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Author Topic: XS750 to XS896 big bore  (Read 13808 times)

Offline XS750AU

  • Posts: 202
Re: XS750 to XS896 big bore
« Reply #75 on: Aug 21, 2016, 00:28:02 »
If I could have found an XS850 oil cooler, either OEM or aftermarket I would have bought it. But you have to get all the parts, including squish plate and threaded adapter socket. XS1100 and XJ650 are the correct size but have the outlets exiting out the side rather than front and foul the engine mounts. After 2 years of searching without luck, I finally gave up and bought a Ebay Chinese 7 row AN8 Universal oil cooler kit. I knew at the time that the sandwich plate in the kit would not fit, so that's why I am making a new plate. Now if you have a spare XS850 plate & socket in the shed, let me know, as they are a more elegant solution!!!
Confirmed a few more measurements today and I have been able to reduce the thickness from 32mm to 28mm. How thick are the genuine plates?
Photos are of all the features that need to be considered when making the plate.
Cheers
Tim

Offline Psycrow

  • Posts: 77
Re: XS750 to XS896 big bore
« Reply #76 on: Aug 21, 2016, 01:28:54 »
very Cool!

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Online datadavid

  • Posts: 1025
Re: XS750 to XS896 big bore
« Reply #77 on: Aug 21, 2016, 03:49:16 »
http://www.roffesshop.se/index.php?route=product/product&filter_name=Xs750&product_id=14770
They can still apparently be bought from sweden.
Edit: this one was even cheaper, no thermostat.  And it looks like ports are facing the right way.
http://www.roffesshop.se/index.php?route=product/product&path=71&product_id=14765
« Last Edit: Aug 21, 2016, 04:11:45 by datadavid »

Offline XS750AU

  • Posts: 202
Re: XS750 to XS896 big bore
« Reply #78 on: Aug 21, 2016, 04:27:28 »
Thanks Dave
The cost came to AU$390, so I passed on it and will stick with shed time!!!!!! Thank you for your help though.
Lucky day - I was able to spend most of it in the shed - next weekend is a write off!!
Morning was oil cooler and afternoon was the start of the headers. Cut all the 90o bends to length and flanged them with the tool I made and a ball peen hammer. Very happy with the result. I also made up some new header clamps out of the off cuts.
The photos are the sequence of forming.
Cheers
Tim

Offline doc_rot

  • Posts: 773
  • Oh the usual... I bowl, I drive around...
Re: XS750 to XS896 big bore
« Reply #79 on: Aug 21, 2016, 13:06:51 »
You're doing some cool work here. I'm on board.
---------------------------------
'78 KZ1000  Project

'80 KZ750 Twin Project

Offline Psycrow

  • Posts: 77
Re: XS750 to XS896 big bore
« Reply #80 on: Aug 21, 2016, 16:48:36 »
watching this one.. nice work!

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Offline XS750AU

  • Posts: 202
Re: XS750 to XS896 big bore
« Reply #81 on: Aug 22, 2016, 07:23:26 »
When I was playing with the headers I checked if there was much mismatch between the exhaust port and the header ID - it is considerable. The red circle is the 34.5mm ID of the header pipe, as you can see there is a lot of metal inside that circle for the dye grinder to remove. The exhaust valve OD is 31mm and it has a stem which also eats into the flow diameter, so there is no need to take it out all the way to 34mm. I am thinking the area down the bottom of the port where is has flattened out is in for particular attention. Any body who has experience in these matters I am all ears!
Cheers
Tim

Offline doc_rot

  • Posts: 773
  • Oh the usual... I bowl, I drive around...
Re: XS750 to XS896 big bore
« Reply #82 on: Aug 23, 2016, 19:30:16 »
"D" shaped exhaust ports are quite common on a lot of high end machines. Are you porting this head just based on guesswork? There are a ton of factors to consider before you go making the ports bigger. I would clean up the casting marks and have the head bench flowed to see what cfm it's doing. It is not uncommon on these old Japanese bikes to have valves and ports too big, so you may be close to the sweet spot right now. By making the ports bigger you may actually reduce velocity and kill horsepower. Same thing goes for the header ID. Going bigger than the exhaust port is only going to reduce velocity as well. How you plan on riding this thing should be the main thing to consider here. Is it a bike you are going to race or scoot around town? You obviously got some chops  so I apologize if this post is redundant. I have been slowly researching for a kz750 twin hot rod build so I am watching with interest. I may build this DIY flow bench which uses a laptop and a shop vacuum
http://www.flowperformance.com/system.html
« Last Edit: Aug 23, 2016, 19:32:50 by doc_rot »
---------------------------------
'78 KZ1000  Project

'80 KZ750 Twin Project

Offline jcw

  • Posts: 60
Re: XS750 to XS896 big bore
« Reply #83 on: Aug 23, 2016, 20:34:50 »
+1

Touch that floor especially if u take it back to the gasket and u will kill exhaust velocity and power.

Taller higher ports flow better.

In fact, the overhang might even prevent some exhaust gas reversion.
I don't think it's a whore shot until you start posting pics of it on other people's build threads.
So it's all good.   8)
trek97

Offline XS750AU

  • Posts: 202
Re: XS750 to XS896 big bore
« Reply #84 on: Aug 23, 2016, 21:51:33 »
Thanks Doc & jcw.
Greatly appreciate your input and help to avoid disaster. Once the material is removed there is no going back.
This bike is not going to race. I prefer to avoid built up areas and find a nice twisty country road. So the bottom line looks like leave the ports as they are and only touch any obvious casting defects (which there are none).
Thanks again for for you great help.
Cheers
Tim

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Offline doc_rot

  • Posts: 773
  • Oh the usual... I bowl, I drive around...
Re: XS750 to XS896 big bore
« Reply #85 on: Aug 24, 2016, 00:15:46 »
there's no saying what is optimal unless you do a flow check and do some calculations based on your cc size, cams, carbs...etc I'm just guessing that if you do porting it won't be much. You can polish the exhaust ports and clean up the intakes but leave them rough. Finding a header tube size that matches your exhaust port will help a lot as well
---------------------------------
'78 KZ1000  Project

'80 KZ750 Twin Project

Online datadavid

  • Posts: 1025
Re: XS750 to XS896 big bore
« Reply #86 on: Aug 24, 2016, 04:06:29 »
I am nowhere near an engineer so i just gave my in and x ports a light sanding. They were a bit coarse.

Offline XS750AU

  • Posts: 202
Re: XS750 to XS896 big bore
« Reply #87 on: Aug 24, 2016, 07:02:00 »
took the plunge and bought an ultrasonic cleaner after reading a NASA research paper.
They are bloody great - petcocks before and then after  10 minutes in the ultrasonic with a little bit of dish washing detergent.

Offline Ryan Stecken

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  • Posts: 1628
Re: XS750 to XS896 big bore
« Reply #88 on: Aug 24, 2016, 09:08:42 »
Wow really nice!
is there a reason you stick to the stock petcocks, i heard that the membranes tend to break pretty easily?
I thought about swapping out for "normal" petcocks with on and off function on my project.

Online datadavid

  • Posts: 1025
Re: XS750 to XS896 big bore
« Reply #89 on: Aug 24, 2016, 14:27:23 »
I just blank off the membrane part on my taps, and have Up as the off position. One less thing to worry about👍