Author Topic: The G3SS w cr motor.  (Read 9802 times)

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Offline RDryan

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Re: The G3SS w cr motor.
« Reply #30 on: November 06, 2019, 06:05:44 PM »
That's interesting about the cart racing, I know the 125's were a popular powerplant but I really don't know much about the sport other than they look fun.  :righteous:

You just made me think back on when I was 16, had a 87' KX80 big wheel with the 105 kit. Bought it off a friend who made love with a phone pole on it. I remember it needed the clutch case replaced, brake pedal and a few other things. I didn't know much about bikes then still don't but it was a fun bike to work on and ride. I was fearless then. Always standing it up in 3rd gear.

Offline RMRD

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Re: The G3SS w cr motor.
« Reply #31 on: November 15, 2019, 10:41:37 AM »
Hi there Mark,
When you swapped in the CR85 motor, what were the biggest hurdles? 
I'm guessing some motor mount reconfiguration happened... was there anything you had to fabricate on a mill or lathe (2 things I don't have)?  Same chain size?  Did you have to come up with any spacers to get F and R sprockets aligned?
I replaced crank bearings and did 1st overbore on my G3 last summer.  When I was in there I saw some veeeery scary shit going on in the trans.  I wasn't prepared to deal with it at the time so I closed it up knowing I'd be addressing it down the road.
The notion of making that bike more capable has been on my mind for many years.  I would prefer a swap to rebuilding trans and modding existing motor.
Thanks for any input!   ...and, >Thanks for the site<
-Ross

See you at the Gap !!

Offline m in sc

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Re: The G3SS w cr motor.
« Reply #32 on: November 15, 2019, 11:39:48 AM »
Hi,

to be honest, on that particular project i really didn't do any machine work to make it work aside from cutoff wheel and grinding and welding. I did some because it was easier, (bushings, etc) but you dont need to to make it work. keep in mind, the cr85 motor has -no- provision for a charging system so its total loss. you could go 125 and options open up.

chain alignment was the biggest issue, and that was easy. 

Offline m in sc

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The G3SS w cr motor: UPDATE
« Reply #33 on: January 03, 2022, 02:20:50 PM »
So, its been dead for over a year due to a failed rod bearing (oddly wasnt raising hell, just went tits up). I mean, the motor has been in there since 2014, so it cerianly had plenty of hours on it.

so, my goal was to get it rebuilt over xmas this year, but that DS7 showed up and chewed up some time. However, Saturday, i finally dragged it home from the warehouse at work and got into it.

New crank, new piston, seals, etc. welded up a cracked engine bolt boss ont he front of the motor (has been like that since day 1 actually). and finessed a bunch of stuff. moved the CDI box & mount to allow for air filter clearance, cleaned up some welds, added a 'bill's pipe' chamber, so had to reangle headpipe some, and cleaned up some pipe mounting, etc. It should eb ready for spring.

I also plan on changing the front caliper to a 2 piston nissin (grom unit i have laying around) and dumping the single piston RX50 one. Maybe i'll figure out a lighting or charge coil for it as its still total loss, which is 'ok' but id prefer a charging system. however, it gets 7 hours on a full charge so not a priority.

On way home. already had pulled cyl to confirm crank was culprit:



home ready to tear into it:



stock pipe vs 'new' pipe. should be better at midrange useable power. at least thats what 'they' say. judging by the shape id have to think so.



not a cosmetic rebuild, but it came all the way down.



all new, all 'stock' stuff, even the 47mm bore. only difference is a powerjet koso 'pwk' and v force reeds and of course, the pipe. 



not pretty but functional . welded up and added material added to boss on front motor mounts.  when i first built this i couldn't tig aluminum so this was a long time coming. I barely can now but its good enough.  :dawg:



as of last night, all bolted together. I have a new aftermarket radiator coming with new red hoses. the old on is fine but just ratty looking.





« Last Edit: January 03, 2022, 02:28:30 PM by m in sc »

Offline m in sc

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Re: The G3SS w cr motor.
« Reply #34 on: January 06, 2022, 10:46:05 AM »
HPI says they can build me a cdi for the CR motor w a lighting coil, one currently doesn't exist. this makes me happier than it should.  :toot:


Offline Djg8493

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Re: The G3SS w cr motor.
« Reply #35 on: January 06, 2022, 01:23:03 PM »
Man I love this thing!  Awesome work, makes me want to finally build up my GT80 with some street tires, suspension and a YZ top end...
1970 R5, 1975 Rd350, 1978 GT80, 1979 KZ400, 1988 Ysr50, 1990 GSXR750, 2006 WR450 SM, 2006 R6

Offline m in sc

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Re: The G3SS w cr motor.
« Reply #36 on: January 07, 2022, 10:06:06 PM »
thanks!

steering damper updated, old one was long and was never fond of the mounting. fabbed and welded a new bracket onto the frame, this unit is much better and more precise. last pic is old unit just dragging across new pipe. :science:

« Last Edit: January 07, 2022, 10:07:39 PM by m in sc »

Offline 50gary

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Re: The G3SS w cr motor.
« Reply #37 on: January 09, 2022, 08:24:19 PM »
Your G3 swap was my inspiration to buy a lonely looking Yamaha MX100 from FB marketplace.  I meet the guy, look at the thing the motor looked a bit odd to me, ah well what do I know.  Take it home start looking closer and find it's a MX100 chassis with a DT175 motor.  That'll work too.  It's so cute tiny bike.
  Cheers,  50gary

Offline m in sc

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Re: The G3SS w cr motor.
« Reply #38 on: January 10, 2022, 10:52:05 AM »
lol, cool gary. i know someone who has a 175 top on a 125 bottom and he races it, its a neat setup.

Slight update, i miscalculated and faceplanted on Saturdays test ride, the front wheel hit the pipe in a full left hander and stopped it dead and i lowsided at about 20mph in the neighborhood on the way to the gas station. Luckily didn't hurt anything including me. (and the fairing was off for the test.. whew.). it did hit the radiator but not enough to spring a leak.. and i had a new one coming anyway so no loss there. I gassed it up, rode it back home and re-clocked the head-pipe, rewelded and now have over 1" clearance at full compression and lock. I then took it back out and re-testrode, all good and motor breaking in nicely.

I'm a bit embarrassed i missed this in setup.  Luckily i had all my gear on, or my left hand would be chewed up pretty good.    :cheerleader:

Onward and forward!  :celebrate:

Offline SoCal250

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Re: The G3SS w cr motor.
« Reply #39 on: January 10, 2022, 04:00:54 PM »
Ouch. Glad you're OK and no real damage to the bike
79 Yamaha RD400F     77 Yamaha RD400D     
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75 Yamaha RD125B     75 Yamaha RD125B (project)
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Offline Kawtriplefreak

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Re: The G3SS w cr motor.
« Reply #40 on: January 10, 2022, 04:56:05 PM »
Glad you and the bike are OK.

Offline m in sc

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Re: The G3SS w cr motor.
« Reply #41 on: January 10, 2022, 05:25:57 PM »
thanks guys. I usually dont miss stuff like this, lesson learned, and i def got lucky. also why i do local test rides and always wear gear.

spent yesterday rewiring a friends r5/rd hybrid, didnt really feel like getting on a bike for that reason, and rain was forecast. But i embarrassed some young fucker in an older 323 (i think) BMW in the galaxie w 2 passengers, so there was that.  :dawg:   :lol:   

Offline Evans Ward

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Re: The G3SS w cr motor.
« Reply #42 on: January 10, 2022, 06:16:49 PM »
^ Love it!  :olaf: Glad you schooled that mo fo in the beemer cage!  :dawg: :righteous: :nana:
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Offline m in sc

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Re: The G3SS w cr motor.
« Reply #43 on: January 12, 2022, 04:11:20 PM »
so heres where the tire hit the pipe:



after modding the pipe up top as mentioned, the rear stinger just would NOT cooperate angle wise, so i just cut it out of the chamber and made a new one. also cut the end off the silencer and made a new slip collar our of stainless at a slight angle to get the positioning right.

the hole in the pate in one of th epics is where i mounted a machine isolator mount to support the back of the pipe, thats the old 6v battery box.

tacked up:



all welded up and sealed:



there's about 1/4" clearance between the silencer tip and the shock spring. genuine oh!-leans



w side-cover mounted.



Offline m in sc

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Re: The G3SS w cr motor.
« Reply #44 on: January 14, 2022, 10:58:32 AM »
no pics, but got the new radiator and cooling hoses mounted last night. However... more exciting is the fact HPI greenlit the cdi with a lighting coil. Pretty sure this will be the 1st cr85 motor with a charge circuit . wasn't bad, AT ALL, ordered directly from them, was $256 or so shipped for the custom unit. looking forward to this, better cdi curve and can run a battery, which means i can run an electronic tach/speedo if i want.  :toot: