Klxster- I should have considered the ECU as being just as important a part if the equation as the injector. After all, its basically the ECU which tells the injector when to open and how much juice to squirt in. Layman's terms grins.
Thanks so much for your explanation. Can you tell I have been cooped up WAY TO LONG!

 

That's easy. Do the MCM, put on a full FMF or Barker exhaust system, get an EJK, pull off the airbox lid, program the EJK using the lidless settings in your instruction sheet, hang on tight..

 

"That's easy. Do the MCM, put on a full FMF or Barker exhaust system, get an EJK, pull off the airbox lid, program the EJK using the lidless settings in your instruction sheet, hang on tight.."

If a had the money to do all this thing I would definitely try and test it, but I'm asking because I don't have unfortunately

 

Well that is the answer to your original question.

 

Hi,

I live in France and early last year (2019) I was fortunate enough to come across and buy a near new (2016, 900miles/1500km) KLX 250 with EFI where I live in France.

After reading articles about the Marcelino cam mod last year and recently reading the review below:
https://bikesandtravels.com/biker.aspx?ride=7193
I finally decided to take the plunge.

The above article recommends only changing the inlet cam, replacing the inlet snorkel for that of a KDX200 and l leaving the EFI alone (why and how are described in the comments section of the article). This is what I did as well as bridging the clutch switch.

Ideally what I want is plenty of low down pulling power while maintaining the low noise of the the original bike. All on a shoestring budget.

Before buying the KLX I tried the Suzuki DRZ400: I loved the engine but did not find one with low mileage and in great condition. Also it feels a bit long in the the tooth. The KLX looks and feels more modern. It also seems more adapted to dual sport riding: the DRZ seems more at home on the dirt but less so on the road. But I really miss that engine (could it be fit into the KLX 😁?).

With the above mods now done (inlet cam and snorkel removed while awaiting delivery of the KDX200 snorkel) there appears to be an improvement in responsiveness. Although the power now disappears at 9000 rpm. The snorkel-less inlet box is too noisy however.

But I am left wanting more power; I am guessing that 30bhp would be nice (but still a long way from the DRZ400’s 40+bhp). I believe the original exhaust can be modified? Anyone tried this? And I am looking into the 300cc upgrade using Kawasaki OEM parts (for reliability and so as to not mess with the EFI). But will there be a worthwhile gain?

Your advice and experience would be most welcome 😁

 

You are engaging in an untested and unverified experiment by only doing 1/2 of the Marcelino Cam Mod (MCM).
The MCM is fully tested, vetted, and the results are documented. To get the performance of MCM, you must go back in, properly retime the exhaust cam, and pull off the KACR spring.

The stock exhaust cannot be modified for improved performance without also increasing noise levels. Loud, straight through, exhaust, and lidless airbox, allows for max performance when tuned properly.

The article you've referenced only creates modest power improvements when actually measured (on a dyno) - dynobutt assessments are untrustworthy.

Use of snorkels and especially the stock exhaust system means that power levels above 8500 rpm can not be made impressive.. If snorkels and stock exhaust is used, only the MCM and BB kits can be used to create any significant power increases..

No significant performance increase can be made until a tuner is used to provide a proper performance fueling scheme to the engine. It is very simple: A engine that can make meaningfully more power than stock will require more fueling to do do.

 

Hi Klxster,

Good to see you’re still on this forum/thread after so many years. Are you still enjoying your KLX?

Perhaps a big bore is the way to go... Are there still benefits to this with the standard exhaust and inlet lid on? (a relatively quiet bike is essential for me).

Have there been any tests that you are aware of with inlet cam mod only and/or a larger snorkel?

The KDX200 snorkel appears to have at least double the cross sectional area of the KLX250. Is that not enough air for at least double the potential power? As a side note, the KDX200 produces 37bhp with this snorkel and 48bhp on the KLR650a which uses the same snorkel.




The author of the cited article (https://bikesandtravels.com/biker.aspx?ride=7193) appears very thorough in his testing and experienced (see comments section - he owns 5 KLXs and has covered 12000 miles on one in the last year alone - in his own words he has an obsessive personality).

Apart from the aforementioned article, I have not come across any tests comparing inlet cam timing mods versus inlet plus exhaust cam timing mods whilst keeping a quiet setup. But if there are any such comparative tests, I would love to learn more of them...

P.S.

Older spec bikes appear to produce more power as shown here:



2009 KLX250S (Keihin CVK34mm carburettor) produces 27hp.

Compared to the more recent KLX250 with EFI:


Compared to 21 HP on recent EFI versions like mine (although I understand my 2016 European EFI model produces only 17 or 19 HP). Is the reduction in power due to emissions regulations? Does the main restriction come from the snorkel acting as a restrictor? Can the standard EFI map/injector provide enough fuel for 33bhp?

KLX250 with EFI




2007-2010 KLX300R produces 33bhp with an airbox lid and snorkel in place and with a standard exhaust. This is my goal. In addition to a 300cc upgrade, what changes must I make? Will the standard KLX250 EFI and injector be able provide sufficient fuel and air to produce 33bhp?

KLX300R specs

 

None of those power figures are "accurate" in that they do not reflect the actual power output of those engines. Manufacturers numbers are always wrong, for many reasons, but mostly because they are measuring at the crankshaft.

There is no data to prove 1/2 MCM effectiveness. There is data proving MCM effectiveness. The exhaust cam retime modifies the length of the power stroke and increases intake/exhaust valve overlap - it is integral and complementary to the intake retime.

Doing only the intake cam has always been the lazy way to attempt to gain MCM enhancements by avoiding the issue with the KACR attached to the exhaust cam.. Now days, we know to simply remove the KACR spring - which makes the MCM quite easy to perform correctly (both cams)... This is something you should do as soon as possible.

If you must have a quiet bike, you must use bigger displacement for power enhancement. Nothing compares to the Bill Blue 351 kit in this regard.

 

Thank you for your comments. Very helpful. I’m sure in the end the big bore kit will be the best solution as I must keep the bike as quiet as possible. Although it is unclear to me if the standard EFI and exhaust can cope with the additional displacement.

The only comparison I’ve seen between the cam mods (intake or both intake and exhaust) is in the article I mentioned. He tried both and prefers the intake only.

After myself adjusting the intake cam only and removing the inlet snorkel (awaiting KDX200 snorkel) there appears to be some improvement in responsiveness in the lower and mid ranges but I have also noticed higher revs are now more limited.

Perhaps I will try also modifying the exhaust cam timing and see how I like it myself. Thank you for the reminder that the ACR spring can be removed; that certainly is a saver of time and effort.

Are you aware of other KLX250 owners who have only changed the intake cam and what their results were like?

 

B&B (one of big bore kit manufacturer) tested 351cc kit on stock bike - exhaust still enough exhaust and you got a lot of torque. Also he was customer who run 351 kit on stock with EJK for bigbore, but as i know injector will works on the edge. In side thread i wrote about cheap injector nozzles options, so this not problem.

Hopefully by next year I can test myself 351kit + 330cc/min injector on klx with no more mods.