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Fun fact: Harley tuners drill CV40 vacuum ports to 1/8" diameter, versus the 7/64" favored by KLR tuners on CVK40s..
Makes perfect sense to me.

1 carb feeding TWO 600cc cylinders would probably have a stronger more consistent intake vacuum, even near Idle rpms, than a single cylinder 650. So the vacuum slide could be allowed to 'lift' quicker. They are about the same in suggested Maximum operating RPM, I think.

ps, But I 'think' I might beat most XL1200 Sportster riders across an intersection with my KLR650. :)
 

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Too bad developments emerge two years after the cancellation of the KLR 650's 31 model years (1987-2018 inclusive) of production.

Do Harleys still use Keihin CV40 carburetors? Might be a market, profit center opportunity there.

Fun fact: Harley tuners drill CV40 vacuum ports to 1/8" diameter, versus the 7/64" favored by KLR tuners on CVK40s..
I will be looking at the Harley's, i may have to buy 1, to see if the same problem is there. One of the issues MCP fixes Harley partially compensated for by adding the accelerator pump to the CV40
 

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do you recall if that was the first year for them?
I know that my 1990 Electra Glide Sport had a Keihin carburetor with with accelerator pump. And chances are that prior year HDs had accelerator pumps, too, but I don't know when it all started. It may have been when HD switched to Keihin for their carburetor supply, but this is just a supposition.

Jason
 

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I’m pretty sure the last year of HD carbs was 2006.
 

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Some times one needs to back track the conversation. :)
Not to belabor the subject, but I did "back track" the conversation. The following two tracks were in succession and I interpreted the question to be when was the first year for accelerator pumps. :p

Jason

One of the issues MCP fixes Harley partially compensated for by adding the accelerator pump to the CV40
do you recall if that was the first year for them?
 

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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,
Dave
Hey Dave, totally understand your scepticism, and I was too. Had my 2008 KLR for 12 months prior to delving into performance mods. I'm in Australia so I considered it reasonable to at least try and over come the LAMS restrictions, however I didn't want to make any unreversable changes to my bike, so if something didn't work I could just undo it. I started by putting my bike back to as near to stock (I thought) as possible. I wanted to minimise user bias, and was fortunate to find a motorcycle dynonometer in my area. The first dyno run gave a reading of 28BHP, which about what I expected from a restricted KLR. I pulled the snorkel out and swapped the muffler to a more free flowing unit, the next dyno run came in at 35 BHP. Now this is an astonishing gain which didn't make sense, but I was happy with the result. The next step was to install an MCP kit, and this is where it go interesting. Once I pulled my carby out it became evident that it had been previously tampered with, the idle mix screw cover was gone and the float level was mal-adjusted, (what I missed at this point was that the main jet had been changed to something much larger andnot numbered correctly) once this was sorted out, and explaination for the huge improvement seen on the second dyno run was evident, the bike was running rich from the out set.
 

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With your access to dyno runs, comparison between MCP and KLX carb mods would be, well, fascinating!

(Never mind the claims for lower rpm at identical speeds claimed by MCP True Believers.)

:)
 

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I’ll be curious to see your results on a dyno, and compare them to my road tests. To see my testing of the MCP kit, here’s a link to my chronology of installing a 692 piston/cylinder in my 2013.
 

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With your access to dyno runs, comparison between MCP and KLX carb mods would be, well, fascinating!

(Never mind the claims for lower rpm at identical speeds claimed by MCP True Believers.)

:)
Agree, if I meet another KLRian with the KLX mods will try to encourage that to occur
 

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The other observation that I can offer at this stage, albeit a subjective one, is the acceleration and mid range power delivery has massively improved. I attribute this to the combination of improved air intake, free flowing exhaust, corrected jetting and the MCP kit. Unfortunately because of the way things developed I was unable to get a stable benchmark to measure the MCP kit against on the dyno. The old 2 steps forward one step backwards dilemma...
 
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