What did you do to your CT70 today

69ST

Well-Known Member


Reached the 24000-mile mark
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cjpayne

Well-Known Member
You sure have gotten alot of mileage out of that Nice engine. Wish I could get my hands on one. How far do you think it will go?
 

69ST

Well-Known Member
That's a lot of zeros. I hope that doesn't equal the amount of butt calluses.
IDK...never looked that closely:whistle:

You sure have gotten alot of mileage out of that Nice engine. Wish I could get my hands on one. How far do you think it will go?
I dunno, CJ...when I began this adventure, I ordered the 137 tune and that choice was based on some educated assumptions. The goal was 55-60mph, riding two-up, ascending a 10% grade, (which translates to 75-80mph on the flat, sans passenger) while retaining as much of the stock durability/longevity as possible. At the time, the 62mm crank was in the prototype stage, otherwise I'd have gone for 160(ish) configuration. I went at this like an OEM engineer. The stock lump in this bike was more of an afterthought, as the bike was intended to be nothing more than a "beater"...the one that got taken to swap meets, thrown-in amongst camping gear, otherwise only a standby for when my "real bike" wasn't ready to roll. You know, "dull-but-stone-reliable", as in machinery that could be taken for granted (as close as one can get, anyway). There never has been a definitive word on service life. The lowest estimate was 40000 miles the highest in excess of 60000...or 120000 (but smoking and running like :poop:) Those sky-high numbers were from a source in Thailand, where the bikes were/are used as everything from grocery-getters to taxis to fleet vehicles...and he turned out to be shady.

I've seen a few of the smaller tunes (up to 127) make this kind of mileage. The one that failed did so because the owner ran it without oil! There were a couple of 160 tunes that were still healthy around the 11000-mile mark. I lost track of them all, over the years. As for my stocker, beyond the crankshaft oil seal (began seeping at the 17K mark) it's shown no signs of fatigue. Valve lash has been untouched since day one and I do check it. The original spark plug is still present. I always park the bike with the engine on the compression stroke; rotating the kickstart lever by hand, it still feels like the onset of hydrolock when then valves close. My guess is that the bore will eventually be the wear point. That said, I've yet to see a stocker with a worn-out bore and you wouldn't believe some of the junk that came out of Thailand sold as "used & reconditioned"...every last one of them had the stock bore & std size piston. So, the most factual answer is "who knows?". I wouldn't be surprised if mine is still healthy at the 40000-mile mark. At the annualized mileage rates I've ridden since 2002, that'll be reached somewhere between 2027 and 2032. Stay tuned...
 

cjpayne

Well-Known Member
IDK...never looked that closely:whistle:


I dunno, CJ...when I began this adventure, I ordered the 137 tune and that choice was based on some educated assumptions. The goal was 55-60mph, riding two-up, ascending a 10% grade, (which translates to 75-80mph on the flat, sans passenger) while retaining as much of the stock durability/longevity as possible. At the time, the 62mm crank was in the prototype stage, otherwise I'd have gone for 160(ish) configuration. I went at this like an OEM engineer. The stock lump in this bike was more of an afterthought, as the bike was intended to be nothing more than a "beater"...the one that got taken to swap meets, thrown-in amongst camping gear, otherwise only a standby for when my "real bike" wasn't ready to roll. You know, "dull-but-stone-reliable", as in machinery that could be taken for granted (as close as one can get, anyway). There never has been a definitive word on service life. The lowest estimate was 40000 miles the highest in excess of 60000...or 120000 (but smoking and running like :poop:) Those sky-high numbers were from a source in Thailand, where the bikes were/are used as everything from grocery-getters to taxis to fleet vehicles...and he turned out to be shady.

I've seen a few of the smaller tunes (up to 127) make this kind of mileage. The one that failed did so because the owner ran it without oil! There were a couple of 160 tunes that were still healthy around the 11000-mile mark. I lost track of them all, over the years. As for my stocker, beyond the crankshaft oil seal (began seeping at the 17K mark) it's shown no signs of fatigue. Valve lash has been untouched since day one and I do check it. The original spark plug is still present. I always park the bike with the engine on the compression stroke; rotating the kickstart lever by hand, it still feels like the onset of hydrolock when then valves close. My guess is that the bore will eventually be the wear point. That said, I've yet to see a stocker with a worn-out bore and you wouldn't believe some of the junk that came out of Thailand sold as "used & reconditioned"...every last one of them had the stock bore & std size piston. So, the most factual answer is "who knows?". I wouldn't be surprised if mine is still healthy at the 40000-mile mark. At the annualized mileage rates I've ridden since 2002, that'll be reached somewhere between 2027 and 2032. Stay tuned...
Yes, I have noticed that yours has plenty of go and seems to have the ability to eat up the miles. I would bet that your oil cooler has contributed alot to the great mileage you've gotten. The reason I say this is because of my own experience years ago when servicing a strangely optioned 90-91 Chevy S10 with a 4.3/R4700 tranny. At 105K miles, I went to go over the little truck and change all its fluids/tune up. Noticing bolt holes in the middle of the bed, I soon realized that those holes were for a gooseneck trailer hookup. I thought, " What kind of moron would hook a gooseneck trailer to a small carriage like this????? I bet the tranny is toast!!!". Come to find out there was a BIG tranny cooler up front. When I went to change its filter, the tranny fluid still smelt like it was BRAND NEW.lol. Even stranger is, I ended up marrying the pickup owner later.lol. She had gotten the truck from her grandfather, who bought it used. I put 40K on it and the only trouble with it was a failed alternator bearing when I changed the original serpentine belt.
 

69ST

Well-Known Member
Yes, I have noticed that yours has plenty of go and seems to have the ability to eat up the miles. I would bet that your oil cooler has contributed alot to the great mileage you've gotten. The reason I say this is because of my own experience years ago when servicing a strangely optioned 90-91 Chevy S10 with a 4.3/R4700 tranny. At 105K miles, I went to go over the little truck and change all its fluids/tune up. Noticing bolt holes in the middle of the bed, I soon realized that those holes were for a gooseneck trailer hookup. I thought, " What kind of moron would hook a gooseneck trailer to a small carriage like this????? I bet the tranny is toast!!!". Come to find out there was a BIG tranny cooler up front. When I went to change its filter, the tranny fluid still smelt like it was BRAND NEW.lol. Even stranger is, I ended up marrying the pickup owner later.lol. She had gotten the truck from her grandfather, who bought it used. I put 40K on it and the only trouble with it was a failed alternator bearing when I changed the original serpentine belt.
I concur, oil can never be a.) too clean or b.) kept at a temp that's "too ideal". I chose the oil cooler and and oil viscosity based on real-world testing. When I first installed this motor two things became readily apparent. One was the shift quality...that took about 100 feet. The other took a little longer...peak oil temps. Around here, it's mostly race up to 50mph+/-, then grab a handful of brakes every 1-3 miles. That spikes oil temps very effectively. I'd get about 20-30 minutes of "stoplight grand prix" action before oil temps were pushing 235F (113C). That's certainly not fatal. GN4 oil is probably good to ~270F before thermal breakdown becomes an issue...most quality oils are. That said, I wasn't pushing the motor anywhere near as hard as I knew would be required...and...I want the temps held below 110C, peak, with 90-105C being what I consider ideal. Ever notice how shift quality loses that velvety quality once oil temp tops 100C? That's telling you something, if one is willing to "listen".

Oil temps dropped significantly over the first 1000 miles. The surprise was that they continued to slowly decline until mileage had reached ~3500. To me, that sez "low wear index". Since that mileage, oil temp rarely tops ~103C...and that's only on the hottest days, after riding for miles on end near, or at, WOT. The only other "special prep" was my oil change and spinner cleaning schedule which, admittedly, is aggressive. It still breaks down, mathematically, to ~5 quarts annually...bubkes, really...talk about cheap insurance(!)

Funny you should mention a Chevy 4.3/700R4 tranny combo. That's the same driveline in my `93 Astro van, last of the short body M-vans. I ordered the optional trans cooler and never regretted it. The tranny was still working perfectly at 320,000 miles. I changed trans juice every 25,000 miles. At $55 for the fluid & filter, every ~14 months, it was money well spent...imho. It was a stilt rat (turned into "radiator venison") that totalled the van...I still miss the versatility. 150 cubic feet of cargo volume in a vehicle that was short enough to fit parking spaces marked "compact car only" was a handy combo.

BTW, which gave you more happy miles, the truck or its former owner?:whistle:
 

cjpayne

Well-Known Member
Lol. We ended up with 3 kids.

I now have a 91 Sonoma with the long bed option and low miles for its age. About 120K. Its dead stone reliable and very handy when I need it.
The 4.3 w/5speed standard is a great combo. It still drives tight and I love to drive it on country backroads when I want to "get away". 99.98% of the time I baby it and always maintain it to the "T", but every once in a while I love to cut a doughnut with it. Its very easy to do.
My brother has a 2001 Dakota with the V6 and the sonoma will absolutely SMOKE it!!!.lol

Anyway, back on topic.
I've tried the GN4 on my minitrails, but to me, the Valvoline stuff seems to make the shifting feel just a tad more smooth to me. Don't know why since they are supposed to be formulated the same. Have you ever tried the Valvoline stuff in your bike or other bikes that you did drive with different oils? Just curious.
 

69ST

Well-Known Member
Yes, I've run Valvoline and...drum roll please...I agree with you, it does seem to improve shift feel slightly. Going by gut instinct, I'd tend to agree that the Valvoline is the superior product. This is where the old evergreen "best oil" topic turns incredibly murky. In a nutshell, there's a deadly combination of overly-detailed/highly technical info (of unknown accuracy), lack of clear, concise, USABLE info and the "credibility" of the petrochemical industry. I had bookmarked a couple of technical write-ups which had lab specs for literally hundreds of individual oil formulations, both past & present (all of which were sold in the last 5-10 years, however). That bookmark mysteriously vanished after an "important update" was forced on my computer. Ah, life has never been better here in the corporate states...but I'm not going down that rabbit hole. Suffice it to say that specific properties of various oil formulations can vary widely and in ways you'd never imagine, unless you're a chemist specializing in lubricants. The write-ups were so lengthy and painstakingly (read: painfully) long & technically detailed that I couldn't get through either of them. I made it through the first 86 pages of one, less than halfway. Yes, that long...makes my long-winded ramblings look like something you'd get from a fortune cookie, by comparison.

As I've speculated, numerous times, there are most likely a number of comparable JASO-spec oils out there. Some of the synthetics may be far superior. But, that's the point, it's speculation, not proven, hard, fact. Being an old school (growing emphasis on old), hardcore, cynic the bottom line, for me, remains stick with what works. That said, even that approach can be subverted. Oil can be reformulated at any time, without notice...thousands have had to deal with flat tappet cams & lifters that were wipe flat when ZnDDP was removed from automotive oil...and small Hondas with slipping clutches "mysteriously" became commonplace. The one edge with GN4 is that we have a major OEM...Honda...associated with the product (their name on the labels) and they still manufacture engines that are mechanically the same as ours. Imagine the fallout if suddenly there was an avalanche of engine & tranny failures with their new models. So, knowing that some will take what I post here seriously, I feel that I have a responsibility to proceed with careful deliberation when recommending/commenting on stuff that has potentially major consequences. IOW, aim such that potential errors are on the side of caution. I'm not arguing with you, CJ...really. IMHO, there's a reasonable chance that you have identified a better oil for these motors.
 

cjpayne

Well-Known Member
Oh I know your not arguing with me. I'm just asking if you've had the same experience with the GN4 and Valvoline that I noticed. Glad you did and lets me know I wasn't just imagining things. When I had first gotten my K1 that I had, don't know what kinda oil the previous owner had put in it, so I was thinking of putting some Castrol Syntec in it that I had on hand for my cars. I was told by several people that the auto clutch would slip on it. Made sense, but I tried it anyways.lol. It was August and been very hot outside. Put it in and it shifted fine and, to my surprise, the clutch didn't slip, BUT.......it leaked oil out of every orifice it could find. It even started oiling the chain from the drum bolt hole that has the round seal over it. All the seals in that motor at the time were all original and it plain and simply made the leaks alot worse. Another benefit was the engine temp probably dropped 20 degrees than normal for a half tank run around.
 

airblazer

Active Member
I didn't do anything to my CT today, but I did reset my password and login to this forum for the first time in a couple years. It seems every time I get started on the project I change jobs and can't make time for it. So this time I waited until I already changed jobs (3 months ago) before pulling the bike out from under the garage stairs. Only time will tell if this strategy works, but it's great to be on here again and see the same familiar usernames. My CT hasn't run since I found it at the landfill 6 years ago, but I am hopeful that I can get it reassembled and started in the next 6 months. Lets not talk about the odds...
 

69ST

Well-Known Member
I didn't do anything to my CT today, but I did reset my password and login to this forum for the first time in a couple years. It seems every time I get started on the project I change jobs and can't make time for it. So this time I waited until I already changed jobs (3 months ago) before pulling the bike out from under the garage stairs. Only time will tell if this strategy works, but it's great to be on here again and see the same familiar usernames. My CT hasn't run since I found it at the landfill 6 years ago, but I am hopeful that I can get it reassembled and started in the next 6 months. Lets not talk about the odds...

Welcome back! We left the light on for you.:red70:
 

rowdykim70

New Member
I'm on vacation 1100 miles from home. Found a 70 KO engine on CL in Wyoming for 100 bills so I stopped on my way through to take a look as it was only 2 miles out of my way. Couldn't pass it up, the guy had swapped it out for a 125cc years ago and let me have the engine complete with intake manifold and carb, coil, harness, battery, 6v bulbs, rear 44t sprocket, kick and shifter arms, and airbox. Everything is in real decent shape. The guy thought it was from a 69 but the S/N is 126312 so it's actually from a 1970.
Awesome deal
 

rowdykim70

New Member
I looked at my new seat cover and thought about installing it. Then decide just to take it for a spin and install another day. Also looked at a 74 ct90 with only 272 miles in mint condition owner wants $1250 for it looks like it rolled of the showroom floor. What should I do ?
Buy it
 

airblazer

Active Member
I bought a can of PBlaster (although I’m looking to grab a jug of Evaporust as well) and my kids got me the Clymer service manual for Christmas. I’m studying it while the bike sits outside in the garage in unworkable freezing temps. I brought the frozen handlebar assembly inside to hopefully break it loose with warmer temps and PB... my progress is minuscule, but exists nonetheless...
 

airblazer

Active Member
Good thing you're back in Utah, Ryan. Since you left it's been warming up. It's 82 right now.

I’ve been to Naples twice since I saw you, and both times it was cold, windy and rainy. I’m starting to believe I really do bring the weather!

How's your drinking water, Kirby?

Bob might have said this in jest, but I’m actually curious what the water situation is in Flint...?
 
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