DHM 149cc Big Bore Kit for the 2022+ Honda Grom and Monkey!

DHM 149cc BBK: www.dhmotoring.com/collection...
Testing out my second big bore kit on my 2022 Honda Grom with the Repsol livery. Haven't had a chance to dyno yet, but it's definitely making more power than the Yuminashi 140cc kit that was on the bike previously.
Other big bore install videos on my channel:
Yuminashi 140cc BBK install in 2022 Honda Grom: • Yuminashi 140cc Big Bo...
Takegawa 181cc BBK in 2019 Honda Monkey: • Takegawa 181 Big Bore ...
Takegawa 143cc BBK in 2019 Honda Monkey: • Takegawa 143 Big Bore ...
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#DHM #honda #grom

[@Smallbore2wheels]

I knew I saw this notification and then the video disappeared. Glad nothing got messed up

[@e-van839]

Kent another great vid man, awaiting mine to arrive! Thanks for all the effort

[@familygromscarsfun3896]

Cant wait to see what kind of power you are able to pull with the new bbk kit! i just got mine and my oil cooler kit with HiFlo pump to go along with it. Cant't wait to get it installed!

[@reidspeed77]

Spanners of gold ,,looking forward to dyno this one ....⚙🖖

[@joujimiichi1]

Dude I swear; I look into a part or upgrade for my Grom and then you have an install video a week later. This is the 4th time this has happened. You and I have similar tastes

[@mcguyver3215]

Glad I could help. Hope there wasnt any damages!

[@eastcoastish]

Yeh fortunately no contact 😎

[@jsabowabo]

Love your videos. Very well done

[@flatlandriver2471]

Watching your build with interest. Hopefully my 2022 Grom that was supposed to arrive in May will be here soon. I live in Canada. Grom is about the only 125cc MiniMoto available, not counting the unobtainable Z. I’m a big guy so will add a big bore as soon as I get the bike broken in. I’m also a retired engineer. Spent quite a few years as product manager for a farm equipment manufacturer. Have repaired and reworked Canadian, American, Dutch, German, Japanese, Chinese etc power transmission components. Couple thoughts: I don’t care for the paper gasket between the pot and the block. Reduces heat conduction. Not that we want a hotter block, but a cooler cylinder sleeve takes precedence. Also have a look at Evinrude 2 stroke outboards built by Bombardier. They run 2 stroke (injected) oil at a 1:100 ratio. 2600cc V6 putting out 150hp. Two stroke oil is all the lube for the entire engine. I mix the special, really expensive, E-Tec 2 stroke oil at about 1:150 in my 4 stroke garden tractor gasoline. Because I work the crap out of that old opposed twin engine. Exhaust (and cylinder head) temperature is proportional to the horsepower being extracted. Many industrial diesels run pyrometers in the exhaust stack. Stack temp will warn of problems before anything else. Anyway, I believe my Briggs & Stratton runs cooler. No smoke, zero plug fouling. Haven’t measured oil temp directly. Temperature gun says about 10 degrees C cooler on the lower skirt where there’s not so many fins. YMMV

[@Peakwanderer]

We all make mistakes, I'm glad that it didn't result in piston to valve contact.

[@thewheeltroll1833]

This really might be the mod to get me to buy the new Grom! 15hp plus really is the sweet spot for these bikes IMO.

[@xscoops1]

Great video!

[@anthonylim2428]

Shit happens. At least you didn't damage anything. Thank you for the update!

[@lexdfox]

Good catch! I know I've been close to doing that myself. Hmu next time you need a second set of hands ✋️

[@troybilt6752]

I almost pulled the trigger on this kit the other day but I would like to see a 181CC kit ( that may not be right) under me seat. This video is great for us that may have the ability to do this install but not the experience or confidence. Thank you for your time.

[@denttime]

You’ll be waiting a long time unfortunately. These motors get too hot- that’s why they have not made bigger bores.

[@AndrasMihalyi]

Nope... The 2022+ cylinder studs are closer together, you simply cannot go above a certain bore diameter, limiting to about 150cc max.

[@91ludesit]

I'm excited to see what you make on the dyno, I know someone that made 17.5HP to the rear tire, but he's got a ported head.

[@eastcoastish]

Was he on race gas? 17.5 on pump fuel sounds pretty high. I’ve got a ported head (I don’t have bigger valves though), last run with the Yuminashi was 14.4 hp, so hoping these 10cc get me over 15hp at least.

[@91ludesit]

@@eastcoastish He has a CJR fully built race head, and no that was e85 and only the copper gasket. I would imagine you'll probably be in the 15.5-16 range.

[@adamr4003]

Im just waiting on some assembly lube and feeler gauges to come in. Cant wait to watch this video again when I do my install. I didnt see any instructions in my box, your info on ring gaps will be important. I will be running the dhm tune and and S1 cam. How has the bike been since install? Any issues or plans to do more?

[@stevelucha22]

Have you done a top speed run with the 149cc kit installed yet? What sprockets are you running with this setup?

[@promykzpolski]

Hi will this kit from your video + DHM S1 Camshaft for the 2022+ Monkey (Generation 2) suffice for my 2022 monkey 5 speed honda ? in dhm they wrote that an oil cooler is also recommended, which one do you recommend? I'm especially concerned about the durability of the engine! I must have aRacer RC Mini X Standalone ECU and aRacer Speedtek AF2 Autotuning Wideband Module? can i do without them? I am asking because of the huge costs of customs and tax to the EU

[@KakuSpoon]

How to solve the sound of the timing chain after replacing the cylinder?

[@dwninetynine]

Hey good vid thanks, used it to do my dhm 149cc swap.. I have a question though, did you upgrade any of the cam chain gear? I'm getting a cam chain rattle after reassembly and I'm wondering if somthing needs changing or adjusting.. The can chain tensioner is hydraulic right? So as long as i put the lower "slider" back in place and refitted the upper guide wheel all should be quiet right... Dyou have any rattle at all?

[@eastcoastish]

Yeh there’s no external cam chain adjuster. The plastic guide should help reduce cam chain noise, so confirm that’s installed correctly - I don’t have any noticeable cam chain noise…

[@dorybseibes9723]

Hey I love your content, keep up the great work, I have a quick question please, does the kitaco oil cooler on your Grom, works with DHM 149cc kit? Cause I’ve read that it only works on a stock head for the 2022+ Groms. Please let me know if like to upgrade my 2023 grom, please let me know

[@eastcoastish]

Yes it works. The DHM BBK only replaces the cylinder. The head of the engine (which has an oil port that’s accessed on the top tappet cover) doesn’t change.

[@dorybseibes9723]

@@eastcoastish oh cool, thank you very much, I live in San Diego as well, I’m not sure if you do, but I think I’ve heard you say your from this area or close by, if we can be in you h please, let me know, thank you very much!

[@eastcoastish]

@@dorybseibes9723 DM me on IG @eastcoastish - I’m in South San Diego county.

[@mikeleone1805]

I have been following your videos which are very imformational . I'm doing to my 2022 monkey what you have done to your grom minis the head porting and 149cc bbk. Will it be worth doing the bbk as I live in a hilly 60 mph area ? Do you think it is a reliable kit ?

[@eastcoastish]

I’ve got a couple hundred miles on the kit now and so far seems very reliable. Definitely worth it if you’re looking for more power.

[@SSS-mp8th]

I saw this pop up on their site, I expect I'll do this at some point. Currently have their cam and tune and I'd want to add an oil cooler like yours when ones for the 2022 Monkey's are available. Waiting for Opmid to bring out an oil temp sensor at the current Opmid gauge doesn't support the 5 speed engines (different plug and ecu). I tend to be at WOT most times so I'm wondering what temps I'm getting now.

[@timothysummers7034]

I already have a 5 row kitaco on my 22 monkey.... just saying

[@SSS-mp8th]

@@timothysummers7034 This the only one I found that lists 2022 and doesn't list it for the Monkey, is this what you are using? Kitaco 5 ROW Super Oil Cooler 2022+ Honda GROM RR Only (use with STOCK HEAD) - 360-1452260

[@timothysummers7034]

Yes. All I had to do was modify mount bracket a little. Mounts where stock air box did

[@alainnadeau3421]

Did you loose any top speed? Ive also installed ported head and seem even slower but more torque. Did you change of your acraer parameters in particular base fuel? Using 15t front and 39 in the back. Thx !!

[@eastcoastish]

I haven’t done a top speed run, but I assume it gained top speed. I hope to get in the dyno next week but it feels like more power across the board. I didn’t change base fuel but you definitely need to rebuild the autotune map after the install.

[@Cjbuck8]

I see that dhm offers stiffer valve springs for this engine. Would it be beneficial to pair with this bbk or could it offer additional risk of increased wear? Been following the channel since I got my 2022 grom last November and have used most all your videos for my own installs. Great clean thorough work Kent! 🙏🏽 Note: I noticed that site sold out of these springs in the last 24hrs. Was quick then to get my order in for the bbk at least.

[@eastcoastish]

Stiffer valve springs help prevent “valve float” which can occur at high RPM (above 10k) - if you want to run a limiter above 10k rpm it’s a good upgrade. And thanks for being part of the channel!

[@bakotako]

its okay bRo. the bike will just Run backwaRds instead. =)

[@lidanoserra3934]

Hi ..... congratulations for the video ..... a question, for the grom 2022 there is only the 149cc?

[@eastcoastish]

Yuminashi also has a 140cc. Monkey Father (used to be called Finbro) has a couple too, but 149cc is the biggest I’ve seen so far. The headstuds are much closer on this engine so we’re not going to see huge Bbks.

[@lidanoserra3934]

@@eastcoastish ok ..... thanks 👍

[@888jackflash]

An excellent vid. QUESTION please, about robustness/reliability: I'm an experienced tech and want to beef-up my new Grom, but am concerned about (numerous) reports of component failures on a lot of these builds. Any thoughts? How many miles do you have on this build now?

[@eastcoastish]

I have about 1,000 hard miles on it now with no problem. As long as you can keep temps down, this is reliable. Most of the failures I’ve seen are from folks that don’t know how to manage the fueling and overheat. You also want to run an oil cooler with the setup. On the dyno, I’ve found this makes more power with a couple degrees of retarded timing.

[@888jackflash]

@@eastcoastish Great. I just watched your vid at the dyno.. impressive! But I'm not totally clear on exactly what Goodies are in this build - care to provide a list, and maybe which items you feel are critical? You'rs looks a little farther out than I'd have the money for.... - a REAL East Coaster!

[@eastcoastish]

@@888jackflash From a power perspective, it's the aRacer RCMini5/AF1 (now replaced by the RCMiniX/AF2), the DHM 149cc BBK, CJR 27mm intake manifold and throttle body, ported stock head, DHM S1 cam, Dingerbuilt intake, PCX injector. Then for cooling, the Kitaco 5 row cooler and Kitaco oil pump. I have a video for each of those installs but let me know if you have any questions.

[@888jackflash]

@@eastcoastish Thanks a heap. I'm sure I WILL have questions in the Spring! I'm a big guy, so I'm hoping to make a reliable motor with enough Oompah to give me an honest 60mph on demand

[@Queensraces]

Wow u did all this i was hoping u would atleast show the top speed

[@Jdubsgarage74]

Wondering if you have installed a high flow oil pump on this build? I would think it should be done when the oil cooler was installed.

[@eastcoastish]

Yeh: Kitaco Oil Pump Upgrade for the 2022 Honda Grom from Hard Racing kzbin.info/www/bejne/g5bCpZ-Pacd9r8k

[@josefpoole]

Hey any update on how this is running? I have one ready to install, just haven’t pulled the trigger yet as I’m waiting for you always honest review.

[@eastcoastish]

I still haven’t dynod it yet but it’s running very strong, no issues and I’ve been ringing it out pretty hard over the last couple hundred miles. Install it already! 😄

[@josefpoole]

@@eastcoastish this is the motivation I need :) I’m glad you’re happy with it.

[@josefpoole]

@@eastcoastish finally got around to it! It goes so well. Only thing is, your torque setting for the 2x M6 bolts that go down the cam chain side of the head and jug was 9ft/lb which snapped the bolts. Unsure why that happened but I've ordered more and made do in the mean time.

[@ratscoot]

Have you ever considered buying and tuning a classic Vespa 2 stroke? Very easy to tune and way higher power levels obtainable.

[@eastcoastish]

I’m partial to Honda and Japanese bikes but I’m as a minimoto fan in general, I wouldn’t be surprised if I own a Vespa at some point.

[@ratscoot]

@@eastcoastish I love both. My Vespa PX125 has 15rw hp with only a 177cc cilinder, 24mm carb and a expansion exhaust. All cheap bolt on parts. If you mill the engine casing to enlarge the ports you van easily get 25hp.

[@timothysummers7034]

Since the valves didn't slap even with it upside down... what would be the problem with having run it that way??

[@eastcoastish]

Probably ok. I’m running the s1 cam so if you run a more aggressive cam it might push the valves out further. I’m also running both of the rear gaskets, so it’s possible if you just run the copper one that it might touch. Power/performance wise though there shouldn’t be any difference.

[@shmingusdingus]

When you put the gaskets on, did you sandwich the paper one in between the copper ones?

[@eastcoastish]

One of the copper goes between the head and cylinder. Then on the other side of the cylinder i did copper and paper.

[@shmingusdingus]

@@eastcoastish thank you!

[@shirkbros765]

Paper gasket goes against cylinder and copper against case.... per dhm instructions

[@zacward2063]

Hi mate, really hope you can help me out here. So I’ve recently installed my BBK with s1 cam on the 2022 grom and I was wondering if you had to adjust the timing at all? Or did you just use the map provided with the Aracer mini x?

[@eastcoastish]

Hopefully you also have the AF2 so that you can build a custom AF map, the stock maps are junk. As far as timing I’m pulling -2 timing at 60% throttle and -4 at 100% throttle. I have a video of the tune here kzbin.info/www/bejne/bp-ooXWAYrt2apI

[@zacward2063]

@@eastcoastish thanks for the help mate 🤙🏼

[@zacward2063]

@@eastcoastish thanks for the information, also do you remember if you had to adjust anything else? This is a difficult question but When I started my bike up it sounded like the valves were knocking, I’ve adjusted them to be around 0.005 (+- 0.002 ) would I need to check them and get it more accurate?

[@eastcoastish]

@@zacward2063 the valves are being lifted higher so they’re going to be a bit noisier. Did you replace your exhaust gasket when you took off the exhaust? A leaky exhaust will make a bit of a ticking sound.

[@zacward2063]

@@eastcoastish just did a check over and everything is running fine now, thanks for your help, your videos are awesome too helped out alot 👍🏼

[@0xDankberg]

What grade fuel did you use prior to the bbk and do you use now on your bbk?

[@eastcoastish]

91 is the best you can readily get here in CA do that’s what I’ve been running. Thanks

[@g1g1ddy]

I plan on doing the dhm stage 3 kit with the mnnthbx intake. Would the BBK be something that I can run ontop of these other mods?

[@eastcoastish]

I'm not sure what all their "stage 3" kit entails, if it has the high compression piston you won't be using that in the BBK, everything else should play nice together though.

[@g1g1ddy]

@@eastcoastish Ahh thanks for the reply. I can just opt out for the HC piston in the kit and just get the cams then! This is my first ever bike and I’m still learning sorry for my noobness 😅

[@humbertoportillo3603]

Question this is for the ct70 project i bought an ebay coil are those any good and if were can I purchase one🤙

[@eastcoastish]

Cheap eBay could work fine. Just make sure you get the right 6v or 12v one depending on your application.

[@irongoatrocky2343]

May I ask what Fuel Injector are you using with this kit?

[@eastcoastish]

PCX150

[@robinspalding3]

are you running oem starter motor ?

[@eastcoastish]

Yep

[@DaBurntToaster]

If I do this, can I turbo it as well? ive seen grom turbos before so I know they're out there, but Im not too familiar with turbos, or bikes in general, I work on jets, completely different game. my concern is that the turbo wont be as effective, due to the input requirements on the turbo, or the output requirements of the turbo to the engine. if your adding so much power (percentage wise) will that effect how well the turbo performs (percentage HP increase turbo added to stock vs big bore mod)

[@eastcoastish]

I don’t have any experience with turbos on these motors, the few I’ve heard about weren’t very reliable though. If you’re looking for big power, I’d do a cbr300 swap.

[@DaBurntToaster]

@@eastcoastish thanks, ill look into that instead, probably cheaper anyways, if a bit possibly a bit more risky

[@PharaohKoup]

is there an update. I have seen some tiktoks of the heads leaking on this already.. haven't finished the build on mine yet.. interested to see how its been holding up.

[@eastcoastish]

A few hundred miles and running strong, no issues.

[@carlosfrances01]

Whats the color code and name on paint of the wheels ?

[@eastcoastish]

It’s Prismatic “New Tucker Orange” powder coat.

[@UCLemonBEE]

Had a chance to take this to the dyno yet by chance?

[@eastcoastish]

Not yet, but hopefully soon.

[@patrickbresseleers5571]

If I put the 149cc cylinder on the 2022 Monkey, do other things need to be adjusted?

[@eastcoastish]

You probably need additional cooling but not mandatory. You do need fuel management either from a flashed ECU or the aRacer setup.

[@patrickbresseleers5571]

​@@eastcoastish, thanks for the quick reply 😊

[@wileecoyote5749]

How has been long term? I'm scared I'll destroy my perfect engineered '23 Monkey

[@eastcoastish]

About 1000 miles no problem.

[@shunkdiesel777]

Any updates on how this big bore kit is holding up?

[@eastcoastish]

A couple thousand hard miles, everything is running great.

[@shunkdiesel777]

@@eastcoastish That's awesome!! I'm gonna order mine now. Thank you for the video

[@denttime]

Have you had any issues since you added the 149cc bore kit please?

[@btankful]

Am I missing something? Ha ha. You said that this is the 2nd video and that the 1st video had the arrow on the piston up when it should be down. In this video the piston, again, had the arrow pointed towards the top of the bike (up).

[@eastcoastish]

Yeh, I made this video with the arrow up. I posted it and quickly realized it was wrong. So I pulled the video, and pulled apart the motor and added corrected the mistake and filmed the segment of me talking about it. The scenes from reassembly that show it pointed up are from the original video.

[@btankful]

@@eastcoastish Ah, got it.

[@mystic98802]

I have basically the same build, only difference is I have not ported my head, but am planning to buy DHMs head. I am at the point of starting it the first time after the BBK install, but I am confused how to retard timing on the miniX Also I see a quickburn now for the S1 with 149cc kit but I am not sure how to load it. Any pointers would be helpful!

[@mystic98802]

I was able to get Quick burn to work, but I am still confused on retarding the spark angle. Also do you know what the break in should look like?

[@truckacabrarex9831]

Is it still running

[@eastcoastish]

Yep, running strong!

[@SekRanger]

What's the idling rpm for this BBK?

[@eastcoastish]

It’ll vary depending on your mods and setup, mine sits at about 1k.

[@SekRanger]

@@eastcoastish Thanks for the answer. Mine is around 143cc. But the terms here in Thailand differ. We use the metrics to refer to our mods. For example - 56/0 piston means 56mm diameter without changing the connecting rod. - 28/24 valves mean 28mm for intake valve and 24mm for intake valve. - 28mm throttle body.

[@fz1ryder]

can you tell me exactly a complete list of engine mods your running now on this bike?

[@MotoTvWoodsFarm]

I am viewer 1,860 - I liked video 117 - I comment 30 - i viewed the complete video - have a great day

[@eastcoastish]

Thanks man, I appreciate it!

[@civic2323]

Doesn’t DHM sell this kit as a bigger bbk with the rings installed and gapped with the oil cooler radiator? I could’ve sworn