big block XS250 (400) Turbocharged

[bentwrench]

That's what I found when I was looking too.

You will need a wastegate. Turbos don't know when to stop moving faster. A wastegate let's the exhaust gasses pass through, rather than spinning the turbo faster (until massive heat and force cause failure.)

And Turbo Word of the Day: Clocking. The act of changing the inlet and outlet angles on a turbo. "I clocked my turbo so that the intake and exhaust ports worked on my XS400."

 

[drewpy]

Firstly sorry Lcgtr for the slight highjack but i guess you'll need this info.

Looks like i am missing one part a collar maybe for the hose plate but these are the bits i got off ebay.
View attachment 8164
View attachment 8165

But its this part that fouls the engine lifting the plate by about 2mm
View attachment 8166

I think i'm right that this is a pressure plate, built in incase the filter becomes blocked allowing oil dirty or not to still get to the engine, didn't want to take it off and bypass the filter completely

found this on the German site. looks like he got another plate to pack out the one you have!

http://xs400.net/wb/media/faq_anhaenge/oelkuehleranbau/Oelkuehleranbau.pdf

 

[domains]

Waste gate works like a manual valve... half open half boost example.

I wanted to place a turbo on my xr650L other day but found out its best to leave stock for the turbo and I already have a big bore and stuff in it...

Learned 1 piston not really worth placing a turbo... 2 piston not as bad maybe.

no after market stuff for the xs400 so go for it

 

[domains]

And 2 carbs you will have to make a box or connecting tubing for turbo to carb

 

[lcgtr]

Did the porting today. I started the other day but got the Dremel snake caught in my shirt and sheared off the cable. I went to a place that makes spedo cables and they cut off the damaged part and re-formed a hex for me.
Then I shortened the outer and inner spring cable and now Im away.

Im happy with it for my first attempt.
I just read up on everything I could and tried to take the least amount away as possible from the main part of the tract. They were pretty good to be honest, the most work was around the bowls and the guide. Far cleaner than photos of XS650 castings I saw

I started on the combustion chambers but its taking ages with the tiny tool I have. Ill borrow a mates proper die grinder for that

 

[lcgtr]

here is the DOHC piston compared to the SOHC. The crown is a lot more pronounced
Would be good for a high comp motor

 

[drewpy]

don't forget, you want to go snooth/polished on the exhaust and rough finish on the intake.

so long as you just take all the sharp edges away and not get too carried away, you'll be fine with that (can't see pikkies very well)

 

[lcgtr]

Spent all day running around to get, source and collect parts, 8 hours ond 200km on the road.

Inlet manifold flange being laser cut

(its a shame they cant cut the xs logo into it as they need a 6mm radius to cut 6mm plate

 

[lcgtr]

I now have valves faced, also pulled the valves out of the DOHC engine and they are 1mm larger but 1 mm shorter, much lighter and in better nick so I may use them, just have to check the binding on the valve springs

Still cant get rings for my .50 over pistons and cant re-use the .25s (need to rebore)

Head is blasted, so is barrel
brought a CX500 tank
Cut the manifold off the turbo and trial mig welded too it. It welded fine, Its more like cast steel than Iron, hard as, the saw too ages to cut through. Im going to weld a 38mm Vband to the outlet off an external wastegate which will look good and work well.

The cartridge doesnt bolt in on any angle so Im restricted by the orientation of the oil flow requiring the exhaust to enter the housing on a tight angle, along with the fact it sweeps through a tight angle to enter the housing.

After spending 150 bucks on chemicals to try to strip the paint from the head my blaster only charged me 30 to make it look like its just been cast.

Just need to finish the combustion chambers then wash it all in the hydrowash and give it a good paint.

I have my DIY ceramic coatings and anti friction coatings on the way so thats the challenge next.

Im also getting back my old basket case bike to use for mock up as its easier to drop off at Dads work so he can do all the welding for me on the manifold and the exhaust system.

 

[drewpy]

cool, keep up the good work. Looking forward to seeing how this progresses

 

[lcgtr]

I had a mate who builds racing engines check out my porting work and he thinks Im on the ball, just need to take a fraction more out of he bowl on the inlets to improve the radius and polish the exhausts.
Im rethinking making a decomp plate though, especially since the lazer cutting was so cheap including them doing the drawing for me. I could just get it cut out of copper sheet to use between the cases and the barrel.
There isnt much meat in the crowns of the pistons to machine them down
Ill dummy assemble and then check the comp

 

[sprocket]

For decomp provision, early XS650 used a modified valve adjuster cover with a small lever that pushed open one exhaust valve to let off compression. Operated by a cable (like a choke cable)
Different real estate to be modifying, but might be easier and safer than a plate to do this simple task. Why re-invent the wheel?

I have a few XS400s in the shop, I'll look into a device to do the same job given existing architecture. Not sure how many high compression XS400s there are, if there's enough interest I may offer them.

 

[drewpy]

For decomp provision, early XS650 used a modified valve adjuster cover with a small lever that pushed open one exhaust valve to let off compression. Operated by a cable (like a choke cable)
Different real estate to be modifying, but might be easier and safer than a plate to do this simple task. Why re-invent the wheel?

I have a few XS400s in the shop, I'll look into a device to do the same job given existing architecture. Not sure how many high compression XS400s there are, if there's enough interest I may offer them.

He is fitting a turbo and will need to run 8:1 compression as opposed to to standard.

raising the barrel will effectively lower compression to stop the engine blowing up!

 

[Pork Chop]

A longer oil line collar and extra o-ring would be needed on a thick cylinder base gasket, especially as you are turboing the beast. Also, don't just use the paper gasket as a template as it is too thin between the cylinder and the oil line.

 

[lcgtr]

A longer oil line collar and extra o-ring would be needed on a thick cylinder base gasket, especially as you are turboing the beast. Also, don't just use the paper gasket as a template as it is too thin between the cylinder and the oil line.

Will do

3 hours this afternoon with a die grinder and a hand file

V-Band and flange ordered to weld to the exhaust housing

 

[lcgtr]

Ive been thinking a lot about this whole project and I think Im going to go the whole hog

Ducati 998R throttle body
I brought it a while ago to do my Norton but I can always track down another.

Im just worried about how hard this thing is going to be to tune and I dont want to go to all this effort and then have the thing ride like shit and be forever trying to get it right.
With EFI I can map it and tweak it to get it exactly right. So Microsquirt it is

Also I had the idea to get the bellmouth off a Turbosmart Supersonic BOV to attach to the intake which looks cool and hopefully the thing howls a bit more when it comes on boost

Ill machine down the housing a bit to clean it up

 

[lcgtr]

also I ground out the combustion chambers and finished the bowls on the intake. I just need to polish the chambers and the exhaust ports now.

I changed my mind on the flange and have got them to water cut it to keep the logo, they had to mod it to get it to work but it should still look trick

 

[bentwrench]

Microsquirt FTW. I'm running a Megasquirt on my turbo miata. I love open source.

 

[lcgtr]

Got hold of my old Basket Case XS250 on the weekend again (completly gone full circle 2.5 years down the track). It will come in handy to fab the inlet and exhaust along with the plenum, also I have enough parts now to make 2 bikes

Picked up the flanges today, they came out great

Thanks to Action Laser Cutting in Bayswater and their sister water jet company Intracut

Got the throttle boddies apart

Also removed the liners from the DOHC barrel to use to machine out a 250 barrel

Cant get aluminum tube in 32mmID anywhere but Ive found 2 thermostat housings that I may be able to use to fab the intake.

Finally got a set of .75 and now a set of 1.0 NOS pistons and rings on the way to do up both engines as 400s
DIY ceramic coatings are on their way
Assembly to start soon.

Anyone got any suggestions as to how I determine which bottom end is in better condition without splitting the cases?

 

[drewpy]

When I read about an xs turbo done in another forum, the guy had his crank fully welded as the old one twisted due to the forces involved.

I would take the cranks out to measure them and get it balanced and welded.