YL1.. Project thread

[SoCal250]

Nice bright headlight! Auxito?

[m in sc]

Nice bright headlight! Auxito?

nope.. led though. . but the bulb crosses over to a few more modern quads so, bought this. it actually has what seems to be a good beam pattern

https://www.ebay.com/itm/125394779720

[John Ritter]

Mark, evidently the YL1 stuff was scrapped in Calif. for the move but I did find several RD125 engines/parts if one ever follows you home and you feel the need, lol.

[m in sc]

sweet! lol.. thanks for looking though, its a generous offer and appreicated. 

I might buy an extra set of cyls, fire up the bridgeport,  and reed them. just because, why not? (i know i know).



new tires should be here thursday. maybe i can eek in an initial test ride this weekend. maybe.

[msr]

There's no good reason for me to love those tires as much as I do.

[m in sc]

did a bunch of stuff to this over the past week. I'll start off with .. the testride went well.



*note: seat is temporary, need to get stock one sorted. 


that being said... the LH cyl is a getting abit noisy so its getting new pistons/rings/wristpin bearings as i need to pull the cyls and paint them anyway. also, the one side is down a bit on compression as well. But, it will do over 50 w me on it as is. so thats pretty good and i really havent wrung it out. 

the rear hub was a mess. there was a pipe fitting for a spacer... so i fired up the lathe and made a new one.



new sprocket, and all new bearings.



at some point the rear wheel came loose, prob from a slung chain. so the brake linkage was all fucked up. luckily i had the basic parts that were missing and was able to repair the rest:





the shocks worked well, but they were a bit long. dug around int he shock bin, found some shorter tops, but had to lathe down the shoulder 2mm to fit the spring, and tape the hole to 12x1.25 to fit the shaft. while doing this i thought about it and realized... these are nitrogen, i can run them upside down. so mounted them where the shock spring doesnt possibly hit the fender anymore. much better.

[Kawtriplefreak]

 

[m in sc]

thanks. 

[m in sc]

Took it out to its 1st bike night.  the LH cyl i think has a ring or skirt issue, but said f-it, rode it out anyway. did well overall. the headlight decided to quit working, both beams, on way home. hoping its just a loose ground but?

otherwise, success. this weekend i'll rebuild the topend.





new tiny pistons and wristpin bearings and rings. check out the 'hap jones' box. 





next to a cooked rd piston for size comparison:

[m in sc]

So got top-end wrapped up yesterday. cleaning the embedded red clay dust out of the heads was probably the worst of it, had to ultrasonic the heads like 3 times. i considered getting them vapor hones but they would have been way too bright and mad the rest of the bike look like shit so. 

the rings were the culprit, heres 2 shots.

this is the left cyl. 1st pic are the rings I took out  (yes it ran but was loooow on compression). the bores looked ok and measured fine:



same cylinder with the new rings set in.




new wristpin bearings, thanks to Russ (SoCal250) for the crossover. https://www.2strokeworld.net/forum/index.php?topic=55.0

bonus, they have an extra roller on there so a more supportive bearing.

(new one to right)

https://www.2strokeworld.net/wp-content/uploads/70-yl1/running-testrides-etc/topend/DSCI2574.jpg


heads small enough it fits in the carb dip tank.



and i never do this, but then ultrasonic cleaned with household cleaner, then again with carb cleaner in tank.




some gun brushes later and some wd40 and:

this was prior to its last shots with brake cleaner.



i -may- have raised the cyl skirt transfer port sleeve at the base a bit  , but after a hit with the brake hone, then ultrasonically cleaned, repainted, heres the jugs and heads.



new pistons and hand cut base gaskets in:





fresh stat-o-seals on the injection lines:



and 3rd start w topend. 

[soonerbillz]

Pretty Awesome!
Nice write up. Those little bikes are so cool.  Next year you need to bring it to Oklahoma for our Tiddler ride. You would be most welcomed!

[2steve]

I noticed these bikes run nice and cool even at full throttle.

Looking at the tiny bore and comparing the cooling fin area around it, we can see why this is true. Who needs water cooled?

[m in sc]

cast irron cylinder. lol. but yeah it cools really well for sure.

I'll pass on Oklahoma, been there a few times . almost went to OSU actually. But thanks for the invite. YOU should come to the 2 stroke meet at deals gap. Much better riding.   

[SoCal250]

Pretty cool! Those pistons make my RD125 look like a big bore 

and your parts are now bacteria-free!

[m in sc]

and your parts are now bacteria-free!

keepin it clean. lol. that red NC mud/dirt was a mother.