So, I got tired of waiting for the dealer to get my parts (#128 jet, 40 pilot, and N1tc needle/clamp/collar), so I complained. I ended up with some stuff to put in until they pull through, and I went mod crazy. The closest shim to the HMF directions I could find was .040 (they reccomend .032), so I used that, used an in stock main jet in a 127.5 (wierd, huh), pilot jet 2 1/2 turns out from lightly bottomed, and drilled the slide to 7/64. I also installed a Uni filter, and removed the snorkel. I have previously tweaked the HMF for install, and its on (not very well either). So, first off the HMF is VERY loud, WOW. It revs a little faster, and I can actually sustain a first gear wheelie. Offroad I can break the rearend loose at will so I can cut corners sharper, but I really dont see any power difference than stock except in the midrange (its fat there now!!). It revs a little faster, so it seems like its got a little more down low, but no real "seat of the pants" power gain up high. Very little popping, a little occasionally on decel, not much, seems to like a little gas now when starting warm. I dont know if its neccessary to remove the air injection ( I had a modded TL1000 and I HAD to remove it, as it popped like crazy until I removed it), but I wont get any performance gain, so............... I also forgot to drill the airbox for the crankcase vent. I also have a good leak at the slip joint for the slip on, and cant make it go away, doesnt matter where the clamp is oriented around/front to back ( I also modded the head pipe, removing the weld at the cylinder, and doing a homemade "port match" job on the headpipe flange when I did it. Whaddya think?? BTW, did I mention this thing is loud???

 

Rode it up a few of my favorite local trails, difference on the trail is dramatic. Popping on decel starts at 6500, diminishes to almost nothing at 5000, and is gone at 4500. I dont know what idle this is supposed ot be at but it likes 1400. Exhaust has rotated so it is rubbing HARD on the rear fender (had a couple of good jumps!!), time for a longer spacer. Gotta find something to seal this exhaust leak. I WILL be getting the quiet core.

 

Jason, I had similar problems installing my HMF. And yes, it seemed rather loud so I installed the HMF Quiet Core Insert ($20) which helped a lot. Check out my website link below to see photos on what you need to fix the mounting problem to get the muffler away from the rear fender and also make a sealed connection with the header. It's a 10-minute job, if that. I didn't have any problems getting the jets and other carb parts from the dealer though. I can do a 1st and 2nd gear wheelie and I'm 200-lbs. so I'm a little more cautious on the throttle. Let me know how it goes.

 

Ill get the permatex, my issue with the exhaust seems worse than yours. Even after spacing it out an inch, it has to be rotated 10 degrees ( bevelednuts on a grider) so that it stays away from the fender (the bottom on the canister has to be much closer to the bike). It also has to be held firmly there, or it will rotate towards vertical (muffler straight up and down, which looks best, but..............), and rests HARD on the fender. I also need to pay attention to frame clearance if it becomes rotated. I cant imagine that this bike will ever do a 2nd gear wheelie (I tried, even popped the clutch, and just got a baby wheelie). I also am VERY tall, so I tend to sit further back on my seat than most, and it makes the front much lighter (easier). I think this works for me offroad though, because even on the pegs I load the bike rearward naturally, and dont have the issues bottoming I hear reported from very aggressive riding from other members (it doesnt hurt that Im 6"6", and 185-190).

 

Sounds like it might also be running rich with the #128 main. I went to the #125 and it ran stronger. I'm 6'-3" so I sit back on the saddle too. I also had to pull the muffler from the bottom (away from the bike) when I tightened the spacer bolt to keep it "level". I've been riding over 750 miles - 50/50 dirt and street and it hasn't budged. Can you post some pictures of the problem?

 

Mark, why did you have to use the Putty and the Sealer? The slip on does not fit correctly to the header?

I have the HMF on order. Will I be experiencing installation SNAFUs?

 

Jbweld quickstick

 

FM_Thumper, some of us have had some minor issues with installing the HMF - but "usually" nothing you can't fix yourself in less then 10-minutes. To make a "solid" seal with the header pipe I would suggest using the Permatex. You can also see the other fix with the mounting spacer on my website below. Despite these glitches, I still think it's a great muffler at a great price - performance, quality and sound are outstanding!

 

Im not sure that I would "completely" agree with klx250s_rider, BUT..........if price point is by far the most important thing, you should still purchase this, just assume from the beginning its not a true bolt on, and youll have to custom fit it to the bike. I am just angry because the company would prefer to use its customer base for R&D, with no benefit whatsoever to the customer, and it fixes their very flawed product for free (at least to themselves). I work in the aftermarket 4x4 industry as a side gig, and this WOULD NOT BE TOLERATED. I would prefer to pay a bit more for a product that fits, instead of this, but it is up to the management at HMF. Like Ive said before, I talked to them on the phone, and they seem friendly enough, but I am not willing to fix it the right way at my cost of down time, and they WILL NOT refund your money. I think it should be stated that not only are you purchasing a special order item, but that it cannot be returned (at least one member has been able to return it, but they charged him a restock fee, UNFORGIVABLE in my opinion, because it did not fit. If it was just that the customer changed his mind, or whatever, that is understandable).

 

I agree, their customer support sucks! Myself and number of other HMF buyers have voiced our complaints with the company but to no avail. Next step, let's put together a letter to the Better Business Bureau and take it from there. Despite this, I still like the muffler! I grew up tinkering with cars and motorcycles in the '70's, as a former GM mechanic back in the old days, I can tell you almost nothing fit right. If I had to whine about my Holly carburetor, Edelbrock manifold, Cherry Bomb mufflers, etc., etc., not fitting right I'd never get on the race track. Instead, I preferred to develop the problem-solving skills to fix it myself - it was fun and gave me a REAL sense accomplishment. So, suck it up and move on - NEXT SUBJECT PLEASE!


"Every normal man must be tempted at times to spit upon his hands, hoist the black flag, and begin slitting throats."
- Henry Louis Mencken (1880-1956)