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Post by 90GTVert on Feb 1, 2021 19:22:10 GMT -5
Put the cam on V blocks,check lobe lifts with dial indicator.Assemble cam in head,zero lash rockers,dial indicate rocker travel at valve tip,then calculate the rocker ratio..Am I missing something here?? Yeah I know this isnt a scientific method,but works for the average redneck racer in the shed! I've already done the v-blocks and dial indicator and then checked with a caliper to sort of verify. There are a few reasons that I wanted to measure the rocker. One was in hope that it would verify that I'm in the ballpark at least, or perhaps even be more accurate. More accurate is out for me, but it has placed me in the ballpark. The other is that I'm not sure that I'll get a very accurate reading at the valves because it's going to be off to some degree unless you manage to match the angle of valve travel perfectly. Finally, I kinda wanted to do it because I've never had to measure a rocker before and I was curious how it turned out. I know I go overboard and overcomplicate things sometimes, but to me it's different working on my own stuff vs sharing the info from working on my own stuff in detail. I think this particular task is relatively inconsequential to my project and not worth the effort if only considering that. I'll screw up the exhaust by way more than any difference a few degrees makes in a calculator. |
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Post by captincvmn on Feb 1, 2021 21:26:44 GMT -5
You may be overdoing it but that’s also one of the things we appreciate about you. You go the extra mile to investigate minutia completely.
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Post by 90GTVert on Feb 10, 2021 16:28:20 GMT -5
I've been getting the video caught up to where I actually am, so I haven't done much with the engine since I last talked about it. An animation of a cam, valve and rocker and some other graphics tied up a bunch of time. Now I'm going to irritate at least 2 people that watch this thread ( captincvmn & 190mech). In one case because the video is already 45 minutes long covering rocker ratio, cam measuring, making a piston stop and degree wheel adapter, finding true TDC and so on. It's a lot of stuff packed into one video, but fear not... I will have an index so you can click if you want to skip over or to a section. Then John will probably love to hear that I'm still contemplating measuring lift at the valve instead of moving along quickly and efficiently. I think I was incorrect in my approach to finding the most accurate reading of lift from the valve spring retainer last time. My goal was to get the largest reading, assuming that was telling me that I was following the travel of the valve more accurately. After more thought, and the idea of cosine error; I don't believe that's the best approach. Cosine error should mean that my reading increases as I get the angle of the dial indicator farther from correct. It is explained HERE by Joe Pie. I can't quite come to grips with why it appeared that the closer my indicator looked to the angles of the valve, the higher the readings got though. I think I have a pretty no-nonsense idea for trying to get the angle of the indicator to match the valve's travel well though. Well, it may be full of nonsense, but it makes sense to me at least and it's not complicated. I'm thinking that if I put a mark on top of the valve spring retainer in a spot where I can get an indicator in there, I can use that to see if the indicator angle is pretty close. If the indicator starts out on the mark and then ends up away from the mark in any direction as the valve opens, that should tell me that the indicator needs to be adjusted. If the indicator tip stays pretty well on the mark across the range of travel, then I think it should be close enough. I've used the same idea with a basic location on the retainer pretty much every time I've setup an indicator like this, but I don't normally put a small mark there to easily watch. I could take the head off and measure the other end of the valve as it is actuated by the cam to get direct motion, but I'd rather not pull the head off just yet. I don't think you'd ever be able to get a totally accurate reading without a lot of setup time and/or more advanced equipment anyway, so it becomes an exercise in figuring out what works well enough to be practical and is close enough that it doesn't make me feel like I'm spreading bad info. The mark following method seems like it could be that. I'll be doing more editing before I'm back in the garage, so there's still time to tell me I'm all wrong. This is yet another example of doing something that I've done before, but trying to put more thought into it. I'm bound to learn something eventually, but at the cost of a lot of time and a lot of people wondering why bother. |
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Post by captincvmn on Feb 10, 2021 18:08:21 GMT -5
Bring on the Video. At 3/4hr I’ll do my best not to complain. I miss seeing 49content.
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Post by 190mech on Feb 10, 2021 18:31:36 GMT -5
I was going to suggest some machinist dykem on the retainer to see indicator walk a few days back but figured
I'd be beating a dead horse,,guess we are thinking on the same path!!!
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Post by 90GTVert on Feb 12, 2021 18:45:18 GMT -5
I used a dry erase marker on the retainer. I think it would be tough to see travel on that, but what does work is picking the indicator's plunger up and letting it drop down. That will leave a mark and you can do that at the top and bottom of travel and see how close you are.
The funny thing is, the first time I went round and round with it for so long. This time I had it setup in a couple of minutes to match well. I'm not sure what I was doing the first time, other than maybe worrying more about a better camera view without blocking the indicator perhaps.
I got 0.303" this time for the intake valve lift. I'm guessing the rocker ratio is basically 1.11:1. Calculating vs lobe lift for the intake and my graph paper measurements both came out right about there. I don't have the exhaust valve lift number yet, but I think my greatest chance for accuracy is on the intake side anyway, where it's most accessible. I took IVO and IVC at 0.0555" (0.050" x 1.11). While it's setup, I figured I might as well try to get the profile of the lobe so I went through and checked lift every 5 degrees. I also took IVO and IVC readings at 1mm, 0.006", 0.002" and 0.050" so I should have more info than anyone would ever want about this cam.
That was yesterday. This morning, I realized that I forgot to check intake centerline (0.050" in each direction from max lift). I went out to do that and it was so cold in the garage that the indicator's plunger didn't want to reach full travel. I had to wave a torch around in it's general vicinity to get it nearer a reasonable temp and then it worked fine again.
I'll probably do the exhaust tomorrow.
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Post by aeroxbud on Feb 12, 2021 19:36:25 GMT -5
That's telling you it's too cold to work on the bikes.😞
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Post by 90GTVert on Feb 12, 2021 19:58:52 GMT -5
That's telling you it's too cold to work on the bikes.😞 If there is such a thing, it has been good timing for the piston to melt on T2. Since that happened, we've had multiple snow storms, constant salt covered roads, and now the next 7 days forecasted have 1 or 2 that aren't rain/snow/sleet. Aside from the temp, it has been a good time to be in the garage and even better for video editing. I've got kerosene heaters in the garage though. I just can't or won't afford to fire them up all of the time and generally go for 50-55F when I'm gonna be out there awhile. I'm very grateful for the workspace that I have, but I have a friend with a central heated and air conditioned garage that does make me a little jealous sometimes... especially since he doesn't even work in there. |
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Post by captincvmn on Feb 12, 2021 21:55:37 GMT -5
Cold garage space and numb fingers are the pits.
If you ever want to heat it used mobile home forced air furnaces “can” be had cost effectively. If you have natural gas you can get a plumber to run a line into the garage. If you don’t source a fuel oil model. They are narrow and can sit in the corner with a duct aimed into the center bay.
No of course I don’t have one.
Yet
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Post by ryan_ott on Feb 12, 2021 22:10:08 GMT -5
I moved out of the garage and the kitchen counter has been a nice work bench lately..
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Post by 90GTVert on Feb 20, 2021 7:33:20 GMT -5
I thought I was going to have the video done last weekend, but I am finally getting to the end now. Hope to have it up today/tonight. For now, here's a profile and some info. Click to enlarge.
 The extended area at the exhaust valve closing is caused by a decompression system that holds the exhaust valve open at very low RPM to make starting easier, so it should not be present at operating RPM. There are 2 LSAs and 2 different ground-in advance figures because I believe the exhaust lobe to be asymmetrical, so I get different centerlines depending how it is measured. I just included both sets of info, though some define LSA and centerline as a function of max lift so the 0.050" from max lift numbers are probably the correct ones. |
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Post by captincvmn on Feb 20, 2021 8:36:58 GMT -5
I’m looking forward to this video. The amount of time you put into each one is extraordinary. My favorite as far as complexity is the calculating displacement video. My brain just can’t keep up.
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Post by 90GTVert on Feb 20, 2021 18:47:52 GMT -5
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Post by 190mech on Feb 21, 2021 6:52:28 GMT -5
Great vid Brent!Thanks for taking the time to detail the intricate geometry of 4stroke valve timing..That intake port looks like a rough casting,can you see the pocket area?Now if we could just come up with a way to do away with those valves and make the engine fire every stroke,,Oh Yeah!Somebody already has,its called a 2stroke!!!  |
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Post by 90GTVert on Feb 21, 2021 13:38:57 GMT -5
Great vid Brent!Thanks for taking the time to detail the intricate geometry of 4stroke valve timing..That intake port looks like a rough casting,can you see the pocket area?Now if we could just come up with a way to do away with those valves and make the engine fire every stroke,,Oh Yeah!Somebody already has,its called a 2stroke!!! Thanks. I haven't even tried to look the head over. I only removed the stick-on cover that came on the engine so I could bolt on the metal piece for the indicator base. I noticed the rough cast and told myself NO. Don't mess with it. My goal is to get this thing running without ever taking it apart farther than it was to check the cam. I'd like to see how it does with whatever crappy exhaust I build, the 28mm carb, and an upgraded CDI (low initial advance, then up to 38 degree flat line). If it turns out to be something that I like, then maybe take a closer look at race cams and port work or possibly what heads are out there. IIRC I can still go up a little on cc with this crank, but they already talk about the cases cracking sometimes just trying to start them at 150cc and up. I think the thing that caught my attention the most was the mention of roller rockers in some engines. Something about v2 heads having them, but I'm not sure if that even applies to this style with the KLX 110 knockoff heads or if that's v2 of the Honda knockoff heads that these pit bike engines started with. Haven't looked into that either. Honestly, if I put much time/money into horsepower right now, I'd prefer that it goes into the 2T. This thing is not likely to ever touch T2 unless I swap in a big 4T or put a 2T in it. At that rate, I might as well just focus any energy toward getting it going and making it enjoyable to ride. |
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