Grom muffler fit for stage 1 header?

#1
Finalizing a 1st mini bike order for side streets and trails.

Likely going with a 212 Predator from harbor freight on a mega moto 80/105 from gopowersports or maybe a mega 212 frame since it already has a TC and dual hydrolic and I prefer the larger size but I feel way more confident I won't get in trouble riding side streets with the smaller 80/105 frame.


For street I want a Honda Grom muffler so it's quiet as possible.
I read a RLV muffler barely makes it quieter difference despite some youtubers saying so after showing before and after.



I don't really want top speed. I want fast acceleration though.
I doubt I'll do any modifications past stage 1.
I'll likely not remove the internal governor because I don't want anything exploding without having to upgrade internal flywheel etc parts.

I want the stage 1 header/exhaust pipe to exit under the seat, not to the side, but either is fine as long as it'll fit a Grom??

I read some needed adapters etc for the Grom but I prefer a simple clamp-on to easily remove it for trail riding and have it loud in the woods.
With an open header for trails, I might get some sorta spark arrestor or an RLV because I'm paranoid about having a spark fly out and start a forest fire with how dry everything has been with drought and everything despite I'll likely also attach a mini fire extinguisher to the bike, which would suck to fall on and have it explode but maybe in a padded box or something or maybe just one of these flair-shape Element brand ones.

But do you think I can even fit a Grom on the 80/105 either under the seat or to the side?

gopowersports doesn't have a complete stage 1 kit in stock with the header bracing bar and heat wrap etc which I want, so I'll likely order it elsewhere.

Could someone link me a good deal on a stage 1 keeping in mind the dimensions of the Grom so it'll slip right on the header pipe?
Do I even need the carb included in the kit or just the jet? I think only the newer coleman engines have a fixed jet. So these carbs in these ~$150 kits are just for that, and also I don't have to research any 'performance carbs' or anything besides? Again, I don't want fast top speed but anything that'll make it faster from a stop is a plus without getting too advanced with stage 2 type internal upgrades etc.

much thanks if anyone can add some good input.
 
#2
welcome and to be honest i think your best bet is to leave the stock muffler in place if sparks are a big concern on trails as I don't think any other muffler (includin the factory grom or monkey mufflers) have a spark arrestor. I have a 2022 Monkey and I don't recall anything about a spark arrestor in the manual or seein a decal on the frame etc, but I'll check. The 2022+ groms and monkeys have a straight through single chamber muffler, so those will likely be almost as loud as a RLV on a 212. You'd want a 2021 or older which is a 3 chamber design. However they are fairly large and won't lend themselves well to a mini bike frame IMO and may still be loud. The groms and monkeys come stock wit ha catalytic convertor, thats where a lot of the noise is kept down IMO. If trails are your thing, you can't go wrong with the mb200 trailmaster bike or the larger MM212 frame bikes, they are the top 2 IMO as far as new bikes go. I love the smaller mm80/105 bikes but even with a 15" tall tire and suspension front fork, you still feel too many bumps, but i got a very bad back, so your results may vary. I think a stock 212/tav 30 on a mm212 with some nice 20"x7 knobby tires will be pretty damn slick trail rig. I don't know your weight, so you may need to gear up or down to get the right feel you want, not a huge deal in any case.
 

SAS289

Well-Known Member
#3
If you don't want the noise use the stock muffler. The performance gains from a header pipe are minimal on a stock engine running stock RPM.

A guy on YouTube recently tested a stock muffler versus a header pipe on an already modded engine. The low end gains were so minimal that it wouldn't even be noticed without the use of a "stopwatch" running his 0-30 tests. The advantage of the header pipe came at much higher than stock RPM.
 

toomanytoys

Well-Known Member
#4
I welded a 3/4” coupler to my header and put a hotdog muffler on it. Not quiet by any means but quieter and at least no hammering like no muffler. It would cackle, back fire and just scream.

open header is extremely loud and a good way to piss off your neighbors.
 
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