TCI swap

Anyone have experience swapping TCIs from YICS bikes to non YICS machines.? The TCI in my 81 has issues so I was thinking I could use one of the red labeled units from a YICS machine. Would the timing be affected?

 

When I swapped my blown yics engine for a non-yics in my cafe racer I didn't change the TCI unit. Sometimes it ran ok but it would frequently fire on only 3 then 2 cylinders.
With the bike running pod filters I had initially suspected these to be the cause but as soon as I swapped the TCI unit to the one from the non-yics bike (the one that it was originally fitted to) the misfire cleared and the bike has been close to perfect ever since with no sign of the misfire.
So to answer your question, yes I think the ignition timing will be affected.

 

ha ha ha , i was just going to tell him it would work
Robbie, you said your ran on 3 then 2 but a tci takes out cyl in pairs ....?
back to the question, would it run, i think so
would it change the timing, yes
could you tell, ?
all that said, if it advances the timing too far the engine will run hot, that's not good.......read the plugs

 

Well I'm definitely no expert in this area and maybe the first TCI unit was developing a fault but it definitely cured the problem I was having with the misfire by changing the TCI unit to the one that came with the engine. I think we are agreed, Polock, that it probably will change the timing. Wheather or not it will be totally successful I can't say for sure. However, it is unlikely to do any harm. As you say Polock, read the plugs.

 

Ok I have swapped a red label for the black label which was the cause of an intermittent shutdown. Since the change I have not noticed any changes except for the fact that the engine does no just turn itself off whenever it felt like it. I guess the definitive answer will be to check the timing with a light and see if there is a difference thru the rpm ranges. Like Polock said can I really tell? Most likely not as it would only be a degree or 2 Performance after the change was no different.

 

I'm glad the TCI unit change seems to have cured what must have been a very frustrating and possibly even dangerous fault.

 

Always match the number on the timing plate with the number on the TCI Ignitor and you will always have a matched pair.......anything else is a mismatch on the timing....

Example: 5G2-10 timing plate with matching 5G2-10 Ignitor

 

Thanks for clarifying the subject fiveofakind. I inadvertently did this to correct my misfire. Now I understand more about why it actually worked.

 

so if you put a 650 disk on a 750 you could use a 650 tci ?

 

Polock,

So what are you trying to tell us ???

The plate along with the pickup coils behind it.....

 

i'm not telling anything. you said to match the box with the rotor, so if a guy had a tci and a rotor from a 750, could he put both of them on a 650 and be in business?
or in other words, is there any physical difference in the 650/750 rotor?
other than the #'s stamped on them.
does the timing come from the box....the rotor....or a combination of the two.

i wrote that and it confused me

 

My educated guess & I could be wrong.... but I would said the Ignitor, The timing plate & the pickup coil assembly should be a match set.....it makes sense to me......if you switch Ignitors to a different one other than the marking on the timing plate, the bike will run but the timing will be off......that is all I am saying.....the is a reason why they have the plate stamped & the Ignitor stamped....

 

The 5G2 indicates the first model it was used on. A different prefix will indicate some difference. It could be major or something as simple as the color.

I suspect the only difference between the non-YICS TCI and the YICS TCI is that the YICS version has an extra pin to support the side stand circuit. If I'm correct you could put a YICS TCI on an earlier engine with no difference. Going the other way though you'd disable the side stand circuit.

 

Len's catalog has all sorts of useful information in it. I recall seeing the specs for all of the TCI units and the pickup coils in there, but I can't find it in the new catalog.

 

Found it; from a post of Chacal's that I saved for later use.
The pickup coil specs are in the new catalog, so I'll just post the TCI info.

 

Where is lens catalogue and can i get a chance to read through it. Im still learning about my 82 xj550 ycis bike and am having a difficult time with the timing. I think reading the curve could better help with my situation.
Thanks.

 

Big flashing thing in the upper right hand corner of every page. Click it

Spark timing is controlled by the TCI. There is no provision for adjustment.