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Author Topic: Project "walrus" Yam XS 750  (Read 26717 times)

Offline jpmobius

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Re: Project "walrus" Yam XS 750
« Reply #75 on: Aug 15, 2016, 15:42:11 »
Brake fluid (most types) are quite hygroscopic which means it attracts and absorbs moisture.  That's why the pistons corrode if you don't swap out the fluid once in a while.  Stainless helps a lot to stop this (stainless still rusts under this sort of situation) but the fluid performance can go terribly wrong if allowed to accumulate enough water so you still need to change fluid at regular intervals.   I wouldn't use any sort of power tool on any interior brake part unless I was honing a bore which is these days pretty much a last resort.  I also don't let any sort of chemical near any brake components except brake fluid (anti-squeal vibration dampening goo and grease for sliding pins and housings being the exception), and commonly have a little bowl to dunk parts in as they get assembled.
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #76 on: Aug 17, 2016, 12:18:15 »
Thanks Mobius for chiming in!

I´ve been busy with minor things (life), the last days but i´ve collected a variety of new parts.
Just ordered new seal kits for the brakes,forks et cetera.

How do you guys decide if a fork needs servicing or not?
My fork seals seem to be good in shape (no oil or dirt whatsoever),the chrome on the fork legs is good, no pitting or scratches.
Would you guys just drain the fork oil and let it be?the forks seem to be a bit saggy, but that could also be because of the weight of the bike...there are some kind of adjusters on top, maybe i can just readjust them.

thanks in advance!

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #77 on: Aug 17, 2016, 18:54:00 »
Hi Ryan
Don't let forks scare you, 1970s forks are very simple. As a minimum drain the oil and replace with new. After 40 years with a heavy bike resting on them the springs will have sagged. So a new set would make a difference. They are easy to get out. You may need to spray some penetrating oil around the end plug to free it up.  You push the end plug down 1 or 2 mm and with a small blade screw driver lever  out the retaining clip. The spring can then be removed. Once you have removed the spring you can wash the fork out and flush out any rubbish. New oil and springs at the correct length will make a difference.
Cheers
Tim.

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« Last Edit: Aug 18, 2016, 05:47:03 by XS750AU »

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #78 on: Aug 19, 2016, 04:43:51 »
Hi Ryan
Don't let forks scare you, 1970s forks are very simple. As a minimum drain the oil and replace with new. After 40 years with a heavy bike resting on them the springs will have sagged. So a new set would make a difference. They are easy to get out. You may need to spray some penetrating oil around the end plug to free it up.  You push the end plug down 1 or 2 mm and with a small blade screw driver lever  out the retaining clip. The spring can then be removed. Once you have removed the spring you can wash the fork out and flush out any rubbish. New oil and springs at the correct length will make a difference.
Cheers
Tim.

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Thanks Tim!
Then I guess I will do the forks too.What do you think about Progressive Springs for the XS?generally new springs are darn expensive (100 euros here in austria)...

Offline XS750AU

  • Posts: 211
Re: Project "walrus" Yam XS 750
« Reply #79 on: Aug 19, 2016, 21:16:54 »
Hi Ryan
Originally they did not have progressive springs. I fitted Progressive Suspension part number 11-1117 to the 750 when serviced my forks. The XS factory spec states the free length was 503mm as you can see in the photo the original springs measure closer to 493mm. Not much sag but still have sag. The  Progressive Suspension 11-1117 free length is 521mm with a progressive rate. That meant a 18mm preload - they do bottom out (and thats not on the Paris to Dakar either!). I weigh 90Kg so you can judge from there how they would suit you.
Unfortunately there is not a lot of choice on spring rates that I have found. I believe Hagon sell fork springs but I have not got the data on them. Progressive do make a higher rated spring (11-1107) but it is only 457mm long, so would need a 50mm spacer, which is doable.
The longer springs you can see in the photos are from the XS750SE which is the basis for the 896 which I am building up. Their specified free length is 606mm and they are measuring 600mm. I am going to have a play with the 2D  springs which are currently measuring 493mm to see if I can reset them to 500+mm. Involves stretching and heat - just got to confirm the heat process. I believe it is just low temperature stuff though!! Anyone out there that has reset their springs???
Cheers
Tim

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #80 on: Aug 21, 2016, 11:07:02 »
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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Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #81 on: Aug 21, 2016, 20:28:04 »
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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Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #82 on: Aug 22, 2016, 04:42:55 »
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...

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #83 on: Aug 22, 2016, 05:34:56 »
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

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #84 on: Aug 22, 2016, 07:55:29 »
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!

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #85 on: Aug 22, 2016, 09:10:54 »
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

Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #86 on: Aug 22, 2016, 09:39:14 »
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!

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #87 on: Aug 22, 2016, 18:59:43 »
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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Offline Ryan Stecken

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Re: Project "walrus" Yam XS 750
« Reply #88 on: Aug 23, 2016, 08:00:28 »
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!

Offline XS750AU

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Re: Project "walrus" Yam XS 750
« Reply #89 on: Aug 23, 2016, 09:16:13 »
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