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Engine swap 1986 xv1100 into an 1981 xv750se

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Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Mon May 03, 2021 1:26 pm

Is this possible?
My engine broke and it needs a rebuild so I'm thinking of replacing it instead of rebuilding. I could get that 1100 for a good price but would it fit in the 750se frame?
Last edited by Jake on Mon May 03, 2021 1:49 pm, edited 1 time in total.
Reason: Moved topic » from Yamaha Virago XV750 to Virago Help - Motor Swap

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Jake » Mon May 03, 2021 1:51 pm

Yes, with the 1100 TCI and a few wiring changes, plus using the 750 engine mounts, and you’ll need the 1100’s foot rails.
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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Mon May 03, 2021 3:10 pm

Jake wrote:Yes, with the 1100 TCI and a few wiring changes, plus using the 750 engine mounts, and you’ll need the 1100’s foot rails.


Thanks Jake!
Can you be a bit more specific about the "few wiring changes"? :bg:
And, why would i need the 1100's foot rails?

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Jake » Mon May 03, 2021 3:41 pm

The solenoid for the starter is wired differently, and the engine side cases are rounded whereas the ones on your 750 are flat.
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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: faffi » Mon May 03, 2021 4:09 pm

You can read some of what's required here viewtopic.php?f=61&t=51585&start=40#p450855

I eventually converted my 1100 engine with the clutch, including stronger springs, and clutch cover from my old 750 in order to be able use the stock Gen 1 footpegs. I also used most of the wiring harness from the Gen 2 bike, blended in with the old bike's instruments and fuse box viewtopic.php?f=33&t=55106&sid=8012ccd2e9581617dcc9ceeea1ef2a44#p450816 and viewtopic.php?f=140&t=55339 might help.
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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Jake » Mon May 03, 2021 4:27 pm

Thanks faffi.
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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Tue May 04, 2021 4:08 pm

Thanks a lit guys! I went and picked up the 1100 engine and removed the 750 from my bike. A couple of questions:
- the 1100 engine doesn't have the TCI. Can I use the 750 one?
- the 1100 doesn't have carb. Can i use the 750 carbs. Should i go with two or convert it to a one carb setting.
- any instructions on how to modify the solenoid wires for the starter
-the 1100 engine has the rectifier still attached. Should i use it or the 750 engine one?
- the 1100 had no ignition coils so can i use the 750 ones?

I still might have some questions after i install the 1100 engine on, but thanks for all the help.

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: faffi » Tue May 04, 2021 4:38 pm

A couple of questions:
- the 1100 engine doesn't have the TCI. Can I use the 750 one?
Not unless you can move over everything else related to the ignition

- the 1100 doesn't have carb. Can i use the 750 carbs. Should i go with two or convert it to a one carb setting.
I would retain two carbs. You can probably use your old ones, but jetted like the XV1000/TR1. The later carbs used on the XV1100 are better, though, and easier to get parts for.

- any instructions on how to modify the solenoid wires for the starter
I didn't modify anything AFAIR, just hooked everything up like it was on the 1100. But I could be wrong, it's been 5 years of forgetting since I did it.

-the 1100 engine has the rectifier still attached. Should i use it or the 750 engine one?
The 1100 one. Make sure it is probably grounded.

- the 1100 had no ignition coils so can i use the 750 ones?
See your first question. You will be happy if you can make it work, because fitting the coils from the Gen 2 is a PITA. But you cannot mix and match the two systems, it's either Gen 1 or Gen 2.

You should try to engage member nanno for confirmation, though - he has forgotten more about these bikes than I can ever hope to learn.
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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: nanno » Thu May 06, 2021 12:42 am

Hi there,

you can of course modify your 1100 engine to run with the 750 ignition, but be warned:

1) you have to make a spacer for the pickups (750ies have the older twin-pickup system)
2) you have to swap the rotor (as the older has got two teeth for ignition triggering)
3) then you have to alter the wiring for the later starter system, because you definitely want the later starter (the version on a late 1100 is the best Yamaha ever had to offer, even the V-star-version is getting backwards converted to the 1100 system in Germany a lot these days.) For reference what you have to change, go to www.tr1.de, go to the technical section and get the wiring diagram for a XV1000 TR1 and one for the XV750SE. What you have to do in essence is copy the wiring setup of the TR1
4) I'd go with the 750 regulator mainly because the older setup has got bigger cooling fins, but it shouldn't really matter
5) 750 coils will check out at around 3 Ohms and so should the later, so it's really up to your preference. I run stock coils on my daily-rider TR1.

Regarding carbs, I personally like the Hitachis, they are good carbs. Also the jetting on the 750 and XV1000 TR1 is almost the same, so don't sweat it. My personal opinion on single carb setups would lead to some un-gentleman-like language, so I better don't comment on it. If you really insist on changing the carbs, go with twin VM38s and search this forum for the detailed instructions I posted.
http://viragotechforum.com/viewtopic.php?f=12&t=43227 - Nanno's accumulated findings (and blatant show-off) - infos on my TR1's, my performance and reliability mods and a bit of show-casing of the stainless steel exhausts I build

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: faffi » Thu May 06, 2021 3:50 am

I learn something new every day. When I swapped engines, I was told I could not use the old coils with the ignition system from the newer model. If I could have stayed with the old ones, it would have saved me a ton of work.
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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: nanno » Thu May 06, 2021 10:29 am

Playing around with a lot of stuff in the last few years... :bg:
http://viragotechforum.com/viewtopic.php?f=12&t=43227 - Nanno's accumulated findings (and blatant show-off) - infos on my TR1's, my performance and reliability mods and a bit of show-casing of the stainless steel exhausts I build

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Thu May 06, 2021 11:39 am

Thank you so much nanno!
ATM the engine is in. No problem with the swap. I managed to secure the TCI from the 1100 engine and I'm going to install it on Saturday. Do I need to change the wiring at all or is it a straightforward out with the old in with the new?
I will keep the 750 coils and carbs.

I will let you know how it goes :bg:

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: nanno » Fri May 07, 2021 6:46 am

Starter system on the 1100 is different so that has to be altered. Aside from that: no straight forward swap.
http://viragotechforum.com/viewtopic.php?f=12&t=43227 - Nanno's accumulated findings (and blatant show-off) - infos on my TR1's, my performance and reliability mods and a bit of show-casing of the stainless steel exhausts I build

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Fri May 07, 2021 12:48 pm

nanno wrote:Starter system on the 1100 is different so that has to be altered. Aside from that: no straight forward swap.


So i have the 1100 engine in with the 1100 TCI unit and the 750 ignition coils, and i have the 1100 starter motor installed.
Just to make sure I understood you right, the things I need to still alter/change are:

3) then you have to alter the wiring for the later starter system, because you definitely want the later starter (the version on a late 1100 is the best Yamaha ever had to offer, even the V-star-version is getting backwards converted to the 1100 system in Germany a lot these days.) For reference what you have to change, go to http://www.tr1.de, go to the technical section and get the wiring diagram for a XV1000 TR1 and one for the XV750SE. What you have to do in essence is copy the wiring setup of the TR1

2) you have to swap the rotor (as the older has got two teeth for ignition triggering)

So, i take the 750 rotor and put it in the 1100 engine?? Why do i need to do this?

1) you have to make a spacer for the pickups (750ies have the older twin-pickup system)

What pickups?

I'm sorry for the stupid questions. Just want to make sure I'm not doing s'thing that can damage the engine.

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: nanno » Fri May 07, 2021 3:08 pm

In your case as you have the correct TCI, you have to alter the wiring for the starter system and for the 1100 TCI, because depending on the year that will have more pins.

#1 and #2 are only applicable if you want to run the 1100 with the 750 TCI.
http://viragotechforum.com/viewtopic.php?f=12&t=43227 - Nanno's accumulated findings (and blatant show-off) - infos on my TR1's, my performance and reliability mods and a bit of show-casing of the stainless steel exhausts I build

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Sat May 08, 2021 12:41 am

nanno wrote:In your case as you have the correct TCI, you have to alter the wiring for the starter system and for the 1100 TCI, because depending on the year that will have more pins.

#1 and #2 are only applicable if you want to run the 1100 with the 750 TCI.


Got it! Thank you!!

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Sat May 08, 2021 10:57 am

Question about the starter motor and the starter solenoid:
There are three wires coming from the starter solenoid, a thick one that connects to the starter motor, a thick one that i presume is going to the solenoid and then there is this single white wire that i don't have any idea where it goes!!
What is that white thin wire??

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: nethopper214 » Sat May 08, 2021 3:49 pm

Kivar20,
May I suggest that a search be done on the internet for
Virago Engine Swap
for there are items discussed there that haven't been addressed here.

For example:

Covering Carburetor jetting issues. 1st generation XV750 Hitachi jetting is different than Hitachi Carburetor for the '86 XV1100.

Carburetor mounting boots need to be considered to mount carburetors correctly depending on Carburetors chosen.

Fuel pump controller for the XV1100 and other necessary relays.

Pressure sensor requirements for XV1100's to retard spark when the throttle is closed. XV750 harness doesn't have the harness for that.

TCI pinning differences.

Carburetor single cable to dual cables on the second generation XV1100.

Just to name a few.
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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Jake » Mon May 10, 2021 9:08 am

nethopper214 wrote:

Covering Carburetor jetting issues. 1st generation XV750 Hitachi jetting is different than Hitachi Carburetor for the '86 XV1100.


It was mentioned previously.

nethopper214 wrote:Carburetor mounting boots need to be considered to mount carburetors correctly depending on Carburetors chosen.
If the OP uses his Hitachis ???

nethopper214 wrote: Fuel pump controller for the XV1100 and other necessary relays.
Unnecessary, gravity feed, no sub tank.

nethopper214 wrote: Pressure sensor requirements for XV1100's to retard spark when the throttle is closed. XV750 harness doesn't have the harness for that.
Others have done the swap and not used the pressure sensor, it is documented in this forum.

nethopper214 wrote: TCI pinning differences.

The OP has asked that question in a thread.

nethopper214 wrote:
Carburetor single cable to dual cables on the second generation XV1100.

The ‘86 throttle cable is a single cable as opposed to your dual cable ‘96.
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It’s what you know for sure that just ain’t so.”

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Re: Engine swap 1986 xv1100 into an 1981 xv750se

PostAuthor: Kivar20 » Mon May 10, 2021 10:33 am

Jake wrote:
nethopper214 wrote:

Covering Carburetor jetting issues. 1st generation XV750 Hitachi jetting is different than Hitachi Carburetor for the '86 XV1100.


Thank you, Jake for answering!

BTW any idea what that wire is from the starter solenoid
"What is that white thin wire??"


[

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