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First Build - Tips/Pointers

JimmyNibbles77

New Member
Joined
Jul 24, 2020
Messages
23
Hey guys! I'm starting my first build here in the hobby of motorized bicycles and I'm looking for any tips/pointers/things to look out for before I start the build.
I'm putting an 80cc two stroke with a jackshaft kit on a GT Aggressor mountain bike. I grabbed the jackshaft kit for my bike so I don't have to mess with the disk brake I have on the back wheel. The engine and Jackshaft should arrive in the post by the end of the week.

Also, If anyone has a reputable tutorial article/video for both the engine install and the jackshaft install I would greatly appreciate a link to one.

Thank you!
 


Benchdweller

Member
Joined
Jul 22, 2020
Messages
61
Don't be afraid to get a dremel and file set and someone port work and skirt your piston. Even if you just clean them up a tad bit and chamfer it makes a noticeable difference. I know that horse has been beaten to death but noobs are often leery. A new jug cost peanuts so just go for it. The worst that can happen is you learn something.
Hear are some things that many noobs miss because they become so basic, everyone forgets to retell it to a new guy.
Grease your bucking bar and ball bearing.......CONSTANTLY. Every other day of riding. Get it in a squeeze tube, pull the bucking bar out. Hold the tube up to the slot and squeeze her in there like she's about to do her first anal scene. Put the bar back in and just the right amount squeezes out for the clutch cam to go back on.




Ditch the Stock air filter on the NT. It's sh*t, the carb is fine, the air filter sucks. Especially if you're in a dusty area.

Number 1. Find some kind of pouch or pack you don't mind carrying at all times and make a tool kit with a ratchet, spark plug socket, and appropriate Allen head sockets( preferably the long ass ones with ball ends, if not and six inch extension) and regular socket for whichever your head bolt nut size is you will need to tighten engine bolts down, an extra exhaust gasket or two, zip ties, lock wire, a tube of white lithium grease (for bucking bar lube), flat and Phillips drivers( I recommend a multibit handle that stores the bits in the handle like Milwaukee makes to cut it down to one), master links, , chain breaker, extra spark plug, 6 inch crescent wrench, a tire patch kit, and good needle nose pliers with a side cutter in the jaws. This will fix damn near anything that will go wrong on a ride. You will be using it and if hounding bring it, you sooner or later will wish you brought it. Especially on a new build and doubely so on your first. Just about any breakdown can be fixed in 20 minutes at a park bench with no headache if have this small kit, bit pushing home isn't fun at all. Throwing in a couple of nuts, bolts and washers with a small tube of blue thread locker, extra brake pads, and a wd40 pen doesn't hurt either. This sounds like a lot when listed but women carry ten times as much in their purse going to their sister's house, You don't need a lot of space for it all.
The US Army M40/M24 gas mask bag/messenger bag is what I use and recommend. It is pert' near taylor made for all this leaving lots of empty room for some trip specific crap available. It organizes everything perfectly and has a wrap around strap to make sure it stays closed and a small adjustable strap with a clip that is for securing looping through your belt in back so it won't flop around on turns and while peddling.

Oh and it has a little side pouch that is just the right size for a small 1 gallon bottle of 2 stroke stihl 40:1 oil. Which is 77ml of oil. Just a few decimals shy of the right amount of oil for a 25:1 mix on an empty 2.5 Liter tank or 20:1 on a 1.5. I run 32-36:1 but 25:1 or 20:1 is fine in a dire emergency just to make it home once and drain the rest. Oh and don't be cheap, run 91 non-stop gas. Even if you have to fill a 5 gallon tank and drive 10 miles once a month.
If you can't get it, run super.

Oh and MSR fuel bottles for camp stoves make a great way to pack some extra "get me home" gas.


Akutey is spot on as well about the stock chain.



Use a sealer on your intake gasket just don't use RTV. Permatex Indian Head shellac, aviation Form-a-gasket, and high-tack works well.
 

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Benchdweller

Member
Joined
Jul 22, 2020
Messages
61
Also, order a few extra gasket kits if you aren't good at cutting your own or have templates
 

JimmyNibbles77

New Member
Joined
Jul 24, 2020
Messages
23
@Benchdweller

Thanks a lot, man! Sometimes you need some stuff laid out plain and simple for you when you're getting started. I've got a Dremel so I'll definitely work on cleaning up the engine before I strap it on. FedEx says the engine is due to come today, so I'll let you guys know how it goes shortly

Also @Benchdweller: are you saying just tear off the airbox and leave the carb naked?

Another question: I bought a black painted engine because I thought it would look cleaner, yet I've read that it hinders air cooling performance. Is this lack in performance significant enough to worry about buying a new head, or nah if I'm just commuting 5 miles every day?

I'm planning on using TruFuel 40:1 from home depot, will 1 32oz can with a mixed in 2.6oz 2 stroke oil bottle do the trick for breaking it in, or do I have to be really elaborate with working the engine up?

Once again, this is my first kinda motor on two wheels and I'm hoping to get a motorcycle once the DMV opens up again, so I'm not REALLY looking for peak performance here, just decent workability. Plus I'm on a short budget here a tad and I blew my summer work money on the engine and jackshaft and some gas, so I won't be able to do a ton of stuff. I just want it working so I can rip and run and have a little fun. (and commute a bit)

Also, will storing a tube of grease in a ziplock bag and then spreading with my finger do the trick rather than a gun? And does grease type matter? I just picked up some red grease that's extra tacky cause I saw a guy on youtube using it for his bikes.

Thanks a lot, guys!
 

JimmyNibbles77

New Member
Joined
Jul 24, 2020
Messages
23
And I know you said the piston head is really cheap but is chamfering really necessary? How much more performance does it eek out of the motor? I've heard that my stock 80cc engine will hit about 35, and with my jackshaft kit it should get me up to 40, and I've heard claims of 50+, but 40 is completely sufficient for me... is that realistic?
 

Akutey

Well-Known Member
Joined
Dec 10, 2018
Messages
454
Do not run without an air filter. Even a sock off your foot is better then nothing in a emergency.

Paint or color should be negligible in performance as the effect on thermal dissipation is about 2%.

Use actual gasoline and mix up some quality oil (Lucas, Redline, Castrol). Preferably ethanol free gas. (Cheveron 94 in Canada). Cheaper too.

The cylinder should be chamfered for reliability, piston can be done too for same reason's. This won't increase rpm or torque, just limits wear and the second increase's oiling ability. Without cylinder chamfers rebuilds are needed more often for the ring wear and dynamic compression loss involved.

With the jack-shaft you're top speed is limted by gearing and the horsepower required for it. You should hit around 35-40 mph. Stock gear I do that.
 

Chainlube

Well-Known Member
Joined
Jan 5, 2020
Messages
2,263
I have to agree with Akutey use petroleum based (dino) oil mixed with gas for break in. Synthetics are too slippery and the rings won't shape to the cylinder walls properly. Go through a couple tanks of gas and vary your rpm as you ride, don't hold a steady rpm for too long and go up and down the rpm range.
 
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