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Author Topic: Project "walrus" Yam XS 750  (Read 45958 times)

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #130 on: Sep 11, 2016, 07:14:30 »
Hi Ryan
The info you have is for the XS750E which had mark II Mikunis
Your bike is a XS750-2D with Mark I and 17.5 pilots were standard with 145 mains.
Cheers
Tim
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Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #131 on: Sep 11, 2016, 10:03:19 »
Thanks tim!

Do I measure the float height from the gasket surface with or without the gasket?

Just investigated more...what is the starter jet?idle and main is installed in the float bowl but where do I find the starter jet in the diagram?
Thank you!

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Offline advCo

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Re: Project "walrus" Yam XS 750
« Reply #132 on: Sep 11, 2016, 12:31:48 »
No gasket when measuring float height, but measure from the surface be gasket sits on to top of the float. I lean the carbs at about a 45* angle, too. Put them on the side so the floats are hanging away from the needle valve (not touching) then rotate them back until they are just barely touching the spring loaded pushrod at the top...to make sure the weight of floats themselves are not skewing your measurement


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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #133 on: Sep 11, 2016, 19:16:19 »
Hi Ryan
Bloody repair manuals, you can't live without then, but sometimes they send you crazy!
Apart from that listing, I cannot find any other reference. Now I have never worked on a BS34 series I, but the only other "jet" I know in the starter circuit is the air pilot jet. It is located in the air inlet area. On the series II there is a jet that is removable. If your series I also have a removable jet in the air inlet, I am guessing that is the starter jet????
Hope there is someone else who knows exactly online.
Cheers
Tim

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Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #134 on: Sep 12, 2016, 04:06:10 »
Looks like I might have found the issue...
Had a telephone call yesterday with the a german triples club member.
The starter jet is pressed into tje float bowl.
There is a brass tube running into that tiny orifice in the float bowl.
When I cleaned the carbs I forgot the clean that orifice thoroughly (the float bowl was filled with gummed up gas).
This is the reservoir for starting gasoline.
The tiny bore ends in a small hole which tends to gook up.
I currently soak it in carb cleaner...lets see...

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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #135 on: Sep 12, 2016, 04:44:45 »
Got to love the internet and modern communications.
One question - I thought you had bought a new set of Triumph Makunis? Why bother with these BS34 series I???
Good luck
Tim
« Last Edit: Sep 19, 2016, 08:28:47 by XS750AU »
“Engineering is the art of being approximately right rather than exactly wrong.”

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Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #136 on: Sep 12, 2016, 04:49:58 »
Got yo love the internet and modern communications.
One question - I thought you had bought a new set of Triumph Makunis? Why bother with these BS34 series I???
Good luck
Tim

The "new "Mikunis didnt arrive yet...it takes 2 weeks (!!) for stuff to arrive from the UK going to austria.
Since I have 2 Xs 750´s (the one i´m working on right now wills stay stock) I have to deal with that carb anyways :-)

Offline datadavid

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Re: Project "walrus" Yam XS 750
« Reply #137 on: Sep 12, 2016, 05:00:56 »
Late night carb cleaning.

Jets and passages were clean.
Blow trough all orifices and jets,even the idles were clean.
I have no idea why there 17.5s idles in this carb....
Will swap for 42.5's and see what happens (manual says 42.5 should be stock).
Cylinder 1 float was maladjusted.
Do I measure float height with or without the float bowl gasket on the carb?

Thanks in advance!

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First you need to verify the jetting for these specific carbs. Mk1's may or may not have a completely different fuel delivery system compared to mk2's. I dont know, i never read anything about them and only ever worked on mk2 carbs. 17.5 may well be the correct stock size.
Soaking may not suffice in cleaningg the fuel passage, probe it with a wire as well.
You measure float height without gasket.
And as i said in pm, those triumph mikunis have a reputation for rapid needle and needle jet wear, that is why they swapped to keihins on later models.
I would not buy them as they are fundamentally flawed.
« Last Edit: Sep 12, 2016, 05:04:35 by datadavid »

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #138 on: Sep 12, 2016, 05:17:10 »
Thanks data!
Checked and doublechecked,17.5'd are the right idles for the MK1 carbs.
I will blow them trough and check with a wire.
Which bike models had these keihin carbs?when I receive the carbs i will have look and probably send them back.

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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #139 on: Sep 12, 2016, 09:03:00 »
You have to at least stick them on and see what happens!!!
If they slip straight on, it would be too tempting for me to not try them.
“Engineering is the art of being approximately right rather than exactly wrong.”

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