Splitting the cases

[Old Rider]

All FJs had it. It is a hose going to the CDI (may be already disconnected).

Nope i think only USA models had the vacuum advance mine does not have it here are some pics with and without.

[Troyskie]

Very interesting.

I've a number of OEM CDIs and all have the vacuum advance nozzle, these are a mix of direct to Australia and USA models.

Perhaps there was a batch of the assembled in Holland that did not have it.

[RPM - Robert]

Something to do with restricted models, perhaps?

[Troyskie]

Possibly. There was a post from Austria recently (or Swiss), with some sort of restriction issue.
The easy way to check for Holland assembled bikes is they often start with a * before and after the engine number.
There are a couple of these bikes getting around here in Oz, so I'll check one when I next see it (shed day ).

Rolf, does your engine number begin with a *?

[Pat Conlon]

Remember, starting in 1989 with the new DCI boxes, they did not have an internal vacuum advance built into the box, they had a remote vacuum switch (aka: pressure sensor #22N-82380-10-00)  which had a vacuum line connected to it and so it sent an electrical signal back to the DCI ignition box.

If you look for a vacuum port on those boxes, you won't find one, yet they still had the vacuum advance feature.

If you're dealing with the early 84-87 TCI boxes, that's easy to spot the vacuum port for a yes/no answer.
Later model bikes, look to see if you have that pressure sensor part on your bike. (and a vacuum line)

I have been told that the early Aussie FJ's did not have the vacuum advance, I'm unsure of the other markets.

[RPM - Robert]

Isn't the 1TX box Rolf posted for the 86-87? That's why I was thinking it may have something to do with power restrictions.

[Old Rider]

I have now done some research about the vacuum advace i don't think it has anything to do with restriction i believe it is only for emission control to burn the
exhaust gasses when shutting throttle.I found that even a restricted Switzerland bikes has the vacuum hose on the cdi box see pic 6.

Pat  strangely my bike does not have the electronic pressure vacuum sensor or the vacuum hose to the cdi  and it is a full power version see pic 2

pic 1 is just a California model i found with the electronic vacuum sensor

pic 3- 4 and 5 is just to see the different parts on a full power Europe version and restricted Switzerland and Austria versions.Austria has restricted
inntake and exhaust mufflers same has Switzerland but has also restricted airbox inntakes

Troy i was going to check if i had the engine number starting with a when i was doing some work on the bike ,but of course i forgot   i will try to remember
later

[balky1]

I have now done some research about the vacuum advace i don't think it has anything to do with restriction i believe it is only for emission control to burn the
exhaust gasses when shutting throttle.I found that even a restricted Switzerland bikes has the vacuum hose on the cdi box see pic 6.

Pat  strangely my bike does not have the electronic pressure vacuum sensor or the vacuum hose to the cdi  and it is a full power version see pic 2

pic 1 is just a California model i found with the electronic vacuum sensor

pic 3- 4 and 5 is just to see the different parts on a full power Europe version and restricted Switzerland and Austria versions.Austria has restricted
inntake and exhaust mufflers same has Switzerland but has also restricted airbox inntakes

Troy i was going to check if i had the engine number starting with a when i was doing some work on the bike ,but of course i forgot   i will try to remember
later

True, my came from Switzerland.

[Old Rider]

Yesterday i did an oilchange and also checked the Compression on the cylinders. Not sure  i like the high compression readings.
The manual says Standard is 9.8 BAR 142 psi  Minimum is 8.8Bar 128psi   and Maximum is 11.8 BAR 171 psi.

All testing was done with WOT Throttle

The engine uses no oil and has great power so that is fine ,but can these high compression readings blow the head gasket? I think that the high copmression readings is because the head is shaved off a little and also the cylinderblock  was shaved off a little when installed new sleeves when doing the rebuild. I used 2 steel gaskets under the cylinderblock to get the pistons flush with cylinderblock surface.I inspected the sparkplugs that was new a week ago and did
not see any black spots on the white porcelain so it is no ignition detonation going on i think. I also used a borescope and had a look inside the cylinders
sorry for not having any picktures of that .The cylindelwalls still had honing patterns and could not see any scorings ,but it was difficult to see with the borescope.

My readings is 9 august 2022
cyl 1  12.3 bar 180 psi
cyl 2  11.9 bar 170 psi
cyl 3  12.5 bar 180 psi
cyl 4  12.1 bar 175 psi

Last year 21th of june i also did a comp test and then the numbers was
21 juni 2021 cyl 1 170 psi
21 juni 2021 cyl 2 172 psi
21 juni 2021 cyl 3 180 psi
21 juni 2021 cyl 4 168 psi

So question is Can these compression numbers blow the headgasket??

[Pat Conlon]

Max spec. 171psi vs 180psi actual is only 5% above spec. I think you are fine, but I will defer to the engine experts.

Do you have your ignition advanced (via rotor) or are you running your stock timing curve?
Do you have richer pilot jets and mains in your carbs? Our bikes were lean from the factory.
Remember our engines were designed to run on regular unleaded 87 octane (RON+MON/2)

My point: At 5% above spec. I wouldn't worry so much about blowing a head gasket but the potential for pre ignition, a problem easily solved with carb jetting and/or a mid grade octane fuel.

You do good work, Kudos.

[oldktmdude]

   You will be fine. I've been running 180-190 psi compression for 4 or 5 years with a standard head gasket without
any problems. Just ride it!
   Regards, Pete. 

[Old Rider]

Max spec. 171psi vs 180psi actual is only 5% above spec. I think you are fine, but I will defer to the engine experts.

Do you have your ignition advanced (via rotor) or are you running your stock timing curve?
Do you have richer pilot jets and mains in your carbs? Our bikes were lean from the factory.
Remember our engines were designed to run on regular unleaded 87 octane (RON+MON/2)

My point: At 5% above spec. I wouldn't worry so much about blowing a head gasket but the potential for pre ignition, a problem easily solved with carb jetting and/or a mid grade octane fuel.

You do good work, Kudos.

Thanks for reply Pat i think you are right .I try to run the engine a little lean so iit does not build to much carbon deposits because then it will increase the compression even more if im right.
I had a look with a borescope and it was difficult to se but the valves and pistonheads looked clean.My bike has stock ignition settings on the pickup rotor and also original jets so no mods done there.
Since my bike does not have the same TCI box as the us models with the vacum tube system that burns off the sot when throttle is shut  i try to run it a little lean .
Im a little concerned that the high comp also can wear out the rod bearings ,but as you say 5% is not much.i did not know that the engine was designed to run unleaded fuel ,but know it works fine.I always use 98% fuel because here in Norway that has less etanol added and will prevent pre ignition if im right

[Old Rider]

   You will be fine. I've been running 180-190 psi compression for 4 or 5 years with a standard head gasket without
any problems. Just ride it!
   Regards, Pete. 

That is good to hear oldktmdude !