For Old Guys Only

Greg58

Well-Known Member
May 1, 2011
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Newnan,Georgia U.S.A.
We came through the storm ok, only lost a couple of trees, none close to our house. The storm tore through the historic district of Newnan, there are so many old oak trees down it will never look the same. Newnan High school and Atkinson elementary have major damage, as most people know I work for the school system as maintenance supervisor and will have a lot of work ahead of me. Thanks Tom for thinking of us.
 

indian22

Well-Known Member
Dec 31, 2014
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Oklahoma
Hi Greg it's been a great engine for you. The CG engines are much maligned but when properly set up, maintained and ridden responsibly they are marvels! I'm approaching 20,000 miles on one of mine and that's over seven years it's on it's second set of rings & clutch pads...that's it so far. So I'm a fan and love hearing others with super results.

Here's to the next 10 years.

Rick C.
 

indian22

Well-Known Member
Dec 31, 2014
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Oklahoma
Greg mine is also the Grubee but 66cc and I checked the bore before putting in the new rings and they seated fine in the old cylinder bore. I've rodded a great deal using the stock cylinder and piston. Reed valve and piston window cut and added an additional port as well for the reed to fully function. This one pulled over five horse with the stock CG exhaust on the dyno. I've added an expansion which helps the low end torque. Can't tell any difference up top though.

I have three of these motors setup in identical fashion and running a Dellorto carb. The only difference being the other two are not Grubee 66cc & though I haven't put them on the dyno they are not as strong. The original Grubee was really well made compared to some of the other CG motors, but with some bottom end work and cleaning up some rough internal machining from the "manufacturers) they will run fine in most cases.My original Grubee's rotating assemblies were balanced perfectly from the factory and I attribute this & close tolerances to longer motor life.
I also add a big aluminum head not for power but for greatly enhanced cooling. I don't add much if any compression with the head and adjust with various copper head gasket thickness to get good performance without adding much to head temps.

Rick C.
 

indian22

Well-Known Member
Dec 31, 2014
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Oklahoma
One additional thought. I built a Grubee some 7 or 8 years ago, time passes quickly so it may be longer than that. I used every hot rod trick I could think of and then some to get max power out of 66cc. The thing ran like a bandit to over 12,000 rpm and was really spooky fast with modded 100cc Kawasaki expansion chamber and Mikuni big bore carb etc. all the power boost stuff, but the thing was not fun to ride at anything close to rational speed and was horrible at speeds under 30 mph. Gearing it really low was a help, but still not a bike I would pick as a daily rider ever. I first ran it as a port timed motor & it was ok as a daily rider then I went full reed and stuffed the case. The big power increase ruined the bike as a daily rider. Plus the expansion pipe was super loud and I'm mostly deaf! It also tended to run hot at slower speeds. It was an obnoxious beast to be sure.

Strange thing about the bike when it was port timed. I struggled with getting to 6,00rpm for some months and remember being frustrated with the bike and some mods still not being a 40 mph bike My mods were sound power makers and the engine sounded good, felt good and the plug chops were perfect yet no rpms. I was still running a stock CG muffler, though I'd tried some motor bike type expansion chambers before with no help. It was a really cool, high humidity Spring day with no noticeable wind & I went for a ride. I determined to WOP throttle till this pig blew up & I proceeded to try just that. I tried several quarter mile runs and the motor would not go past the 6,000 rpm mark in fact 5,500 was iffy. I decided to try half mile runs WOT not including run up to speed. I was running a 40 t rear. On the very first run the bike was running at around 6,000 rpm at the end of a quarter mile of WOT & suddenly it seemed to hit a higher gear and really smooth out and I shut it down when the tach hit 10,000. The engine came up on pipe at a little past 6,000. I just needed some patience. Now I can't tell you how much power that motor made on port timing but it easily added 10 mph to top speed. The radical mods came latter. Which actually ruined the motor for my riding requirements, but as I sat out to blow the engine I eventually did take out the top end several months and quite a few miles latter on a high speed pull.

I managed to lose a ring on a plus 10,00 rpm run & pulled the motor to inspect and clean up the carnage. No bottom end damage, but rings, piston and jug were history. I still have that bottom end on the shelf as a replacement for my Grubee hybrid should I ever need a replacement for my favorite two cycle ride. I think 5hp to 8 hp 2 stroke, 4 stroke or electric or hybrid enough to call perfect for my use, though I have a couple of 4 stroke bikes which double this power range....really motorcycles with pedals!


Rick C.
 

Greg58

Well-Known Member
May 1, 2011
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Newnan,Georgia U.S.A.
Rick I have a 66cc but most of the bikes I've built have been 48cc, I have always enjoyed the challenge of getting more out of a engine than it was designed for. I do all the standard tricks I've learned here and some I learned on motorcycles in the 70's. I did a lot on 100cc and 125cc suzuki and yamaha's, there was a local motocross track that would sometimes have 25 in each class, they also had the under 80cc plus the 250cc and open class. I learned a lot about pipe design then, I've applied some of that to the pipes I've built for my bikes.
 

indian22

Well-Known Member
Dec 31, 2014
4,112
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Oklahoma
Rick I have a 66cc but most of the bikes I've built have been 48cc, I have always enjoyed the challenge of getting more out of a engine than it was designed for. I do all the standard tricks I've learned here and some I learned on motorcycles in the 70's. I did a lot on 100cc and 125cc suzuki and yamaha's, there was a local motocross track that would sometimes have 25 in each class, they also had the under 80cc plus the 250cc and open class. I learned a lot about pipe design then, I've applied some of that to the pipes I've built for my bikes.
Kindred spirit Greg and the small engine fixation for performance extended to my love of small block Chevys and Fords. The 340 Mopar was one I really liked but never built one up. There's always the rush of knocking off a big block with a built motor of small displacement. Race blueprint clearances and great heads which really flowed were my primary setup of course all the standards then worked together to produce big power.

I don't miss much but I do miss the simple race mentality of the sixties...line 'em up and find out!

Rick C.
 

Russell

Well-Known Member
Apr 19, 2009
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MA
Hi Greg it's been a great engine for you. The CG engines are much maligned but when properly set up, maintained and ridden responsibly they are marvels! I'm approaching 20,000 miles on one of mine and that's over seven years it's on it's second set of rings & clutch pads...that's it so far. So I'm a fan and love hearing others with super results.

Here's to the next 10 years.

Rick C.
20K Wow I thought I was doing well wit 5K+
 

indian22

Well-Known Member
Dec 31, 2014
4,112
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Oklahoma
20K Wow I thought I was doing well wit 5K+
Hey Russell who's to say you are not doing fantastic ? 5 K going on to 35K. I don't know what is possible for the CG, durability wise, some don't last through break in and yes I believe that's a real thing, though many just flog the heck out of any motor I don't. I actually break them till I feel them free up. This is usually a couple of hundred miles. I constantly run through a range of motor speeds on every ride during break in and don't ride a a constant rpm setting. Accelerate and back off always varying my speeds and never approaching any high rpm level. I use regular 2cycle mix, not too heavy on the ratio, and add a little Marvel Mystery oil to each tank of fuel. When break in is complete I switch to semi synthetic smokeless Lucas oil. I continue to use a little Marvel oil to each tank; about a tablespoon full to each gallon. This keeps the head and piston clean and I don't have to de "coke" the top end very often at maybe 3K or 4K. The Mystery oil seems to really extend plug life too. I've never had to change plugs on this or any of my bikes though I do every couple of years on the hybrid CG. NKG is my plug of choice though heat range seems a little different on each of my 2 strokes though two of them are pretty similar in build up.

Keep riding & telling others that hate on CG motors...the hobby was built around these motors & would not be the success it is without these at the entry level kits at cheap. Though they have some real quality issues on some CG motors there are others that are built to reasonable tolerances.
This is the real problem the actual design is pretty simple and good. If the China stuff is so terrible how come the Predators are so great? They are and if the 4 stroke can be built to decent standards the 2 stroke is even easier to get right. Hundred bucks for either one so tell me they don't make money on each CG kit. Because of the current ,inconsistent nature of the CG kit motors I would, as a builder opt for the Predator either large or small, but the skill level to successfully build one out is a step beyond the CG kit level. The Predator needs a "complete kit" offered like the CG has to really make entry level 4 strokes a DIY project going forward.

Rick C.
 
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Tom from Rubicon

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Apr 4, 2016
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Rubicon, Wisconsin
I hate 2-smokes :mad: :D
When my 1973 750cc Mercury outboard engine blew a piston top. I had long lost my love of mixed fuel.
Fisher Peirce maker of Boston Whaler boats had acquired a 4 cycle 55 hp outboard engine. A perfect match for my 1973
Boston Whaler Cohasset II. I can idle all day without fear of load up. About the same engine sound as a Farmall M.
A great read.
Tom
Classic Whaler: Boston Whaler: Reference: History (continuouswave.com)
 

Greg58

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May 1, 2011
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Newnan,Georgia U.S.A.
I’m living proof that God looks after foolish people, in 1975 my brother bought a 1974 close out 750cc Kawasaki triple, that was the fastest bike around, I was only 17 riding a rocket. We would swap out his bike for my car at times, I don’t care how mild mannered a person is, when you climb on something with that kind of power you have to let it rip.