Honda Monkey | DHM High Compression Piston Install | Garage Time

Finally found some time to install the DHM High Compression Piston into the Monkey. This video is just the install, including how to gap rings on the piston. There's a few things I've done differently on the install (installing the piston into the cylinder before putting the head back on, for example) but overall I think it went pretty well.
@nicksoup in the comments mentioned the need for a split socket to remove the stock O2 sensor. I haven't had the stock O2 sensor there for a while, so I completely forgot about it. I did show how I removed it in my Yoshi RS3 install video ( • Honda Monkey | Unbox, ... ) just in case someone needs a bit more help.
In previous videos I showed my installation of a Yoshi RS3 full exhaust, MNNTBX intake, TB Cam, aRacer Super2, 14t/34t sprockets, and 60% stiffer clutch springs. It will be interesting to see how it all ties together.
DHM Honda Monkey Stage 3: www.dhmotoring.com/products/d...
Ring Gap Tables: www.wiseco.com/PDFs/Manuals/Ri...
Follow Me On:
• Instagram: / unown_shadow
• Twitter: / unknownoverland
#hondamonkey #garage #highcompression

[@Spartan375X]

Thanks for the guide, I went with the stage 3 kit for my SF Grom 2 months ago (going 500+ miles). Some notes for others, don't forget the dowels, I missed one and had to undo some of the work. I put it back together, pulled the old spark plug and saw I crushed the old spark plug in the cylinder when I was finding the timing marks, so I had to go in again and clean out those porcelain fragments. Thankfully, just a tiny ding on the piston. The stock airbox can make the intake valve adjustment a bit more difficult to access. After that, the kit is definitely what I needed to get over the hills in my area, now I just need to loose weight for the interstates. I also used this as a reference for my CRF230M piston upgrade. EDIT: 6 months later, I checked my valve clearance a 3rd time since I thought my own math was right when I though 0.75mm was the same as 0.003 in, when it was actually 0.076mm. 😑 I was thinking the whole time the slight ticking noise from the valve clearance was normal. I got a new set of feeler gauges that had both mm and in. labeled, made a huge difference once I set the PROPER valve clearance and I know now that I have missed out on some power for too long.

[@UnknownOverLand]

This is awesome information and reminders, thank you for sharing!

[@reidspeed77]

Superb

[@UnknownOverLand]

Thanks!

[@giannissakalis1230]

Great video man . I hope your bike will get a little bit more low-end power . I want to say that in my country (Greece) ,this same engine was fitted to Honda innova bike ANF125 . These engines have an 'Achilles heel' with their connecting rod. I would recommend to drive your bike carefully for at least 1200kmh (~800miles) and don't rev it past 6-7k , just to make sure that all the metals especially the rod and the piston will break-in as they should. Btw one of my friends has this bike an has a 67mm piston and +10mm stroke. It has 30+hp hehe

[@UnknownOverLand]

Thank you for that warning, I’ll definitely keep an eye on the break in. I hadn’t heard of issues with the connecting rod here but I can see where it could be stressed more than they expected with some of these changes. Sounds like your friends bike could be quite fun.

[@giannissakalis1230]

@@UnknownOverLand Yeah it is a beast . These engines are at least 15years old in my country. Saying that It actually means that different models of the Honda bikes, use the exact same engine. A lot of people here are experimenting with bigger bores and tuning.. so they know where this engine is lacking rigidity. For example the new Honda GTR(150) in Thailand is 8 years old but in my country the bike came in 2019 ...

[@UnknownOverLand]

That makes a lot of sense. We're a bit behind on getting these bikes out here, especially the Monkey version. The Grom community has had a good head start at least.

[@PizzaCologne3]

Thanks for the install video, current got oil flowing into the headers, I think I broke something

[@UnknownOverLand]

You may want to check the gaskets at least to make sure everything is seating well. Otherwise, look for cracks.

[@PizzaCologne3]

@@UnknownOverLand video was very helpful, took it apart yesterday under 3 hrs "first time" and found that the piston cracked on one edge and blew the rings allowing oil to flow through and gasket seems old, so new ones on the way, can't wait for the fresh install.

[@bentareholmsen2163]

The ring is bigger when it's hott.

[@Adv.Wannabe]

What were your final setting on your Aracer? I’m running the mini5 with af1. Do you have base settings on everything?

[@UnknownOverLand]

It’s mostly base settings, making sure that everything idles and warms up correct then AFR sits around 13. Then I turn on autotuning and let the system fine tune itself. I have played with the timing a little, but really the most important is putting 93 or higher octane in the bike and it just runs.

[@CANE1202]

Thanks for the video. Always enjoy them while you hook Albert up with more goodies. Question, what oil are you running?

[@UnknownOverLand]

Thanks! I run Motul 7100 Synthetic 4T 10W40 oil in the bike. After the initial oil change I had swtiched to synthetic and hopefulyl a good weight for the weird temperature swings we tend to get in Colorado.

[@Ultermategamerz]

I'm looking at a similar setup to you, just wondering did you have to adjust your ignition timing on your Aracer for knock prevention? And what octane did you end up running? Excellent video as well! Cheers.

[@UnknownOverLand]

Thank you so much. Depending on what's available, running 91 octane or higher (or at least octane boost in your fuel) will be needed for most of the knock prevention. If you look for the comments on the video from DH he also mentioned pulling some of the ignition timing in the Aracer if there's still some knocking (about -2 to -4 in many cases). Just keep an eye on the color of the spark plug.

[@jakerigby5935]

Hi. I followed this video to support me fitted the same piston to my grom. I had a question for you about the sparkplug. I received a sparkplug with a spacer taped to the box, it also had a spacer inside the box. Did you use 2 spacers or just 1 spacer for the sparkplug?

[@UnknownOverLand]

I only used one spacer on my spark plug (in only received one). I’d be surprised if you needed them both.

[@Zerffed]

Did you have to hone out the cylinder? I’ve got a grom I want to run this kit on but some people said I should hone the cylinder out cause the rings might not seat properly, mine only has 500 miles on it though.

[@UnknownOverLand]

To do a cylinder properly you really should hone it it out and make sure everything has a chance to properly run in together. I did not, mostly because honda engines have a tendency to live through anything and this bike was more of my toy bike. If you look into the cylinder and see a lot of carbon or scoring you'll have to decide.

[@BubbaB43]

Your head dowels were staggered when you initially disassembled the top end, is there a reason why you put them both on the timing chain side during reassembly?

[@UnknownOverLand]

There were some in all of the pins, but some stayed in while others came off with the head. I suspect in between steps I probably took them all off and didn’t think about where they go (or at least show some consistency for the video).

[@auomauom]

Thanks for the video Unknown. Did you have to set the valve lash after the install? Looking to do this soon!

[@UnknownOverLand]

I did go back in and recheck them just in case. They shouldn’t really move much (especially since the cam didn’t get pulled), but didn’t hurt to check. Added bonus, they’re a lot easier to check when the head is off the bike.

[@ashleymarmolejo9226]

Is this the DHM Honda Grom Stage 3 Package what does it come with

[@UnknownOverLand]

For the Honda Monkey I used this one: www.dhmotoring.com/products/dhmstage3monkey. If you have a grom, the one you mentioned should work for you. Depending on what you need, he has different options, but my kit came with the piston, rings, and spark plug (with the needed spacer).

[@AnonymousYoutuber69]

What octane fuel do you use for this piston?

[@UnknownOverLand]

Along with my tune I ran whatever the highest octane was available around me. I had heard some also like to use some octane boost as they had seen a slight knock from the timing.

[@budlight143]

just finding this video, thank you, what sockets are those? I like how they are numbered.

[@UnknownOverLand]

Glad the video was helpful. I’m actually not sure which set that is specifically, I’d had it for quite a while.

[@cloggsy1971]

What difference did the piston make to the speed, torque etc.?

[@UnknownOverLand]

There's definitely more torque as the piston is doing more work. There should be a bit more speed increase, but I'm still trying to figure that out.

[@jonathanweisman8657]

Hey I love the video , I have a question about the rings I have the kit and I'm trying to figure out if the silver ring goes in top spot or second on piston and what is the placement for the black ring. And what was the order of the measurements . 008 , .009, .010 and . 011?

[@UnknownOverLand]

You should have 4 rings and an oil ring. The two thinner ones are basically the same and go above and below the oil ring. The thicker compression rings should have a 1 and 2 marking on them (I think at least the 1), the silver one should have a 1 and goes on top. The top one for me was .009 and the second compression ring was .011.

[@jonathanweisman8657]

@@UnknownOverLand you did not have to file down the rings that go over the oil ring did you?

[@UnknownOverLand]

It's good to check them, but I did not have to file them. They're more spacers than for compression.

[@jonathanweisman8657]

@@UnknownOverLand thank you very much for the information

[@UnknownOverLand]

No problem.

[@suupaltti]

It seems that you put dowel pins back on different pattern. Was it purpose?

[@UnknownOverLand]

I don't believe so, it's likely just editing where in between shots I pulled off dowels I forgot in the first place and then put them all back in without thinking.

[@jeffward6166]

Set ring gap from the bottom of the cylinder.

[@user-vl2sg1tu3v]

The instructions from DHM say the top ring gap should be .007-.008, and the bottom ring should be .008-.009. I understand your logic behind the Wiseco recommendations and measuring the bore, but which would be the better route? Using the DHM provided recommendation, or measuring and using the chart?

[@UnknownOverLand]

Generally measuring your cylinder is the better option because there may be slight variances in how your piston was manufactured or worked in or anything. Because of how tough these engines are (and how good DHM is) you might find things to be pretty close to what they say.

[@user-vl2sg1tu3v]

Thanks tor the prompt response!! I really appreciated your video!

[@chuckley54494]

So did u gap ur oil scraper rings?

[@UnknownOverLand]

No, I didn't.

[@brandonhall9998]

Did the Dhm piston come with new rings or did you buy them separately? also the gaskets ect....

[@UnknownOverLand]

The piston came with rings, spark plug (if you add it to the order) and the spark plug spacer. I believe the gaskets are also included.

[@brandonhall9998]

@@UnknownOverLand thanks for the info man, looking at thier stage 3 upgrade kit (for previous customers) and it doesn't say or give the option to add them.

[@UnknownOverLand]

If you email them, they have been pretty fast getting back to me previously. So I’m sure they can help also.

[@Shmack_]

Oil cooler needed?

[@UnknownOverLand]

I think that depends on how hard you push it and how hot it is where you live. I had an oil cooler on mine and temperatures seemed to stay reasonable, while I believe many others don’t run an oil cooler on it.

[@jakerigby5935]

Did you get a spark plug and spacer with the kit ?

[@UnknownOverLand]

Yes, I did. I should have shown it in the video, but the kit did come with both.

[@jakerigby5935]

Yeh I can't find info anywhere on how the spacer fits, I'm looking to do the same install next week

[@UnknownOverLand]

Ah, the spacer will go on the end of the spark plug where the threads are. It’ll keep the plug just slightly further since the new piston is going to be a bit closer than stock.

[@rickst.3330]

Ordered mine yesterday from DHM, did you put any mileage on it yet? And what are your thoughts and/or concerns?

[@UnknownOverLand]

I’ve put a few miles so far and no issues. Hoping to get out today and really warm the bike up and see. My main concern is just getting the timing dialed in, but otherwise even just trying to ride sane you can feel the change in the bike.

[@rickst.3330]

Unknown Overland Nice, after the installation of the parts that are on the way I practically have the same setup (Chimera intake, Yoshimura straight cyclone exhaust, Aracer RC mini 5 with AF1 and the Takegawa N-20 camshaft) so very interested in your story and your the ignition settings on the Aracer. Although here in Europe we only have the higher RON fuels (95 and 98).

[@UnknownOverLand]

Look for the comments here from DH about the timing, here in Colorado I can primarily find 91 which is why I really needed to look a bit at the timing. I did notice a bit of a knock at partially open thottle so pulling back the timing a little has helped clear that a bit. Another thing to watch out for is idle RPM, I noticed that my air screw needed a fair amount of adjusting to keep the bike idling at about 1400RPM.

[@tonza3086]

what may be the problem, when i opened my engine to check how big my cam and piston are and when i put the engine back together the top speed was like 13kmh less and the acceleration was worse and overall it lost power

[@UnknownOverLand]

You only opened things up to check and not replace anything? It depends on how much of the engine you took apart and what might going wrong. If you pulled the cam out, you may want to check you put it back in right and then also check the valve clearances to make sure everything is looking good. You may also need to double check that you got all of the timing back in line (make sure the bike is top dead center and that the cam gear is lined up with the mark). If it's not these, you may need to go and start looking for any leaks maybe with gaskets that got folded over or something.

[@tonza3086]

Unknown Overland how do i know if i put the cam back right

[@UnknownOverLand]

I have a video (kzbin.info/www/bejne/o3Ldl5J3mMyngJI) that shows how I removed and upgraded my cam. There should be a fair amount of steps show in there on how to get to TDC and how to align the chain and the cam properly.

[@tonza3086]

@@UnknownOverLand do the lobes on the cam have to face a specific way at tdc

[@UnknownOverLand]

When you install it, the groove of the camshaft should be facing upward, once inside it should somewhat easily turn a bit more forward (toward the notch in the frame) without much resistance.

[@nekatrall]

Don't forget to tune it. Cjr advances the timing quite a bit

[@UnknownOverLand]

Definitely, I have the aracer in there, I just need to get the timing sorted out on it. Thanks for the reminder!

[@nekatrall]

@@UnknownOverLand good to know.

[@nq2847]

How's the durability of the kit so far?

[@UnknownOverLand]

While I had it, I had no problems with the piston. Things just seemed to work which was great.

[@nq2847]

@@UnknownOverLand Awesome thanks! Just purchased.

[@DHMotoring]

Awesome video! Do you mind if I embed it on the product page?

[@UnknownOverLand]

Thanks so much! Nope, I don't mind at all.

[@DHMotoring]

@@UnknownOverLand I believe you can only get 91 octane up there? You might want to dial back the timing some if you're using the base timing map from the RC2. I believe it sees about 30 degrees at WOT at high rpm. You want to be around 28ish to be safe on 91 in the heat, and you can pull some out of the part throttle areas as well if you hear any knocking. 14/36 gearing works well, and let it breathe to around 10,500rpm!

[@UnknownOverLand]

@@DHMotoring You're right, 91 is about all I can find around here, so I'll make sure and take a look at the timing like you recommend (especially since we're finally getting warmer around here). I just put a 36T on the back with a 14T on the front, excited to see what this little bike can do with these changes. I didn't quite understand what you mean about what to do with the throttle if there's knocking. Thanks a ton for all of the info!

[@DHMotoring]

@@UnknownOverLand Sorry, I meant if you're hearing knock/detonation at part throttle situations, you can pull some timing out of the part throttle maps on the RC2. So the timing map that is TPS x RPM, at the TPS percentages that are not 100% you can pull some ignition to keep it from detonating. The default timing maps in the aRacer are aggressive compared to the stock ECU (because they're designed for performance) but are usually fine when running fresh 93. But if you're noticing any knocking or hesitation at part throttle situations, try dialing the timing back some.

[@UnknownOverLand]

Awesome, thanks a ton for the explanation; totally makes sense now.

[@jered2177]

That will help pull in 4th gear

[@UnknownOverLand]

That's what I'm hoping for. Just need to let it break in bit and we'll see what it does.

[@ratscoot]

@@UnknownOverLand maybe add a cam too.

[@UnknownOverLand]

@@ratscoot I have the TB Cam installed in the bike as well. Running out of stock things on the bike! :)

[@ratscoot]

Hope you did an ECU reflash or installed a fuel tuner.

[@UnknownOverLand]

I didn't mention in this video, but I have an aRacer installed that's all prepped for these changes. But very good point, especially with the rest of the changes I have.

[@ratscoot]

@@UnknownOverLand Ok thanks, i think you would melt the piston in the long run without a fuel management system.😁

[@UnknownOverLand]

True enough, though I guess that could be an interesting video! :)

[@bfarm44]

Results?

[@ratscoot]

@@UnknownOverLand lol. Just don't change ignition timing with the Arcer on a high compression piston or you will get detonation destroying the piston.

[@salsalvador2]

Great video brotha .. I just installed my dhm piston .. my question is .. what's the process after install with Aracer and brake in ?

[@UnknownOverLand]

Thanks! The first thing after this install is to watch what octane gas you’re using; at least 91 but 93 is available is preferable (I only have 91 basically available). On the aracer, if you have the AF1, make sure that you have Auto Tuning enabled to allow it to get used to the changes. Also, you may want to keep an eye on the “spark angle” (which is used to modify the timing on the engine). If you’re hearing a knock you may need to dial that down a bit, keep an eye on your spark plug coloring. For break in, I basically used the ideas here: blog.wiseco.com/proper-engine-break-in-after-a-rebuild (about half way down the page). It’s a series of warming cycles for the engine but once that was done I just started riding like usual.

[@salsalvador2]

What did you set your spark angle to ? I have mine set at -2 across the board

[@UnknownOverLand]

You’ll likely need to just watch how your bike is handling and sounding. -2 should help cool down the engine a bit by making sure ignition is closer to compression but make sure and pull your spark plug to see if it looks like it’s coloring is good.

[@tonza3086]

Do you think 98 octane would be enough for this setup without touchig the igninition and without octane booster

[@UnknownOverLand]

I believe that 93 or higher and you’re likely safe. One thing to watch out is who pumped gas before you and what they used. The monkey tank is so small that the fuel in the hose itself could possibly fill up a good portion of the tank, and if they went cheap then you’ll be stuck with that.

[@daisbestDA9]

Didn't mention anything about the o2 sensor

[@UnknownOverLand]

You’re right, in a previous video I had replaced the stock o2 sensor with a wideband for the bazzaz (and later the aRacer) so I didn’t have the stock o2 sensor on the bike.

[@Filmpilot]

Link doesn’t work for ring gap from wiseco- just saying-

[@UnknownOverLand]

I'll have to see if I can find a better one.

[@Filmpilot]

@@UnknownOverLand I thought I posted one. Maybe it got torched.

[@Commsfarage]

Nice video still don't understand Americans not using mm instead

[@UnknownOverLand]

Thanks, and you're right; I'll never understand why we stick to the imperial system.

[@Commsfarage]

@@UnknownOverLand we kinda do but when it comes to small accurate measurements mm is always best. work in a sawmill we use metric for a general size but a 8x8 could be a 203x203 for 4x4 otherwise you'd get odd sizes

[@nicksoup]

I really appreciate this video, it's very helpful but you are setting people up to fail by not mentioning the special 17mm slit socket you need to remove the o2 sensor, that stopped me in my tracks.

[@UnknownOverLand]

Thanks for the feedback, it's really appreciated. In a previous video I had already removed that O2 sensor, so didn't really think about it when doing this video. In that video (yoshi install, this is about the right timestamp, ignore the music: kzbin.info/www/bejne/b2TJf2Oop8yciJY) I actually used a closed ended wrench and slipped it over the "plug" end of the O2 sensor and all the way down to pull the O2 sensor. It took a bit, but worked.

[@nicksoup]

@@UnknownOverLand oh wow, I gave up and bought a 17mm socket and cut out a slit, which was annoying but it'll work. Otherwise I really do mean it when I say it's a great video, it answers so many questions I didn't know I'd need to ask. I felt ready to tackle this and then the o2 sensor stopped me.

[@UnknownOverLand]

I'm glad it could help, and I really am appreciative of you pointing that out since it definitely escaped my mind (I added some info in the description box which is about the best I can do via youtube limitations). When I went to do the Yoshi install I hit that same problem and got really close to buying the split socket so I know that frustration.

[@orgillmathew]

you nee a metric digital vernier lol

[@UnknownOverLand]

I definitely do.

[@bluevalkyrie2517]

OMG lube the piston in drain oil WTF?