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1975 RD350(LC) Preservation-mod Hellride

Started by irk_miller, August 06, 2021, 10:31:38 PM

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rodneya

When my twins were babies I had to go deal with a spectacular poop explosion while doing an oil change on my YZ250.
Well I took it out the next day with zero oil in the trans. clutch started acting weird after about 2 hours and it took another 2 to get back to my truck. All tight technical trails so no high speed stuff. Trans bearings had about 10 hours on them when I did this. Stripped down and only 1 bearing felt notchy and needed replacing. I thought my trans was toast, but only the clutch plates were fubar.

irk_miller

A couple things are happening, most notably the elimination of 7lbs of unsprung weight hanging off the front end.  It was no secret that there was way more brake than necessary on this bike.  It didn't occur to me until riding it that there was way too much brake.  Down a caliper and rotor, it should be so much better.



Also of note, the crown of the piston was a solid dark color with slight brownish stain on the underside.  As I understand it, this means I am rich or it's oil related.  I am running 36:1 atm.  I read 32:1 is a number, as well.  Mainly looking for a base on oil and mix, to situate myself with the least amount of variables to focus on carb tune.  At 40/230/P2, I am surprised to be jetted rich.

m in sc

I THINK THE PILOT MAY BE A BIT LARGE. TRY A 37.5. where is the air screw?  MY method is to throw as much fuel at it as i can till it I lose performance a hair, then back up 1.

and yeah, i had a dual disc setup too. and did the same thing. but it looked tits and was ridiculous braking :gentleman:

then:


now:







irk_miller

Back with updated beauty shots and to report. The Economy clutch makes a world of difference. I thought there was a chance I was losing a decent amount of power in the clutch. It's scary good now. The transmission is oiled and quiet. I think I averted disaster there.

Put it all back together with 1.85 on timing, and holds 6psi in the leakdown. 

Temps can reach 165° during a succession of traffic lights, but cruises below 150°. I'm really happy about this.

The CB650 forks are decent, but I want to see what I can do to make them better.

It's incredible what deleting 7lbs of unsprung mass does. I'm hoping the weight in somewhere near 300lbs, though I have no idea. Regardless, 7lbs is a chunk.  It feels much better, though I still have quite a bit of chicken strips to deal with to really know.

The bike feels all around better now.  Power delivery is pretty crisp.  If I lay it on, it want's to shudder the back wheel.  Not sure if this is something I can tune out with the rear suspension, or if it's just the nature of power to weight.  Regardless, grip is good and it's getting off like a rocket. 













m in sc

great news! thats awesome.

I would guess your weight in the 320-330 range, not that it really matters.  I know, feels lighter but Ive weighed a few bikes in my time, including my hybrid as well. the motor is over or just at 100 lbs alone. But, regardless, glad you go it sorted out.  :cheerleader: :cheerleader: :cheerleader:

NoRiders

That is looking very tasty indeed.

What are you looking to 'improve' on the forks? A fork brace* might help steering and stiffer/thicker fork oil could improve damping. As the forks are CB650 there should be no need to up the spring poundage for such a lightweight? I'm no expert btw.

* Micron braces were/are the kiddie in the UK...other brands are available. :) Prices are rising as I paid sub £50 ($65) but see them reaching £100+ these days.

irk_miller

Quote from: NoRiders on July 15, 2022, 07:16:40 AM
That is looking very tasty indeed.

What are you looking to 'improve' on the forks? A fork brace* might help steering and stiffer/thicker fork oil could improve damping. As the forks are CB650 there should be no need to up the spring poundage for such a lightweight? I'm no expert btw.

* Micron braces were/are the kiddie in the UK...other brands are available. :) Prices are rising as I paid sub £50 ($65) but see them reaching £100+ these days.

I'm working with fluids and looking into emulators. Maybe going down on spring rate or swapping for progressive springs.

ajb

I really love the A/C LC hybrid here.  Also some great tips on tuning the TMs, might try and find a set.

The feel is different with progressive front springs. Some like it, some don't.  Only one way to find out :)

85RZwade

I post waayyy too much

irk_miller

Quote from: 85RZwade on July 29, 2022, 04:07:43 PM
Irk, what happened to your water pump?
I moved it to under the carbs.  I chatted with a guy on one of the RD FB pages who did the swap and he runs a small cylindrical shaped pump who's inlet and outlet are 90 degrees from each other.  The coolant exits the between carbs from the head and 90s through the pump and straight out the end through the opening under the reed cage.  I think I will eventually switch to that pump and setup.  With the Prius pump, I have to run the line around the right carb, but I think I have a cleaner setup not using the oil pump location, plus I now can option back to an oil pump (I won't).  I figure the pump stays cooler under the carbs, instead of inside an engine cover, but I have nothing to prove that.

irk_miller

Looks like a little forbidden love between my stator and the magneto.  This is why we use the red Loctite, my friends.  $250 oversight in the books.  Offerings to the Gods.




irk_miller

Quote from: irk_miller on July 30, 2022, 09:50:34 PM
Looks like a little forbidden love between my stator and the magneto.  This is why we use the red Loctite, my friends.  $250 oversight in the books.  Offerings to the Gods.





Looks like a night of booze and the morning coffee brings back reason.  All I really lost was the plastic coating over the magnets.  I cleaned the rotor up on the lathe, insured balance, got all the plastic off the stator, and coated everything in shellac.  Everything seems good to go.

irk_miller


350GUY

Is the Radian swingarm a direct fit onto the RD350 frame?
Assuming that this is lighter than the standard swingarm?

irk_miller

#89
Quote from: 350GUY on August 02, 2022, 09:47:47 PM
Is the Radian swingarm a direct fit onto the RD350 frame?
Assuming that this is lighter than the standard swingarm?
Direct fit. Lighter and stiffer. Also longer. 19.5" pivot to axle in the center adjustment.