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Hi guys, thought I'd better do a write up of my new MSX209 setup. Yes, that's 209cc. And it feels goooooood!


This kits was a bespoke item from the Monkey Father in Thailand. Otherwise known as 'FinBro' parts, and Awirut Kanploy is *the* man for this. Easiest this is to contact him via Facebook, look for Monkey Father.

As some of you may know my bg end bearing gave way at the end of May. After stripping the engine and getting no help from Honda because I'd done my own servicing (even with the offical service manual), I decided to try a different tac. I had spotted the Monkey Father page before, and recalled that they did long stroke cranks. If I've got to repair it, why not improve it?

Well, after LOTS of discussion via FB (our conversation currently stands at about 511 posts), I finally took the plunge. Things in Thailand seem to run on trust and reputation. I was initially a little nervous of sending a load of my parts to a stranger for work, but it was fine. Awirut's service has been excellent, and I wish more places over here (UK) were as good. Too many places rely of having flashy websites to cover up for poor service. I'm not point fingers at any one in particular, but it's just an observation.


Any way, my cases, crank, barrel, bare head, and intake system were all posted off via UPS... BIG MISTAKE! UPS were SHITE! Really. They ignore my shipping labels, didn't contact me, and then charged me £140 duty that they later admitted I didn't owe. But since they'd already paid it out to Thai customs, if I didn't pay them they would chuck my parts. Not happy. The arguements caused two weeks of delay. Eventually I gave in, although apparently I can claim it back direct from Thai customs, say FedEx.


So, parts arrive in Thailand, and development work begins. Three different cranks designs were trialed. The final design has full heavy webs, and is fitted with a much better rod (NOT from Honda), and premium bearings.


When a guy from the far-east says "do you want Honda bearings, or good bearings?" you know that Honda have been cutting corners!

So after plenty of testing in their development mule, my parts are eventually ready. We're settled on a capacity of 209cc, since I'm after long service life. His normal spec is 221cc, but that's for race use, so a little bit of lean running doesn't hurt. The final spec is as follows:

63.7mm stroke crank, with upgraded rod and (all) bearings, balanced for optimum use around 7.5k rpm. The race spec cranks are balanced for much higher rpm, but at typical road rpm the vibes are a problem apparently.

64.5mm piston and rings (plus a spare 65mm piston for when I've worn this one out - the stock item lasted about 15k miles),

crank case mouth bored out to accept the...

64.5mm bore cylinder with thick iron liner, as per stock. Neither of us trust the skimpy think liners being used on certain 63.5mm bore kits. This also give me the option to re-bore it up to the next oversize when needed.

Head skimmed 3mm (compensated for via 3mm base spacer) and combustion chamber re-shaped, bigger valves fitted (intake 31mm, exhaust 26mm), stronger springs, hot cam (no decompressor), and both ports bored out and polished.

Intake manifold bored out and polished, throttle body bellmouthed and polished (but same butterfly size).

Compression ratio: 11.5:1.

I also got a load of spare odds and sods thrown in: oil seals, loads of gaskets, cam chain. Surprisingly the stock clutch is taking it... just. I will be upgrading to stiffer springs, but no problems so far.


For fuelling, Monkey Father uses the only non-tuner device that I know to actually work safely. It uses a different Honda ECU with a special harness to fit, in conjunction with a 10-hole injection. And that's it. We do have some issues, but they're my fault. I already had a 10-hole injector, so didn't get his. Turns out my 10-hole is totally random, and no-one seems to know what it's from, not even the guy I bought it from originally. It works, but is rather thirsty. The other problem (again my fault) is the exhaust. This spec motor needs a pipe approximately 27mm inside bore from the head end for the first 330mm (approx), then to open up to about 50mm for the last 450mm. I've got a tiny 350mm stuby pipe of mainly 50mm dia, but with a 22mm narrow section at the head end for about the first 50-80mm. Funnily enough this isn't giving optimum results, especially until I removed the baffle (with a 18mm orifice)! With a baffled exhaust, I was fuelling fine, but only getting 65mph, and hitting a wall at about 7k rpm. For reference, I run a reversed intake system, with the K&N R1100 filter sticking out just by the head stock. So much more practical, although the inlet roar is very intrusive.


The performance at this point after about 700 miles of running in is as follows: With a +2 front sprocket and a 428p x-ring DiD chain conversion, I would cruise happily at about 55mph indicated/62mph corrected, sat bolt up right, even into the wind or up shallow hills. This was at about 6,700rpm, with about half thottle. The was also a 'dead' patch in the throttle between 1-20% when the engine note went flat and tried to stop. With a close thorttle or open thorttle it was fine. So trundling along behind a truck at 50mph was not easy - open, close, open, close, repeat. Do remember I was a) not wanting to go over 7k due to running it in, and b) I had the bad pipe fitted. Also, the low down torque was immense, and even with the +2 front cog I still kept trying for 5th gear at revs above 5k!


So earlier I removed the baffle. I now only have a totally open tube stuck on the head, and then went for a ride...


Oh. My. God. My ears! It's loud. VERY loud. But on the upside, the power at higher rpm is immense! It now like to try to lift the front off the throttle in first (remember that +2 front cog), and accelerate briskly. I would say low torque is a little down, but is more than compenssated for by the mid and high rpm range. Which are AMAZING! It just flies! I will not shoot up to 70+mph (corrected) with not issues, hesitations, anything. Sat behind a car at 60mph and you're in top? No problems, just whack it open and go. Currently it's happy to fast-cruise at 72mph-ish (corrected) in any conditions, and doesn't drop below 60 even on steep hills in top. I know that doesn't sound much, but remember I'm sat bolt upright, and this is a genuine 70mph ANYWHERE machine now. Before I would say 55mph anywhere, with 65 on a good day, and 70 chin-on-tank etc. And head wind? Forget it.


Now... WOW! It is just so... well... competant? Able? It just goes. I'm still getting a little asthmatic by about 8k rpm, but below that the throttle response is excellent. No hesistations. I've got a damn good ear for knocking/detonation/'pinking', having had so many issues with my last big bore kit (see my 155cc threads). Any there are no problems at all, even on regular unleaded (95 RON in the UK). The drop-off at 8k rpm is probably due to my pipe still having that 22mm restriction, even if taking out the baffle has got rid of 90% of that dead patch. It could also be due to having the stock (tiny) throttle butterfly. But I'll be sorting the pipe properly as soon as I can.


And before any one asks, no, I've not got a dyno chart (yet). The only local places either don't do small bikes, are too good and hence want too much money (they test direct from the engine), or are very busy. I might come up with something in a couple of weeks, but who knows.


So, tha last bits, prices. I can't really say for sure as my method of sending parts off is a little unusual, and I got loads of extras. I think with shipping both ways, and all my extras I paid about £710 ($900?), but that includes a Morin oil cooler, spare piston/ring set, and a full APItech tuner device with cd of software and USB cable (as a back-up plan). All those at about half the western prices. I also evaded customs coming back, and should be able to get my wrongful £140 duty back soon.


I have heard of offers of £450 (about $600?) for a complete engine upgrade and test if you post the entire engine to him. FedEx 25kg (ok for whole engine) was about £140 ($200) each way. I think that's a steal really. All you have to do is drop the engine out and put it in a box and post it. But don't quote me on these prices.


Might also be worth asking for his own custom header pipe matched to the engine. Cheaper than getting them made up here.


One thing I can DEFINATELY say is that Monkey Father's customer service is second to none. I mean that. He is excellent. And no, I have no financial arrangement with him other than as a happy customer. And like I said, I think this is one of the few, if not the ONLY, big bore kit to work straight out the box (my screw ups exlcuded) with no dyno time needed. And don't forget that this kit also sorts out the bike's weak spot - the shitty Honda crank.
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Good write-up thanks

Could he send the whole engine assembled? So all we'd have to do is bolt up and put oil and gas?
 

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Yes they are in Thailand, excellent communication and is very knowledgeable about the grom and what works best. I have his head with 28-24 mm valves and his cam. I will be switching them out next week from my stock head with Crower cam.
 

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Agree. Very responsive service. Emailed me right away with questions I had. Maybe if people are interested enough and his kits become popular we can arrange a group by?
Nice write up thanks,

P.S. Keep us updated in performance or any changes. I wonder how a PCV WBC2 would do?!
 

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Discussion Starter #7
I've got an AIPtech tuner than should be able to too most things, but at the moment we're working together to fine tune a setup that works well in the UK climate. Regarding posting completed engines, yes, I have heard that he can do the lot for you. This would mean that you could drop the panels, pipe, intake, and oil, and a few cables. Then drop out the engine, put it in a box, and post it out to him. He would then do all the work and testing, and post it back. You would then just put it back in the bike, reconnect a few parts, fill up with oil, and off you go. At least that's what I think he's able to offer. :)
 

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Discussion Starter #8
Done another 80 miles on the de-baffled 209cc kit. Still amazed at the 'go' factor. Unfortunately the stock clutch just isn't man enough for the torque now, which is meaning I have to be very gently with the throttle. Monkey Father is sending out the stiffer clutch springs we've been waiting for, and I've ordered an new set of stock frictions plus two spare steels. My original clutch has about 21,000 on it now, so is probably a little past its best. There's plenty of meat left on the frictions though, so I'm going to look at if it's possible to squeeze an extra pair of plates in, while I'm waiting for the stronger springs.
 

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Discussion Starter #9
Right then. The MSX209 had its first post-tune service at the weekend after about 800-900 miles in about 2 weeks. During this time the engine has gotten noticeably freer, in that I had had to tweak the throttle stop down about 3 or 4 times to get the idle back down to normal. The oil was filthy and a very dark grey not black/brown, the strainer was nearly full, and the flinger needed cleaning out. All this was expected due to the engine in effect being completely new - only the gears and clutch were original in the actual powertrain. I also refreshed the clutch friction plates. Having done 21,000 miles I was expecting it to be shot, Awirut (Monket Father) expected it to have been shot by 15,000 miles! Yet it was fine, despite slipping now and again this last week. I replace and the friction plates with new EBC item and.... the stack was just 0.3mm thicker! The actual stock plates looked as good as new really. I think I'll be keeping them for next time! I tried fitting an extra friction/steel pair but it was just toooo thick. I did also try fitting just the extra steel. No extra friction area, but it would increase preload in the springs. And it worked! The clutch doesn't feel much heavier, and the slip has gone. This cost a might £4.18 for a spare plate from EBC. The new springs Awirut's sending me should help as well. Belt and braces. I then re-fitted all the parts, adjusted the clearances (exhaust fine, intake too wide again), and rebuilt the oil cooler. The Morin cool is not an excellent design. The slot in the head bolt is too shallow to flow well, the banjo bolts have too narrow holes. The banjo bolt holes were so tight you could barely blow AIR through them, let alone oil. Holes opened up from ~2mm to 4.5mm. Massive improvement. Still need to do the head bolt slot. The case for the cooler core was also poor. The core is not well held and hence rattles and then chafes. I've disassembled it and packed it out with adhesive foam. The core is now held very snuggly. I should point out that the oil cooler is NOT a Monkey Father part, I just bought it to help handle the extra heat output. I also fitted a +3 (18T) front cog to my DiD 428VX x-ring chain.
 

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Discussion Starter #10
Following the service the bike is a bit of a different beast. The engine is now smoother and revs far more freely. It also seems less vibey. Not sure how and oil and filter clean has done that, but there you are! The clutch works flawlessly thus far. With the 18T front cog top gear is very much an overdrive option. It will still run along at 30mph in top, but it feels more sluggish. The benefit is that on the motorway (or 'freeway' for you foreigners! :p ) you now have the legs to make the most of the power without running off the limiter. Today is was sitting at 79mph (corrected to 'stock' gearing) at 7,800rpm with my sat bolt upright, with no screen, wearing a flappy rucksack, no noticeable wind. And it held that for about 4 miles (until the end of the motorway). I will admit though that I was not able to do a return run. It now rides more like a 'normal' bike. Dropping down to overtake cars sitting at 60 is normal, and 3rd actually has the legs to do a full overtake. 4th is definitely for cruising. I think 17T is more fun, but I might try going up one on the rear before reverting back to 17T. I like having those long legs too much. For reference, with an 18T front cog your 'stock' speed is 3/15ths more than your indicated speed = 20%. So 60mph indicated = 72mph on a 'stock' geared bike. I make no claims about actual or 'GPS' speeds mind you. The main difference is 1st gear: with 17T you can still feel the front go light and wobbly when you snap the throttle open, but with 18T is more normal (or less fun).
 

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Discussion Starter #11
So overall, with 1,000 miles on the 209cc Monkey Father kit, I'm a very happy bunny. His quality is excellent as are his price. His ECM works perfectly too. :D
 

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i just ordered his full 183 kit and im stoked cant wait to get it. I did alot of research on his stuff and its definetly top shelf. and hearing how happy you are with your kit it makes me feel even better.
 

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Discussion Starter #14
Kit's great, just don't bother with the Morin oil cooler. After spending half of my Saturday fixing the core enclosure, the blasted mounting bracket snapped on my way home. Came 40 miles with just the hoses supporting the cooler. To clarify, the Morin cooler was nothing to do with Finbro, but I figured more people with be fitting a cooler of some form.
 

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I usually don't go on long road trips so I'm going to try it with out the oil cooler first plus I live in Detroit it don't get to hot over here . I should be getting my kit Saturday first thing I'm doing is installing it. I was impressed with the takegawa 143 kit I can't wait to see what this kit will do
 

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Discussion Starter #16
more torque than revs. Hit 86mph today at about 8,500rpm, but that was tucked in with a tail wind. Normally it's about 75 on the level sat up.
 

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more torque than revs. Hit 86mph today at about 8,500rpm, but that was tucked in with a tail wind. Normally it's about 75 on the level sat up.
Now we're talking, that is my goal to hit 80+mph and I would be very very happy.

right now messing around with the 170cc kit with different configurations, so far very happy with the low mid-range torque and pull, still messing with the top end which would include front sprocket change and maybe spark plug change from NGK CPR7EA-9 to what is next!!!!!!

looking at the inlet tube that is bigger I like that plus their own cam and not a grounded cam should be better.

Wonder if they cracked the Software for the Honda Grom ECU and reflashed a new one or figured a ECU from a Honda scooter of bigger cc would do the trick.

Anyway keep up the good write up and ride safe
 

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Wow 86 at that rpm is impressive I'm hoping to do 80 on mine. I have pcv/wb2 and using there injector. I'm also hearing that the 183 kit can rev up to 12500 safely I'll probably set the limiter at 10500. What's the highest you can rev yours
 

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Discussion Starter #19
mine is in effect a stroke-up 190cc kit to give 209cc, so the max theoretical rpm will be less, but more torque at said lower rpm, and hence approx. equal power. Theoretically.... So far that was the only time I've gone over the red line. The crank was set up for no more than stock rpm, and optimised for 7,500rpm. Most vibes are at idle, but fine when running above 2,000rpm. Your full PCV/WB2 will probably liberate a few more ponies. Mine seems a little asthmatic at full rpm, but could be due to restrictive exhaust. Take some advice... get a big bore pipe. FinBro can give you the correct dimensions for your kit.
 

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I got chimera intake which should work good. I have the 2 brothers exhaust and it should also work well. I wouldn't want to change cause I love the sound plus when I go nite riding I could still be quite at low rpm when I'm sneaking around lol
 
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