1968 Honda Step Thru road racer.

[ducatiman]

If I've managed to do this right you should be seeing a couple of pictures of my 68 postie road racer. She's had a yx160 transplant (stock), a CB125 front end with an extra big drum and a bit of extra frame bracing. She weighs bugger all and goes like stink. I've got a bit of work to do to get some more top speed (advice?) but It's awesome fun through the corners. I've only raced at Broadford (vic) so far but she might end up at Mac park in the new year, lookin forward to getting out there.

 

[my67xr]

that looks pretty good for a postie !
nice work.

have you tried a bigger front sprocket ? that will give you more top end

 

[timeeh]

Awesome looking machine mate, what carb are u running, oko 26mm is the sweet spot for a yx160, also a v2 race head should give you a bit more power and top end revs.

 

[my67xr]

could even add the 64mm BigBore kit too, and take it out to a 184cc
can also go a 67mm bore/piston too, but your gearbox may not be up to it ?

 

[ducatiman]

Thanks Guy's, I've already gone to a 17 tooth front sprocket which I believe is the biggest that will fit and a quite small rear sprocket and will try to find an even smaller one soon. Carb is 26mm and I have been looking at the big bore kits and the V2 heads. Any clues on where to get the best deals in the Melbourne area or a good site to buy online?

 

[my67xr]

http://www.dhz.com.au/buy/tb-150-160-race-head-v2-upgrade-kit-gpx-yx150-160/TBW9017

there's a couple of dealers in Vic-
http://www.dhz.com.au/view/dealer_location

 

[timeeh]

Another option (before or after V2 upgrade) is to run a lightened/adjustable stator, this will give you a few extra rpm up top. It also stops the nasty kickback that you get from the stock stator/ignition. The only draw back is that you loose a touch of tourque down low so it requires a few more RPM on take off. The one i put on was this
http://www.miniriders.com/ask-tech-masters/33526-electrics-2.html

They need to be machined to fit on a YX, but is is a great/cheap little upgrade that at least kickstart gear will thank you for

 

[ringo]

Awesome ride mate, matbe a bigger overall rear tyre?? That'll give you a bit more gearing, but may screw the handling??

Yeah as stated above get a Daytona stator kit with adjustable rev limit and timing!

 

[ducatiman]

So I can buy a lightened stator kit? You called it a Lifan Daytona stator kit in the link timeeh and you got it from Terry.
1. How do I see Terry's shop/site?
2. What machining is needed to make it fit?
3. I have already followed some advice from this forum and retarded the timing making it MUCH easier to start, can I now just lighten the standard Stator (flywheel?) and if yes does anyone have any ideas of how much and from where? It might be obvious if I was looking at the bike but I'm slacking at work at the moment (again). Cheers Guys.

 

[timeeh]

I got mine from Terry (one of the best names in race engines in the business) and his website is
www.firepowerminis.net
I think other sites sell them like DHZ, but Terry did the machining for me and helped heaps in the setup (as i had no idea what i was doing). It was the first upgrade i did to my YX and deffinately a good one. If you want to get real techo with it too, you can mark out the degree angles on it (as they are not marked when you get it) to give you a better idea of how many degrees advanced or retarted you want, Iv'e never bothered as Terry said just run it about 50% up from centre seems to be the sweet spot, but easy enough to adjust and play. If you get it from Firepower let him know it's getting put on a YX, he'll charge you a touch extra to do it, but saves you having to mess with it.

 

[my67xr]

the YX160 Flywheel is pretty light standard, it weighs about 540 grams

the Lifan150/Daytona Flywheels are about 650 grams, so they are actually heavier than the YX160 flywheels
i have the same Adjustable Lifan 150 kit on my Atomik Fuse 150

so fitting the adjustable kit, it won't rev any quicker if you fit the Daytona style kit,
but it will have slightly better engine braking, as well as being very easy to adjust the timing.

the backing plates that fit into the case, that the Source/lighting coils mount to,
use different o/d stators too, so you cant fit the adjustable Lifan 150 type stator behind a YX160 flywheel

 

[my67xr]

this pic shows the 2 Flywheels from the inside, side by side, YX160 left, and Lifan150/Daytona on the right




and the 2 Stators, YX left, Lifan 150/daytona right, compare the O/D of the coils

 

[ROLLAS13]

This thing rad mate!

 

[Momus]

My two bob's worth. For a bit of extra poke try a longer exhaust pipe- say about 30 to 32" from the valve, with the muffler mounted conventionally on the end.

 

[timeeh]

My two bob's worth. For a bit of extra poke try a longer exhaust pipe- say about 30 to 32" from the valve, with the muffler mounted conventionally on the end.

What makes you say that? Tried and tested?

 

[ducatiman]

I've heard of matching the length of the headers on multi cylinder engines and length tuning 2 strokes but I'm not sure of header pipe lengths making any difference on a single cylinder. Tell us what you know Momus.

 

[my67xr]

here is a bit of reading for helping to calculate exhaust diameters/lengths-
http://www.physicsforums.com/showthread.php?t=594484
http://www.bgideas.demon.co.uk/tmanual/Tm_Ch4.pdf