Recent Posts

71

OEM-CYCLE / 2006 KX250F CDI

« Last post by BeRespectful on November 23, 2023, 01:40:10 PM »

Anyone have one for a decent price, I feel like the used ones on eBay are all going for over $100. Is that the standard for a CDI on one of these bikes?

72

KX250 / KX125 / Re: Kickstarter skipping fix! (88 KX250, and the like)

« Last post by GCrites80s on November 21, 2023, 01:11:15 PM »

Would this also apply to the 125? Similar design -- different part numbers though.

73

Introductions / Re: Fmf grizzly ?

« Last post by cloudjian rider on November 21, 2023, 08:20:20 AM »

Hey, nice bike. The '96 is definitely something special. The only one with the sought after purple tank 
Back then there were some FMF pipes without any description to them except for the embossed FMF logo.
The only thing that comes to my mind when I hear FMF grizzly are the FMF "Gnarly" pipes.
Those are meant to give you a little more bottom end grunt. Maybe that is what the seller meant and got the words mixed up.
And yes, quads probably came up with your search because FMF offers pipes for the Yamaha Grizzly quad.

Have fun with your new old bike 

74

Introductions / What is a Handheld Laser Welder?

« Last post by comwelder on November 15, 2023, 02:45:50 PM »

Comwelder Handheld laser welders are portable fiber laser delivery machines capable of welding various metal materials within seconds. They comprise a main unit that houses the laser source and amplifier, connected to a handheld gun-like unit called the laser welding head.

What is a comwelder Handheld Laser Welder?
Comwelder Handheld laser welding machines are compact and roughly the size of a desktop PC. Almost all commercially available machines come with wheels at the bottom of the machine for more effortless mobility.
The handheld unit is considerably more lightweight than traditional welding methods, providing operators with a high degree of freedom and control when welding.
Additionally, the exit nozzle on the gun is interchangeable, further adding to the flexibility provided by the machine. Nozzle shapes direct the laser beam and ensure only the desired part gets welded.
Comwelder Handheld laser welding machines are compatible with several metals, including titanium and stainless steel. Research has also shown that fiber laser welding is compatible with rare metals like Vanadium, Tantalum, and tougher Stainless Steel Alloys.

What is a comwelder Handheld Laser Welder?
5 Major Benefits of Handheld Laser Welders
Handheld laser welding offers all the benefits of fiber lasers and more. Here are some of the many benefits of a handheld laser welding machine.

1695261558531
1 – No Filler Metal Required
Traditional MIG/TIG welding equipment necessitates using a filler metal rod. As the metal is heated, the filler metal melts between the two surfaces and bonds them together.

Laser welding doesn’t need a filler metal, as it selectively melts two metal surfaces together. The lack of filler metal reduces the operator’s welding complexity and the overhead costs of buying and storing filler metal rods.

A handheld laser welding machine is a one-stop solution compared to the complex and cumbersome MIG welding.

For wider gaps between metal surfaces (>0.2mm), a filler metal is also required for laser welding machines.

2 – Cleaner Welds
Laser welding provides a nice and clean weld finish that is otherwise impossible with traditional welding methods.

Traditional means of metal welding (TIG/MIG/Arc Welding) result in a strong weld with an undesirable weld bead. The extra mass of the filler metal ends up as a thick line on the final product.
Post-processing equipment becomes necessary to clean up these welds. Laser welding forgoes all this by making a clean weld in the first place, saving you time and money in the post-processing stage.

3 – Less Heat Input
Laser welding is a highly efficient process, utilizing a fraction of the energy of traditional methods while delivering the same quality results.

Laser welding equipment is designed for pinpoint heat input. Therefore, the laser welding machine can avoid a lower energy deposit.

Less energy input into the metal materials means negligible post-weld warping.

4 – Finer Welding Control
A good and robust weld requires an experienced operator and quality welding equipment. Studies have shown poor welding control can lead to larger weld pools, resulting in welding defects.

Experienced welders can compensate for the instability in the welding equipment, but the solution is never perfect. A handheld laser welding machine is lighter and more flexible, allowing welders to hone their skills further.

An experienced welder can match the quality and precision of an entry-level welding robot. Additionally, laser welding is more forgiving to novices and minimizes chances of operator error. You can learn about ways to improve welding control in this process.

5 – Wider Material Compatibility
Laser welding is quite versatile when it comes to material compatibility. It can weld all the usual metals and even some uncommon other metal materials like volatile magnesium, unstable vanadium, and tough titanium.

Additionally, due to its low heat input, it can easily weld thin materials. One big problem in welding thin materials is that traditional arc welding deforms thin materials.

You can even weld some thermoset plastics using a handheld laser welding machine.

A standard laser welding machine is compatible with the following materials and their alloys.

Steel (High Carbon & Galvanized)
Stainless Steel
Copper
Aluminum
Magnesium
Titanium
Nickel
Plastics
etc.
Factors to Consider When Buying a Handheld Laser Welder
Handheld laser welding machines have gotten so good over the past few years that you shouldn’t have any problems buying a capable welding machine from a reputable seller.

However, buyers should be well informed of the most important factors that contribute to laser welding machines’ performance.

Power and Performance
Laser welding machines shouldn’t be judged on their laser power alone. Due to the laser beam’s higher power density, a 800W-2000W laser is more than enough for most metals.
Consider a handheld laser welding machine’s advertised continuous and peak power. Most lasers will only operate at their peak output for a few seconds. A 2500W peak power laser welder will revert to ~1500W afterward.

Portability and Design
Portability is a big selling point for laser welding equipment. Large projects mandate that the welder be moved around to accommodate the workpiece.

Choose a laser welder that can be easily moved around and is not too bulky or heavy. Next, you want a design with no protruding parts that can be easily damaged in transit.

Ease of Use
A laser welding machine should be treated as any other tool. It shouldn’t require a complex and tedious instruction manual to operate.

Choose a welding machine that comes with simple and intuitive controls.

How Handheld Laser Welders Compare to Other Welding Machines
Laser welding is a newer technology compared to traditional welding methods. It still has a long way to go, but it already shows several benefits over its older brethren.

Handheld Laser Welders vs. TIG/MIG Welders
MIG/TIG welding is a decent all-rounder metal joining solution. However, this process is challenging to automate and lacks laser precision.
TIG welding generates more heat, requires filler material, and produces a less desirable finish.

However, it is a low-cost solution and has a short learning curve. Studies also show that the tensile strength of TIG-welded metals is slightly higher than laser-welded ones.

Handheld Laser Welders vs. CO2 Welders
Gas welding equipment is bulky, unreliable, and obsolete. It lacks fine-tune precision, is very inefficient, and has a fragile gas chamber made of glass.

Fiber lasers have a lifespan of 20,000 hours compared to the 2,000 hours of CO2 lasers. On long, complex welding projects, you run the risk of a failing CO2 gas chamber. The industrial sector doesn’t have two thousand hours of machine operation time.

The only saving grace for CO2 welding is its dirt-cheap pricing and broader availability.

Safety Tips for Using Handheld Laser Welder
Before we wrap up this article, let’s review some basic safety guidelines for handheld laser welding.

Proper Storage
Laser welding machines are sensitive devices; moisture and dust ingress can hamper performance and damage internal components.

Additionally, on the factory floor, ensure that small metal chips and debris don’t enter the laser welding machine.

Cable Management
The optical fiber cable connecting the weld gun to the laser system is fragile. Bending at sharp angles or running over one will damage it beyond repair.

Hand & Eye Protection
Always wear proper hand and eye protection. Safety goggles and fire-resistant gloves are your friends.

Conclusion
Laser welding has slowly grown over the years, starting from CO2-based lasers and then shifting to optic fibers. Their compact size has paved the way for handheld laser welding machines that are just as capable as traditional methods. Additional benefits of laser welding include higher quality weld finish and excellent energy efficiency.

All top laser welders offer 800-2500W of power and come with changeable welding heads (nozzles). Thus, buyers should focus more on ease of use and portability when getting a laser welder.

In the fast-evolving world of welding technology, handheld laser welders have become one of the most convenient and reliable solutions. Whether you are a professional welder seeking the perfect tool for your trade or a DIY enthusiast looking to take your projects to the next level, there is a handheld laser welding machine that’s perfect for you.
laser welder
handheld laser welder
hand held laser welder
laser welder for sale

75

Discontinued parts and replacement ideas / Powervalve 'cheerio' spool-thing

« Last post by jamesohoh7 on November 10, 2023, 01:15:54 AM »

Lost the powervalve cheerio-thing on my bike a few weeks ago. 

88/89 KX250 and I imagine the early 90s ones/KDX250 etc...

I didn't know it was gone for a ride or two, but bike was acting funny, and I eventually spotted the issue after removing the little plastic cover.  Looks like the outer e-clip popped off, and the thing must've flung off somewhere.  The rubber boot on my powervalve cover setup is torn up, so it wasn't captured for me.

Anyway, AFAIK, this part is not sold anymore.  I looked for something close enough in the machine-parts world and then finally found something to work with in the RC-boat world.  A prop-shaft drive-flange.  https://www.amazon.com/dp/B07R9JHCBW?ref=ppx_yo2ov_dt_b_product_details&th=1
I wrote it all up in a review on Amazon... the title is 'Not the use intended, but it worked great'.

If there's a real replacement out there, I'd love to know about it.  This thing I made has worked for several weeks and 2-dozen rides, but I'd still prefer the OEM part.

These things from Amazon are metal collar-bushing sorts-of-dudes... I don't know what the real name is... a flange I guess.  Anyway, they have a 5mm id already, and has one 'side' in place to start with.  The 5mm id is tight on the pv-shaft.. you'll have to ream it out a smidge.

Steps to make your own:

Tools: a mig welder, or a buddy with one.  grinder or a set of flat-files.  metric calipers.  vise or some way to clamp these small parts... vise-grips would prob work too... be creative.  Assorted small parts/hand-tools dang near anyone with an old dirtbike will have lying around.  Safety gear for grinding.

0) I believe the original part's overall width is on the order of 8mm.  You need to work -to- this width, so to speak.  I believe the inner-width between the flanges is 4mm.  The overall diameter is about 17mm.  I measured a 2nd one of these I have on another bike.

1) file/grind down the inner 'hub' part such that the width of the whole part is now about 6mm (we're leaving about 2mm to add on a 2nd 'flange'). The finished product needs to be able to fit on the shaft with both e-clips holding it in.  Test-fit often to make sure you're on-track.  I had to run a 5mm drill bit through the hole in the middle and work it a smidge to add some free-play so it'll spin on the pv-shaft.

2) find a nice flat steel washer with a 5mm hole in it (and an OD on the order of 17mm, you can grind down to fit later if need be) and weld this to the hub that you just ground down.  Again, try to ensure overall width for the part is 8mm. The reduction to overall width in step 1 is to provide for a 'well' to push tack welds into.  This will initially close up the 5mm bore.. you can drill that out later.

 --- Its ok if you are initially at a point where it's too-wide... you can grind it all down later.  Don't try too hard to make it exactly-sized right off the bat---

3) Set the spacing between these 'wheels' to be 4mm.  its probably really 4.0something.. I don't know that exact measurement.  A later step is to file these flanges to get good clearance.  So, whatever you need to do to fixture this up to achieve this, I used some feeler gauges on each 'side' of the middle just laid in-between the washer and the 'base'.  Try to make the new washer parallel to the existing flange.  I use welding magnets to hold things down to my welding table.. but a vise would surely work.

4) tack-weld in a spot or two... check your work... measure and check for parallel.  It doesn't have to be 100% perfect, but try not to make it really out of whack.  Add more tacks to get a complete weld.  There's 4 in the set from Amazon, you have some spares if needed.  Turn the heat and wire-speed down and sneak up on it.. don't blast it on full-juice and turn it into a molten glob.

5) the weld-beads will make the overall width wider than 8mm.. so file or grind them down.  This may wind up grinding through your existing tacks... just be patient and re-do as needed, you'll eventually stick them together.

6) the overall diameter of the flange on the Amazon part is too large... you'll need to take it down a couple of mm.  I found no great way to do this other than putting it on a screwdriver, fix-it in place with two small hose-clamps but w/room so it'll spin, then ran it against a grinding wheel with some angle so that the grinder both spun the part and ground it down.  Ugly, horribly inefficient.  Very likely deadly.  Wear all the protection (I wear a full-face shield and a leather apron and gauntlets) this is hair-brain stuff.. no real machinist would do this.  If you're just super offended that this was even suggested, I'm sorry you're offended.  I do a lot of unsafe stuff that would make you uncomfortable... like, riding dirtbikes at speed in the woods   I don't have machine tools, so I gotta make-do.

---The OD you wind up with doesn't have to be 17mm like OEM... mine was prob 18.5'ish.. there's some room in there for it to be slightly over-large. Test-fit.. you're just looking to make sure the nub on the pv-arm registers well and that the spool-wheels don't rub on the shoulders of that pv-arm.---

7) lather, rinse, repeat until you've got something that fits between those e-clips and that the little arm will register into w/out sticking.  This spool will spin on the shaft, so make sure there are no tight-spots with the little nub on the arm.. spin this spool and check that the 'nub' doesn't get stuck.  If it does, mark that spot, remove spool, and take a flat-file to the area where it was sticking.

There is no doubt that this solution is way less accurate than the OEM part.  Every ounce of slop or mis-fittment you wind up with will affect how the powervalve 'comes on'.  People pay big money to port cylinders where they move a port 1.2mm or whatever.  And we're probably messing that all up.  I'm not suggesting anyone do this on their race bike.  I ride single-track trails, I'm not a racer and no winnings/money is at stake that I would use to feed the family.

I went to this solution b/c I could not find a powervalve cheerio anywhere and I figure 'an underperforming part is still better than nothing'. 

I saw a listing on ebay for something that might be a replacement, but the part-numbers the guy listed put it for a mid-90s 125, which is different than what I needed.  I'd take the other one I have to a machinist to fab up, but I can imagine that would cost, what.. couple of hundred bucks in his time/effort?.. meh.. this one I cobbled-up works well enough for me.  I spent maybe an hour b/c I had to figure out what to do from scratch.

76

KX250 / KX125 / Re: Kx250 1994 bottom end build… help!!

« Last post by jamesohoh7 on November 08, 2023, 07:10:26 AM »

I realize this is an older'ish post, but just in case... and/or maybe it helps the next guy with the same issue...

I 2nd the primary cause likely being one/both crank bearings are not seated.  Been there/seen that.

However, also check the side-clearance of the crankwheels to the case (assuming you still have the case bolted together).  There should be very nearly equal clearance on either side.  If one side is very tight, it'll rub and tear stuff up.  This is usually caused by the opposite side bearing not being seated (which offsets the whole assy in the cases). 

It -may- (rarely) be caused by the crankwheels themselves not being pressed on to the crankpin equally.  The crank is 3 parts... a pin with the bearing and rod and two wheels, pressed onto that pin.  If one wheel is not pressed on all the way, it'll be tight against the case when assembled.

There's probably a spec for overall crankwheel width (ie., outside edge of crankwheel to crankwheel, across the rod-gap).  Measure that to make sure its where it should be.  If its too wide, you may need to go back to the vendor and see what they can do for you.

77

KX250 / KX125 / Kickstarter skipping fix! (88 KX250, and the like)

« Last post by jamesohoh7 on November 08, 2023, 02:57:34 AM »

I did a search on kickstart-skipping and found most posts were years old already.  I didn't want to necro an old thread, so here we are.

Preface to all that follows:  I am not a mechanic.  You will no doubt spot this as I stumble through my discussion.  If I state something blatantly wrong, I am sorry and please correct me.  I am trying to offer some help, that is all.  I am not trying to trick anyone into blowing up their bike.

Now then...

Cliff's notes version:

The skipping of a kickstarter is, in my experience, very likely to be excessive play between the outer case cover and the shoulder on the kick-shaft just above that plastic centering-bushing.  If the kickstart shaft has any loose in/out play, this is likely your problem.  Shim this clearance out by buying some thin stainless washers and putting them on the kickstart shaft.  If you look at the microfiche for 88-early-90's KX's, you'll see they show a thin washer that goes there in some applications.  The generic shop-manual I have mentions 'some years have this washer'.  Its not very specific.

Importantly, the shims you use will -not- rest directly against that plastic spring-centering bushing..they will register against the small shoulder on the kick-shaft.  I don't know why this is, but I bought the shim (a Kawi oem part) for my bike, and the shim stops against this shoulder, not all the way to the plastic bushing like I was expecting. 

My bike was a basket case build, in parts in plastic tubs.. the motor was all apart.  I have no real proof that all of the parts I have are from the same year engine, for instance.  What I have did eventually all go back together, but.. I can't swear it is really 'all an 88 engine' internally. I suspect that some 89/90 parts are in there.  So, caveats apply here, but I believe the base problem of shaft play would be found in an older 'all homogenous' setup too. I think the play is a result of normal wear/tear.

/cliffs

Overly-wordy, long analysis of the problem (take with grains of salt here... ):

The bottom line is, if you can pull 'out' on your kickstart shaft and it moves even a couple of mm out, then you are going to very likely get this skipping problem when you kick it over.  This extra clearance lets the ratchet and spur gear misalign under load and skip.  What's happening (in this trouble-case anyway) is that the kick-shaft, carrying the spur gear, rides 'out' of the case, so to speak.. a couple of mm, and this then means the ratchet gear is barely connecting to the spur gear ratchet teeth by just the tips (mind you!).. this isn't enough solid purchase to do the task, and with the clearance the spur gear has on the shaft to allow it to spin, the spur gear will now deflect off-axis slightly and the ratchet gear slips right past the ratchet teeth on the spur gear.

I do not believe the problem is that the spur gear is worn on the ID.  I took mine off and did not notice any obvious wear signs/chattering/etc... neither was there any obvious wear on the bearing surface for the spur gear on the kick-shaft.  It was shiny and smooth.  I think the spur gear has clearance to let it rotate and get splash oiling, and that's all.

It is also not, as I've read in dozens of old posts, the idler gear being worn out or anything else.  If the idler gear teeth were that worn, you'd know it b/c you'd have shrapnel in your gear-case and lots of other carnage would result.  I've never seen 'just one gear' have worn teeth either.  Not saying some kick-skipping issues couldn't be the result of 'broken off teeth' from idler gear (and you happen to catch it 'just right' so that the missing teeth prevent rotation).   What I am saying is, if you pull the case cover and you do not see actual broken off idler-gear teeth (or any other broken teeth on other gears), then your idler gear is fine... do not replace it hoping to fix the kick-skipping.

Further, you probably do not need to replace the ratchet and spur gears either.  If they show wear on the tips of the ratchet-teeth, this is the result of the excessive clearance issue letting them misalign during the kick-stroke.  Over years, that will burnish down these teeth and you will see 'some' wear/shiny spots.

Unless this wear is so excessive that you see real gaps when the ratchets are meshed, you are probably not needing new gears.  I'm sure there are use-cases where there is enough wear to warrant new ratchet and spur gears, not saying this is impossible... just unlikely.  The problem with the older 2strokes now is, Kawi doesn't stock the spur gear anymore... so you can't buy a new one unless you get lucky and find a shop with NOS parts sitting on the shelves.  They don't appear to stock the spur gear for any KX250 2s.. up to the last year it was made.  The ratchet-count on the later ratchet and spur gears vs late 80s ones is different, so you cant just buy the ratchet gear and hope it works with your older spur gear (ask me how I know).

The real, more obvious culprit is excessive shaft movement (heh heh... minds out of the gutter!).  Shim this up and you'll be amazed at how solid your kickstarter will work.  I suffered for years with this until I took it all part a few weeks ago and realized what the problem was with my setup.

OH, also.. yeah, it might be a weak ratchet spring causing your problem, but I doubt it.  That spring has like 1/2lb rate brand new (I bought one to see).  I installed -two- on my ratchet mechanism (with a thin washer to separate them so they were not enmeshed) to increase the total rate.. and this really didn't fix anything... just made the ratchet click louder.  The spring's apparent (to me) purpose is to return the ratchet gear to 'mesh' position when the kickstart lever returns to 'home'.  You are not getting enough extra 'clamping' force from this tiny/weak little spring to overcome the slop/play that is the real problem.  If you put a 30lb spring in there.. ok, that would probably band-aid the issue b/c it would force the entire kick-shaft 'out' and into the case cover.. eliminating the play we're trying to fix with a shim.  So, I'll modify my prior comment and say .. perhaps if your oem ratchet spring has zero tension, a new one puts just enough pressure on the assy to take up the small play in your kick-shaft to case cover.  Maybe.  Happy for you if this really fixed your problems

I think the majority of the problems are really what I've been describing though.  Since this problem builds over time from normal wear (the kick-shaft shoulder rides against the case cover.. steel on aluminum it appears!), it creeps up over the years.

Be very careful to measure the existing play/clearance first!  If you shove a 2mm thick washer in there to tighten up 1mm of play, then reef down the case cover bolts, you'll very likely crack your case cover or worse.  Measure it all as best you can, then go with a slightly thinner-still washer setup.  If you get the play down to under 1/2mm, you'll prob be fine.

I bought a bunch of very thin, precision washers online in thicknesses ranging from .03mm to 1mm and wound up using, I think, a .03 and a .5.. something like that.  I want to say the ID was like 18mm... its whatever the primary dia of the kick-shaft is outside of that shoulder... and the OD was prob 22mm or there-abouts.  Probably only really needed the .5mm thick one, but I was trying to get every ounce of play out.  This may bite me later on... I don't know if Kawi designed this to always have a smidge of play... like I said, the non-Kawi manual I have barely touches on this subject and gives no real spec/clearance. 

Go at your own risk, but I do think the notion here of taking out that shaft-movement is the true fix for skipping kickstarters on these old bikes.

Oh, Also!.. one more important point I'll add here just for completeness's sake ... there are -timing- marks on the kickstarter shaft and ratchet gear that you must get right.  This is what allows proper clocking of the kickstart return spring.  If you get this wrong, you may wind up with a 'lazy' kickstart return where it never really retracts all the way home.  There are posts on here about this, but its simple... with the kickstart assy in your hand.. look at the ratchet gear end (the ratchet gear is the one with the little 'arm' on it).. look to see if the punch mark on the gear aligns with the punchmark on the shaft. If not, align them by turning the ratchet gear (you'll have to pull it away from spur gear) until you get them to align when the ratchet gear returns to 'home' position (meshes with spur gear under that little spring-tension).  What this does is set up the correct kick-return-spring preload.

Whew... sorry.. very wordy, very likely to have many technical mis-statements.  I wrote a lot of stuff here, I'll prob proof it after this posts and edit it later.
 Again, I'm trying to add some knowledge to help folks.. assume positive intent.  If I stated anything blatantly wrong, please correct me if you are sure I am wrong.  If you just think I'm wrong and can't prove it, well, we disagree perhaps, and that's fine too.  I just ask that you state 'you are not sure' either.  Let the folks get all the opinions.

78

Introductions / Fmf grizzly ?

« Last post by Seanny deep on November 01, 2023, 01:08:13 PM »

Hey guys new here.  Just picked up a 1996 kx 500 Been in storage the last 14 years it’s a 1996. Never owned a 500 own a 1998 kx250 and a 2000 kx 250. My kids on a kx 112. Looking for information tips and tricks. The 500 I picked up needs a head gasket some new tires and what not. My biggest question is it has a fmf pipe that doesn’t say much else on it. The original owner was in his late 60s and thought it was a fmf grizzly? I can’t find this mentioned any where? Curious if anyone’s ever heard of such a thing. Tried the search bar just quads and drill bits came up. I live in British Columbia Canada, look forward to all the knowledge that appears to be on this site. Cheers Sean

79

KX250 / KX125 / Re: 1994 KX125 Carb Boot

« Last post by GCrites80s on October 24, 2023, 01:14:41 PM »

I have no idea why someone would put a 380 main in there. Maybe they were used to Yamahas since they want you to make massive main jet changes for some reason. But even then that's a lot. Get that main down to the stock range. Your pilot doesn't seem too far off. Then you can fine tune with the needle clip since that is a huge part of where the bike spends most of its time. You can make a massive difference in spooge with just the needle clip once the jets are nailed. Spooge won't go away until the needle clip and airscrew are done -- which you do last unless you want to change the needle or slide which then come last unless they are the wrong parts. And finding accessory needles and slides for old carbs is difficult and often very expensive.

Now as far as the piston goes, the 93-94s were very bad about blowing up unless you ran race gas. I haven't heard of the '97 piston mod but if it fits properly and lowers the static compression it probably does get the pinging down since they weren't blowing up by then. I can't remember if it was solved for '95 but is was definitely by '96.

80

Introductions / Please delete

« Last post by sie16b on October 17, 2023, 07:38:24 AM »

Please delete.

Trying to add pics but says folder full contact administrator