New Member w/ 2-Stroke Kit. Tips?

[shoggoth80]

Hey all.
I figured I would jump to the 2-cycle section of the forums post introduction. There is some seriously cool machinery out there!

So, I have a Chinese engine kit. It's been sitting in a relatively safe garage for a couple years. Gonna put together a bike to bolt it to.

A few things I have been thinking about in terms of setup:
First, tear it mostly down. I mean yank off the head, and cylinder to inspect the top and bottom ends. Give the piston, and cylinder walls a thin coat.

Maybe run a little oil into the bottom end,and give it a few spins by hand?

Check the cranks seals (it does have them right? Never tore into something this small).

I was going to pull all the studs, and go with bolts to replace them, as I have read the studs have a way of breaking. Good idea? It's mentioned in the engine prep thread. What would be an ok torque spec? Anyone know? I wouldn't want to strip anything.

I have seen anecdotal mention of removing the head gasket, and just running sealer there. Good, bad, indifferent? Read these motors are generally low compression.

Gonna check what spark plug I have. Probably replace it, unless the kit came with an NGK. I don't remember. It's been a while. I moved out of my parents' place before this build project got off the ground.

I figure while I am at it, I should look at the plug wire coming from the coil. Read this is also a problem area. Probably cheap to replace. It really wouldn't surprise me if I could just yank a better wire off a car that I have yet to part out.

Dig into the carb, and check to make sure that the needle valve is set at the second from the top slot. Always able to adjust later. Better to follow the guidelines of someone who has done it before, than to just assume that the guys who assembled the kit cared that it was done right.

I know that even though this is a "new" engine kit (well, at this point, it is unused) it is possible that there may be some issues that need attention. I am a bit of a tinkerer by nature, and the money put into the kit is a sunk cost... so I might as well have fun with it. I'll either buy a cruiser to stuff it into, or see if I still have something around my folks' place to mount it to.

What do you think though...going the right direction/head in the right place?

 

[shoggoth80]

Hmmm.... Now that I think about it, I want to say that the kit was a BGF/Boy Go Fast engine kit, that name sounds familiar. I dunno how different this makes it from other Chinese kits though. I know it does not have a pull starter, is bare aluminum, no paint. I recall paying like $130 or so for it after shipping a few years ago.

Basically just cruising around the forum, reading the different threads...drooling at some really cool homebuilds, steam powered bikes, and board track styled motorbikes. I think I like the board trackers the most. Very notorious bit of racing history in that sport. Bikes were spartan as can be, fast, and loud... what is there NOT to like?

Anyway, I saw some threads saying to make your own gaskets out of material. That is not a big deal... been doing that off and on for years. I also see that Sick Bike Parts should be local, so I might just buy a stud replacement set from them instead of hunt for replacement hardware at Lowe's. Ha ha ha!

 

[shoggoth80]

"They won't be from the factory, but you can sand them against a piece of glass if you're careful"
-This was my idea, if Permatex doesn't seal any irregularities. Planned on using the gray stuff, which works well if you need to tear it back down.

I just figured if I could set it up a bit better before it gets run in, it should keep on ticking for a good while.

 

[shoggoth80]

Out of curiosity, has anyone trimmed their piston skirt in order to get a little more intake duration on the port? Old trick I remember from a 2-cycle motorcycle forum I belong to. This was a cheap way to cram a little more power out of a small engine. Could be done with a file or a dremel if you were careful. We're talking like 1mm or less trimmed.

 

[timboellner]

A lot of people have trimmed their piston skirt.
Old tricks still in use.
A sharpie works the magic with the piston at TDC.
You can carve the jug instead by lowering the intake hole.
Make sure you chamfer where it meets the bore.
I'll warn you that the chrome cylinder bore is pretty crappy and the chrome can flake if you're not carefu

Here's a link for some good advice that I used with great success:
http://www.motoredbikes.com/showthread.php?t=5516
TIM

 

[phoobarnvaz]

Anyway, I saw some threads saying to make your own gaskets out of material. That is not a big deal... been doing that off and on for years. I also see that Sick Bike Parts should be local, so I might just buy a stud replacement set from them instead of hunt for replacement hardware at Lowe's. Ha ha ha!

With you living in Washington...the place I got mine in Idaho was Tacoma Screw. Good selection and will have everything you need to replace everything you need to.

 

[shoggoth80]

Tacoma screw has supplied me with lots of hardware over the years... stainless bolts for VW fenders, stainless hex head screws to replace exhaust studs on my Kawasaki, countless other things. Oh yeah, and at least one tap.

I'll probably rip the exhaust, and intake studs off and replace with good hardware. I'll get the stud kit from Sick, just on principle. I am imagining around $2 per bolt to replace the studs, so $10 for a better set...can't complain. I wonder if Sick's stud kit has nylock nuts? Might be something to ask. I like "aircraft" hardware... just less maintenance and of mind. If I don't have to worry about it vibrating loose, I'm a happy camper.

 

[shoggoth80]

Oh... for those of you that run expansion chambers...
what size do you rejet to, and do you alter your needle position?
I know that using a spanny will more or less require that I up the jet size. Moving the needle is not always necessary. I have read for starters to set the needle second slot from the top. That is where my needles ended up on my Kawasaki with modified pipes, and larger jets... though I know that is not the best gauge. I just know that when you add something that vastly increases the efficiency of the engine like a chamber, you need to compensate a little.

 

[phoobarnvaz]

Tacoma screw has supplied me with lots of hardware over the years... I'll get the stud kit from Sick, just on principle. I am imagining around $2 per bolt to replace the studs, so $10 for a better set...can't complain. I wonder if Sick's stud kit has nylock nuts? Might be something to ask. I like "aircraft" hardware... just less maintenance and of mind. If I don't have to worry about it vibrating loose, I'm a happy camper.

Let me know what you find out. Was thinking the same thing myself...until I read a description on his site about the toughness of these replacement bolts. No matter...am going to get a new kill switch and front mounting bracket from him.

Myself...it's going to be hex head bolts to do the install...rather than replacing them piece by piece with studs. This way...I'll have a cleaner and studier look.

As for the engine and other parts...have talked to Duane over at Dax and will be getting the rest of it from him. He impressed me like crazy when I had questions and emailed/called me right back. He answered all my questions and told me info I couldn't have found anyway else. Put my mind at ease that anything I get from him is going to be a great buy at whatever the cost.

 

[LS614]

Also, the plug wire is a good thing to replace, yanked the entire setup off and brought it down to NAPA. I said, give me something better, so I got a foot of plug wire, a red boot (pretty sporty ) and a contact for around 3 bucks. Installed in less than 2 minutes. A good thing to do Keep up the good work! I wanna see this!

 

[shoggoth80]

I was gonna see if I can pirate a plug wire off my old car (it's totaled, but hasn't been entirely parted out yet). If that doesn't work, I'll swap it with something better. One of the first tips I ran across was "the plug wire, and plug are junk"

Liberating the kit from my folks' place tomorrow, so I will be sure to photographically document it, for the sake of attempting to ID it. Lol.

After reading about match porting, and how simple it is with these kits, I might dremel out the ports, and clean them up. Going to trim the skirt of the piston, and eventually want to end up with a spanny for the exhaust. Squueze as much oomph and power as I can. Lol.

 

[LS614]

assuming the plug wire is metallic core and not resistor core and it is the right diameter it should work fine. If not , $3 ain't an expensive mod

 

[shoggoth80]

assuming the plug wire is metallic core and not resistor core and it is the right diameter it should work fine. If not , $3 ain't an expensive mod

-Exactly. But free is still one better than $3
This means that I will have to sacrifice a cable to see... buuuut.... like I said... junk/totaled car... no great loss at this point. Lol.

 

[LS614]

Totally worth a shot, that's the thing though, I think resistor core will not work, so just check it out

 

[shoggoth80]

No go on the car plug wire. The coil is epoxy sealed too. But the plug wire attaches by screwing the core onto a screw. Ick. Gonna look for something better!

Got the China Doll stripped in terms of exterior covers, intake, exhaust etc. Got all the studs for those pulled. Need to get to my car, and yank out my ratchet to get the head off. The gaskets are JUNK. Wow. The engine was assembled, and then enameled silver...so many of the gaskets didn't come off in one piece.

So, the debate there is do I make some of my own... or go with Permatex gray for gaskets? Permatex gray is good stuff, and have used it as a gasket sealer/gasket a few times on other bikes. It seems suited to 2 cycles, as it doesn't fully harden (yet seals) so it is easier to tear down again. Cleans off easier than stuck gasket material too. I might reuse the head gasket/base gasket. If anything is a good candidate for a home cut, it's these.

What spark plug again? The NGK B6HS? I think my Kawasaki uses the same plug, funny enough.

My ports actually look pretty good. Not much cleaning up in there from what I can see. I tried to hit my piston skirt with a sharpie at TDC... and all I managed to do was write on the port walls. Lol. There really isn't much piston skirt to trim.

Checked the carb...and the needle was pre-set at the second from the top slot. Depending on what I do, I might jet up, and move the needle one notch down to richen up the engine for use with a spanny.

An engine that you can work on in your lap.... what's not to like?

I took pics of most of this stuff, so I just have to upload them and post.
Should I continue in this thread? Or should I start a new one?

Little puppy has a dry clutch. Cool.

I don't think I will be splitting the cases on this one though. Depends... if my instructions have a good diagram... I might, and then seal them like I seal everything else.

Good times!

 

[shoggoth80]

Mmmm.... pics...
Clutch side

Exhaust port

Intake port at TDC

The loom

Magneto and countershaft side

All the stuff that I have unbolted is sitting in labeled bags. Not that there is much to confuse. Lol.

 

[flybytaco]

I say install it and enjoy the ride..

 

[flybytaco]

by looking at the transfers on side of the case you got a pk there I would run that thing but seems like you already tore it down have fun i guess

 

[shoggoth80]

PK? Not familiar with the shorthand there. Lol.
Not much that I can see that needs tweaking on the engine. Maybe add a little grease to the gear teeth, light coat of 2 cycle on the cylinder walls and piston, and maybe a dribble on the bottom end for security... but the engine turns easily. The spark plug is getting swapped, as will the wire.

I need to email SBP, and ask about their hardware kits. Might be cheaper to just buy their's than to hunt it down at the hardware store for $1 a bolt. Lol.

 

[LS614]

he means it is PK brand, a pk80 probably