econti
Hi guys
Got a '94 888 with a ST4 engine in. I bought the bike unfinished.
The exhaust headers have issues. The vertical and horizontal cyl pipes don't match up at all, and the horizontal one hits the crankcase very badly. I believe they are the original 888 headers. Part number stamp is ZDM-M07 on the vertical and M20 on the horizontal. is this original?
What's going to be the easiest solution? The facebook page suggested 916 heads but I'm not too convinced, and money is very tight at the moment due to some family issues so I'd rather not have to buy new heads just yet.
I do have oxy acetylene gear at work, has anyone bent the pipes to fit by heating and bending?
This bike is proving to be a serious test of my patience. Original bikes rule.
brad black
port locations are the same on all, so it matters not what they are. i have st4 headers on my 851, but the vertical header needs some massaging where it goes through the swingarm.
stiglarsenDK
I belive your rear/ vertikal pipe is from something else .. a std strada set Will have M07 on the horisontal and N07 on the vertikal.. a SP4/5 Will be M09 and N09.. upload some fotos mate !
I have the large diameter system from Sp5 on a st4s engine , perfect fit
econti
Hm. That might be why. The horizontal touches the casing on the very back corner where the centre stand would bolt, so perhaps the ST4 has a deeper sump than the 888?
Attached pic is the headers. The vertical is sort of close to fitting, as in I think I could make it fit with some massaging with the oxy gear. They are obviously not seized together, I just sat them there for the picture.
stiglarsenDK
Cases are the same.. vertical sektion is not right.. look for an org one. Im sure some one here have one..
econti
I wonder why the horizontal hits the cases. Perhaps someone tried to bend it to make the vertical fit and has made it all worse.
Out with the oxy torch this weekend, if no joy then I'll find/make some
Mr.R
The OEM 851/888 headers are a little on the small side for good performance, since you've now got a 916cc motor I'd look for a set of ST4/ST4S headers and modify them to fit.
Both Brad and Griff have posted about this mod' in the past on here, do a search to find out what to do.
The OEM 851/888 parts will strangle any extra performance from the extra cc motor.
Steve R
econti
Update: I am a moron (as usual).
I looked again today. It seems the vertical header is an original 888 item, and the horizontal header is off a Monster S4.
I tried to bend the horizontal with oxy to get it to suit but it didn't want to go.
I have been searching to no avail to find someone fitting a S4 system on these bikes. I guess it just doesn't fit. Can anyone confirm?
I might just try find an original horizontal piece just to make the bike run. I don't have the money to dick around with custom bits at the moment.
econti
Seeing as the S4 header is not worth anything, I ripped in today. Lopped the end off it after the collector, found that it would be 20mm too short, cut up an old driveshaft from a Toyota Supra I had lying around, cut and bent it to suit the size, and welded it in.
Ran out of welding wire 2 beads before finishing it. Cool.
Looks like it fits well though.
I will need to bend or cut+weld the muffler attachment points however, or make drop brackets for them. It'll look pretty bad if I do that however.
Being Good Friday nowhere is open but hopefully tomorrow I'll get some wire and continue.
brad black
to get the st4 headers in you need to hit them with a hammer about where it goes through the swingarm. s4 would be the same, but being smaller might need less hitting.
mine made no more power from memory once the beaten section was cut out and replaced with a nice piece of pipe.
if you can fabricate i'd get a 748/916 header set (should be cheaper being reasoning) and use that as a basis. cut the vertical pipes off the flange and flip them to exit on the lh side.
econti
What do you reckon the optimal diameter is for a regular ST4 engine, as in is it worth getting some flanges then fabbing a full drainpipe 2-1/4 or 2-1/2?
Or the 2in (50mm?) is fine for all but a race motor?
Mr.R
Equal length headers/spaghetti system with 50mm diameter work pretty well for me.
...and the factory 888/966cc race motors.
I got 128 rwbhp and 76.8 ft lbs of torque from my mildly tuned 851/916cc motor, using a 50mm Spaghetti system.
It would pull like a freight train from as low as 2,500 rpm all the way to the red line.
I'm using the same exhaust system for my slightly higher tuned 955cc motor, I expect to hit somewhere between 136-140+ rwbh and 80+ ft lbs of torque with this motor.
Steve R
econti
Jesus. What was done to make it "mildly tuned"?
