breakdirt916's busted MX machine thread

[breakdirt916]

I stopped by Harry's just to take a peek at the work, and all the machine work necessary on the case came out great!

the parts will be en route to Adam at Out-Of-Control racing in Worcester by Tuesday, and the bottom end should be going back together soon

hopefully by next weekend I can slap on the clutch side, top end, carb, and start sliding it back into the frame for a test run

here's a q: should I re-jet the pilot to the ideal/predicted size? Since the exhaust valve was pretty much, stuck wide-open 24/7, the exhaust gases never made enough vacuum pressure to suck in an air/fuel ratio at low rpm's, in order for it to idle. To compensate I installed a PWK36, used the idle adjustment to raise the slide as high as it could go (to let in more air) and installed the smallest pilot jet size available for that carb (to block out more gas, and give it even more air). Now I feel like the low-speed air/fuel ratio is REALLY low on gas and really high on air. Seems like the bike is going to get high on air and idle at the moon, when I first start it, unless I change it

[lrrs313]

Yes. Go back to base recommended jetting. Do not attempt to run the bike as lean as you have it jetted right now.

[Chippertheripper]

Stimilon? They got a piggish ds class?

[Kurlon]

They sure do. It's the 'Headlight' class.

[breakdirt916]

cases are back!

from a visual standpoint, the shifter shaft seal looks like it'll seal quite nicely and any necessary machine work was done right

transmission and crank are back together, and I just need to start piecing together the clutch side, and top end before putting her back into the frame...

[Kurlon]

[typeone]

nice!

[breakdirt916]

the clutch and external shift mechanism are in, exhaust valve actuator hooked up, water pump impeller installed, new top end is on, exhaust valve cleaned and assembled, new gaskets got thin layer of grease on them before, clutch push rod is working properly, the original PWM36 carb is back on and jetted to 70 degrees temp, engine covers are on, stator & flywheel are in, engine is back in the frame, engine mounting bolts are tight, the swing arm pivot bolt (surprisingly) went back in smoothly, wiring from the stator is hooked up to the CDI box/kill switch, mid pipe mounted, sub frame bolted up, transmission fluids/radiator fluids topped off

tomorrow morning I'm getting a fresh tank of pre-mix, mounting the tank, seat, silencer, chain, shifter and...then we'll see

[Kurlon]

SAWHEET! It's gonna be the Ye-Olde Two Stroke Show at Stimilon!

[breakdirt916]

ahhh...not quite...still won't start...now no spark?

new plug? check...OEM stator mounted? check...wires not pinched? check...disconnect kill switch and re-try? check...everything unplugged and re-plugged in? check...wtf?

going to check the manual, then try the stator from the "other" bike

[Paul_E_D]

Are you *sure* about the no spark? These things can be really hard to start after a complete rebuild. I have had to bump start mine on a good hill to get the fuel flowing in the right direction...

[Kurlon]

Are you *sure* about the no spark? These things can be really hard to start after a complete rebuild. I have had to bump start mine on a good hill to get the fuel flowing in the right direction...

I wore my leg out kicking mine to life the first time. I think I spent a good 20 minutes on it. Should have seen the grin on my face when it finally lit though!

You sure you didn't leave the spark in the same hiding spot as the woodruff key there breakdirt?

[breakdirt916]

hmm...now I'm starting to second guess myself

here's the weird part:
-old plug, covered in black goo, cleaned, grounded, and kicked over engine = very faint white spark
-new plug, grounded, and kicked over engine = no spark

stator from donor bike test: 26 ohms (should read 20-30) - tested in the wires and on the pins of the connector
stator from original bike test: 126 ohms (should read 20-30) - tested in the wires and on the pins of the connector

install stator from original bike (with erroneous 126 ohm reading?) = thicker blue spark with oily/black plug

spark? presumably there!

but still...the bike doesn't start

while re-attaching the master link in the chain, I didn't have enough slack, so I pulled harder to muscle the chain links together, tipped over the bike, somehow bent the pin on my excel triangle stand (so it doesn't hold the bike anymore), and somehow (even with metal handguards) snapped off the front brake lever...and spilled gas all over the driveway...wtf, haha

I finally get the chain on sans front brake or stand and tried to bump start it. the compression feels high...REALLY high...so high that it won't bump start the bike in 2nd gear like I used to be able to

I'd use a higher gear, but there's too much drag in any gear to roll it with the clutch disengaged...it has to roll out in neutral before popping it into gear

I'll take a compression reading for reference, but that's enough for me for one weekend...going to clean up, piece as much as I can together and park it...I'm pretty frustrated that it still doesn't run, so I'm going to take a quick street bike ride

thanks for the feedback...

[Kurlon]

How old is your plug cap? I had a good spark with my original cap, swapped for a new NGK unit and the bike was 10 times easier to start.

[breakdirt916]

well way back in 2010 it ran with the old plug cap, so I didn't think that was an issue

and...holy crap of 100 million courics...this machine is such a black hole of time spending

I was ready to park the ol girl and get back to real life, when it just looked so sexy all put together.



Now...if only it RAN!

so for kicks, I tried a couple more extended roll starts, when all of a sudden, I thought I felt a "pop". Unsure if it was all in my head, I tried again, and got 2 more "pops".

Then on the 3rd roll, it popped over and over again, and was rolling on its own!!

[breakdirt916]

ring, a ding ding dingading...


it won't idle, there's no "hit", the low rpm operation hesitates, the air screw was ~4-5 turns out (wtf? hahaha) for it to run, if huffs smoke, it needs the pilot jet changed, the rear tire is flat, the front brake lever is broken, and it will need a fresh plug after the rich jetting kills it, but IT RUNS!

proof! (clickie to watch, although the video sucks)



couple shots...plate is coming off soon







edit: ran it again today with a 50 pilot jet instead of a 55; much better low-mid throttle response. It still won't idle, and the "hit" definitely isn't there (must be an exhaust valve issue), so I plan on jetting even leaner & playing with the air screw for an idle, then pull off the covers when I get a chance and see if the governor is hooked up properly, and that the spring tension isn't overdone.

but wow...it feels soooo good to get back into sliding the rear end around turns and holding some wheelies . Street bikes aren't nearly as much fun as a 2-smoking dirtybike!!