MaineDad 85 #26 Posted July 4, 2011 Mike, I ordered my Mahle Piston at opeengines.com. You can also email them at sales@opeengines.com. Jerry, Go ahead and open it up! It's nice to know what's happening inside We'll help you through the process too... Share this post Link to post Share on other sites
shorts 182 #27 Posted July 5, 2011 Mahle, is a tier 1 engine parts supplier to the auto industry, just like, Federal Mogul, DANA, and many more they all have extensive research and development programs and application engineering departments involved in improving and selling their parts to the manufacturers. typically the non production parts of the company work on pieces that won't see production for 5 years or try to improve current production parts. Share this post Link to post Share on other sites
JC 1965 1,530 #28 Posted July 6, 2011 Jerry, The Mahle Piston or Piston style "D" is the 3rd generation Kohler piston used in the newer Magnum engines. They're manufactured in Germany and made of tougher material than the older Kohler pistons. They hold up to heat better and wear longer, too. And they weigh the same as a Kohler piston assembly. Mahle pistons have the same compression height as the K-series pistons. Mahle pistons just last longer under severe conditions, that's the only difference. You also have to get a stronger matching connecting rod if you go this route. Porsche engines use the Mahle brand too I used a wire wheel brush on my electric drill and some emery cloth to do the carbon cleaning. Regarding lapping the valves it's pretty easy. Do a 'Valve Lapping" search on this forum and you'll sure find something. Micah I did A valve lapping search but didn't get much info. Does the valve lapping process clean the groove around the top of the valve or does it just clean the flat top surface of the valves. I know that you use A lapping tool ( rubber suction cup on wood handle ) And lapping compound. Just not clear on how and where to use it. Any info appreciated. Thanks :woohoo: Share this post Link to post Share on other sites
shootinok 15 #29 Posted July 6, 2011 jc1965 - check this out to remove the valves - Pay no attention to the brand of tractor! and this for lapping - Share this post Link to post Share on other sites
JC 1965 1,530 #30 Posted July 7, 2011 jc1965 - check this out to remove the valves - Pay no attention to the brand of tractor! and this for lapping - Shootinok, Thanks a bunch for the video links. I now know how to remove the valves and how to lapp them in. I had imagined that it would be really hard but it doesn't look that bad. Thanks again for taking the time to help me out !! :ROTF: Share this post Link to post Share on other sites
SousaKerry 502 #31 Posted July 7, 2011 A word of caution on those cheapo calipers. I have been a machinist for over 15 years and have worked as a gauge calibration technician. Them calipers are not worth the stainless they are made from. I worked in a shop where a manager bought about 30 pair of those cause they were a "good deal" and I can tell you that after calibrating many of these they aren't much better then a good tape measure. Out of the box the jaws can have .005" taper, I was never able to get a set to repeat better then .002" on a gauge R&R test (repeatability and reproducibility) the telescoping gauges you pictured should work fine and as long as they are not abused should last many years. For measuring engine bores I would suggest you use a good pair of micrometers, a good set of 3"-4" mics will run you about $100 but will last a lifetime (or more) if properly cared for... Don't buy them at a retail store what they sell the general public is over priced and junk (sorry guys but the craftsman ones at sears are not worth a darn either) go to an industrial supply store such as Fastenal, Granger and the like. Brands to look for are Mitutoyo, Brown & Sharpe, Starritt, Another good source for used ones is pawn shops just inspect them closely for wear and that they turn freely. When you are measuring tolerances in small engines you need .0005" accuracy as a general rule of thumb all calipers are not accurate below .005" (even the nice Mittutoyo and Starrett models) Ok now I will get off my I apologize for the rant but I would hate to see anyone loose an engine due to a miss measurement Also a local machine shop can do the measurements for you if you do not have the equipment or confidence in your accuracy. Share this post Link to post Share on other sites
shorts 182 #32 Posted July 8, 2011 Way to go Kerry You didn't say anything about making sure that you get guage blocks with/for micrometers, and how to check for zero prior to measuring everything, all parts and tools should be temperature equalized to get accurate measurements. their is a certian amount of feel involved in getting good measurements, have someone that knows how to use precision tools help you the first time or two and help you develop the feel. remember these are precision tools not C clamps, they should be kept clean and dry and only handled by the barrel or C do not leave your acidic fingerprints on the anvils. also never leave a 0-1 mic with the anvils touching. as far as good instruments lasting for ever I have both my dad and grandpa's 1'' mics, 1 brown&sharpe and 1 starrett Share this post Link to post Share on other sites
SousaKerry 502 #33 Posted July 9, 2011 good advice shorts feel is especially important on the telescoping gauges. One very important feature to the telescoping gauges is they can be used to check for an egg shaped bore by doing several readings from different angles(like working your way around a clock) Those fancy expensive 3 pronged hole mikes and dial bore gauges can't do that very well. Of coarse the absolute best way to measure one would be with a CMM(coordinate measuring machine) but unless you have friends in high places, or about $50,000 laying round burning a hole in your pocket forget it. We have two at our shop and the quality guys get nervous if you even glance at them, even tough I used to program them at my last job I would never even attempt to ask. :D Share this post Link to post Share on other sites
MaineDad 85 #34 Posted July 9, 2011 Thanks guys. Unfortunately i do not have all of the fancy tools, but i have taken the reading several times and have logged the same results. I zeroed out the digital calipers each time. I am going to assembly it assuming it is still within a "Standard" bore and will suffer the consequences if I am wrong. Live and learn :woohoo: Share this post Link to post Share on other sites
MaineDad 85 #35 Posted July 19, 2011 Lived and learned: Update: I installed the new piston, rings, and connecting rod and put it all back together. Well, it did not help the situation. Started fine and ran fine for about 1/2 hour then had another smoke show So I removed the head and noticed a bunch of oil. I will take it all apart and take it to the machine shop for measurements and boring. I'm out about $150 - lesson learned. Share this post Link to post Share on other sites
WH nut 553 #36 Posted July 21, 2011 Did you install the rings right and stager the gaps? Also, is the breather clean and installed correctly Share this post Link to post Share on other sites
shorts 182 #37 Posted July 21, 2011 have the machine shop check the valve guides and replace them as needed while they are doing the cylinder Share this post Link to post Share on other sites
stevasaurus 22,904 #38 Posted July 23, 2011 This is a fantastic thread. I've done 6 & 8 cylinder engines, and I have just acquired a K-90 to "practice" on...can't wait now. I was looking for a fall/winter project. Thanks for all the great information and sites to check out. Micah...waiting to see what the machine shop found out. :D Share this post Link to post Share on other sites
MaineDad 85 #39 Posted July 23, 2011 Did you install the rings right and stager the gaps? Also, is the breather clean and installed correctly Yup. Rings gaps were checked and breather was installed correctly. What I should have done is grab hold of the flywheel and see if I could get the piston to move side to side. It does I am hoping to take the flywheel off this weekend and get this engine on the bench again, but it too cussid hot in the garage! I will take it to the machine shop as soon as I can. Share this post Link to post Share on other sites
WH nut 553 #40 Posted July 24, 2011 Did you install the rings right and stager the gaps? Also, is the breather clean and installed correctly Yup. Rings gaps were checked and breather was installed correctly. What I should have done is grab hold of the flywheel and see if I could get the piston to move side to side. It does I am hoping to take the flywheel off this weekend and get this engine on the bench again, but it too cussid hot in the garage! I will take it to the machine shop as soon as I can. You will get movement side to side, probably .004-.006, Id have to go look to make sure Share this post Link to post Share on other sites
MaineDad 85 #41 Posted July 28, 2011 Update: All of the internals have been removed so I can bring it to the machine shop for measuring then the necessary boring. I did however make a mistake during the removal process. I forgot to identify which tappet was for the exhaust and for the intake like the manual describes. They both look identical so how much does it matter at this point? Can I get a Homer Simpson Doh! Share this post Link to post Share on other sites
illinilefttackle 399 #42 Posted July 28, 2011 Update: All of the internals have been removed so I can bring it to the machine shop for measuring then the necessary boring. I did however make a mistake during the removal process. I forgot to identify which tappet was for the exhaust and for the intake like the manual describes. They both look identical so how much does it matter at this point? Can I get a Homer Simpson Doh! Should be no biggy- The tappets should be designed to rotate slightly as they operate so wear should be uniform-unknown about whether the different temperature of the hotter exhaust valve will have any influence in wear. Good luck- I did my K-301 a while back-I couldn't be happier with the results-Al Notice how I could move the piston back and forth in its bore-at the beginning of this video-but it still ran! Share this post Link to post Share on other sites
SousaKerry 502 #43 Posted July 28, 2011 Nice C-125 really like the high gloss back on the hood Share this post Link to post Share on other sites
MaineDad 85 #44 Posted July 29, 2011 The block and crank are packed in the car ready to be delivered to the machine shop tomorrow. I am also having them measure the crank journal to see if I can still use a standard rod. hopefully they can polish it too. I figured I might as well do everything right while it's opened now so I don't have to open this again for a long time :woohoo: Share this post Link to post Share on other sites
can whlvr 993 #45 Posted July 29, 2011 looks like you are giving her the full monty and as you said you will have an engine good for decades when sevised regularly :woohoo: Share this post Link to post Share on other sites
MaineDad 85 #46 Posted July 29, 2011 Forgot to mention that they will also recut the valve seats. Share this post Link to post Share on other sites
MaineDad 85 #47 Posted July 30, 2011 Update from Machine Shop: The cylinder needs to be bored .010 over and the crank needs to be turned .010 under. The valve seats will be recut too. Total cost will be about $125. Share this post Link to post Share on other sites
illinilefttackle 399 #48 Posted July 30, 2011 Update from Machine Shop: The cylinder needs to be bored .010 over and the crank needs to be turned .010 under. The valve seats will be recut too. Total cost will be about $125. Micah- have bought the new parts? My experience tells me the machine shop should have the parts so they can bore & grind to their specs. Much better fit that way-Thanks-Al Share this post Link to post Share on other sites
MaineDad 85 #49 Posted July 30, 2011 Al: Yes I have ordered the parts and the machine shop is waiting until they arrive to do the work. In fact, he insisted he get the new connecting rod before he started to make sure he did it right Thanks for asking though... Share this post Link to post Share on other sites
MaineDad 85 #50 Posted August 18, 2011 Update: The engine is all back together and it runs! It actually runs pretty good. I've adjusted the carb and I am eager to get mowing with her. Question - how long should i run it before attempting to mow the lawn? I have ran it now for about 1/2 hour with no issues and no smoke etc. Thanks :thumbs2: Share this post Link to post Share on other sites
