KLX250/300/351 Stories

[BergDonk]

I got sidetracked....

I'd previously widened the stock pegs for an improvement in foot placement and comfort. Widening back has the effect or rear setting. I decided moving the pegs a bit down and a bit further back would be good, improving the rider triangle standing and making life a bit easier on the knees. I had an old pair of stock KTM pegs I figured would do the job, so out with the angle grinder and welder.

A splash of silver spray pack and a ride confirmed the effort involved, and $0, apart from welding consumables.

 

[BergDonk]

With the forks on hold for a bit, I'd talked to Frank and he was going to help, I decided I should get the shock fitted up.

Slightly more compact than the stocker, it went in easier than the old one came out.

I drilled a hole in the sidecover to access the compression clicker. and hacked up a bracket to mount the preload adjuster, attached to the frame via the passenger peg mount, no pegs fitted, but could be. As is, position is good, it all clears the chain run, sits inside the frame and under the sidecover, and the preload knob is accessible enough. The swivel joints on the hose definitely make a difference too.

I wound the preload up to full, didn't touch the clickers or look at the sag, except to note that there is some static. It does sit noticeably higher with me on it. With fading light I rode it up and down the driveway, over a couple of rocks and small logs nearby, and it did nothing that surprised me, it even felt good.

 

[BergDonk]

Having sorted the adjustable fork caps with the bits from Cogent, I lined up a visit to Frank who'd volunteered to help me with the rest of the fork build. He's about 4 hrs drive from here and I spent the previous night at his place so we could get a timely start on them.

We fitted, well Frank did, the proper Cogent shim stacks and valve bodies. Took about 6 hrs of Frank's labour to sort the forks, after I'd done the caps, so not cheap if I had to pay $s for it, and that's over and above all the machined custom bespoke bits from Cogent that enabled it to happen. Also had to drill some bleed holes that Rick had missed. Good thing I have mates that know stuff.

Frank liked the Cogent rebound stacks, but wasn't so sure about the compression stacks. He kept the spare stock stacks I'd acquired and told me he'd build a pair up to his spec and send them down. The compression stacks are on the bottom bungs, so easy enough to swap out, and Frank knows how and where I ride, so be interesting to compare.

 

[BergDonk]

Some fork testing and its promising.

I played with fork springs a bit and I think I've settled on 0.46 kg springs with 13 mm preload. They're actually 20 mm shorter than the stock 0.38 springs which obviously have heaps of preload. The oil level is currently at 120 mm and seems about right based on the O ring on the fork leg, and feel.

In the meantime, Frank's compression stacks turned up, but as yet untried. The springing is now where I can play with the clickers to fine tune it and its very very good so far.

Yum, suspension, everyone should have some.

 

[BergDonk]

In for a penny, in for a pound someone once said, and has been quoted for ever since. So having got this far, why not a pumper carb and a muffler upgrade?

A TM33 setup for a KLX from MikuniOz duly arrived from for more shed time. https://mikunioz.com/shop/1-kawasaki-klx-250-300-mikuni-tm33-8012-pumper-carb-kit/?v=13b249c5dfa9

Supposed to be good to go, once the supplied jets are fitted. They supply 3 mains for fine tuning, plus a preferred pilot, plus whatever Mikuni had in there.

I decided I wanted an extended fuel screw. I have a few stock FCR ones in the shed, having replaced them with Flexjets. The thread is the same, so I stuck one in the lathe and freehanded a Dremel with fine cutter and linisher to sort of replicate the stock one. Sticks out a bit, and with some engraved marks on it, and some needle nose pliers, it seems to work OK.

Then I pulled the needle, what a PITA that is compared to pretty much any other needle I've pulled.

Rummaged through my needle collection to see if I had anything similar. Got a few that are a lot leaner, the TM33 one is the one with the washer on it, and the long one is an FCR needle for comparison. I wondered whether I might end up grinding my own needle from one of the spares, or not, depending.

Back together with Allen heads instead of JIS screws and ready for mounting.

Just got to feed it in here, easy.

 

[BergDonk]

The carb kit's referenced instructions suggest just need a little bit of steel removed from the frame lug where it connects to the head. That's what the instructions with the kit say anyway. Other info suggests that the closing cable needs to be removed, but seemingly only because the TM33 pictured in the instructions has no facility for a closing cable. Anyway......

Pulled the old carb out the left and compared them, on the bench. The sleeve supplied for the airboot makes the new carb about 8 mm longer overall. The head side of the carb is 1 mm dia smaller.

I found an aerosol can cap that fitted and thought about matching the carb to the intake manifold with the Dremel, but when I clamped it up is matched pretty well and was secure so I left it as is. The manifold is attached to the head with a couple of Allen heads and removing it as part of carb R&R makes it much easier.

As per the instructions, the bit of frame that has to be relieved comes off easy enough with a carbide cutter in the Dremel and time for a test fit of the new carb

Either I come up with a new longer intake manifold, or adapt

Nothing in the way of suitable inlet manifolds handy and lathing up and extension might be an option, but WTH, off with the closing cable on the spindle drum.

Then there's no room to fit the opening cable mount to the carb even after cutting it down. On the RHS side of the frame is a bolt on tank mount no longer used with the Acerbis, so I made up a bolt on mount for the cable to take its place.

Bolted the idle screw to the old fuel tap frame lug instead of the carby as supplied.

Then 'T' vented the vents and added the tube and contemplated the fuel line.

And came up with this. The original bracket bolted to the regulator for the stock idle screw keeps the hose nicely positioned with a couple of zip ties.

Then removed the closing cable from the bike.

With all the likely welding jobs identified, two only, fired up the welder and silver spray can. Stuck the cable mount together for the throttle and tack welded a 10 mm nut to the frame/head mount plate. The 8 mm ones are captive stock. Then hit it with the grinder until I had 1 mm clearance to the top of the carb. The plates used to be the same shape, not any more

 

[BergDonk]

Did a mention "In for a penny, in for a pound"?

Before I fired up the new carb and started tuning it I figured I should also get the exhaust sorted. As mentioned above, when fitting the 300 piston I fitted a bigger bore Staintune header, keeping the stock muffler and dialed in with my bum dyno and a Dynojet kit.

To this end, I acquired a Barrett muffler and midpipe, and I needed to figure out how to connect them, and as I was planning to do the carb tune with a wideband AFR meter I have in the shed, I needed to fit a bung to the header to take an O2 sensor.

Drilled a hole in the header at a convenient location, opening it up with the Dremel. Then 'fitted' the sensor bung and tacked it in place.

The Staintune header dispenses with any clamping to the midpipe and it didn't appear to seal 100%. Interestingly, and conveniently, a DR650 clamp end bit fits perfectly. I had a crash damaged header in storage just in case it'd be useful one day, so cut the end of that off and buffed it up.

I welded the bung on and brazed the clamp end on. Its slipped right over the Staintune pipe end, after shortening it the requisite amount.

 

[BergDonk]

The Barrett side by side with the stocker.

The muffler is a straight through design and came with a 'tea strainer' under the end cap. They also supplied a smaller diameter outlet with 2 layers of 'strainer'. Not wanting to have it noisy, I fitted it. It can go the way I fitted it, making the pipe longer, or can be reversed and go inside. No advice from Barrett either way as yet, so made it longer.

The mid pipe bolt hole needed a couple of mm ratting out to get it to line up without adding tension/pressure to the system. The muffler clamp hanger didn't quite line up either, and if it did, would be right to the front of the muffler. A bit of scrap 5 mm al flat sorted that. So almost bolt on

Barrett here; https://www.barrettproducts.com.au/store/p53/KAWASAKI_KLX_250_SLIP_ON_EXHAUST_UP_TO_2019_MODELS.html

 

[BergDonk]

Happily It fired right up and sort of idled, so it was time to start the tuning. A bit of riding to warm it up and get a feel first.

As was, even with my dodgy extended fuel screw, I struggled to access it, so I pulled enough bits off to swivel the carb to the left and pull it out. Then drilled a couple of 1.5 mm holes in it and pressed in a couple of roll pins to enable a screwdriver to push in there and tweak it. It was at 1.5 turns which I felt might have been a bit rich, so set it at 7/8 for the heck of it.

It fired right up again, so I took it for a ride up and down and around near the house to warm it up. Tweaked the fuel screw a tad, to 1 turn with a nice steady idle at <>1500 rpm. Starts instantly, its running before you can release the starter button, has snap off the bottom and pulls hard into the mid range with no fluff, just instant throttle response. Cracking it in 2nd gear off the bottom lights up the tyre and lifts the front, which it never really did before.

So I rode it around bits of my 9.5 km single for 30 mins or so and can't fault the throttle response and grunt up into the mid range. On the more open driveway and under the power line, it pulls hard into 3rd too, but maybe goes a bit flat when the revs are up 3/4 throttle on, or maybe just back to how it was. Might be a bit rich on the main and needle, but I decided to ride it some more on the open proper outside the gate, then fit up the AFR meter and O2 sensor to find out.

The pumper equipped bigger bore KLX351 I rode in the US a couple of years ago didn't go any better, maybe even not as well, if my memory serves me OK, and the suspension and ergos on it did not work for me.

 

[BergDonk]

I lashed the AFR meter to the GPS mount, accessed its power supply, and fitted the O2 sensor and hooked it all up. It was time to have a ride outside the gate and up 'my' hill, 8 kms of twisting undulating sealed road that's ideal for carb tuning.

First up I marked up the throttle in 1/8s. Then warmed it up for a bit. Idle AFRs through to 1/4 throttle were 10.5 -11.2, 1/2 throttle cruise 11.5-12.0 and WFO 12.0-12.5. So as suspected, too rich, shooting for high 13s low 14s, maybe 13.5 WFO. The needle transitions seem fairly linear, so I figured it might be OK.

So I pulled the carb and

One of the sharp edges on the head interacted with the intake manifold O ring and sliced it cleanly

A couple of options, try to super glue it back together or see if I have a substitute in my collection. Found one with the right diameter but a bit thicker which seemed like it'd crush up OK.

As supplied, the carb came with a 37.5 pilot and 127.5 main fitted, and a bag containing a 45 pilot and 140, 142.5 and 145 mains. The instructions said to fit the 142.5 main and 45 pilot, which I did to start out with. The needIe was on the middle clip as recommended. I have no other other suitable jets in the shed, lots of FCR ones, but no TM33 ones, or anything I might be able to adapt. I do have a good selection of jet drills though.

The bore of the 2 pilots gauged the same, with 0.55 mm going through and 0.60 mm not The 37.5 has 3 holes that gauged at 0.85 mm neat. The 45 with 4 holes gauged loose at 0.85 mm and no go with 0.90 mm.

So to lean it all off, I dropped the needle all the way to the 1st clip, drilled the 3 holes in the 37.5 pilot to 0.9 mm for maybe a 40, dunno

and fitted it and the 140 main.

Then I noticed the float bowel O ring decided it wanted to be bigger

I did a test fit of the manifold with the 'fat' O ring. The Allen head screws went tight, but it did warp the manifold slightly, with a perceptible gap top and bottom. Upon removal, testing with a straight edge showed it was flat, so no permanent distortion. Probably work OK, but....

I then decided to try super gluing the O ring back together. I also ordered a couple of replacements, $17 ea + $15 postage.



Back together seemingly OK and time to get some data on setup #2.

Initially I got the baseline and a 2nd run done with the revised jetting. It felt lean at 1/4 throttle and a bit flatter at WFO than before. The idle mixture was now pretty much where I wanted it. Its a PITA making changes as the carb has to come off, so takes a bit of time, and has to cool down lest I burnt myself.

As noted, I'm not sure what my drilled pilot equated to, but guessing maybe #40. I started with my dodgy fuel screw at 2 turns for run #2 and leaned it off to get a good idle.

My generic target is more or less:
Idle - 12.5 ~ 13.0 Bike needs to be really warmed up properly before the idle mix will be stable - at least half an hour from cold start. Idle AFR will change if you sit idling for very long as it all heats up without cooling air flow.
1/8 throttle - 13.0 ~ 13.5 This is almost totally the needle root diameter.
1/4 - 1/2 throttle/light throttle cruising - 13.5 ~ 14.5
3/8 - 3/4 throttle - Progressing from the light throttle AFR through to 13.0 or even richer.
WOT - 12.0 ~ 12.5
Cold Start with choke on - 9.0 ~ 10.0

 

[BergDonk]

I use these graphs when I'm thinking about jetting.

The plots are FCR specific, but fairly generic too I reckon, and they're not the same either, but do overlap.

The 140 main seemed close, but it did feel better with the 142.5. I decided to leave the 140 in while I played with the needle.

The O ring I cut worked OK with super glue. Its not under any tension, and with some high adhesive grease in the groove it was on and off and in and out a few times without any issue that I noticed. I have two new O rings now too, anyone need an O ring?

Every jet or needle change means the carb has to come off, and that means the intake manifold too.

Right now I'm happy with setup #Five. Dunno what the pilot actually equates to, but estimate its <> 40, the supplied 45 is definitely too rich. I was pretty happy with run #Four, until it went over half throttle when it rich bogged, like #Three did too.

I drilled out the too small pilot supplied in the carb. I also drilled out the too small 127.5 main to a bit smaller than the 140 supplied. Its been interesting seeing and feeling how much the needle effects the upper throttle, and how sensitive it is.

A few rides now and fuel consumption is good I think, the last check yielded:

I've got a few more posts to come, but the main stuff is now here. I've really enjoying the process of making HE300RS better than stock. There's still some suspension setup to come, but even as is, its really good now, and pumper carb and allied fine tuning have really woken it up, fun times.

My motto is 'shed time is quality time' and so is the riding it enables.

 

[Bitingdog]

Yep, good things.

About mid 2007 I fitted the factory 300 kit and bypassed the carb heating. I don't recall much of the detail, but it was pretty straightforward. The kit came with a couple of jets and a new needle along with some carb settings and instructions to block off one of the holes in the carb slide, which I did with some epoxy.

Internet research at the time suggested that the header was the limitation in the exhaust, not the muffler, so I/we decided to keep the stock muffler and I acquired a Staintune big bore header to go with the 300 piston. I had also acquired a Kouba T extended fuel screw to simplify fine tuning.

The jetting with the new hardware was:
125 main
needle middle clip
35 pilot
2.125 FS

We ran it like this for a while and she was happy. The extra torque made it heaps easier for her, throttling on to deal with an obstacle meant it responded and didn't bog.

I still thought the jetting could be better and acquired a Dynojet kit for it. Fine tuning with my bum dyno resulted in the following:
120 DJ main <> 128 Keihin
35 pilot
1.5 FS

My records don't identify a needle clip position, so not sure about that all these years later. Anyway, the DJ kit was another step in the right direction and she was happy, and therefore so was I.

I also bypassed the neutral switch and maybe a couple of other small details.

So good to have you here. Truly

 

[BergDonk]

Can't have too many earths.....

Apparently according to the internet, some year KLXs have a poor earth setup. I hadn't noticed any issues, but when the subject came up, I figured another earth connection from the battery to the cases couldn't hurt.

I fit a 50A Anderson plug/socket to my adv bikes or easy connection of jumper leads, and carry a set too. Then I carry a lead long enough to connect 2 Anderson equipped bikes together and a short addition lead with alligator clips in case that option isn't available. The KLX is so equipped.

I actually had the battery dies recently. We'd been using AGMs and the last dead one was #3, maybe 4 years old. My local battery shop had an SSB lithium available, so I fitted that. Its heaps smaller so i had to pack it out with some high density foam, allied with some double sided tape. Apparently its the size they fit to KTM MX bikes. I've had a good run with SSB lithiums on my DRs, so now its time for the KLX. Saved a bit of weight for what its worth, and its got heaps of CCA. The bikes starts really easily, instantly when hot, so should be fine.

 

[BergDonk]

With my agenda to make the KLX more me friendly I wanted a bit more seat height. But I didn't want to lose the option of keeping the stock setup for those that prefer it. I was able to acquire a complete one on eBay for $100 so I could play with it and keep the original as is.

When pulling the cover off some of the staples were rusty and broke, so Dremeled them flat.

Had a little used stock DR650 seat foam in the shed which I cut up with a electric carving knife and fine tuned it with a drum sander in a drill. Then I tried to fit a generic cover I had and there was no way I could get the wrinkles out, so I abandoned that and took it it all into my local upholsterer who extended the sides of the stock cover.

The stock seat wasn't terrible for comfort. My seat is now better for me with an extra 25 mm or so of height, and its a bit wider. Its easier on the knees when both sitting and transitioning. Looks stock too, and nearly is. With a few rides on it now, its proven to have a bit too much slope, which means I'm always ending up in the perfect sitting attack position, but I may add a bit more foam to flatten it a bit, so I can stretch out and stay that way easier. Like most things, work in progress.

 

[BDKW1]

I ran a pumper carb on mine for a while. I liked the snap but when the GF rode it there were problems LOL...... It's ultimate downfall was mileage. Going on long trips to Baja it cut down on the range to much for comfort.

I went with newer KX250 forks. Pretty much bolt in and way more adjustable. Rear, the linkage is the biggest obstacle. I made a new rocker and pull rods. The shock was a combo of KX250 body and a YZF 450 shaft.

 

[BergDonk]

Nice work. The pumper really shouldn't use much more fuel though, if any, once properly jetted. With the TM33 we are getting 67-68 US mpg which seems decent to me. I never really measured it with the earlier carb setups as it was good enough for a few hours trail ride.

After a similar tuning exercise on my DR790 with its 41 FCR it gets <> 5% better than a stock DR economy when ridden side by side. The wife's DR650 with its 40 FCR is <> 10% more economical than stock too.

 

[BDKW1]

Trail riding in anger put it down in the low 20's. With the desert tank 100 miles was about the safe range limit. The CV carb was up in the 30's.

That was the proto-type rocker, I machined one out of billet after I got all the bugs worked out. It allowed mey to switch from the stretched stock shaft to the YZ one. Mush less ghetto fabulous.

From this

To this

Unfortunately I don't have pics of the final version of the rocker.

 

[BergDonk]

Playing with suspension is always fun and you always learn something, even if sometimes its that you maybe should have left it alone

My first suspension conversion was back in the mid 1970s when I fitted Ceriani forks to my CB500F. It got lots of other tweaks too, like a monocque frame conversion, 600 pistons, CR gearbox etc etc.

In more recent times I've fitted USD forks to DRs and Yam 660s, as well as DRZ400E ones, and adapted a few shocks.

Shed time is quality time

 

[huskyfatman]

Great thread, thanks BD!

For a time we we’re on an ‘05 650 Berg (me) and an ‘05 KLX300 kickstart model for her.

More recently, a 570 Berg and ‘22 KLX300 that still requires a lot of dialing in for her.

She still has the old 300, which is a far better dirt bike than the newer much heavier model. I did some mods over the years, shock spring, pipe, jetting and shift star among others. Nothing nearly as in depth as you. I plan to go through it and freshen it up for the dirt, while setting up the newer estart FI bike for dual sport. She loves the old ‘05 and says it’s her favorite bike ever.

 

[BDKW1]

She still has the old 300, which is a far better dirt bike than the newer much heavier model. I did some mods over the years, shock spring, pipe, jetting and shift star among others. Nothing nearly as in depth as you. I plan to go through it and freshen it up for the dirt, while setting up the newer estart FI bike for dual sport. She loves the old ‘05 and says it’s her favorite bike ever.

Be aware the kick only bikes like to eat the bushing on the kicker gear. Eventually it will get loose enough to wedge between the clutch basket and case sideways. This will break the clutch basket and the case sometimes. If you have a lathe, bore the gear out to get rid of the large chamfers. Then make a new wider bushing out of 952 bearing bronze. Lifetime fix. Or just buy a new gear and replace it every couple of years.