications is really time consuming, and it's hard to know whether a forum post from some dude 20 years ago is accurate or not.
That’s a really nice design to redress the cam surface. Will no doubt improve engine life. I don’t know how deep others commenting here think the heat treatment hardens the lobes but pretty sure it’s a lot deeper than any cuts you’re taking. I’m assuming the fact you’re using linear rails means it moves so freely that the lobe itself becomes the guide if careful with pressure. Enjoyed watching 👍
That's not repair, that's changing the cam to a whole new spec and a loss of hard facing. The base circle, ramp and everything to do with what that cam was has been changed. Cool way you grind a cam tho!
@@shanesigston8817 : Cam's grinded all way around, hence its profile is not changed much at all, will need thicker shims though. The difference would not be notice by any none-world-class rider at all, but a dyno might pick it up in an strict A-B-A test, other factors probably would influence more so that tiny reground diff would drown in the noise of those other unless you do statistical measurements. In regard to hardness, it's intact. Face hardness goes lots deeper than that (a magnitude more at least).
I see how that would work with a ohv engine. You can shim those. What I was thinking was a pushrod engine. Thanks for giving me another perspective because I work on pushrod engines for a living. 👍
Very cool, and to the average, or even better than average rider, the minor change in the lobes will not be noticeable at all. As seen by how far they were worn to begin with, and I bet the only thing noticeable was maybe the bike became hard to start. It’s a smallish bore single cylinder engine, that repair is perfectly acceptable, in a situation where new cams are hard to get or too expensive to justify. I’m sure this guy will be able to get them adjusted properly, as he did use a mic to be sure the round(open) area of the cam was perfectly round and centered, adjusting them will be just like normal.
seen a machine like that build by a stock car racing team , the guy used a racing cam on one end on a folower to grind a normal cam on the other end across a grindingwheel the same diameter as the folower wheel worked pretty good the cams where clocked the same way and connected together to get the correct timing , they did 4 cilinder cams that way
El acabado es mu bueno... ahora las medidas de las levas ya no son las mismas y estarán probablemente fuera de parámetros... ademas el problema parece falta de lubricación espero que este revisado si no es así pronto volverá a fallar... y si los apoyos de los arboles de levas están machacados dudo mucho que la presión de aceite en el circuito sea correcta... No se si será una reparación adecuada... Un saludo y espero unos buenos resultados después de 500km (no le doy mas de vida)
Looks pretty and that’s about it. Dips in cam ramp is still there, nothing to saw cam timing profile is out the window. Nice piece of equipment if you add a master cam profile to follow. The cams heat treatment is a real consideration.
paul X Case Hardening on cams is usually around 1.5 mm so 0.15 mm (close to 6 thousands of an inch) is still within the hardness area. However 0.15 mm off the cam does reduce the valve lift. Dressing the wheel would be of value here to get an even finish across the surface. You Tube machinist Keith Rucker does it on his grind jobs, it's a diamond tipped tool. How much 0.15 mm less could only be seen on a dyno or a straight out drag between this repaired bike & an undamaged engine model. A BALLPARK UNEDUCATED guess is that if the valve lift is 10 mm than it's 0.15 mm less so in % terms it's 9.85 mm/10 .00 mm. That's near to 1.5 % less. If the bike when new makes 40 H P at redline, with these repaired cams it will make 39.4 HP. At lower rpm's the difference is a lot less. At 1/4 of maximum it's just 0.15 H P. At 1/2 the maximum it's only 0.3 HP. For most riders you would not notice it as a lot of riding is done in the bottom 1/2 of the rev range & hardly any difference at redline. Saving money is the name of the game here.
He did dress the wheel with a diamond tip, I think it was the cam mounting that was off maybe? Or the original surface was messed up. Also, you can grind the round backside of the cam by the same amount as what you took off on the lobe, and this will result in have the same lift as before (you compensate by bringing up the bucket with a thicker valve shim). It would be hard to do by hand though, But he could upgrade this with a bearing mounted to a post, and 3D printing a cam profile on a big 8" disk. (measuring the cam profile to make that is a pain, but he has the rotary piece, just needs a long travel dial indicator to measure it every couple degrees)
@@nickopedia5669 My error as yes he did dress the wheel. If you grind a cam you reduce the valve lift. Here it was only 0.15 mm. Take it to the extreme & keep grinding so that the cam is 50 % smaller. The valve lift will then be only at 50 % of the original. In many engines with rocker arms you need to fit ones with a longer ratio to restore the valve original lift if required. Leaving the rocker arms/finger followers* (*this KTM has them) the same does reduce the valve lift. Placing a thicker shim or tightening the lock nut & feeler gauge type of designs will not alter the valve lift in practical terms but could burn your valves if nil clearance. All engines require some valve clearance unless they have hydraulic lifters (the hydraulics adjust for wear & heat at higher revs but usually aren't used in performance engines because they don't perform well at high RPM). This engine puts out 58 hp according to the factory. Excellent, as a 1970's Honda 750 put out out 67 hp.
@@hughmoore810 You have to think about what a camshaft is doing. It's creating a difference in height between a base circle and a peak. So if you make the base circle smaller while keeping the peak the same height, you know have MORE lift. Or, if you had to grind down the peak, you can just grind the base circle by the same amount to get the same lift as before. Of course, when you grind the base circle smaller, it raises the cam's surface away from the surface of the cam bucket, so you have to put in thicker shims. This is NOT to make in have less clearance than factory as you said, but to bring it back to within the factory specified range.
I see you doing some good things but I learned the hard way that no good deed goes unpunished. If you're rebuilding someone else's motor, use new parts unless you want to eat the job
and another one: to all those who don't understand timing and lift: yes the Camshaft controls timing and lift. if the ircumference of the cam lobe is just "shrunk" by grinding, you can either: 1. shim the hydros (automatic/hydraulic valve lash adjustment engines) 2. adjust the valve clearance accordingly (classic style, like adjusting screws and nuts) Never seen those? please educate yourself... youtube got plenty of explanations to offer. The "Shrunk version" offers the same timing and lift if the clearance is adjusted / shimmed properly. Basic Stuff: The Factory cam lobe profiles are GOOD! depending on what the user wants they are NOT perfect! Factory cam profiles have to meet power, versus emissions agressive profiles vs. durability. the list goes on.... Don't get toooo excited about factory tuning parts. they're only as good as emission regulations allow them to be. :-P An NO, in most cases- just because one spends a lot of money on factory grade stuff, it still doesn't mean it's the best to get out there. Sry, but it's true. Cheers, S.
Stephen Baer Not true on a ground cam. If you reduce the size of the cam you can't get the same valve timing & lift. No amount of adjustment or shimming will alter that. Valve clearance is a different animal to cam geometry. Bucket shims won't work to design of valve lift with ground down original cams & engines with rocker arms or finger followers need a longer ratio arm to compensate for the smaller cam profile. That's why they have different ratios such as 1.5, 1.6, 1.7 & 1.8.
@@hughmoore810 Hi, I'lll say it again. It works as described. Of course within reasonable limits. The Leverage is crucial, yes! But again, within certain limits. How come, that tuning-cams are profiled by grinding from stock-cams? Because shimmimg / adjusting works. No Offence meant. just think about it. Here's a link on cams, that might help to understand the leverage thing: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JPAeepqrY-0.html good source for understanding cams in general. secondly: imagine a cam being profiled from raw stock. this traditionally is made by grinding from a first round, then pre-profiled stock. then ground to measure with a master lobe on a grinding fixture. if the same principle as the master lobe (finger follower on master lobe translates to movement of cam stock relative to grinding wheel via levers) is possible to build it, the same goes for running it in an engine. It is maybe too simple, which might be, why people fail to understand it. again, no offence meant! it really is that simple. regarding leverage: Yes! if you "overdo" it on the grinding, the geometry hits limits where the valvetrain can run properly. the main issue here, is the leverage of rocker arms. Thing is: it's not about duration, timing and lift. Still not! it's about the forces inside the valvetrain causing issues. F = m * a (general) F = s * R (springs, general)) E / W = 0.5 * R * s² (springs, energy / work general) So, changing the geometry toooo much leads to vast rises in acceleration, which leads to more wear. But we're talking several millimeters here, not just a few hundredths! Back to start: if just the lobe extension is altered, the geometry is changed! Yes! there is no shimming / adjusting this. if the circumference of the base of that particular lobe is ground off as well, you end up with a just simply "shrunk" lobe on it's whole profile. Then shimming / adjusting works just fine! Again, within reasonable limits. What Paul does here, is just trimming off the lobe surface, which is no issue. Go have a look at how tuning cams are made. pretty please! Sry for my "bad english", i'm just german. Cheers, S.
@@stephenbaer2273 We're on different pages here. I'm talking about this KTM cam that Paul X is working on here. Not V8 cams that you buy a new from a speed shop or have your cam ground to a different profile & make up the difference with a longer rocker arm set. The difference is relevant if you use your own cam. As this is what's happening with the KTM units shown on here. Let's take 3 scenario's here for this KTM cam & stay with me on this, in particular scenario 3. The stock brand new factory profile as 100 %. Then Paul X's ground cams which are 0.15 mm smaller all over. So at BDC from the cam centre line the rubbing surface is 0.15 mm less. At TDC again the cam from the centreline is also 0.15 less. So when Paul X get's the KTM running again he will have had to put (in theory) 0.15 thicker shims to what was there before eg 2.80 mm ( let's say they were at specification before the oil pump failure damaged the cams. However Paul X's repaired cams would have 0.15 less lift than the cams had prior to the oil pump failure (very unusual, more like it wasn't refilled with oil, but that's another story). In scenario 3 lets say you had a top notch cam grinding machine & chose to grind a set of KTM "special profiled" cams at 50 % of the the original factory profile size (imagine that there is enough "meat" inside to do this). The profile is then small but all the degree profiles are the same in % terms.& we're not worrying about hardness of the cam surface for this exercise. You do it & install the cams but find that the valve clearance is now very large. I don't have the actual KTM profile measurements but lets say the original is from the cam centreline to BDC it's 25 mm & at TDC it's 45 MM. The 50 % grind is then 12.5 mm to BDC & at TDC.it's 22.5 mm. You could also go larger (eg + 50 %) then the head would also need redesign with smaller length rocker arms to keep the valve lift around 12 - 13 mm. So Paul X has to find/make a shims 12.5 mm thick + the thickness of the available service shims (eg 2.80 mm). He does that & gets the engine back together & has it running but finds it's way down on power. He looks into it & finds that the valve lift is only 5 mm instead of the factory's 10 mm. You could design & fit longer rocker arms to restore the 10 mm lift but that would mean a complete new head design & would need to be much larger to take the longer rockers. Go to that reference video & you find that the air flow at 50 % valve lift is about 65 % of the peak flow. That explains the noticeable loss of power. 35 % less flow might mean 35% less power ? That could be 20 hp less ? It may not be that amount but certainly in the ballpark.
I see an issue with this on flanks of lobes. Hydrolic cams often use a non linear opening slope to help lifter close and not bleed down while being depressed. If this cam is for solid lifters not a problem. I come from the harley world and always got my ass chewed by customers after I installed their andrews cam of choice, and now they got a ticking motor. A quick call to the manfucture verified that they were not ground for hydrolics and will tick.....this was the 90's ...order a bike and wait a year for it to show up, back when Harleys were special. I like the set up and Pink wheel, nicely thought out.
I have 45 years experience as an automotive machinist. This video nearly made me cry. The idea may seem sound to the uneducated but a dyno test would prove how far wrong this method is. sure it would work in a engine built in 1910 but in a modern engine, no, sorry.
Whats soo bad about it? The idea is just to make the surface flat again. He does not take away that much material, I dont think it really changes the timing. And the valve clearence can be adjusted. I think its totally acceptable for a motorcycle.(Not for racing,of course)
@@WolfmanDude no a lot of careful engineering was just ground away. The base circle is no longer round meaning lash will change depending on where checked. The careful lash ramps totally augmented actually all the critical designs thrown out the window really, valve lift curves are designed intensively to compromise area under the curve vs Valvetrain stability
He is not trying to improve the performance, he is just showing how to fix it so that least you can have a running engine if you cannot afford new cams or if the parts are rare to come by.
This is the coolest channel I think I’ve discovered all year. Amazing work Paul. Do you have any customers? I’ve got a 1981 xt250 that needs a cam but unfortunately they don’t make them anymore. You think you could tackle it?
Hello. At 0:47. Can someone explain why sometime we find a groove in the head and sometime not. Sometime juste on the exhaust came end not in the intake came? Thanks you.
I know there is maybe not alot of material removed on this job but would this not affect performance of the engine, also the profile may have been affected by the excessive wear and that has now been mirrored in the regrind.
new cams 389.00 each or something like that I priced out rebuild in parts this happen to my 2018 Ktm sxf350 oil pump gear warped my crankshaft bearing got screw to.. massive up and down play oem parts I was up to 5000.00 dollars just Ktm parts and I wasn't done the rebuild on this bike on this failure is usually 6000.00 or better thats without labor its easier to go by a Honda
So is it true to say that yes, it does change the timing of the cam but only so slightly that it is negligible? In theory you could also change the shape a bit if you are not careful. Especially on those low spots that dissappear the last.
TRANSLATE IN ENGLISH PLEASE. mi dispiace ma questa non è una riparazione. per riparazione si intende riportare i valori alle tolleranze originali, andando a rettificare l'alzata della camma oltre a perdere del materiale vai a cambiare la sua alzata, di conseguenza vari la fasatura e la durata di apertura della valvola, sono sicuro che queste cose le sai già perchè per aver fatto un video simile la tua conoscenza in questo campo deve essere ampia! ma è sempre meglio dire le cose come stanno e il titolo andrebbe modificato secondo me.. comunque bel video! pur senza alcun macchinario specifico sei riuscito a creare una rettificatrice molto interessante! continua così.
Camshaft grinding machines have hydrostatic bearings and the diameter of the grinding stone is much larger. The camshaft supports are also rectified. If you buy a cylinder head, then you buy a complete cylinder head.
@@Noldimo22 For reasons of economic efficiency. There may also be sentimental reasons. So easy to give up, ready! when it breaks we don't repair anymore we buy another ...
I did a Suzuki 450 head that was so trashed ! They let it get so bad , the valve stem wore all the way through the guide into the head . You could not get the new guide to go in straight . It was pretty ugly , but it wasn't the ugliest that I have ever seen .
Lift is not a problem , you can even add lift by grinding the bottom part of the lobe, and then compensate the valve clearance with thicker valve shims. But you never can compensate the valve timing event start and end. Degree wheel and Cam analyzer by performance trends experience proved that to me.
But anyway , Paul X is the person i watch after , he does many things that nobody can do in his videos, so big respect to Paul X for sharing his experience.
The damaged cams have worn through the heat treatment (and you added insult to injury with the sanding wheel), cleaning them to look nice and shiny will only have you taking them out again in the very near future, possibly with worse damage to the valve gear.
@@glennmerriman8382 in that case he should contact all manufacturers of cams and cranks and let them know that case hardening and heat treatment are a waste of time, they'd love to save money and increase profits.
@@Visionery1 Don't get me wrong, I know it is not correct. My point was that I have been in the same situation countless times, telling customers no,, no it can't be done, it's no good, parts need replacing etc But farmer insists he has no money & needs bike running for weekend, just put it together. More often than not, the bike starts & runs beautifully, and does so for a long time.
Like others I have my concerns over the work you have done removing surface hardening, maintaining the correct profile and valve timing to the engine. I would like too see a valve train stripdown 50hrs from now too see how the cam lobe surface has worn.
Amazing work dude, but you dissapointed me in this occasion cause you lacked the copy arm which for you is easy to make, and made the initial ramp harder and probably lost a few degrees but hell yeah its finger follower, it will work!
You're a smart and talented guy.....however I see this working on a Briggs&Stratton, not so much on KTM. As people have mentioned you're probably through the hardened surface. That's a problem, but as careful as you are you have changed the ramp profiles and no doubt timing of the cam. On a B&S engine it probably wouldn't matter much, but on a performance KTM this can cause all kinds of havoc, like valve float and engine that just won't run or tune correctly. Someone else mentioned that you lost valve lift, but if you grind the base circle of the cam correctly you don't lose anything. In fact that's how they grind performance cams out of your stock ones, they reduce the base circle of the cam. When they do that though they have cam profile guides for the grinding process so you can have an accurately ground cam with correct timing and lift. You would have to put a degree wheel on your engine and a totally stock engine and measure lift per each degree of engine rotation, to create a "map" of the cam to see how far you were out. It would be interesting to see.
Not sure I understand this idea. I understand that the cam has duration and lift and if it is ground equally all the way around, it can still project the same measurements. But are you merely hand controlling the lobes to the grinding wheel? If so, how do you know you haven't change everything from the original specs? Maybe you need to plot the lobe before and after so you can see if you need to go over an area a little more to match what it originally was.
You should have made a stop that is set at the exact same point as the grinding wheel along the Y axis. Then gradually move the stop in as you grind. That way the other cam can ride on the stop and match the exact same profile as the other. And you would be removing the same amount of material no matter how the cam is oriented in the collet..
In one of your videos you bought new cam fingers/followers because they were worn. Maybe you could setup some type system to regrind the arc on those worn followers/fingers as well. Just an Idea... Thumbs Up!
Nice your home made grinding machine but, if you haven't the copy profile cam it's impossible to create the same profile by hands. Your machine it'ok if need to grinding the bearing, but not a cams.
Hi Paul. We have just seen this video. Looks amazing after the repair. Do you mind me asking Where in the world are you please. We may need you skill if possible. have had some bad luck with a bike. Put a pair of new hot cams camshaft in a yz250f 2014. We Didn’t no the oil pump was on its way out and has taken both ex + in left side cam lobe’s have gone square. In only 4 hours. Bike has just had over £1000 spent on piston new barrel four new buckets and cams to freshen it all up and now the cams are done for. Or I thought till I seen your video. Is this any thing you can help us with as just paid £450 or around for the cams. I hope you get chance to read this and let me no what you think. As I think if any one can repair this I think your the man.
This will affect performance.. regrinding camshaft lobe will make it smaller and the lift and duration will reduce or change even a small amount of cut.
@@krtgaragegeetech5342 In this case a little bit, but normally you also take the same amount off the round backside of the cam, and then re-shim your valve clearances to compensate. This gives you the same lift and same duration. Doing this "backside grinding" to a stock cam you can actually take a stock cam and INCREASE your duration and lift, or modify the profile. companies like comp cams offer these services.
@@nickopedia5669 If you have a reground cam running in the engine with the same rockers as before the grind you will have less valve lift because they machine metal off the cam profiles. That's why they have longer rockers to keep the valve lift the same or slightly higher ? I see many performance shops sell rocker kits at 1.5 ratio, 1.6 ratio, 1.7 ratio & 1.8 ratio & maybe others ? A work shop might regrind a persons cam but they will tell you that the 1.5 ratio rockers are not suitable due to less valve lift than before & you need to buy the 1.6 ratio performance set. If you don't believe me print out these posts & visit a machine shop, let them read whats been said & ask them. Then come back on here & tell us who is correct.
@@hughmoore810 Thankfully due to the internet and regrind shops having websites, I don't need to go to a shop in these troubled times to ask them to set you right. A camshaft provides a difference in height, not just some absolute value. Hence grinding off on the non-lobed portion of the camshaft. Just give it 5 or 10 minutes and you'll figure it out. Here's a quote from Schneider Cams that might make things clearer. Note the disclaimer about shims/caps, because those have to be made thicker by the amount the base circle is ground by. "With any regrind, the base circles of the camshaft lobes are reduced to add lift/duration and/or remove excess wear. Schneider Racing Cams is not responsible for whether or not a reduced base circle camshaft will work with your engine. We always try to keep the reduction moderate in attempt to prevent any issues. Shims/caps/etc. are not provided as part of the regrind cost. "
Absolutely do not do this. You don't want to mess up the factory heat treatment unless you somehow know what alloy it is, and therefore what temperature profile to follow for the cooldown phase. These are very aggressive cams on dirtbikes, so I would imagine they are very easy to wipe a lobe on (compared to say a small block chevy with a flat tappet cam). Very light grinding as shown in the video will not affect the heat treatment, nor go through the carburization. If they're nitrided that may be a different story but AFAIK most camshafts are carburized, while the plain round bearings are usually what get nitrided.
How much does that change the lobe lift and duration? Seems buying a slightly hotter cam would be a cheaper, more foolproof option. You’ve ground away the hard face of the cam, and the rocker arms will dig into those lobes in short order. Not to mention the profile has got to be WAY off, you can’t get them precise like this. Hackery at best. NO WAY I’d run that cam, no way.
