Grom versus Monkey (price difference)

[Old Guy Too Many Bikes]

Very good, keep me in the loop. I noticed there's no street tires available in the Monkey sizes . So I was thinking that when my tires wear out, I could install Grom tires and compensate for the shorter tires with a sprocket change.

 

[Deoodles]

Heidenau makes a rear tire in 130/80-12 and Kenda has a 120/80-12. I haven’t found a set from anyone yet. Hope I do by the time I need tires. Pirelli SL60 is on my short list for replacement when the time comes

 

[Old Guy Too Many Bikes]

Yes, but the Monkey tires have an aspect ratio of 90. I'll have to see what's available when my tires are worn out. By the way, did a nice 60 mile ride with my son on his '21 Monkey. We even swapped bikes for a about 10 miles. The clutch and shift action seems lighter on the 5 speed. At 45 mph the 5 speed also a bit smoother, due to lower rpm I guess. In a drag race to 50 it was a dead heat. The main difference, though was how much softer the shocks are on the older bike. Made the seat on the new bike seem more comfortable and makes you sit a bit higher. Father and son motorcycle rides, doesn't get much better than this. Finished the day with 798 miles on the odo.

 

[Deoodles]

Nice day. Good for both of you. Monkey aspect is 80. Grom is 70. I’m confident my speedometer is calibrated. Did 49 on speedo and gps. That said I still can’t figure out why the Monkey is slower than the Grom so I did some research first gear through fifth gear ratios on both bikes are identical the primary gear on both bikes is also identical 25T they also share the same cam and fuel injector, have the same stroke and compression. now I have to look at the tires The Monkees tires are bigger so the gearing Has to be adjusted to account for that what I learned was the monkey is 1.3% taller stock by going to the 38 I’m now 2.6% shorter than stock and 1.3% shorter than the Grom I think that will help the Grom by the way is perfect the only other factors I can think of are the tune in the ecm and the tires and resistance as well as riding position and resistance can’t wait to get out on the road and put some miles on the new gear set up. 275 miles now

 

[Deoodles]

I did a ride yesterday with the 14/38 gear combo. I was able to hit the rev limiter in 1st thru 4th. 5th had more pull as well. This is a subtle change and for the better. It’s all I was looking for. Now for the surprise. The rev limiter kicks in around 8.25 or 8.5k. That’s 1k below previous years. I went to Honda and asked the service manager. He wasn’t sure but agreed to verify the limiter setting and let me know next time I’m there. With the new gear combo I recorded the following in 1st thru 4th shifting at the limiter. 20. 33. 45. 54mph. 5th gear improved and I was able to pull to 7.5k and hit 61mph. Not any buzzier and I’m in 5th gear more than 4th now. Now at 309 miles

 

[Old Guy Too Many Bikes]

61 mph on level ground is pretty impressive. In a previous post, you said with the stock gearing at 7000 rpm, 4th gear equaled 48 mph. That means that if the rev limiter cuts in at 8200-8500, in 4th with stock gearing it translates to 56-58 mph. So a stock bike is probably a little faster in 4th than 5th. So what you did makes sense. If you're looking for top speed, 4th gear is a little too short and 5th gear is a little too tall. But with me, most of my riding is between 40 and 50. Rarely do I find myself needing to go faster than 50. Keep on ridin'!

 

[Deoodles]

This doesn’t really belong here but it does. I rode my 2022 Grom tonight and it has the same motor as the Monkey but the tune is different. All stock. The rev limiter is at 9.250. I hit the limiter at shifts. 1 thru 4th.
25, 38, 52, 62 mph. I didn’t have enough road to see where 5th would go. How is the Grom so much faster???

 

[Old Guy Too Many Bikes]

And why is the rev limiter set higher on the Grom. Maybe the motors aren't identical. Does the Grom feel like it has a hotter cam in the upper rev range, maybe softer on the bottom end?

 

[Deoodles]

Good questions. The trans ratios are identical, so is the primary gear. Same part number for the cam and injector. The final ratios are within 1.3%. The Grom 1st gear and bottom end are stronger. I’m leaning towards the ecm tune. There’s smarter people than me that may have a thought. If it really is in the tune I feel ripped off.

 

[Old Guy Too Many Bikes]

You shouldn't feel ripped off due to a couple of miles per hour. Did an 80 mile ride today on the CL90 and although it's substantially quicker than my Monkey, I never went faster than 45 mph nor had to. Even if the Grom was 10 mph hour faster than the Monkey, I'd still stick to the Monkey.

 

[Deoodles]

I owned the Grom for several months before getting the Monkey. Some of the decision to buy was that they had the same motor. Some was based on how the Grom exceeded my expectations. As cool as the Monkey is it dose not perform anywhere near the level I need to ride safely around here. The Monkey performance is par with a 108 build. The Grom is closer to a 140 build. I can say a lot of good things about the bike but the fact is it’s performance lacks when compared with the same year Grom. It needs correcting or it has no space in my garage. I’ve invested minimally in a gear change so far and have no plans to do much more to it. Last stop for me will be an ecm tune modification and if that works I’m done. If not…

 

[OLD CT]

A mini with a top speed of 70 mph is needed here. You do not have to hold 70 for long distances but you need to cruise 50-55 and have more in the tank to pull away. My 108cc bike can hit a top speed of 60mph and hold it for a mile or so. It isn't optimal on the main roads here.

 

[Old Guy Too Many Bikes]

I've never ridden a Grom, but I have ridden a lot of little bikes for comparison. My CT70 when it had a Lifan 110 in it could do 50+ and could pull a little harder than my neighbor's CT110. When my son got his Monkey, and we raced, he pulled me pretty good. When I put the 140 in my CT70, I pulled him pretty good. We raced Monkeys last week and I was on his '21 and he was on my '22. It was a dead heat, however, he weighs 50 lbs more than me, so the '22 ought to be a little quicker. I think a top speed of 70 is a lot to ask for. My Yamaha 250 V twin will do 80, but it's working pretty hard at 70. Can your '22 Grom hit 70? Was the top speed in your older Monkey slower than your new Monkey? Anyway, I did some thinking and remember that when my neighbor swapped out his trail tires for some street tires, his bike got a little faster. Also, when my son swapped out his all season tires for all terrain tires on his truck, he lost 4 miles per gallon. I also noticed on my Monkey the vibration due to the treadblocks on my tires (my CT has sport/scooter tires with no vibrations). I believe a switch to Grom type tires would result in a faster (and better handling) bike. With all other things being equal, that may be the difference. But if you really need that kind of speed, you'll need to increase the displacement. How fast have you been able to go in your KO with the 140 in it. Mine will top 60, but it's scary.

 

[Deoodles]

That’s a lot to take in. My KO 140 top speed is 63. So far the Grom top speed is 64. My 124 build CT70 is 69. None are at 70 but that’s a good target. Roads In our area are mostly 55 mph if your going anywhere. The problem is folks do 65, not everyone but the idiots I’m worried about do. The Monkey is the slowest of the bunch and has nothing left if I get to 55 whereas the rest have a small bit left. That keeps me worried about being run over. I will spot a driveway or side street and pull in to let cars go by but I may need to wait a mile or two. I don’t think the monkey is held up by tires or tire size that can be accounted for with gears. I think Honda was way too conservative on A/F ratios, timing, and the rev limiter. All of those reside in the ecm. I have reached out to a tuner to see if it can be re mapped to perform at the same level or higher than the Grom. It is after all the same motor. Btw my 2020 monkey would pull 57 in 3rd and maybe 62 in 4th but that had some grunt behind it. The 22 has none. It’s there and untapped imo

 

[OLD CT]

With all other things being equal, that may be the difference. But if you really need that kind of speed, you'll need to increase the displacement. How fast have you been able to go in your KO with the 140 in it. Mine will top 60, but it's scary.

This won't take very much to take in. Displacement only goes so far literally. Horsepower and torque is the answer. My 108 can do 60mph and the low compression 140cc can do 63. My 124 stroker can do 65. Not much more speed to cc's comparing a 108cc to a 140cc. 32 extra cc's ought to do better than that.

 

[Old Guy Too Many Bikes]

Torque is more the answer than horsepower. It's not so much the top speed, as the pull in midrange. It's what you got left when you're cruising at 50-55 mph. Displacement, cam, valves, porting, it's all a matter of how much mixture you can stuff into and out of the engine. Displacement will give it to you at lower rpm without having to give it full throttle. The bad thing about high horsepower, small displacement engines is that the power band is all on the top end. And 4 gears aren't close enough to stay in that narrow band. The 5 speed Monkey is no rocket, but it'll cruise at a smooth 50 with a little left over and knows how to squeeze over 125 miles out of a gallon of gas.

 

[Deoodles]

As promised I was able to confirm the rev limiter setting for the Monkey. 8250. The Grom is 9250. That explains a lot. I can pull to the limiter in 4 of the 5 gears. If I have it moved up in line with the Grom it should give me what I’m looking for In the mid gears and performance will be close to the Groms and I’ll be happy. Getting this info was like pulling hens teeth. Even Honda couldn’t tell me the setting. I found a tuner guy who knew.

 

[Old Guy Too Many Bikes]

Good to know. Will it be difficult to up the limiter setting on the Monkey? At least I'll feel as if I'm not hurting anything if I hit my 8250 rpm limiter.

 

[Deoodles]

Not difficult but $$$

 

[Deoodles]

Before I go all in on the Monkey I thought I would try the tune on my Grom. I know it’s a keeper even stock so spending a few $$ on having the ecm flashed makes sense. If I don’t like the results I can pop the original back in. I purchased a new ecm for the test. If the improved tune helps the Grom I’ll be thrilled. If it doesn’t do much I won’t bother with the Monkey. It’s going to be a week or two before I can give an update. I’m expecting 2 to 2-1/2 hp and another ft lb of torque.