2017 - 2-Stroke Minibike

[David Ham]

So this is the minibike I sort of started last year (I'm only keeping the handle bars though), but heaps better because I'm ditching the electric motor and using a 160cc Victa which should have heaps of power once I'm done with it!!
Its my last year at school so I may not be able to work much until the end of the year but I've started buying things so here it is!...

 

[RobertD]

Long way to go! Have fun

 

[landuse]

Nice!

 

[pRoFiT]

I like the seat belt in the image. Buckle up when mini biking

 

[David Ham]

Been doing heaps of porting work on the engine.
gonna use an expansion chamber
I want to make the bike small as possible so I'll probably end up drawing it on cad first once I have the dimensions of the pipe to see how I can squeeze it all together as much as possible.

 

[Ltdkc]

Hey mate, I'm doin some go fast mods to a victa 160 myself. Check out some of my pics if you want. Victa kart/performance mods. If you get a decent expansion chamber design all set up, then I'd love a copy if you don't mind.cheers

 

[David Ham]

Yeah I had a look at those pictures and it looks like you have a full crank version, which is better than the half crank I have. I've been looking for full crank models but half cranks are so much easier to find lying around. If you want to use the same pipe as mine you will have to port it the same. I am paying to get a pipe designed by Michael Forrest. here is his website: http://www.dragonfly75.com/motorbike/portsMS.html
so once I get the designs from him I'll see what I can do.

just a picture of what a half crank looks like... it not the most ideal design for loads of power.

 

[Flyinhillbilly]

Yeah I had a look at those pictures and it looks like you have a full crank version, which is better than the half crank I have. I've been looking for full crank models but half cranks are so much easier to find lying around. If you want to use the same pipe as mine you will have to port it the same. I am paying to get a pipe designed by Michael Forrest. here is his website: http://www.dragonfly75.com/motorbike/portsMS.html
so once I get the designs from him I'll see what I can do.

just a picture of what a half crank looks like... it not the most ideal design for loads of power.

I can see where that could get catywhompus with some serious cylinder pressure.

 

[Ebrownie]

Wait, so what does the other end sit on? No bearings or nothing? That seems like it won't last very long if you are doing modifications to it.

 

[David Ham]

Wait, so what does the other end sit on? No bearings or nothing? That seems like it won't last very long if you are doing modifications to it.

Yep, so I'm gonna have to take it easy and keep on the lookout for a full crank or something else, but I'm still gonna test this engine out...maybe to destruction.

 

[Whitetrashrocker]

Uh oh. FHB might have some competition.

 

[Ltdkc]

Yeah thanks mate, that'd be spot on. It will be interesting to see how many rpm your little powertorque does before it grenades itself. Lol. Ring it's neck mate! Haha. I noticed you from Benalla, I'm from Shepparton so your not all that far from me. If you want a full crank victa I recon you should go to your local tip/ transfer station. There should be some there dirt cheap. I accumulated about 10 or 12 full crank 160's from the tip in bendigo for no more than $20 each and less. I also ended up getting about 6 or so 125 victas, all cheap tip jobs, and I've got 12 of the early victa 125's that have the transfer port covers on the cylinder. Having baught most of those ones in bulk lots I saved a bit of coin, they ended up costing me like $25 $30 each. Go to the tip mate, you'll love it.

---------- Post added at 07:19 PM ---------- Previous post was at 07:13 PM ----------

Actually, even try eBay and gumtree. Gumtree always has fairly cheap full crank victas. Sometimes bulk lots pop up fairly cheap too.

---------- Post added at 07:31 PM ---------- Previous post was at 07:19 PM ----------

I can see where that could get catywhompus with some serious cylinder pressure.

Yeah mate, it'll definitely have some pretty narly compression.

 

[David Ham]

Yeah mate well I've moved up to NSW now but I do come back to Benalla from time to time, Theres a good salvage place in Wangaratta where I got this engine from, I quite sure there were a few full cranks there. theres a couple of bulk deals on Gumtree but they're all near Melbourne and Sydney and too far to go for me.
I might head over to the salvage place soon and see If they really are victas if they aren't and your not doing anything with some of yours you could maybe sell a couple to me!!

 

[Ltdkc]

Cool. Yeah no worries, I should be able to spare a couple of 160's.

 

[Ltdkc]

I've just seen on eBay quite a few victas in Nsw. There's 5 victa 18's there that all run. The guy wants $450 for the lot by the looks. You could get em, raid the motors which are the best to modify, and sell the rest of the bits off and get quite a bit of money back. Used victa 18 wheels in reasonable usable condition usually go for $80 a set sometimes more. Some original air filters go for good money too.

 

[Mr. Spindle]

The 2 stroke mini bike... sounds good.

 

[David Ham]

right so I've got the measurements, I want to see a full crank engine to see if the pipe will work for them as well. maybe next weekend...

 

[Ltdkc]

What do you need mate?

---------- Post added at 08:55 PM ---------- Previous post was at 08:54 PM ----------

Do you need port timings or something?

 

[David Ham]

I need to see the inside of the cylinder, to see if it can be ported out the same. timing will likely be too short, but it can be changed. I think I saw a picture of a full crank and it has an oval exhaust port? plus the transfer ports are probably very different. just my specs: bore and stroke should be the same.

Bore: 61.493mm (2.421”)
Stroke: 53.975mm (2.125”)
peak power rpm: 6000
Psi compression: 90 (could be more)
Single exhaust port diameter: 27.5mm diameter
Exhaust port open duration: 145, (107 ATDC)
Fuel/air inlet: 22mm
Piston port transfer system.
2 transfer ports, rough size and shape in picture. Open duration of transfer ports 108, (126 ATDC)
Carburettor: 22mm
New exhaust duration 159

 

[Ltdkc]

I'll take a picture of a full crank cylinder