Project "walrus" Yam XS 750

Re: Project "walrus" Yam XS 750

Thanks tim!
I will probably measure if my stock springs are saggy...they dp feel softer than my RD forks,but they have spacers inside in order to bear with the light front wheel :)

Totally different question:ran across a guy who sells parts of his 850.
I think I will get the CDI box,since I want a spare box and probably convert my stock points to the 850 CDI.
Which parts will I need to get from the 850 to have a complete CDI ignition?

I guess:
-CDI box with cable string and plug
-flywheel?

Little bit lost here.

Next week my Yambits package wilö arrove with a galore of parts...cant wait for workshop time :)

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Re: Project "walrus" Yam XS 750

Hi Ryan
Yes you need the CDI box and then as you sit on the bike, everything under the left hand cover. That would include the pickup plate and rotor assembly including the M8 bolt. Basically everything down to the bare crank end.
Is there an oil cooler and adaptor plate on it? I would be interested - only if you don't want it?
Cheers
Tim

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Hi Tim!

Thanks!

For the oil cooler:Since my model is a stock 750 I guess I will need oil cooler,adapter plates, and the adapter (number 11 in daigram) for the oil cooler dont I?

For the CDI system:Am I right that I need: 5,7,8,10,11,6,9,15,17,16...the base plate does not seem to have a part number on cmsnl...
 

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Hi Ryan
Yes correct on the CDI = all parts you listed. The base plate I was talking about is #5.
On the oil cooler there are more parts = 11,17, 18, 19, 20, 25, 30 & 31 if they are there. 11 & 17 are the minimum to be useful.
While you are at it, didn't you have a charging problem? You should check the coils under the side cover on the opposite side to the ignition, do a quick check with a multimeter as per the previous post. If they are not open circuit then you are a step ahead. If there is a rectifier/regulator it would also be worth grabbing. From the photo the ignition coils have gone!
If you are really keen then the head would give you a step up in compression ratio from 8.5 to 9.5 and better cams - but how far do you go!!!
Good luck
Tim
 
XS750AU said:
Hi Ryan
Yes correct on the CDI = all parts you listed. The base plate I was talking about is #5.
On the oil cooler there are more parts = 11,17, 18, 19, 20, 25, 30 & 31 if they are there. 11 & 17 are the minimum to be useful.
While you are at it, didn't you have a charging problem? You should check the coils under the side cover on the opposite side to the ignition, do a quick check with a multimeter as per the previous post. If they are not open circuit then you are a step ahead. If there is a rectifier/regulator it would also be worth grabbing. From the photo the ignition coils have gone!
If you are really keen then the head would give you a step up in compression ratio from 8.5 to 9.5 and better cams - but how far do you go!!!
Good luck
Tim


I´m thinking about buying the WHOLE 850 motor and putting it into my 750 frame, then I will have no need to mess around with my 750 to 850 conversion...

does the 850 motor fit into the 750 frame?

So I guess I will buy from this guy (if he makes me a reasonable offer):

-850 motor (with all the oil cooling stuff attached)
-oil cooler
-ignition box
-loom if in good condition (is it hard to modify the 750 stock loom to 850 cdi specs?)

the guy said that the motor ran till the end without any hickups,what should i check when I visit the guy?

thanks in advance!
 
Ryan
Getting the whole motor would be the most logical option, if the price is OK and you have enough space. You have to assume the motor is dead and needs to be rebuilt as there is no way to reliably test it as it is. I don't know of many people that just start striping their bike out if it is perfectly OK.You could bore it out to 896!!!
Good luck.
Tim
 
XS750AU said:
Ryan
Getting the whole motor would be the most logical option, if the price is OK and you have enough space. You have to assume the motor is dead and needs to be rebuilt as there is no way to reliably test it as it is. I don't know of many people that just start striping their bike out if it is perfectly OK.You could bore it out to 896!!!
Good luck.
Tim

thats true!you cannot trust noone :) but since both of my 750 motor would need a rebuild too, i wouldnt lose much....

does the 850 go into the 750 frame with no adaptations (kardan and frame mounts) or would I need to modify my frame?
is there a way to turn the engine over by hand (maybe when I take the left hand ignition roto with a wrench)?
Do the coils match the 750 ones too?

cheers and thanks man you are a great help!
 
Re: Project "walrus" Yam XS 750

Hi Ryan
Yes if you take the LH cover off there is a M21 nut you could use to try and turn it over. It should turn easily if it is ok, don't force it.
On my 2D the front mounts are incorporated into the frame. On the later SE the front mounts are made up using 2 plates that you remove = easier to get motor out. Engines have exactly the same mounting points, therefore interchangable.
The 850 is a better motor for you to start with.
Cheers
Tim

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Re: Project "walrus" Yam XS 750

XS750AU said:
Hi Ryan
Yes if you take the LH cover off there is a M21 nut you could use to try and turn it over. It should turn easily if it is ok, don't force it.
On my 2D the front mounts are incorporated into the frame. On the later SE the front mounts are made up using 2 plates that you remove = easier to get motor out. Engines have exactly the same mounting points, therefore interchangable.
The 850 is a better motor for you to start with.
Cheers
Tim

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Thanks Tim!

I will try that this saturday.I will have a good look down the spark plug holes if there´s rust in the cylinders too...since we need to remove the exhaust too I will have a look into the exhaust outlets.

Should I go for the 850 loom too or is the modification for the stock 750 loom an easy task?

Just to make sure.Sorry to ask again man, will the 850 fit the 750 frame?


cheers!
 
Hi Ryan
I have never worked on an 850 bike, so I don't have personal experience. There are numerous posts where people have transplanted 850s into 750 frames, so I believe it is easy enough.
Body harness is all dependant on condition, the photo did not look like the wreck had been stored well?
Good luck
Tim
 
Harnesses are not only different from 750 to 850, they are different year to year and even model to model. And not just lengths.

Best thing is to get the loom for that particular engine but you might be needing to buy certain relays or such. Usually they were for safety features and interlocks. For instance, the 81 850 H engine added a starting circuit cut off relay preventing the engine from starting unless the neutral switch was grounded.

I did the switch with an 850 engine into a braced 750 frame, but I also completely deconstructed the harness to build a racing harness without the safeties and lights. Not worth the effort, though.

Best thing to do is get the wiring diagrams for both and see what you will need.





 
jcw said:
Harnesses are not only different from 750 to 850, they are different year to year and even model to model. And mot just lengths.

Best thing is to get the loom for that particular engine but you might be needing to buy certain relays or such. Usually they were for safety features and interlocks. For instance, the 81 850 H engine added a starting circuit cut off relay preventing the engine from starting unless the neutral switch was grounded.

I did the switch from 850 engine in a 750 frame, but I also completely deconstructed the harness to build a lightweight racing harness without the safeties and lights.

thanks jcw for the insight!
May I ask If you had to modify the 750 frame (motor mount wise) to fot the 850 motor?
 
Nope. But I think I did have to buy shorter front mounting bolts. Or maybe I just lost the old ones.

added pics above.
 
jcw said:
Nope. But I think I did have to buy shorter front mounting bolts. Or maybe I just lost the old ones.

added pics above.

thanks man!stunning bike!!any videos of how its running, and especially sounding :D?
 
Runs perfect. Keihin carbs from a Triumph that have been rejetting (mains and pilots), shimmed (needle) and synced.
Starting is almost there. I just have to fiddle with the idle at start. Engine fires with a 2 second crank. I have to keep the idle up for about 5 minutes, then the idle shoots up and I turn the idle speed back down. After that, it's stable. Torque is really good for an old bike. I have a kz1000 and low end grunt is pretty similar. Power hangs on till probably 8500, redlines 9000. Of course top end power isn't gonna compare to a modern bike. I used to ride a zx-11d, zx-10r and k1200r.

I can post a vid of it running. It's a little loud with the short, straight through, cheap supertrapps muffler I scavenged from one of my old bikes, but the sound is unique for sure.
 
jcw said:
Runs perfect. Keihin carbs from a Triumph that have been rejetting (mains and pilots), shimmed (needle) and synced.
Starting is almost there. I just have to fiddle with the idle at start. Engine fires with a 2 second crank. I have to keep the idle up for about 5 minutes, then the idle shoots up and I turn the idle speed back down. After that, it's stable. Torque is really good for an old bike. I have a kz1000 and low end grunt is pretty similar. Power hangs on till probably 8500, redlines 9000. Of course top end power isn't gonna compare to a modern bike. I used to ride a zx-11d, zx-10r and k1200r.

I can post a vid of it running. It's a little loud with the short, straight through, cheap supertrapps muffler I scavenged from one of my old bikes, but the sound is unique for sure.

sounds good man.
i´m currently thinking about buying these carbs (dunno if they are keihins or mikunis) for my build...maybe I will get them...
would you recommend going straight to the triumph carbs? (it has been already covered in this topic, just want to know youre opinion)
 

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They are the Mikuni carbs. Some Triumph owners go from Keihin to mikunis supposedly for a little more power. I have a set of both and find the Keihin better built. Parts, jets seems readily available for both.

The problem with the Mikuni cabrs is a tendency to wear the needle jet. So a used set of carbs may or may not have this problem.
http://www.factorypro.com/tech/needle_jet_wear.html
http://www.factorypro.com/Prod_Pages/prodtriumph0900Kiehin.html

The Keihin carbs have metal slides instead of the plastic slides.
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And the Keihin carbs I KNOW fit direct of the stock XS boots. I read that the mikunis retaining groove is different, but when I fit my set, it didn't seem bad.

Ryan Stecken said:
sounds good man.
i´m currently thinking about buying these carbs (dunno if they are keihins or mikunis) for my build...maybe I will get them...
would you recommend going straight to the triumph carbs? (it has been already covered in this topic, just want to know youre opinion)
 
Even though tuning my MKII's with pods was super easy, I'm thinking of trying a set of 38mm flatsides that I have on my Edge XCR 800 for fun.


 
Go straight to the Triumph-Mikunis. There's a set for sale for 149 in Vienna (willhaben). Best mod I ever did to mine. I'll go for some VM36 on my XS750, but that's a thing of personal preference.

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

So I started once again investigating into my ignition issues on my XS:

Battery seems to be dead (reads 12V cold,when I turn the starter it goes down to 8V...)
I guess I will try next weekend with a car battery and jumper cables.
Installed a new reg/rectifier.
There are 5 cables going from the stock loom to the reg/rectifier.3 white cables,is it important how these cables are plugged into the reg/rec?

Also no light and blinkers are working,no idiot lights (fuses are ok).any idea what could cause this complete failure of the lighting system?



The cables coming from the coil going to the ignition box are ok.
Changed plug boot.
No spark on cyl1.cyl2 and cyl3 have a nice bright spark.
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