Project "walrus" Yam XS 750

Re: Project "walrus" Yam XS 750

Hey tim!

I hate them too :) my charging system seens to work properly and the regulator too, i think my bike just sat for too long,i will need to charge the battery from time to time.

Today I got the new steel plates for the clutch,i have a question here:
Which side faces in what direction?there is a side with slighlty rounded edges and one side with sharp edges.
My guess is that the round edges should face in my direction when I'm installing the clutch...is that about right?

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Shouldn't make any difference which way you install the plates. I'd guess any radius is a result of the stamping process. As long as the "sharp" edge does not intersect with anything, it won't matter.
 
Doesn't really matter, but I'd put the sharp side towards the engine, so it can't catch anywhere. But this is really just a personal preference.
 
Thanks guys!will fit the steelies next weekend!

didnt have a lot of time this weekend but I fitted a new fuse box and replaced the old grimy and flimsy one :)
Interesting cause the last 5A fuse was named 'yvps'...did the PO use the box of an watercooled RD :)?

Had some reliability issues,next up will be checking all cable connections.

The bike was again running on only 2 and had weak spark,so I have to check all connections and rewrap my loom.




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Hey guys!

I have a carb/petock related question!

Since I didnt really have the time to deal with my carbs except cleaning them, I will start to investigate more in the course of the next weeks.

The bike was running a stock airbox (swiss cheesed by the PO).Jetting seems to be stock.
I´m running pods atm, since I´m not really eager to put that big chunky box back into the frame.

The bike starts well (as long as the battery is fully charged,charging circuit seems to work,14.2 when the engine is revved), but needs a lot of choke and makes terrible popping noises out of the pod filters, when the engine is warmed the popping stops and the engine revvs trough the range.

Is this simply a jetting problem (stepping up the mains for the pods),or could this also be a igntion related problem (maybe I misadjusted the ignition when I dissassembled the left case)?

I just dont understands that effin petcock (will change soon to "normal" one):
When I put the petcock on ON (air vent on the petcock is plugged) the bike starves on fuel, when I put it in PRIME the bike gets too much fuel...
What is the way to go?

Where can I find a guideline to check the ignition (XS 850 ignition) of my XS750?
Where would you guys go jetting wise?
 
Hi Ryan,

the popping noises are a sign that the carbs are a) not synced properly and b) running a bit lean. If you'd want to re-jet them completely, the most simple way would be to use a set of Mik 1 carbs or just all the jets out of these as the stock jetting is over-rich to say the least and works nicely with pods. Regarding the petcock: This one requires vacuum, so on "ON" it will simply not deliver any fuel. If it overflows on "PRIME", either your floats are as leaky as the ones in my Mik1 were OR the float-needles are shot. (I do have a working Mik 1, if you want - but then again, you have the Triumph carb, which can be made to work and if I were you, I wouldn't spend any extra minute on the old Mikuni and go straight for the Triumph carb, as you want to keep that one on the engine.)

A guide on how to setup the ignition is in your Haynes manual. To make sure it works properly, you should use a strobe to check if it adjusts the ignition correctly.

Cheers,
Greg
 
Re: Project "walrus" Yam XS 750

Since my Mikuni stock carbs have a hole in one diaphragm I completely focused on using the Mikuni Slingshot.
If the weather gods are nice I'll maybe finally can take this thing around the block.
Had to tinker a bit with the gas bowden to make it work but now I have nicely adjustable carb bowden.
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Re: Project "walrus" Yam XS 750

datadavid said:
Loctite 408 for the diaphragms

Thanks data!

The tear in the diapgrahm is not really large,how would you procede on using the loctite?would glue a patch on or just use the loctite itself?
Heard that vulcanising glue for bycicles can do the trick too?
 
Re: Project "walrus" Yam XS 750

Ryan Stecken said:
Thanks data!

The tear in the diapgrahm is not really large,how would you procede on using the loctite?would glue a patch on or just use the loctite itself?
Heard that vulcanising glue for bycicles can do the trick too?
No it does not work, unless its a nitrile rubber solution it will be dissolved by petrol. I borrowed some of this 408 from my local carb expert, and you just put a thin layer on the pinholes. Like magic
 
if datadavid's plan doesn't work, you can replace the diaphragms for $19.50/ea from JBM industries. I did a set of them once and was very pleased for the cost.
 
Re: Project "walrus" Yam XS 750

Thanks for the hint!

Just checked a European website...30 euro per diaphragm damn...and you need to destroy the plastic retaining ring and glue on the diaphragm...

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Re: Project "walrus" Yam XS 750

focusinprogress said:
if datadavid's plan doesn't work, you can replace the diaphragms for $19.50/ea from JBM industries. I did a set of them once and was very pleased for the cost.
Definitely not taking credit for my local carb expert's knowledge
If he says its good its good
 
Re: Project "walrus" Yam XS 750

Ryan Stecken said:
Thanks for the hint!

Just checked a European website...30 euro per diaphragm damn...and you need to destroy the plastic retaining ring and glue on the diaphragm...

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Librane? (At least that used to be the name they went by a few years back...)
 
So guys!
I pretty much "dumped" the stock carbs, after I saw the torn membrane, maybe some time I will fix it.Thanks for the hints guys!

I had a productive weekend.Had a terrible time remounting all the stock parts (mounting the reg upside down to the battery box is my favorite :))
Starting rewrapping the loom, which I had stripped for checking bad connections.

The Mikuni Slingshots are mounted and seem to run fine.Bike starts easily when cold.

Had an issue with a "hang up" of the revv´s when I checked the ignition with the strobe gun.
Checked the ingition timing on idle then turning the gas grip and the bike seemed to "hang up" in the revvs and took quite a bit of time to come down.Could false air intake cause this?
After the bike was "hotter" the problem vanished.


Ignition timing point seems to be a bit off, so I need to readjust a bit.

Here´s a little video (no hanging up in this):

https://www.youtube.com/watch?v=6KcasjGYDW0
 
Re: Project "walrus" Yam XS 750

Sounds reasonable,I checked one plug after running it and it was very clean and slightly light gray (not white).so that means fatten the mains I guess.

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Light gray should be fine... or spot on to be fair. There's some mix-screws on the bottom of the carbs, you could fiddle around with those as hanging usually happens in connection with lean-conditions on midrange.

Cheers,
Greg
 
der_nanno said:
Light gray should be fine... or spot on to be fair. There's some mix-screws on the bottom of the carbs, you could fiddle around with those as hanging usually happens in connection with lean-conditions on midrange.

Cheers,
Greg

Thanks for chiming in!

My needles are in "mid" position right now, IIRC you had your needle clips in bottom position didnt you?
Mixture screws are 2,5 turns out.
 
Hi Ryan
Before you start playing with jets you need to make sure the ignition is spot on along with everything else. Otherwise you will end up chasing your tail!!!
I have attached a collection of blogs I found online which helped me understand tuning carbies - hope it helps. The theory is the same even though you are working on different model carbies.
What was with the brake light on your video? Were you grabbing the front brake when you twisted the throttle?
Great progress.
Cheers
Tim
 

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