MCP carb kit for KLR 650 - Kawasaki KLR 650 Forum
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post #1 of 42 Old 03-03-2020, 11:01 AM Thread Starter
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Location: Cody, Wyoming
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MCP carb kit for KLR 650

Hey guys. Let me start by saying I am NOT a salesman! I am also NOT a bot! Please don't shoot!

Secondarily, I will admit to being a bit hasty at times in life.
I tried the carb correction kit from a Canadian company called MegaCity Performance (MCP for short).

I saw another thread posted here regarding this kit, and I saw some favorable info in some of the KLR groups on Facebook, so I decided to give it a try despite it being mostly unknown and unproven.

I read here at the KLRforum alot, but I don't post here much. In fact, this may be my first post.

I have great respect for the knowledgeable regulars on this forum like Paul Westman, Dave Pelletier, Tom Schmitz, and Norm Keller, and several others. I understand I may be labeled as gullible, or recused for my non-scientific testing methods by these gents, but I am putting my 2-cents out there in the hopes that it may help some or all of the KLR community get a better running bike.
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post #2 of 42 Old 03-03-2020, 11:04 AM Thread Starter
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INITIAL review on the MCP Stock+ Carb recalibration kit for the KLR 650.
These are only my initial thoughts on the MCP kit after about 1.5hrs of street ride time.

Rider Background: 42-year-old male, 6ft tall, 250lbs (kind of tubby), riding dirt since age 10 and street since age 15 (definitely not as fast off-road as I once was…). This KLR is my first dirt-oriented 4-stroke. Had a few street bikes over the years. Mostly big Yamaha parallel twins. I’ve always ridden 2-strokes in the dirt, and have never been without a KX500 or CR500 in the garage since age 17. I consider myself to be, and am quite familiar with big-bore 2 strokes.

Location Background: I live in the northwest corner of Wyoming, USA near Yellowstone Park. Elevation here is approximately 5000-5100ft above sea level. Area can be best characterized as high desert. Very little annual rainfall, and almost always very low relative humidity. Basically, the air up here is thin and dry.

Bike Background: 2013 KLR 650; just turned 3000 miles on the odometer. No known oil consumption issues. I’ve owned the bike since April 2018 when I bought it with 1550 miles on the clock. Previous carb setup was KLX needle and associated jetting (142M, 40P, needle in clip position 2, & slide hole drilled larger) installed by me at 1650 miles. Engine is all stock internally, but has an eagle Mike AIS block off installed, all smog equipment deleted, and has a thermo-bob from installed. Exhaust is all stock. Airbox has snorkel removed, “L-Mod” holes in airbox roof, and UNI foam air filter installed. Stock airbox screen is intact. Gearing is 15T front and 45T rear. I ride more dirt than street, so the bike has a two tooth larger-than-stock rear sprocket. Bike is currently shod with OEM Dunlop K750 front tire and a fresh Shinko 244 rear.

Carb upgrades - KLX needle: First let me cover my seat of the pants impression from the KLX needle install. I know that the purpose of this review is not to illuminate the merits of the well documented KLX needle upgrade, but telling you my impressions of the KLX needle will help me convey the relative improvements of the MCP kit. Remember, I am only relaying my own experiences. Your experience may differ.

The stock carburetion had seemed acceptable when I first tested the bike prior to purchase on a warm, 60-degree April day. However, the next 30-degree spring day revealed an engine that refused to warm up, which only worsened the lean factory jetting. The factory stock KLR was so corked up and held back by its lean OEM carb calibration that I momentarily considered selling the bike. Let me just say that the combination of the airbox enhancement mods (inlet flow improvement) and the installation of the KLX needle made a huge seat of the pants improvement in power. The bike could now get out of its own way! All ranges of the power were now improved. The low RPM area of the power curve was definitely smoother, but throttle response was only slightly improved. The midrange was greatly improved, by about 20% over stock (according to the seat of my precisely calibrated pants), and the high rpm range from ¾ throttle and up was about 15% better than OEM. All-in-all, the improvement was very noticeable, and definitely worthwhile. I rode the bike in this configuration for 1350 miles of 50/50 street/dirt riding.

I was still a bit less than satisfied with the low speed throttle response. But I had resigned myself to the fact that KLR’s are like that, and I should just accept it.

Then, in January of this year (2020) I saw a few Facebook posts from some thing or some place called MegaCity Performance (MCP). The posts began to appear in the usual KLR groups on Facebook, and promised improvements in the carburetion across the entire range for the KLR. Me being the greedy S.O.B. that I am, of course I was curious. I attempted to make contact with the MCP Facebook page, and I was surprised when the owner of MCP reached out to me personally to ask if I had any questions. From that moment, the game was on! I asked him every possible question I could come up with relating to CV carburetion theory, the operation of the 40mm Keihin CVK carb the big KLR uses, and the specifics of what his recalibration kit could really do, and more importantly, HOW his kit would do it. He was glad to answer almost all of my questions, but was understandably a bit tight-lipped about the specific components of his kit, and the theory behind them.
But….my desire for improved throttle response led me to take the risk and purchase his Stock+ recalibration kit (for bikes with opened airbox, but stock exhaust). I figured all I had to lose was my $55USD (which is something like $734 CAD. I don’t know much about exchange rates…LOL). At the time of purchase (Yes, I paid my own money. I was not given a kit to review), I mentioned that I would be posting my findings to the web after the kit was installed. If he sold junk, I would make sure everyone knew it. But…if his kit delivered as promised, the web would know that as well.

So, here I am…. finally getting to the part of the review that you have read all this previous BS to get to. This is what you REALLY want to know. Does the MCP kit work? Is it better than the KLX needle/jetting setup?

For me, the answer is definitely YES!

Let me qualify my statement. I am just an average dirt bike guy, probably a lot like you. I didn’t do back to back scientific comparisons between the KLX needle and the MCP kit. There was no onboard data logging equipment on the bike. No exhaust gas analyzers were used. Again, all data was collected by the seat of my precisely calibrated pants, filtered by my 2.5 years of KLR experience and 30 years of general motorcycle riding/jetting/mechanical experience, and processed in the slightly problematic biological storage device perched atop my neck. In other words, I twisted the throttle and hung on!

Carb upgrades - MCP needle: So, to better quantify the improvements of the MCP kit over the KLX needle, lets use percentage increases again like we did when discussing the improvement of the KLX needle over stock.

Again, all ranges of the power are improved. The low RPM area of the power curve is about the same in terms of quantity, but the quality is much improved! The throttle response warm or cold is instant! The significantly cold-blooded nature of the stock KLR at low rpm is only a bad memory. Like I said, I’m a lifelong 2-stroke guy. I’ve only ever ridden a handful of modern EFI thumpers, but the throttle response I’m experiencing on the big KLR seems to be nearly on par with what I remember of those injected bikes. The midrange was again greatly improved, by about another 20% over the KLX needle setup. This thing is now a MONSTER in the midrange when compared to the stock setup, and is still better than the KLX setup as well. Between 2500rpm and 6000rpm…it flat out runs! I could not stop myself from twisting the fun handle. Smiles were frequent. The high rpm range from ¾ throttle and up was about 10% better than I experienced with the KLX needle/jetting. The huge improvement that this kit gives in the midrange actually overshadows the top-end increase a bit, but make no mistake, it definitely feels stronger up top. I ran mine right up to the redline a few times to make sure it was willing and able. I was not disappointed.

Also, remember I live at over 5000 feet of elevation. Most bikes don’t feel nearly as strong up here as they do at sea level without a bit of work. This KLR feels so much stronger now, and all of the improvement is just from getting the carburetion correct! No aftermarket pipe, no hot cams, etc. I am still running 100% stock exhaust. The MCP kit makes the KLR run like a good condition stock 650cc thumper should run!

Two additional pieces of info:
1. I have no idea the effect of the MCP kit on mileage. I also have no idea what the mileage was with the KLX needle, or when the bike was completely stock. I will keep track of my mileage as I get more time on the bike, weather permitting. NW Wyoming is going through Winter/Spring weather cycles about every 5-7 days at the present time, so my riding may be a bit limited for a while yet.

2. A thought that had been floating around the back of my mind every time I rode the bike before the MCP kit was that it just generally still felt a bit too lean. It didn’t feel particularly strong on upshifts unless you revved it up a bit more in rpm and timed all shifts perfectly. After the MCP kit was installed, I instantly noticed how much easier the motor handled the rpm drop at every upshift. No more struggling! Previously, I attributed my dislike of the weak power after upshifts to my familiarity with the shifting characteristics of the transmissions of big-bore 2-stroke MX bikes, where close ratios and big power made every upshift effortless. But….I always thought a big, torquey 4-stoke single should pull gear changes easily, especially with the lower gearing my bike is fitted with. Now, after the MCP kit, you can be sooo lazy around town, shifting far too early and the motor just pulls it! I may need to go back to stock gearing because of the additional power.

Last edited by Enginerd; 03-03-2020 at 11:09 AM.
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post #3 of 42 Old 03-03-2020, 11:10 AM Thread Starter
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So there it is gents. Hit me with the comments!
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post #4 of 42 Old 03-03-2020, 12:18 PM
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sounds good to be true but if it works, you might be on to something.
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post #5 of 42 Old 03-03-2020, 01:10 PM
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Originally Posted by Enginerd View Post
So there it is gents. Hit me with the comments!
Any tangible, measurable, repeatable performance data, Enginerd? Before-and-after air/fuel ratios? Dyno runs? Quarter-mile dragstrip timing slips? Comparative top speed runs?

Your testimonial comments appear totally SUBJECTIVE, to me--nothing quantifiable. Doesn't mean the testimonial praise is incorrect or invalid, but . . . confidence in the developmental new product's worth and actual effect would be bolstered by some OBJECTIVE evidence, IMHO. Merely assigning an arbitrary number (as you do, " . . . improved by about 20 %," etc.) does not mean the actual numerical claimed improvement, or any improvement, exists.

Nor does hyperbole, as in the developer's claims, such as, "CRAZY Power," as posted on ADV, confirm any improvement.

Similar testimonials followed implementation of a KLR mod: Increased power, improved fuel mileage, lower oil consumption, enhanced ring seating, and more. Enthusiastic declarations of performance improvement issued forth from the seat-of-the-pants dynamometers of many who availed themselves of the modification; all subjective, none objective and corroborated by any measurable data.

The mod: A check-valve in the crankcase vent line ("PCV Valve Mod"). Without objective measurement data, hard to confirm or deny the mod's efficacy. With an open mind, I'd say your vaunted product appears in the same situation.

So, maybe you have your hands on the, "Rosetta Stone;" the key to high-performance modification of the KLR650's Keihin CVK40 carburetor, secrets hidden for over thirty years of production and tuning. If so, congratulations!

DISCLAIMER: You asked for comments; I've shared mine.

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre

Last edited by Damocles; 03-03-2020 at 01:37 PM.
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post #6 of 42 Old 03-03-2020, 01:15 PM
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@Enginerd, thank you for the very well written review of the MCP carb correction kit. I posted my findings a while back, while not nearly as detailed and precise as yours, my personal findings seem to be the same as you stated.

I've never enjoyed my KLR as much as I have since the MCP kit was installed, and look forward to putting many many more miles on mine.

Thanks again and enjoy your bike.


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post #7 of 42 Old 03-03-2020, 01:51 PM
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Thank you for the report. I have resisted commenting on the FB page as I don't want to pee in Dredd's cornflakes. Further thoughts;

- Like Damocles, this is all good and I'm certainly not suggesting you are making anything up, BUT butt dyno's are notoriously inaccurate - in order to give this any credibility, I need 02 results, dyno tests, back to back acceleration tests or SOMETHING quantifiable.....until then, it reeks of snake oil to me. More on this below.

- Just an observation but throttle response is typically independent from power and therefore jetting; it's about slide movement which is commonly tailored by increasing the slide vacuum hole size.....some (mostly Aussies) also experiment with modifying the spring.

- I remain concerned as to the repeatability (as I understand it) since the needles are modified by hand

- Dredd himself posted that after he finally got the KLX kit that it worked just as well and was easier to install.......since then I've not heard anything plausible as to why the flip/flop or what (if anything) was changed to make his kit any better than the tried and true (and dyno/02 tested) KLX kit.

- I spent too much time in school so I tend to be logical and analytical in my thinking; basically there is an optimum air/fuel ration for power production and I simply don't see the physics of how a different jetting solution can make noticeably more power than a setup that has been 02 tested to be fairly close to that optimum ratio.....particularly when we are talking the exact same carb - only difference is the jetting/needle/o-ring.

I'm glad you guys are happy with your purchase and I appreciate the update but I still have significant skepticism and concern with the claims being made by MCP and I don't see my position changing unit some unbiased party does some actual testing.

2 cents,
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post #8 of 42 Old 03-03-2020, 05:02 PM
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Just an FYI I saw on FB from MCP regarding needle manufacturing...

Seems a few prototype needles were made by hand early on for testing, but now are made on a CNC machine.

Just wanted to pass it along.


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post #9 of 42 Old 03-03-2020, 06:10 PM
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CNC machined of 316 Stainless steel, ok. Accurate to with-in .0002 inches, that is great.

I wonder why he didn't have adjustable circlip grooves instead of the non-adjustable button head? Maybe less chance of installing the needle in an overly-rich setting maybe?

Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #10 of 42 Old 03-03-2020, 06:54 PM
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Years ago I had a BMW R1100S. It was a good machine but I did not ride it enough so I let it go.
I installed a different air inlet duct to the air filter housing and removed the baffle in the crossover
pipe at the exhaust headers. which helped the performance a bit. BMW claimed 99HP but I always have to tinker.
Stock it ran quite lean for emissions reasons. It surged a bit under light load at mid speeds. So I installed a fuel injection controller on it.
The controller had 4 screws that allowed adjusting the mixture at various throttle openings.
One screw was supposed to act like an accelerator pump on a carb.
I played with it to where I got a big increase in performance and throttle response.
I was more than surprised at how much more power I was able to get with just enriching the mixture.
I was also surprised when the fuel light came on when it should have had more than half a tank left.
I calculated the mileage and it was about half of what I got with the stock fuel system which was around 55MPG with a mix of city and highway.
I dial the adjustments back to where it ran smooth had slightly more power and throttle response and left it there.
The mileage dropped by around 10% from the factory settings. I felt it was worth it for the gains.

I wonder if this kit makes the KLR burn more fuel even though the seller claims it improves mileage.

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