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Author Topic: Project "walrus" Yam XS 750  (Read 22110 times)

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #15 on: Aug 02, 2016, 13:07:16 »
Hi Ryan
Just looking at the photos and looks like a 2D and they had triple points ignition!!! A bitch to maintain.
Has it been converted to the later CDI???
Don't mean to tell you how to such eggs - but have you tested that you have spark?
Cheers
Tim

thanks for your insight tim!
the PO converted it to the 850 cdi setup...i have strong spark.this was one of my concerns...is it possible that the timing is off, even when the PO installed a cdi?if yes how can I check?

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #16 on: Aug 02, 2016, 15:30:53 »
I have another question guys concerning the stock brakes:

They are stuck so i'll nees to get them off and give them a good clean...there are three bolts holding the brakes,one has some kind of a rubber dampening to the screw...what is that screw doing?is it also holding the brake on the fork?
Just wanted to ask tou guys before i break something precious ;-)

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #17 on: Aug 02, 2016, 18:30:37 »
Hi Ryan
Difficult to install cdi the wrong way. The main thing to check is that the rotor is correctly engaged in the idex pin on the end of the crank. Also check that the index pin has not been push flush with the crank. Should run at that point, then you need a timing light to get the coil plate exactly correct.
Brakes, 2 bolts hold the brake assembly to the forks, undo first. The bolt with rubber damper  allows the caliper to float and self align with the disc. You can rebuild without removing. but if you are re building pull apart and make sure the caliper can slide on bolt.
Cheers
Tim

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Offline XS750AU

  • Posts: 176
Re: Project "walrus" Yam XS 750
« Reply #18 on: Aug 02, 2016, 19:44:15 »
Hi Ryan
You say your jets screw into the float bowl! That sounds like the Hitachi carbies used on the 850. The 850 cdi is great as it has electronic advance, but the Hitachi carbs have a bad rap. Hard to get parts including jets. What brand is marked on them?
What carbs are on the other bike, they may be a better option. Makuni series II with the 2 position choke are the best factory carb unless you go the triumph option. If you go the triumph option you will need to rejet as yours is a 750 and the triumph triples with carbs were 900.
Regards
Tim

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Offline datadavid

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Re: Project "walrus" Yam XS 750
« Reply #19 on: Aug 03, 2016, 08:20:34 »
Yes throw the hitachis as far as you can. Not worth the bother.

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #20 on: Aug 03, 2016, 09:33:37 »
Here are some pics...carb tops say mikuni...hope that those mkII's....
Edit:looks like they are generation 1 mikunis.
« Last Edit: Aug 03, 2016, 10:22:44 by Ryan Stecken »

Offline datadavid

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Re: Project "walrus" Yam XS 750
« Reply #21 on: Aug 03, 2016, 19:58:36 »
Those are mk1

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #22 on: Aug 04, 2016, 02:35:53 »
Should i throw them too into the bin :-)?

Just found that....
Will these fit my XS?what will I need to modify to fit these?
« Last Edit: Aug 04, 2016, 02:38:01 by Ryan Stecken »

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #23 on: Aug 04, 2016, 07:15:14 »
Yep Mk1
A lot cheaper to clean and new mounting rubbers than spend Euro199!
You are going to need new mounting rubbers no matter what carbi you have on it. I my humble opinion get the mounting rubbers and see how it runs. You are going to need to rejet the Triumph carbies before you even get started!!!

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #24 on: Aug 04, 2016, 15:16:16 »
Thanks tim!

Just finished cleaning my mk1 carbs lets see what they will do...i will set the mixture screws to 1 1/2 turns out for starters.

Just figured today that i have mk2 carbs on my parts bike...when i opened the carbs they were nice and clean but two posts where the floats are fixed were broken off...so i guess they are paperweights now.


Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #25 on: Aug 04, 2016, 23:31:35 »
What a shit!!!
The PO must of used a hammer to get the float pins out!
From the repair  manual, for carbs with 145 main and 17.5 pilot the float height should be 26.6mm and pilot air screws at 2 1/4. Does it have an aircleaner? Should start though but if the mounting boots are buggered and you don't have an aircleaner it is going to be lean.
Good luck
Tim

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Offline datadavid

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Re: Project "walrus" Yam XS 750
« Reply #26 on: Aug 05, 2016, 13:32:12 »
Yep Mk1
A lot cheaper to clean and new mounting rubbers than spend Euro199!
You are going to need new mounting rubbers no matter what carbi you have on it. I my humble opinion get the mounting rubbers and see how it runs. You are going to need to rejet the Triumph carbies before you even get started!!!
The bike runs so much smoother and better with those carbs, i believe its a justified investment. I also think the daytonas power figures are resembling the xs, a bit higher of course. May just need a different main and 1 needle shim.

Thanks tim!

Just finished cleaning my mk1 carbs lets see what they will do...i will set the mixture screws to 1 1/2 turns out for starters.

Just figured today that i have mk2 carbs on my parts bike...when i opened the carbs they were nice and clean but two posts where the floats are fixed were broken off...so i guess they are paperweights now.

I welded up a float post i broke on my ladys xs1100, they break too easy even if you do it the right way. Was good as new afterwards though, you cant even see its been broken. Kintsukuroi as the japanese say.

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #27 on: Aug 06, 2016, 04:55:14 »
If you can find someone to weld them for not much, then they would be great. If they want to charge shop rates then might be better getting the Triumph carbies.
Just check that the pitch and mounting boss on the engine side matches the mounting rubber boot internal diameter on the triumph carbies.
I am using a triumph 1050 header on the 896 and the pitch was perfect, but the head interface needs work to make it fit. The triumph carbies Dave used were a simple fitment. Was that correct Dave?
It should run OK on the Mk 1 carbies, at least to see if the rest is OK.
Cheers
Tim

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #28 on: Aug 09, 2016, 13:25:07 »
Hey guys...so today i tried to start the xs with the freshly cleaned carbies (mikuni 1).
Checked for spark and cylinder 1 has no spark,cyl 2 weak spark and cyl 3 strong spark.
It kinda ran on 2 cyl but only when I was holding onto the throttle.
The PO told me that the regulator unit might be shot,could this cause this issue?
Could it be some shot coils?

Red white and orange goes to the coil i checked for continuity to the ignition box the cables are fine.
Checked for volts coming out of the box...no volts on red white and orange.shot ignition box?

I also opened the oil cap of the motor and tried to move the main chain and I could move it up all the way to the motor lid...looks like theres a lot to do on that thing...




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« Last Edit: Aug 09, 2016, 13:30:44 by Ryan Stecken »

Offline Mi3ninos

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Re: Project "walrus" Yam XS 750
« Reply #29 on: Aug 09, 2016, 15:00:57 »
float posts can be repaired fairly easily.

http://www.yamaha-triples.org/workshop/Mikuni_MKII_Post_Repair.pdf

another common problem with the MKII is the air pilot screws often break at the tips. no replacements and the tip often breaks deep.

 as recommended prior 2.25 turns out is a good start and make triple sure the passages are clear. mine starts best at 2.75 turns out but runs and synchs  best at 2.5
« Last Edit: Aug 09, 2016, 15:09:13 by Mi3ninos »