Quote from: 86FJNJ on August 17, 2025, 05:55:01 PMHow do you know it was an 1188 piston kit and that they didn't go larger?

I was told that by the fellow who sold me the bike.  He got that information from his mechanic who went over the bike and apparently removed the head to see what had been installed. He gave me the exact Wiseco kit part number.  So I haven't checked it myself but I have to go with what I'm told. 

How do you know it was an 1188 piston kit and that they didn't go larger?

Gents,

After noticing a clicking at low speeds I took a look at the 93 today. Looks like my chain has 2 tight spots. I have absolutely no idea what I put on there last time. It's been about 25k since I did chain and sprockets. If I had to guess I used a DID chain. Looks like the pool has gotten deep in the chain world. What do people like for a "stock" replacement. My go to is Sunstar sprockets, open to opinions on chains.

Thanks,

Daniel

Nice tour! Kudos on the pannier mods. Good fix on the failed fuel pump. Many of us had to also do the same thing. We keep in our cubby's a brass barbed fitting to tie the fuel pump inlet/outlet fuel lines together.
 
When you get the replacement pump, resist buying the Chinese knock off pump. Ask me how I know.
Oem Yamaha pumps are the way to go.
The fuel pump set up is much more reliable than any aftermarket vacuum valve you could install
The 1984-'87 Yamaha FJ vacuum petcock won't fit your tank, it has a different base.
Access to get to the manual petcock is a problem, needing to cut an opening in your left side panel.
Now that you're home, just plug the fuel line until you get a replacement pump so you don't spill fuel on the floor of your garage. 
RPM has a great price on the Yamaha fuel pump: http://www.rpmracingca.com/proddetail.asp?prod=YamFPump&cat=39


Cheers

Pat

I just purchased a 1985 FJ1100 that has a Wiseco 3mm oversize piston kit installed (77 mm pistons, 1188 cc, 10.25 compression ratio).  This upgrade was done at least 2 owners ago and the fellow I bought it from knew very little about the bike.  When I test rode the bike, it started well cold and hot, idled well, pulled hard and there were no flat spots or hesitation as far as I could tell.  So I bought the bike but I'd still like to know more about it.  Specifically, what else should have been done to the bike when big bore kit was installed?  I found very little information on the Wiseco website, which is surprising to me. 

I assume the stock jetting would have to be changed to accommodate the increased displacement.  I believe the FJ1200 stock jetting is different from the FJ1100 stock jetting but I don't know if that is because of the displacement difference or to satisfy emissions regulations (I read that the 1986 FJ1200 had to comply with more restrictive emissions regs - may or may not be true). 

What about the intake and exhaust?  What mods should be done, if any, to allow the engine to breathe at this higher displacement.  My bike has the OEM exhaust, but that doesn't mean it's right. 

I'm assuming others have done this upgrade and can tell me what else should have been changed at the same time.  Again, the bike runs well so I'm not looking to change anything right away, but I'd like to know what to look for.  Thanks in advance.

Thank you gentlemen.  This is really good info. I've been away from home pretty since I bought the bike, but I'll have a look at these items when I return. 

running great. i put a new front brake master cylinder on. getting ready for cherohala skyway. we had rain friday.
staying near bryson city nc

UPDATE:
 
4500KM Twisty and Super fun tour to and fro and around Hokkaido (northern island of Japan) done!

Panniers workes great, no issues in storage and rain protection and strength overall, however, Cant leave the handlebars at 40 to 70 kph as they shake. This doesn't happen when the panniers are empty. Funny.

Also, one fine morning, the fuel pump stopped working .... in grizzly bear territory.. so had to take the hose and directly plug it into the filter instead of through the pump while being scared lol.

Now I either plan to keep the fuel pump removed and place an in line fuel cock to prevent flooding when I keep the bike parked for a while (as the under tank cock is hard to get to) or replace the fuel pump. I'm assuming any old fuel pump of a similar motorbike should work, as it's simply a cock replacement, correct me if I'm wrong though. A vaccum petcock may also work if I find one, though routing a vaccum line may be a bit of a pain


Others than the above issues it was pure pleasure on wheels for the past few days.

Got a fuel consumption of 19.3 km/L for the entire trip on an average (calculations full to full)

Welcome Tomek!

Quote from: Bozo on August 15, 2025, 10:19:04 PMIf you are on a budget I bought a set of 2000 model 37mm FZ1 carbies for my FJ with some engine works, they fit direct just require jets. They have bell mouths and a much better setup than the standard carbies. Depends on the day I got mine for A$250 delivered - BARGAIN.

A huge improvement on the standard

Thanks for the tip....IMO for a street bike, CV carbs are the way to go.
My 1380 struggles on the top end with my oem 36mm FJ CV carbs, so I'm always looking for a bigger carb for better top end airflow. A 37mm carb should help.

A couple of Q's
The FZ1 cylinders are spaced different than the FJ, so how did you get the FZ1 carbs spaced out to 77-85-77?
How did the throttle shafts mate up or did you have to use the FJ throttle shafts?
Are there any write up's or posts on this mod?
I see several US eBay listings for 2001-2005 FZ1 carbs, but none for the 2000 year, any differences?
Example: https://www.ebay.com/itm/265996536368
Is there a difference in the sizes between the Australian FZ1 carbs and the US models?
I wouldn't surprise me if the US models were choked down to 36mm.

Thanks again.

Pat