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Author Topic: I stepped in it - XS750/896 build  (Read 2998 times)

Offline Frenchtom

  • Posts: 18
Re: I stepped in it - XS750/896 build
« Reply #20 on: Feb 10, 2018, 08:32:35 »
Dang!  Ok, I'll probably keep the Mikunis and get what I can out of them. 
Tom
1963 Honda Sport Cub
1977 Yamaha XS896

Billet: about as creative as duct tape

Offline datadavid

  • Posts: 1333
Re: I stepped in it - XS750/896 build
« Reply #21 on: Feb 20, 2018, 11:56:56 »
Hi Tom
Nanno (If you search you will find his blog on this site) used 3 x Mikuni TM carbies to work on his XS750 sidecar. I think they were 36mm, but it was a lot of work, a real lot of work!! You have to figure out how you are going to get 3 carbie cables going into 1 throttle cable. And then you have the issue of 3 individual chokes - how do you activate them. You can only reach 1 of the 3 choke plungers. It has been done but Nanno has put his TM carbies on the market and is now using others that are more simple.
If you get a set from a Triumph 900 triple they basically fit straight in.

The Cruising Image pistons are meant to be made in Japan not China, but who really knows, they are what they are. As long as you have them and give them to the shop that will bore the cylinders on a proper rigid set up there will be no problems.
My machinist was pretty certain they (cruzin pistons)were not chinese. He would not have touched them if he thought so.
Some guys are picky..

Offline Frenchtom

  • Posts: 18
Re: I stepped in it - XS750/896 build
« Reply #22 on: May 09, 2018, 20:58:47 »
Ok, i swear i am going to do somehing on this bike this weekend
1963 Honda Sport Cub
1977 Yamaha XS896

Billet: about as creative as duct tape

Offline der_nanno

  • Posts: 384
  • Faster!
    • Greasy Greg
Re: I stepped in it - XS750/896 build
« Reply #23 on: May 10, 2018, 03:37:31 »
Hi Frenchtom,

Nanno here... Honestly: Don't do it with the individual VM/TM carbs. They work a treat, but sync'ing is a nightmare. Also I went with 36mm carbs and they were too big. I am currently running a heavily modified set of flatslides out of a snowmobile, but even then, simply getting Triumph-carbs is a way simpler method of doing things AND a whole lot cheaper. (See the link to my sidecar-thread or maybe on my blog, if I forgot to post on here with regards to how much work the flatslide carbs took to get going...)

That being said: Cruzin-Image is Taiwanese and as they seem to come from one of the big automotive engineering companies, they only contain a very small portion of recycled soda can's and what else was lying in front of the factory. Haven't used them on the XS-Triple, but on a Zed recently and yes, they are fine indeed. Tell you machinist to clearance on the tight side of stock pistons and you'll get lots of life out of them.

Maybe rearsets although I do not want to lose kick start capability.  I may need it with the high compression 896 kit, the starter may not do the job.

Take the starter apart and clean it from all the graphite dust on the inside. Plus add a NEW ground and live wire (get the cables made at a welding shop and tell them to solder and shrink wrap the ends as per specification for welders in humid climate, IIRC IP54 that is in American nomenclature) and you should have no problem whatsoever to start the bike. If needs must, the Honda CB900/1100 Bol d'Or run a 1.1kW starter, but if you add hotter cams anyway that will take away quite a bit of the dynamic compression and the engine will spin over just fine.
Real freedom starts with the freedom of thought.

My Blog:
http://greasygreg.blogspot.co.at

My Mule TR1.1 build here on DTT:
http://www.dotheton.com/forum/index.php?topic=75458.0

My Turbo TR1.1 (XV1000) build here on DTT:
http://www.dotheton.com/forum/index.php?topic=72571

My XS Triple Sidecar build here on DTT:
http://www.dotheton.com/forum/index.php?topic=74211

Offline Frenchtom

  • Posts: 18
Re: I stepped in it - XS750/896 build
« Reply #24 on: May 31, 2018, 15:28:57 »
So I dropped off the cylinders and big bore pistons yesterday at the local machine shop.  Should get those back in a week or two. 

I have been thinking about this whole carburetor thing and was wondering if buying a set from a 4 cylinder 1200cc bike would work?  I would only need 3 of them on my 900cc engine and could use one as a backup spare.  If this might work, what would be some models to look out for or avoid?

Thanks!
Tom
1963 Honda Sport Cub
1977 Yamaha XS896

Billet: about as creative as duct tape

Offline datadavid

  • Posts: 1333
Re: I stepped in it - XS750/896 build
« Reply #25 on: May 31, 2018, 16:34:27 »
So I dropped off the cylinders and big bore pistons yesterday at the local machine shop.  Should get those back in a week or two. 

I have been thinking about this whole carburetor thing and was wondering if buying a set from a 4 cylinder 1200cc bike would work?  I would only need 3 of them on my 900cc engine and could use one as a backup spare.  If this might work, what would be some models to look out for or avoid?

Thanks!
Tom
I think it would just be a matter of finding bikes with the right cylinder spacing. Fuel feed might be an issue as well as most 4 cyls will have t fittings between carbs 1-2 and 3-4.
Triumph carbs have a single inlet between carb 2 and 3 and makes life easier in general. Look for keihins at bike scrappers.

Offline der_nanno

  • Posts: 384
  • Faster!
    • Greasy Greg
Re: I stepped in it - XS750/896 build
« Reply #26 on: Jun 01, 2018, 02:57:18 »
Hi Tom,

do yourself a favour and get a set of Mikunis or Keihins for a Triumph Triple. You'll at most end up spending 50 extra bucks on the carbs and save yourself hours of hassle. I will build another set of flatslides for the XS-Triple in July, but Triumph carbs will definitely be cheaper.

Cylinder-spacing on the triple is even, so no carb-set out of a fourcylinder, that I have ever laid my hands on will match straight away, as they are usually 77-85-77mm spacing. (Except for some Honda Bol d'Ors and some of Yamahas FZR-line!)
Real freedom starts with the freedom of thought.

My Blog:
http://greasygreg.blogspot.co.at

My Mule TR1.1 build here on DTT:
http://www.dotheton.com/forum/index.php?topic=75458.0

My Turbo TR1.1 (XV1000) build here on DTT:
http://www.dotheton.com/forum/index.php?topic=72571

My XS Triple Sidecar build here on DTT:
http://www.dotheton.com/forum/index.php?topic=74211

Offline XS750AU

  • DTT BOTM WINNER
  • *
  • Posts: 416
Re: I stepped in it - XS750/896 build
« Reply #27 on: Jun 01, 2018, 07:27:37 »
Quote
Triumph carbs have a single inlet between carb 2 and 3 and makes life easier in general

Quote
do yourself a favour and get a set of Mikunis or Keihins for a Triumph Triple.

I totally agree with this advice. The standard Mikuni BST36SS from a Triumph T300 are working perfectly on my 896 after they were rebuilt. The Mikuni's are much cheaper, due to their reputation about the slide guides wearing. But parts are available. Buying the carbies and the parts to rebuild them, cost me about AU$300. which is very reasonably for what you get.
“Engineering is the art of being approximately right rather than exactly wrong.”

Yamaha XS750-2D
Yamaha XS896
Husaberg FE550
Yamaha TT250
Yamaha IT200N

Offline Frenchtom

  • Posts: 18
Re: I stepped in it - XS750/896 build
« Reply #28 on: Jun 03, 2018, 13:57:57 »
So I removed the valves from 2 sets of heads that I have.  I noticed that on my black colored head, the exhaust valves had a bit of play in them as I removed them from the guides.  The intake valves had no discernible play at all.  On my silver colored heads the exhaust valves had less play in them than the black heads but one of the intake valves had the slightest bit of slop.  I am thinking new guides are in order no matter which head I use.  How hard is it to replace valve guides?

I was thinking of smoothing out the intake and exhaust runners but after looking at them I cannot see and real opportunities.  Both runners are real smooth and clean.  Any advice on what I should do here?

Also, what should I look for on the valve and seats when it comes to damage or problem areas?  What are some things I should consider now that the heads are apart - re-machine or polish the seats, polish the back sides of the valves, clean everything, etc.?

Thanks,
Tom

First pic = black head
Second pic = silver head
third pic = intake runner
Fourth pic = crud on exhaust seat
Fifth pic = valve tool on bench
« Last Edit: Jun 03, 2018, 14:03:15 by Frenchtom »
1963 Honda Sport Cub
1977 Yamaha XS896

Billet: about as creative as duct tape

Offline der_nanno

  • Posts: 384
  • Faster!
    • Greasy Greg
Re: I stepped in it - XS750/896 build
« Reply #29 on: Jun 04, 2018, 03:11:23 »
Both inlet valves need a bit of play in their guides or otherwise they will seize up, once used under normal running conditions. If you pull out the inlet valves and have them 5-10mm off their seats you should have a forward and aft play of about 1mm. If you're not sure, whether the guides are worn, try moving them left and right. If you have (about) the same play in that direction as well, then the guides and valves are still good. If not then your should have a closer look. Usually the guides will have gone towards and oval shape, if worn. This can be seen very well if you put a light under the head, so it shines through the guides.

With regards to touching up the ports, as the pictures show, there's quite a bit, that can be done to these, but I have the nagging suspicion, that this would be your first go at porting? (no problem, just asking)
Real freedom starts with the freedom of thought.

My Blog:
http://greasygreg.blogspot.co.at

My Mule TR1.1 build here on DTT:
http://www.dotheton.com/forum/index.php?topic=75458.0

My Turbo TR1.1 (XV1000) build here on DTT:
http://www.dotheton.com/forum/index.php?topic=72571

My XS Triple Sidecar build here on DTT:
http://www.dotheton.com/forum/index.php?topic=74211