Redbox Racer post build build thread

[2Slow4U]

I've had this built for a while but i'ts been collecting dust for at least 6 months.

The thing about hobbies for me is that I'll either be completely obsessed or not care at all and right now I'm obsessed again.

What I've mainly been working on now is all maintenance work for safety and reliability.

I think I might like working on it more than riding it.

Bike is Diamondback Approach. At first I didn't want to use an "expensive" bike to put a motor on but the parts seem to be higher quality than just a walmart special and it takes the engine like a champ.

She likes going 25 but if I really gas it and believe in myself i can get her up to 30 on a flat.

Kit is a ebay flying horse and has a 44t sprocket.

I think I'll use this thread to plan out my upgrades

image gallery

 

[2Slow4U]

MODS

NGK B6HS spark plug
koch #41 chain
turbobuick1 spring chain tensioner
sick bike parts expansion chamber
dual pull brake lever
milled the head down a bit, no idea what the compression is
ebay tachometer
high performance dust
high performance zip ties
air filter that fell off

I’m thinking I want to try to get the max speed up to 40 while not being a dog on hills. Before I start adding/removing stuff I want to get a plan set up so I’m doing everything optimally. I got a rotary drill and a set of carbide bits and I'm reading Two Stroke Tuners guide so I can destroy (improve) the engine

Planned:
exhaust wrap so I can have kids eventually
tempature gauge
new air filter
high performance head
high performance streamers
possibly a cdi if I feel I need it
ultra bright headlight
turn indicators
smaller sprocket probably

 

[2Slow4U]

When I was putting the engine on I didn't have enough pedal clearance so I had to try and bend the crank. I got it hot with a propane torch and put it under the shed in the back and bent it with with a giant breaker bar. I think I bent it the wrong way the first time so I had to bend it back again.

I messed the thread up and stripped it in the crank so the pedal fell right off when I started pedaling. I ended up going to Lowes and rigging up a "high performance low profile pedal"

 

[ZipTie]

I love the high performance low profile pedal the most, but the high performance zip ties and dust are darn nice upgrades too. Enjoyed your post and your bike.

Yep replace that pesky air filter, pea gravel in the piston can be troublesome.

Zip

 

[2Slow4U]

Haha thanks

I figure each zip tie adds .5hp. The dust doesn't add speed but does improve mpg by creating increased turbulence around the bike allowing for better airflow..

You're definitely right about the air filter. I was checking ebay and found a carb and air filter for 20 bucks From what I can gather it's a clone of the dellorto SHA. Some things I've read say they are good and other say not so good.

It seems pretty interesting for 20 bucks but at the same time I think I have the stock carb tuned pretty bang on So I'm not sure how much better the new one would be assuming I can get it tuned properly.

So I'll probably find a good filter and call it a day.

 

[ZipTie]

Actually being certified in zip tie technology it only adds .45 horsepower per zip tie, you were close however. For optimum turbulence and air slippage always leave the long end hanging into the wind so it flaps back and forth, thus adding thrust to the slippage.
As far as the carb I prefer the old NT...it's kind of dummy proof once sealed on the intake with a good o ring and besides if my piston moves too fast I get paranoid about parts flying off here and there and everywhere. Slower piston speed plus lots of zip ties improves reliability along with smooth trouble free speed. Your low profile pedal will also help with spin boost.

Zip

 

[Rudz]

You'll like the SHA clone, the jets are the same as the Italian brother and the filters fit as well. For more top end try a 41 or 40 tooth sprocket. You can still climb hills.

 

[2Slow4U]

So last Wednesday I busted out the rotary drill and headed into the oven(garage)

NSFW if you work as a machinist.

I thought I had the tuning down but when I took the head off there was a bunch of carbon build up. does that mean it's getting too much gas? From what I understand there shouldn't be any build up if it's running right. I run it at 32:1 on 93 octane now but when I was breaking it in I believe it was at 16:1.

Took the head gasket off, looks like it's leaking oil. Which isn't surprising considering there is a ring smashed into it from the head. I used a torque wrench when I put on the head so I must of used the wrong number or the wrench is jank. I had an extra gasket that I wasn't using because I got the wrong size but i was able to just enlarge the holes. The hole for the piston seems to be a lot bigger though, not sure if that matters.

Instead of going to the tool library and getting the right bits for the rotary drill I ended up trying the carbide bits and the cheap ones that came with it. Even though I knew I shouldn't. The sandpaper bits that came with the drill were way too big and I couldn't get it in there but the carbide bits fit perfectly...

They definitely weren't the right tools for the job haha. I couldn't get it nearly as smooth as I wanted and there is still some paint in there that I couldn't get off. I had the plan of leaving the intake a little rough and the exhaust really smooth, but the best I could get for both was really rough haha.

A couple times the drill shot out and i hit the cylinder wall and it left a small pit.

I could of taken some from the piston skirt but I figured It would be easier to fix one 1 thing at a time if i messed it up. I also completely forgot about the transfer ports.

It was crazy hot outside and I was insane from not sleeping that night and too much coffee. So I know I didn't do as nearly a good enough job as I could have. It was so hot I had sweat dripping off my head and there were puddles on the ground where I was standing. I should of just gotten some sleep and waited for when it was colder but I had been thinking about doing it for a long time.

I also cut off a bunch of metal of the intake and exhaust gaskets. The carbide bits ate those right up.

When I was putting the head back on I ended up wallowing out one of the bolt holes and my heart fell out of one of my ears. I tightened it up as much as I thought I could and went for a ride. it was going fine and I thought it would work until I heard a horrible screeching sound and I started feeling air hit me in the leg. It took a little longer than it should have to realize what it was.
The bolts on the head are are the higher quality replacement ones. I got the idea to try one of the stock ones that I kept where i stripped it and it worked!
I'm still not sure why though, maybe I got the wrong ones? The ones I have on there now are M8-1.25

All in all I'm happy with it. I didn't ride too much because it was hot and I was tired, but the difference seems to be that before it would pull hard up to 25 then die, but now it seems to pull up to 30 before giving up. It also seemed to have gained an extra 500 rpm. Although the tachometer I used broke on me and now it says 1700 when the engine isn't even on.

I'm not sure what was more effective, matching the gaskets or "cleaning" the ports up. But considering how terrible the port work was it was probably the gaskets. These are definitely must do mod. I got better performance gains than I expected.

You can find way more higher quality pictures from the link in my original post.

 

[2Slow4U]

Some of the things that happened on the first ride after port work:

Gas tank flipped upside down(twice) and killed engine
Got blasted by air on leg from loose head bolt
Tachometer broke
Turned off choke on accident with leg on run and engine died

 

[ZipTie]

2slow4u, You should just install the gas tank upside down to start and then when it goes haywire it will flip upside down which will then be then on the way you want it, right side up! Gotta outsmart these Chinese parts. Good to hear your port job made it run better I've yet to do port surgery for fear i'll be a bad port surgeon.
Sorry to hear of the tachometer death. Just wondering out loud - How does one break a digital tach? By the blow of a stout Hammer or by melting it with a torch... Curious minds want to know the details.

 

[2Slow4U]

Haha the logic with the gas tank is perfect. I only wish it was my biggest problem.

I don't think you should worry much about doing a bad port job, all I did was "clean" it up and take all the rough stuff out. I think as long as you don't push down too hard it will be fine. That's coming from me who had all the grace of Operation Dumbo Drop I didn't do a good job and it still seems to be ok.

The tachometer is a ebay special I got for 10 dollars shipped that's been rebranded by a bunch of companies. I got my money back within like an hour of when I requested it from the seller so that was cool. I'm debating getting another one of the same or getting an "expensive" one. I think it broke because there was just too much raw power going to it and it couldn't handle it. Haha I just chock it up to the high quality Chinese quality control. It only lasted about 2 rides before pooping out. It's still displaying the same thing it did from when I last posted, surprised the battery hasn't died yet.

 

[2Slow4U]

So I tried to fix the striped out head studs with Helicoil.

The bike is sitting in the garage with parts laying all over the ground.

I got it all drilled and tapped with the Helicoil installed just fine except for the fact that I put in 2 of the 4 in way crooked. I used the philosophy of measure 0 times and cut 8 times.

When I drilled out the original threads the bit went right through it, but when I tried to drill through the Helicoil to fix it.. well it didn't happen. It's much much stronger. I ended up snapping the end of one of the drill bits and cutting out a chunk of the cylinder. It's pretty much borked.

So I guess now I have to get a new crank case body. On the bright side I still have 5 Hexicoil inserts that I can put on the new one and they will probably be the strongest part of the engine and it's one less thing to worry about.

I can also replace the bearings and do whatever when I have the engine apart.

 

[ZipTie]

Your killing me with your ups and downs and your cool attitude toward total don't give up and fix fails. Remember you brought this whole problem on yourself by venturing into uncharted territory of Chinese cast aluminum. I think your tach just committed suicide if you want my opinion, id get another of the same but with a better attitude.

Parts laying all around the floor... since when does that happen when working on a motorized bike. I have parts plus tools... rags, paint cans, flashlights, drills so you triple the mess here. Ha. Takes me longer to pick the stuff up all over the floor than actually doing the work I set out to do. I just installed a throttle on a new build I am working on and I counted some 38 tools on the floor mixed together with metal shavings after I was done, darn big mess every time. BUT...nothing is worse than a crooked helicoil when one goes for a straight one. Never used one here and doubt Ill ever get the pleasure of messing one up, cause I know i would mess up ahead of time and just have the whole engine taken to a scrap yard in hopes of saving valuable time and my pride, a mans got to know his limits when it comes to Chinese 2 stroke engines, and I know mine...clutches, carbs, grease, cables, air cleaners, Heads are fine along with sprockets and chains and that is it. I wont touch engine bearings, pistons, ports or I would need a bigger swear jar installed in my garage. I would buy a 79.00 engine faster than you could say Helicoil 3 times and save the borked engine for spare parts or a conversation piece. As far as Measuring 0 and cutting 8 times, I just do every operation twice cause I always screw up every install once no matter how simple it seemed at first. Although I am getting better and have first time successes now and then nowadays on these motorized bikes. They are the definition of finicky in not too tight not to loose. Anyhow your posts are like therapy to me and no doubt many others in the future that we and our bikes combined with our incredible mechanical skills are subject to many fails and some wins. Just remember 2slow4u...that it is all ok as long as your gas tank isn't upside down more than once a day and only in 10 second increments while driving down the road. Now that is some serious Motorized Bike philosophy right there.

 

[2Slow4U]

One of the reasons I like the bike so much is that there is always something I can work on to improve it and I can do "mods" based on my current ability. Even though I'm not where I want to be i'ts fun looking back and seeing how much more I know compared to when I started.

These engines are nice because they aren't some $10,000 race engine and it's cheap to work on/learn. Although I've probably already spent more on repairs than a new engine would cost haha. These are good because I like fixing stuff, although it would nice be to able to ride every once in a while.

Maybe I can say if the gas tank is upside down or not to describe how good the repairs went heh.

 

[ZipTie]

Precisely why especially these engines are so refreshing to play with and work on as a hobby. The simplicity and the cheap cost of parts and or entire engines combined make for no problem scenarios for experimentation, customizing, fixing, and self inflicted destruction.
Plus upside down gas tanks are a totally free bonus.
My sons parasitic gas tank flipped the other day and he blamed it on me because...before I installed it on his bike I put a piece of duct tape under it to keep his paint from getting scratched up. (Good intention here) Then I accidentally tipped his bike over one day to his dismay but we saw no damage. However such jarring action caused a tiny tiny , gas leak at the stud and the gas turned the tape adhesive into a new top secret lubricant. When his tank flipped upside down suddenly while riding...he immediately remembered all the dumb things I did and connected all the dots and rightfully blamed me for it. I denied it all with a crooked smile and then burst out laughing and said I meant well as he glared at me and proceeded to grab my spare gas tank hanging on the wall and in his words, install it the right way. So he is, as you are, an official member of the upside down gas tank club. New members...Please sign up below...

I am an official member of the upside down gas tank club.


--------------- -------
Forum name. Date.

 

[mogollonmonster]

High performance parts are a must! I see your bike also drips with them. I recently had to make a set of high performance bushings for my motor mount.

Port surgery is no big deal, although I must recommend skipping the power tools in favor of a set of needle files. You can always take more off, it's putting material back on that's hard. My next trick will be piston mods like notching and ramping.

 

[2Slow4U]

@ZipTie That's a good story, welcome to the elite club!

@mogollonmonster yea I agree, power tools are easier but make it a lot easier to mess stuff up.

The more I read about bearings and replacing internals the more I get bogged down on info and I can see the price shoot up. I'm starting to think a new engine will be cheaper in the long run and better on my sanity.

Where's the best place to get one? The only thing I can find from the sponsored links are kits and not just the engine.

These engines pretty much the same right? just need to make sure the head bolt sizes. are the same.

 

[ZipTie]

Hey I'm not in that darn club, but i did cause my son to join the upside down tank club, so maybe I'm a honorary member or a surrogate member.
Please know i am no engine expert, but I go for the ones with a balanced one PC crank and a 40 mm stroke. All is a bit better balanced, and the rod i believe connects to the middle of the piston too, for less funky vibration and a tad more horsepower I'm told. They go by name of PK80 or called by some sellers BK80 etc run about 140.00-150.00 with free ship in most cases. Plus has 8 mm mount studs etc. Dax engines are good but his web site confuses me a bit.
its a reasonable priced quality engine with hex bolts throughout too I've Purchased balanced engines from bekit on eBay or try speed 66.com a forum sponsor with a ad here can help you with a real good one pc crank engine with the same features I believe.
Heck i get the whole kit as the stuff with it is pretty much free to you and never hurts to have spare parts laying around (like gas tanks) cdi carbs etc. and the chain guard can make a good bread knife I hear.
or just get the cheapest engine money can buy. Kapluey...brrrrr...kaboom.
Something I haven't heard yet... Thankfully.

 

[ZipTie]

Ps. 2slow4u...I looked at your pictures and a few odd things come to mind.
1 Your tach blew because you have the 5 feet of spare slack wire wound too many times around your steer tube causing a severe electromagnetic field interference thus the digital overload. Also now your bike is a giant electro magnet as it rolls down the street, it will no doubt collect every wayward nail in the gutter and street causing an increase in flat tires.
2 Wipe the bike grease off your camera lens before taking more shots.
3 Your plug, head and head gasket are hopelessly covered in a mixture of un-burned and fried fossil fuel, plus unknown black crusty stuff. Looks perfect to me. Carry on.
He hee


Zip

 

[mogollonmonster]

Call Duane at that's Dax, get an FS80, it'll run you about $150 shipped. Balanced crank, 40mm rod, grade 8 hardware throughout. Best bang for your buck.