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Motorcycle and ATV Cylinder Hone Instructions – Flex-Hone

Motorcycle and ATV Cylinder Hone Instructions – Flex-Hone

Hi, I’m Eric with Rocky Mountain ATV/ And today I’m going to show you how to hone a cylinder using a flex hone. We’re going to need a drill, a flex hone, a cleaning brush and flex hone oil. Rocky Mountain carries flex hones specific for your machine. The Flex Hone tool is perfect for de-burring and de-glazing cylinder walls. Refer to your owner’s manual for recommended honing instructions and intervals. You can use them on both steel and nicasil plated cylinders. On the nicasil you need to make sure and be really careful. The goal is to simply remove the glaze
and the carbon without damaging the plating. To do this make sure you use plenty of Flex Hone Oil and minimal time honing the cylinder. To start with we’re going to apply the flex hone oil to the flex hone. We want to make sure we get plenty on the hone as well as the cylinder. The Flex Hone needs to be rotating when you put it in the cylinder to start with. It’s a slow spin, you only want between five and twelve hundred RPM’s. Don’t use air tools. You want to stroke it quickly. The goal is a 45 degree cross hatch. You only want to do it long enough so
that you’re de-burring the cylinder. Between 5 and 20 seconds is usually enough. Now that we’re done honing we need to clean out the cylinder using hot water and soap. We’re also using the Flex Hone Brush.
This brush looks big but it will actually work on many different sized cylinders. Once we get it all cleaned out and rinsed off we’re are going to dry it. Then we’ll apply a light coat of oil to prevent oxidation. This is what your cylinder should look like. It has a nice 45 degree angle cross hatch to it The cross hatch allows your new rings to seat better. It also helps with oil lubrication

100 comments on “Motorcycle and ATV Cylinder Hone Instructions – Flex-Hone

  1. @crazygondo113 – Not if it is done right. You want to use a hone like the "Flex-hone" that barely scratches the surface. The intent is to "deglaze" and put the crosshatch marks in the cylinder, not to remove any material from the bore.

  2. @RockyMountainATVMC Have a question I am rebuilding my 03 banshee I would like to bore it 30 over but it worry's me that if I do that it would create more probloms for me like (Over heating) (Faster clutch wear)and trans) And also wondering if I will have to get an oversized head for the new bore I would really like to upgrade the power I just want to know how to do it properly without causing probloms

  3. @Browndemolitia – The hone won't take off "shavings", but tiny gritty particles from the hone certainly could fall in ports (2-strokes). That is why you wash it out when you are done.

  4. do you need to hone a cylinder if its brand new? with brand new piston? or is there anything you have to do to prepare brand new cylinders? doing a cylinder/piston/head replacement on a ktm 450

  5. So do cylinders have to have a glaze or seal, or how you finished cylinder will be fine? Does it make a difference in power between the two?

  6. @PuffBongsAllDay – It sounds a little wore out. I am sure it is causing loss of performance. Time to send the cylinder to LA sleeve.

  7. @RockyMountainATVMC i have a kawasaki D tracker 300cc and the engine is stack.
    The problem is that the engine worked a lot of time with out oil…

    Will flexhone help me rebuild the engine? or do i have to sent it to a workshop for repair?

    If so where can i buy flexhone from? i live in Europe-Greece!

  8. @andre1995ish – you want to take the glaze out and have the light scratches from the hone. This will help the new rings seat and allow the cylinder wall to hold lubrication better. If nothing else, use a scotchbright pad to lightly scuff it up (cross-hatch like the hone leaves).

  9. @PuffBongsAllDay – are you getting fuel? Spark? Are you sure you have the piston in the right way? i would double check everything.

  10. Wasn't honing done originaly because old cylinders and rings were cast iron and wouldn't seat? With the metals used in rings & cylinders today wouldnt honing just cause unnecessary wear on cyl wall? reason I ask is I use rotax two strokes on my light aircraft, when I get cylinders back from A&P mechanic they are mirror like smooth w/out a single scratch. My compression stays around 140-145.

  11. @razed1022 – I don't know about airplanes, but OE nikasil plated cylinders (and steel cylinders) come honed from the factory. The factorys also recomend light honing to remove any polished spots.

  12. @razed1022 – My question is why use warm water to clean the cylinder out of honing oil when oil and water don't get along? Why not use mineral spirits or parts washer solution to cut threw the oil better ?


  13. @jamie123dog – you can certainly do that too (warm water with dish soap will clean out the hone oil as well).

  14. @rockymountainatvmc hey say if i wanted to rebuild my kx250 topend would i need to hone it , what if i just needed new rings what does honeing do thanks,

  15. @ch0l0sk8r – it depends how the cylinder looks. Honing puts fresh cross-hatch marks in the cylinder which helps seat the rings and keep the cyliner walls lubricated properly.

  16. I have a 54mm bore and the chart goes from 52-54 or 55-57 what size should i get i heard that you are suppose to get one size bigger
    Please Help

  17. I want to save some money and re hone my cylinder myself. I have a yammy warrior 350 and I see you sell vehicle specific flex hones but my cylinder is bored bigger than stock should i still go with the warrior flex hone?

    And also is it required to get new rings? My piston shows no damage. And my ring end gaps are in spec.

  18. i have a 65 and the cylinder sleeve has deep scratches, would this work or would i have to get a bigger piston or a new sleeve?

  19. @ImTrickeh – a hone will take out real light scratches, but nothing significant. The goal is to just remove the glazing. you will need a bore (if the sleeve is borable).

  20. what is the difference between honing and boring??

    boring is when you increase the bore diameter?
    honing is just cleaning the sleeve?

    right? or wrong?

  21. @171apples171 – Yes we do, even though it isn't listed in our specs. It depends on your bore size. Your KZ should be around 72mm. Please double check and refer to the following part list. 68-70mm hone part # is 1284240005, 71-73mm is 1284240016, 74-76mm is 1284240006.

  22. @greenmonster687 – 320 silicone carbide. Aluminum oxide works great too on nikasil. i worked directly with the manufacturer to get the best one for motorcycles and atv's, and the 320 silicone carbide is what they suggested.

  23. i was using a flex hone to hone a 2stroke cylinder n noticed the hone was eating away the area around the ports more then the rest of the cylinder,it actualy made an indentaion between the ports,why would this be? thank u for ur help

  24. HEY NOTICE THIS FAST PLEASE!!!!! <—- So I am going to change piston from my ktm 125 and I will hone cylinder with my dad so I have these questions:
    1. Flexh-hone vs normal honing tool which is better ?
    2. Does this work on ktm 125 Ø50 mm cylinder (Nicasil)
    3. Can I use 2-stroke oil to grease the operation ?

  25. Hey I have one more question, it is when I don't know size of cylinder so I am going to take the cylinder to to shop so they measure my cylinder, ok. Should I hone the cylinder before measure, honing doesn't make big difference in size of piston or does it ?

  26. I need help! I want to do the top end on my 92 cr250r..couple things, if the cylinder and plating just need to be honed what size hone should I use? I ask because I think std bore size that year is 66.40mm( I think) so would I use a 67mm hone? I will measure it before I do buy,just thought id ask a pro…thanks

  27. – list the correct size on our site for your specific machine. It is a 65-67mm hone.

  28. My '01 Kx250 is a 66.40mm bore… should I use the flex-hone 64mm or 67mm tool? Also what grit should I use?


  29. For the 2003 CRF450R part # 1284240010 – Flex-Hone Cylinder Ball-Hone 96-105mm would be the correct hone and with as little as the hone is ran through the cylinder it's not going to change your bore size at all.

  30. how do you get the thing in the drill straight?? i keep trying to put it in my drill as straight as possible but it keeps wobbling every time. at first i throught it was just the drill so i tried the other one and same thing

  31. Obviously since the shaft is made of two wires twisted together you can't get it perfectly straight in the drill so it will wobble a little but just try and get it as straight as you can. Also make sure the shaft is straight and isn't bent at all.

  32. thanx. i got it in as straight as possible and it honed the cylinder good so thats good. and it wasnt bent at all i checked. it was brand new.

  33. These can be used on cylinders with ports however you want to be sure and run it through slow making sure you have plenty of hone oil.

  34. What about the ones with the 3 arms that spring out with the stone. Should I not use that and just get one like you have?

  35. Those are not recommended for nikasil plated cylinders. I would recommend investing in one of these Flex Hones.

  36. thanks man I thought I noticed all the videos didn't have ports.. prob better off leaving mine alone then taken this ishraff to my cylinder

  37. I am doing top ends on a 2000 rm125 and 2005 rm85. Both ran O.K. I found problems with power valves/resolved. Jugs/pistons were great. 125 WEAK  compression. My question is do I deglaze nikasil? I've heard don't because the rings don't seat, like old school smokers with cast iron jugs. I just want a yes/no answer. And maybe a logical reason. Who knows, maybe this will help low budget do-it-yourself-ers, like me

  38. if you have an engine that must replace piston often it can be too much and hone each time. think and hone every 10 hours , then I would honet after 1000 hours. with Nicasil hang that thing easily in ports and destroys I have heard , I use another type.
    I run only Nicasil then stopped and hone because it seems like I spend up 10000 km on a honing , but I'm running under 100cc day so it 's not like a 250cc

  39. Im doing a top end rebuild on polaris snowmobile and there's nothing wrong with the motor, do i still need to hone my cylinders?

  40. I read, for example, a 50ccm scooter with ~1,5in (~40mm) cylinder needs 600-800upm.
    But in the video (OK, more diameter) it seems very slow.
    Also your movement looks slow.
    And the (manually) movement speed sets the crosshatch angle?
    For example, what would be the right upm, movement speed (up/down) and granularity (120?) for a ~1.5in (50ccm scooter) cylinder?
    The final crosshatch.

  41. so i just ordered a brand new cylinder for my 2009 yamaha yz85. will it need any of this work done or will i be able to just toss it on and ride?

  42. I just bought a 3-3/4” flex hone for my wr450f. Is it true that i would be doing more harm than good? I only plan on rotating it in the cylinder for about 10-15 seconds. Thanks! Im nervous to do it but also know i need to create more cross hatch

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