Crawdaddy adds a 2 smoker to the stable after a 12 year hiatus

[Crawdaddy 96]

What caused the piston failure ? It's usually jetting, somehow the motor got hot. It's possible that after 75 hrs the piston broke, granaded, for some weird reason. I once blew a hole in a Yamaha piston when I ran outta gas going down the hiway but thats a lean condition. I've got 202 hours on my stock piston with 4200 miles and it runs great.

Wish I knew what caused it? .....bike is jetted per JD recommendations for our altitude (stock pilot, 62 main, blue needle, 2nd clip)

Stopped by AAKTM on the way home.....Piston/cylinder didn't look as bad as I expected given afternoon "grenade" description.......but still bad enough that cylinder must be sent out. Shop is recommending complete top AND bottom given amount of aluminum that slid by and dropped down below (and almost ~400 hours on crank/main bearing)........definitely selling 520 now .....need the cash to rebuild 300

[DustyRock 0]

I am guessing the guy didnt use OEM parts on the rebuild. Talked to a guy Sunday on our ride said he has 6k miles on his 300 no issues. He said he put a new piston in it cause he felt like he should, not because it was running poorly.

Sorry to hear of your loss.....

This bike has ~8K miles/~375hrs on it. First top end at 210 hours with Slavens engine mods (porting and polishing). Second top end at 304 hours. Suspension done at 287hrs. Heim joints replaced last year. Bike appears to have been well taken care of and the previous owner seems like a nice/honest guy to me....I rode it pretty hard......I guess it was just its time.....especially given all the "time" already on the bike....

When you get it rebuilt you will know exactly what is in it. I know you can tell if she was way too lean. After the rebuild she will be bullet proof again. Dont give up on it, too much fun to be had ripping around tight single track technical stuff or just hangin it out.

[Guest Crusty]

That sucks!

My 500 has lots of hours "21years"

Got a quote for 2000.00 for complete re build.

Gona do it myself.

I am looking forward to my 250 blowing up, it needs to be a AF500

Good luck on the build.

Craig

[Crawdaddy 96]

Dont give up on it, too much fun to be had ripping around tight single track technical stuff or just hangin it out.

I won't. I really enjoyed the ~150 miles I put on it prior to the "Chernobyl in Borrego".

520 is getting head to toe full service then I'll throw it up for sale......and get the 300 back in the game.....

[Bagstr 287]

OK, so it wasn't a loose spark plug. I was just hoping it was something easy. Not!

[racerbill 0]

I just looked at the jetting chart in my Ktm manual and it says for sea level(Borrego) a 168 main and a fat needle in the 4th position!!! Your piston and cylinder are burned on the exhaust port side which indicates real lean jetting. I've found that the stock jetting guide is very accurate. My guess is that lean jetting and running down the hiway was your 300s undoing.Jd strikes again. That all sucks. You know normally with a top end seizure the lower end is fine. Did I mention I know a guy with 17000 miles on a 2000 300 and he has not done the lower end, that does not suck!

[Spaugh 1]

I just looked at the jetting chart in my Ktm manual and it says for sea level(Borrego) a 168 main and a fat needle in the 4th position!!! Your piston and cylinder are burned on the exhaust port side which indicates real lean jetting. I've found that the stock jetting guide is very accurate. My guess is that lean jetting and running down the hiway was your 300s undoing.Jd strikes again. That all sucks. You know normally with a top end seizure the lower end is fine. Did I mention I know a guy with 17000 miles on a 2000 300 and he has not done the lower end, that does not suck!

wow, that piston is melted!!! Sorry it happened so quickly after your purchase. That sucks!

what kind of oil and ratio were you running?

Did the motor sound like a bell ringing when you had it pinned?

[Crawdaddy 96]

I just looked at the jetting chart in my Ktm manual and it says for sea level(Borrego) a 168 main and a fat needle in the 4th position!!! Your piston and cylinder are burned on the exhaust port side which indicates real lean jetting. I've found that the stock jetting guide is very accurate. My guess is that lean jetting and running down the hiway was your 300s undoing.Jd strikes again. That all sucks. You know normally with a top end seizure the lower end is fine. Did I mention I know a guy with 17000 miles on a 2000 300 and he has not done the lower end, that does not suck!

I just looked at the JD kit instructions again (I don't know how or if I can attach the PDF to a post)......it calls for air screw at 1.5, stock idle jet, Blue needle, 2nd clip, 162 main for sea level to 3K.....

I also have the KTM manual stock jets/needles....I'll go that route on the next pass. I agree Bill, the 09 KTM manual calls for Air screw one turn, 35 idle, N2ZW needle, 4th postion, 168 main for 1K-2.5K' (170 main for sea level to 1K)

What I found odd is that it ran really good up to the point of dropping in "fresh"(?) gas in Borrego Springs.....I put in 2 gallons and ~4.5 oz. Motorex Cross Power 2T oil (~55:1) Rode three miles and it died......(tank still had .9 gallons in it when I topped it off). Previous owner was jetted even leaner for 5K-8K per JD instructions.

AAKTM is recommending lower end as well given aluminum flung into bottom end from piston and hours on crank/main bearngs.....I trust them to steer me right......I wouldn't want to drop a bunch of cash on a top end with a suspect bottom end....they'll make a final determination when they pull motor and split the case to clean out lower end/check crank/main bearing....but they're fully anticipating the bearings are shot/crank is loose....I'll be swinging by the shop again to see what they uncover....

No noticable (to me) pinging/ringing other than typical 2 smoker......but I haven't ridden one in years either...

[racerbill 0]

I used JD in my 4 stroke, 525, and it ran a lot better but was still on the lean side- got great gas milage. My buddy Don has a Slavens needle in his 300 and it to is lean. His bike runs great from 9000' up. I've been using the stock jetting in Utah and actually richened the needle one position. Congratulations on your new engine, thats what I would do at 375 hrs.

[Bagstr 287]

Chris,

Just to add one more bit of info to discussion: What is the gearing on the moto; Where you @ 3/4 throttle or 100% at failure?

That gas dump soo soon before failure is certainly suspect. Sure you didn't use brake fluid?

[Crawdaddy 96]

Chris,

Just to add one more bit of info to discussion: What is the gearing on the moto; Where you @ 3/4 throttle or 100% at failure?

That gas dump soo soon before failure is certainly suspect. Sure you didn't use brake fluid?

I think I was probably at 3/4 throttle when it died? As you know, I hit it pretty hard with a few short bursts in the desert, but I didn't take it over ~55-60mph on the street sections. Brake fluid? Nope, I was carrying ~12oz of Motorex 2T in my Ogio flight vest.

I'm not even sure what gearing is on the bike.....pretty sure it has a 13 up front, not sure about the back....

I think another error I made was following the JD kit recommendations without taking into account that the Slaven engine mods *may* have also left the engine in a leaner running condition.....therefore JD recommendations based on an "OEM engine" wouldn't necessarily apply.

See the thin/tapered middle blades in the cylinder in the picture below.....Tim/R.J. at AAKTM told me this mod by Slaven leans out fuel delivery......it may yield better gas mileage but at what cost? They gave me the impression a more blunt edge will yield slightly better power and help the bike run a tad richer.....so they plan on blunting those edges back up a bit when they button it back up....

[PastaPilot 17]

Sorry for the trouble Chris. This whole thread is making a real strong case for buying new.

[Crawdaddy 96]

Sorry for the trouble Chris. This whole thread is making a real strong case for buying new.

Yes and No. Before I pulled the trigger on buying this bike I posted over on KTM talk about my indecision given the hours on the bike. Opinions varied given the price/bling on the bike. Some said run away and some said don't worry about it. General consensus was, "just change the top end out at minimal expense......the bottom end may be fine for many more hours and/or years"......My friends at AAKTM told me NOT to buy it given the hours. They told me to focus on a bike with lower hours rather than getting caught up in all the bling on this bike......"I" chose to ignore that counsel and roll the dice anyway since the previous owner has only been riding for ~3 years, he's 57, and he's a trail rider not a racer......It was/is clear to me that the bike has been well taken care of and I was/am confident that the previous was/is a stand up/honest guy.

I still don't think the hours on the bike are really the main issue here......I think the greatest miscalculation I made was to operate in a vacuum and just naively follow the JD manual recommendations for carb settings without soliciting any advice and without taking the Slaven's mods into account......dumb .......In hindsight, I should've tapped into the collective knowledge base of friends at SDAR, AAKTM, KTM talk, etc. regarding appropriate "real life/hands on" settings for the carb at our altitude (after taking the Slaven's mods into consideration). And, needless to say, I should've done that BEFORE riding the bike.

I have a saying I used to lay on my kids when "they" made a dumb decision and they were looking for a scapegoat, "Hey, if you're looking for someone to point the finger at there's a mirror in the bathroom" .......no sense pointing at the previous owner, makers of JD jet kits, Slavens, etc.,........ this fiasco was self generated

[bikeslut 1]

very mature approach Chris... hindsight is 20/20

it'll run better than ever when done, and you'll keep all the bling

[DustyRock 0]

I have a saying I used to lay on my kids when "they" made a dumb decision and they were looking for a scapegoat, "Hey, if you're looking for someone to point the finger at there's a mirror in the bathroom" .......no sense pointing at the previous owner, makers of JD jet kits, Slavens, etc.,........ this fiasco was self generated

I like this one too. "When you point a finger at someone there are three more pointing back at you"

[PastaPilot 17]

I didn't intend to point blame at anyone. To me it seems that it was operator error and the engine trouble was caused by an excessively lean mixture. What I meant to say, and just didn't put enough words into it, was that when you buy new you know what you're getting and where to start. There's a perfect baseline drawn before you. Whenever I've bought used stuff there always feels like there's a rain cloud lingering overhead. When you buy used you just never know what you're going to get, in your case it was an older guy that putted around on a fully tricked out dirtbike. Sure it appeared in great shape and looks superb but you really have no idea what to expect.

Unless you buy new.

And even that isn't guaranteed, but it is warrantied.

[jbw 0]

What I found odd is that it ran really good up to the point of dropping in "fresh"(?) gas in Borrego Springs.....I put in 2 gallons and ~4.5 oz. Motorex Cross Power 2T oil (~55:1) Rode three miles and it died

I am new to 2 strokes but from what I have heard when running lean the bike can still feel good, running rich the bike will not. edit: Oh, I just re-read the quote and I misunderstood the meaning.

When you opened the throttle quickly would you get a bog?

Also, I have heard that lean running 2 strokes will ring like a bell but it seems you did not hear any of that.

[hobiee 28]

All the more reason to ride a four stroke

[Spaugh 1]

All the more reason to ride a four stroke

touche

[racerbill 0]

All the more reason to ride a four stroke

Once again.....valves and cams are the work of Satan!

[Uncle Champ 116]

Don't feel alone Mr C, I bought a two stroke "all dialed in", rode it around felt great. 1st hard ride locked up no ping no warning. I have had two strokes blow up before and usually had some warning, this time I actually suspected the trans.,turned out the guy I bought it from was meticulous , read all the books, but never pushed it. OHHH meltage. Wrong jetting in my case.

Just think how cool it will be all fresh!

[Crawdaddy 96]

All the more reason to ride a four stroke

I obviously don't have much time on it yet, but I had a good time Sunday morning......snappy ~225lb mountain goat with Rekluse (brakes on bars), GPR, etc.....a different/lighter feel and powerband than the 250, 400(s), 520, 620 fourstrokes I've been riding the last ~12 years......not better or worse, just different......change is good/fun

[Uncle Champ 116]

I put an older model Recluse on mine, next I want to put the brake in place of the clutch lever. Did I misunderstand, is your foot brake nonexistent?

[Bagstr 287]

Yet another entertaining moment here @ SDAR. Much of our fascination with dualsport / offroading is that we are "Out There" riding by our whits, physically and mentally. Rocks, drops, sand wash to negotiate. Suspension, tires, gps etc. to manage. The largest decision of all, "What Bike to Ride." Operating under the illusion that there is one perfect cycle, we strive for perfection. New, old, 350, 990, 2 or 4 stroke, DOT, bling a blizzard of choices. Which provides us with the distraction from normal life we crave. Over the last two weeks, I have been around two broken bikes and two sets of broken bones. Living by our whits is tough!

Props to Chris for sucking it up and taking responsibility, whether the fault is his or not. My advice...wait for it...Love the One You're With.

Apologies to Buffalo Springfield.

[Crawdaddy 96]

I put an older model Recluse on mine, next I want to put the brake in place of the clutch lever. Did I misunderstand, is your foot brake nonexistent?

Correct, no foot brake.....I got used to it pretty quickly.....harder to train myself to not grab for the clutch lever when shifting/stopping. I have all the stock parts if I ever wanted to switch back.....but I don't think I will.......I did notice that I tended to drag the rear brake a bit more with a lever control as opposed to a foot control (at least I think I was dragging a bit more?)......need to be careful not to overheat rear brake.....or engine!