big block XS250 (400) Turbocharged

Engine is mostly together, got temporary carbs to get it registered and adaptor plates water jetted to adapt them.
I've just smashed my laptop so it's not easy to upload photos.

I'll makeup proper entry soon, thanks for the encouragement guys
Awesome build and info. I LOVE spinny things, though I doubt I'll be putting one in my bike. (Will be a budget build challenge :D) But that IHI turbo link should have been hidden from me. I am seriously contemplating ordering several. I'm thinking a turbo push mower and a turbo chainsaw at the minimum :pimp: (Oh, oiling solution nightmares, here I come)

Anyways. Keep up the awesome work. Can't wait to see the "It Lives" post.

Sounds interesting mate, post some photos
Will do a thread when I get started. OT here has been great but time-consuming. And broke a rib yesterday :doh: I'll get things done one day. Keep the updates coming.
So put the bottom end together, then bumped into a mate and ex-motorcycle racer who said I should definatly use shaft loctite on the gearbox bearings...... so I split it again, then put it back together again and got the pistons in and the barrel on.


Its a dam shame but the paint flakes, scratches and comes off with chemicals really easy, despite all my effort....... such a shame.
I possibly didnt bake it long enough or hot enough.

Just lapped in the valves so head will be assembeled and back on next week.

I decided not to ceramic coat anything in the end as I simply dont trust it (or dont trust my luck) and if any of it de-laminated and went through the motor it would break my heart.




looks so nice but nobody will see it


Wish I took this photo BEFORE I pulled it apart


This dude came with my spares from They have been way better to deal with than local suppliers

Brought some cheap Mikunis off Ebay, VM flange type, Im sure you guys have seen them. They are advertised as 30mm and measure that at the intake but are only 26 through the guts

I got some adaptors lasercut to fit them
Should work out as a cheap and good upgrade. Ill post jet sizes when I work them out
Heres the carbs next to some TM28 carbs I brought for my Tornado which would also go will on the 400.

The more reading I do the more I think the FCR is way too large..... plus Dad hasnt gotten anywhere building the 2-1 manifold so Im going to register it with these carbs and probably run around on it in the summer NA and finish off the turbo and EFI conversion once the rain starts coming. Then Ill use these carbs on the parts bike which Im doing up for a mate to come riding with me.









those smaller carbs will be good for torque with the turbo feeding the upper end (that's the theory)
looking great though and can sympathise re the paint. the only paint worth its salt was PJ1 but its no longer made in silver.
I thought that myself but cant find info on blowing through VM type carbs, everyone uses CV carbs.

your not wrong there, I've also seen stromberg carbs on turbo's too. the CV meters the fuelling based on air flow and not rider input.

You might have to rethink that one
if you tune the motor right and play with the igntion timing alter the frame and running gear your looking at atleast 90bhp as a max , im build a xs250 turbo currently but im putting a cb450 motor in as the bottom end is bullet proof and changed all my running gear to gixxer 600 and mono shock conversion ! if you tune the bike right and support all stress it can easily touch 90bhp and give a 600cc+ sports bike a run for there money :)
4th oversize (1.0 ) only because I managed to get 2 sets of rings.
I have a NOS set of .75 3rd oversize pistons and rings and a set of 2nd oversize pistons only left over.
Rings are getting harder and harder to get, if you love your bike and intend to keep it I'd be looking out for a set.
You can get custom ones made but you could by another bike cheaper
here's some interesting facts for you concerning the entabulator which you may need to use with the turbo

picked up a genuine Nitroheads from Gumtree for $250


I think it will look good for the time being



Finished up the adaptor plates to mount the carbs




good fit



My mate wasnt happy with the combustion chambers so he decided to do some more dentistry



Engine together







Ready for rego now
that seat is sweet and the engine's looking hot!

not sure how that entabultor's gonna work in there though!