79cc Monster 80 Bike Engine Kit - Complete 4-Stroke Kit

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lobsterman61

New Member
Aug 6, 2017
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Just bought a 80 cc 2 stroke off ebay. worked good at first but now it won't start., does anyone know what replacement spark plug I can use other than one off ebay?
 

KCvale

Well-Known Member
Feb 28, 2010
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Phoenix,AZ
Just bought a 80 cc 2 stroke off ebay. worked good at first but now it won't start., does anyone know what replacement spark plug I can use other than one off ebay?
If you have 'slat head', meaning the spark plug does not go strait up, the best plug you can get is an NGK 5944 (BPR7HIX) Iridium spark plug.
You will will not have to mess with again, and why I put them in all my new builds.
 

waynesdata

Active Member
Jul 10, 2017
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RT and NT carb swaps are a GREAT mod for 79cc four strokes. The stock carbs are prone to clogging and idle issues.
Slide carbs are designed for throttled engines, something most 4 strokes lack, so you get better throttle response and MUCH easier cleaning/upkeep/replacement.

Will 79cc four stroke need a bigger or smaller jet size than a HT engine? Looking to reuse my NT carb.
 

lobsterman61

New Member
Aug 6, 2017
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0
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If you have 'slat head', meaning the spark plug does not go strait up, the best plug you can get is an NGK 5944 (BPR7HIX) Iridium spark plug.
You will will not have to mess with again, and why I put them in all my new builds.
Thanks KC. I still can't get my 80 cc to start, I tried everything I could think of, except check the woodruff key. How do I take off the magnet? Will I just use a puller for that? Thanks
 

smilesforyou650

New Member
Feb 15, 2018
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For the intake you can use the exhaust flange from your 2 stroke kit, you just have to file out the holes a little wider. I cut it off with about an inch of pipe to work with. And if your 2 stroke intake is steel then you cut the flange off and use the bent tubing from it and shove it in at the angle you want for your 2 stroke carburetor then weld it solid or have it welded. For your exhaust you can cut the stock flange off and put your own tubing on it. I used bike handle bar and the 2 stroke muffler with some pipe still attached. And also use your 2 stroke gas tank

Here's my photo bucket album of the 79 predator I built for a guy I work with. It's his daily driver and I think he's got 30ish hours on it and it's running strong. I did pull the governor out for more rpms than stock too. If you have any questions feel free to message me. I'm happy to help

There's good pictures of my intake I described in there too


View Album, http://smg.photobucket.com/user/Furcat/library/Daves bike
hi where did you find those cantilever brake mounts?
 

xXNightRiderXx

Active Member
Jan 12, 2017
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Boise
I actually built a nice 79cc 8 speed bike. Turns out, with a little modification, Sick Bike Parts' four stroke shift kit is strong enough to be used in a 79cc build, with each of the two parts being 1/4" plates. On the other hand, I did couple the Monster 90 kit with this shifter, so it came with an exhaust pipe and an air filter. I did pay a little extra for the kit, and yes, it is overpriced, but I got all the parts I needed without needing to search for them, and it all came in one package. I also chose to do the kit for the simple reason that I would be searching for other parts relating to the frame, such as a suspension fork, wheels, disc brakes, and electronics controls (not to mention parts and bargain prices).

There were a few things that I didn't use, and a couple things that are used, but not for their intended purpose. For example, I'm using a spoke from a wrecked bike as a linkage arm for the throttle, bypassing the governor, and a bushing on the crankshaft as a spacer to keep the clutch off the transmission plate bolts. I also upgraded the chain to a jt sprockets motorcycle power transfer chain, sized #420. Never had an issue with that like I did with the stock #415.

I personally, after having put about $1300 into the bike, have decided that this engine is too underpowered with so few upgrades available that its not worth the hassle. I would rather pay for a 250cc vtwin for $1000 (has a charging system), a micargi Seattle, and all the parts fabricated or bought as necessary to make it work. BTW, I'm working on a cad model of a mount I thought of for the 250cc vtwin lifan, and will present it when its a completed product. But I will say this about it, it will utilize the whole flat part of the downtube, and the whole seat tube, with three mounting points each.
 

chairsz

New Member
Apr 30, 2018
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does anyone know if the transmission plate from gasbike for this 79cc will fit on the bigger 212cc? or is the chain from the clutch to back sprocket straight/aligned enough? in the parts gathering/returning/buying again.. stage of my build maself with a 208 cc gx200 clone....
only asking cause i foolishly bought the wrong tav2 for my bike and now trying to decide or selling it or returning to seller...
 
Feb 16, 2019
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I'm new to the world of 4 strokes, and I, just today, finished assembling the Monster 90 kit with the Metallic green Kulana bike it came with. Gasbikes got it to me quickly, (just not the rest of my order). After several hours of YouTube vids and 90 min of failed attempts, I hate the stock carb and want to rip the governor out of the motor just for spite. So I'll read all the links posted above and start modifying. Wish me luck...