2104 Grom.. 2t conversion

[motodreams]

Cool project!

[m in sc]

yeah, im familiar with the yz grom. its cool but the details are.. if you look really close, not my cup of tea. The reason its taking me so long to do mine is the details im doing. serviceability, not cutting the frame, adding a cradle, etc. Not taking away from that one, its very cool. Just not the way i wanted to do mine. 

[m in sc]

And, it lives. Did a few fire ups but with no cooling system plumbed up, just a short test fire. this was the 2nd one. trans, clutch, and charging system all good. 

next up: plumbing and tuning. I have to say, the kicstart situation on this sucks.. it clears but its awkward. I'll figure it out.

http://www.2strokeworld.net/wp-content/uploads/GROM/250-conversion/running-early/grom-2ndrun.wmv






and, this cost me a day. it was one of those 'whats this part in the box?' (after the motor was assembled   ) No, i didnt run it  prior to getting this in. luckily i caught it. 

[Kawtriplefreak]

Sounds good!

[PIOUGHD_RD350]

This is super rad!
I love little things!
Such a good job. And, I am glad to hear that there is a cradle. And, not a cut up thing.
There is a little hacking on my Derbi with the YZ motor.
I am wanting to do a cradle for a RZ350 motor I have laying around.
But, I am still pondering what frame to use.
This thing would be a hoot at the Barber!
Keep on trucking and smoking!!!

[m in sc]

THANKS. It not really a full cradle , front and rear and lower mounts are all independent and hand made. I just got all the plumbing finished last night, had to make a really compact in-line temp sensor fitting which took a while on the lathe, but it should eb good to go. Hopefully tonight i can fill er up with coolant and get started on tuning and hopefully have NO leaks.

heres some pics from over the weekend:

made a hardline from pump to LH radiator.





if that proves to be a problem, i'll order up some stainless tuning and tig weld it together, the tight bends were the challenge mostly.

this is where it terminates on the LH lower radiator



the upper setup, the head outlet is just below the Y fitting. the temp sensor is (now) off to the right of this pic. (more to follow)




I don't have a direct picture, (you can barely see the clamp & hose end in the pic above bottom of the radiator) but hands down the worst part was the lower crossover on the radiators, the clamps were near in possible to get to, have to use a LOOOONG screwdriver to get to them from the back, as it crosses over the intake on the cyl. But, its in there.

[Kawtriplefreak]

Looks really good YO.

[m in sc]

another run video with the zeeltronic installed.

took a tip from chuck on float level on the TM and def helped.

https://youtu.be/tOFJVqmuJ_0

[Kawtriplefreak]

 
Sweet!

[Czakky]

Let me know if you need a test pilot.

[m in sc]

I wont bore anybody with more pics as of yet, but in fiddling with it yesterday, it seems the longer intake runner likes to run it a bit richer than i anticipated. Im assuming the velocity is just cranked way up across the venturi of the carb. to the point the intake gets ice cold running it, which isn't necessarily a bad thing and not really unexpected. To the point to get it to rev cleanly i needed to lean the needle out quite a bit. 

one odd problem i am having however is the cdi seems to 'double trigger' when you really rev it. to the point the zeel was reading at 5k, then just went to 10k on the readout and hit the rev limiter over 5500. so, i set the revlimiter on the zeel to 20k  and now it revs happy. Im not sure exaclty whats going on there. its an oem rotor and original 'style' but new pickup
and only has 1 trigger ramp, and no debris or whatever is ont he outside of the rotor. Im going to swap the trigger and see if its defective, and also add a ferrite choke to the wiring, see if its pickup up some RF from somewhere. the tach is verifying this anomaly as well. But, its getting there.   

[Kawtriplefreak]

Righteous.

[m in sc]

sooooo...

testriding this weekend did NOT go as planned.  Im not sure -exaclty- what happend but Im pretty sure i damaged the piston on the last run. I didn't even get a mile out. Im super confused. wasnt lean, timing wasnt too far advanced, etc.

Im pretty sure it was timing related though. the plug looks dark, no aluminum off throw or signs of overheating. timing, according to book, is 'supposed' to be at 6 degrees BTDC (which seems super late to me).
Jetting was on the rich side. But under load it just went super flat.  was smoking a lot then just lost power.  restarted to turn around and limp home maded it a bit further back and then quit again, this time water temp got hot, fast, real quick.

everything in motor is new. (well, was). upon running in shop, sounded well, cooling system would cycle and work well. 

My -theory- is that the timing is too far retarded witht he box i have and it was firing with the exhaust port open, heated the front of the piston. and stuck the ring. why? my compression gauge now is reading only 70 psi kicking over.

I cant say ive ever had one run as well it did on the stand or in the shop. and then fail so gloriously on a test ride. 

On the upside, everything else seemed to work great.

jetting was 230 main, (for safety). needle middle, 45 pilot 3/4 out thats stock setting on the pilot.  32:1 ratio.

will put head tonight I think see if theres anything I can find.

so, looks like new piston time and some research on the ignition unless i find a smoking gun somewhere else

[sav0r]

I've seen guys stick their motor on track after the engine having run amazing on the stand. Things change when you're under way, load, vibration, etc..

[2 Stroke Jamoke]

Man that blows! I've been there and its gotta be one of the worst feelings. I hope you get it figured out, I'm sure you will. Heres hoping it's an easy fix Mark. Cheers -Ian