Yx 160 BIG BORE INFO.. (2025)

KierenCrawford

Join Date: Mar 2014

Location: Down a hole under a tree.

Age: 30

Posts: 355

Bike: Shovel master

A standard YX160 has a 57mm Stroke and a 60mm bore

OORACING make various big bore kits for the 2v head and the 4v head right the way up to 67mm making it a 200.96cc But it requires the crank cases being bored to 70mm, What I need to know is how big can you go with the bore before having to bore the crank case?

Cheers Kieren, also is there anyone out there running a yx160 with the 67mm big bore kit and was there a noticeable gain in power?

I ALSO HAVE THE FOLLOWING PARTS THAT IL FIT WHEN I GET THE KIT

VM26 Carb a twin exit WPB exhaust and a 7mm lift cam from OORACING Will these parts be man enough for the big bore kit?

katoom

Join Date: May 2009

Location: Where ever i leave my hat

Posts: 7,794

Bike: A big pumpkin

64mm usually. Tb kits are popular.

Don't bother with a ported 2v or a 4v unless the 4v is a really good make.

A Tb V2 or +R heads are better upgrades and with a better/wider choice of cams.

Try a V2/+R head first, maybe a 64mm kit, see if it's enough, if not, go bigger.

A 26mm carb will hold it back, go 28. Pe/PWK etc.

The twin pipes won't do anything, look great if they're a good make though.

KierenCrawford

Join Date: Mar 2014

Location: Down a hole under a tree.

Age: 30

Posts: 355

Bike: Shovel master

Okay cheers for the info buddy, Who imports the Tboltusa parts? And would there be a noticeable gain fitting a 64mm kit and a 28mm carb from a stock set up ?

Cheers Kieren

Ashmam06

Join Date: Apr 2013

Age: 32

Posts: 1,197

No

down rider

Join Date: Jun 2011

Location: Co down NI

Posts: 1,251

Bike: Honda msx,z50j

Try fiddyparts,motosyko and I've notice red circle on eBay are doing some TB stuff also.

I've ran TB 64mm 184cc/v2 head engine with a 28mm carb and it goes quite well.

Bones

Join Date: Nov 2012

Location: In my house

Age: 40

Posts: 914

Bike: z155v2 KLX PB

katoom

Join Date: May 2009

Location: Where ever i leave my hat

Posts: 7,794

Bike: A big pumpkin

As Bones said. Tbolt and Tb parts are different companies. Tbolt is a USA company, Tb parts can be had thorough various importers. (like some of the site sponsors) lol.

I'd go with the V2/+R head first, S25 cam, maybe piston to suit, (check for clearance) larger manifold and 28mm carb. (proper one, not a cheap one)
You'll notice the difference straight away and they'll still work great with further mods. (slight re-jet on the carb)

The BB kit with standard carb fitted first will work, not great though as it will be restricted by the crap standard head.
No point spending money on working the standard head, it'll never be as good as a V2/+R. (unless maybe you spend a small fortune on it)

KierenCrawford

Join Date: Mar 2014

Location: Down a hole under a tree.

Age: 30

Posts: 355

Bike: Shovel master

Okay cheers for the replys, I'm guessing that the V2 and the +R cylinder heads are pre worked or just better casted heads from two different company's ?

I am also winning a 4v head on eBay at the moment would a 4v with a cam be as good or better than a v2 or +r ? I've heard so much about how they are and aren't better but at the end of it 2 more valves are always better surely

KierenCrawford

Join Date: Mar 2014

Location: Down a hole under a tree.

Age: 30

Posts: 355

Bike: Shovel master

What's people's opinion on this kit, Is this a good price or can I get it cheaper else where? And Will it make a noticeable gain in power ?

katoom

Join Date: May 2009

Location: Where ever i leave my hat

Posts: 7,794

Bike: A big pumpkin

The 4v chink heads aren't very good unless loads of money is spent on them. (hell of a lot)
The V2/+R's are better straight out of the box and can be worked on for greater results.

Bigger valves, bigger/better shaped ports, ally roller rockers, and wider choice of cams inc De-comps.

To answer your other Q's.

Good.
Not sure.
Yes.