Too big bore or not to big bore.

[Pat Conlon]

Ok, so I contacted Hank Scott Racing..... His opinion is that the big bore kit is a reliability upgrade.

Please clarify: What did Hank mean "reliability upgrade"?
eg. If you upgrade to a big bore motor (w/forged pistons) you will have reliability problems?

[capitanoinsano]

No I mean it is an improvement to reliability to go with forged pistons.  He has a kit which is half way to the 1219 kit (.5 mm rather than 1mm I think).  He said my smoke may not be valve seals but could be bore out of round.  Pretty surprising after not quite 20k, and it's done it some since 15k.  It did it when I got the bike 3-4 years ago, but was not noticeable when purchased because it needs to sit for a couple days to happen.

That really makes me think it is valve seals though.  The longer it sits the more smoke I get.  It's as if oil is filling a cavity and being released.  Bore/rings won't do that unless the bike is parked upside down, or I have anti-gravity additives in my oil.  I never get a ton of smoke just a medium cloud and its gone.  That's because there is only so much oil that will sit on top around the bucket in the head.  So I kind of doubt it's rings/bore. 

But if a 500 dollar forged piston kit can be put it with similar clearance as stock cast pistons, I'm thinking I'll do it.

[Marsh White]

Hello
I am getting my head redone due to a leaking valve seal.  Bike has only 20k miles.  I get a small cloud of smoke if the bike sits for a couple of days, but problem goes away if its warm enough outside that the engine never gets cold.  

I had this same thing happen on an FJ that had been purchased. I
was pissed off at first thinking the same thing that you did...a bad/burnt
exhaust valve seal. Then Klavdy took the bike on a long trip to the 05
Central Rally...after 500 or 1000 or so miles...the problem cleared right up
(actually we did 680 miles in that first day). The previous owner never
rode it enough to clear the crap out of the system...so to speak.
Anyway...it is perfect to this day. The white smoke was pretty bad for the
first 5-10 minutes of startup when I first purchased it...It no longer
exists. So in other words...give it a good LONG ride before you screw with
the seals. If it was owned by a pussy previous owner who only took it on
short rides....it could be a deposit build up issue.

[Ratchet_72]

I've had the exact same advice with old cars and it works. Drive the crap out of em for a while and it clears right up...or it blows up. After which I rebuilt anyway so no harm no foul.

[Pat Conlon]

No I mean it is an improvement to reliability to go with forged pistons. 

But if a 500 dollar forged piston kit can be put it with similar clearance as stock cast pistons, I'm thinking I'll do it.

Ok thanks. I agree with you, with your low mileage most likely valve seals. However before you pull the head do a compression test with a couple squirts of oil and see if your compression doesn't come up. Rule out cylinder bore/rings issues.
Yeppers, I remember Klavdy's (now Marsh's) FJ smoking but Marsh is right, that long run to the drum (Gunnison,CO.) cleared that bad boy right up....

[racerrad8]

I think you are trying to address two differing issues with your questions: Smoking & reliability/performance.

What Hank is talking about in regards to cylinder out of round is a manufacturing issue. In the 1100/1200 engine, the thick wall sleeve is sized and marked prior to installation into the aluminum cylinder casting. If you look at the bottom of the sleeve(s) they are marked with an "A, B or C" which is the size indicator. They are then placed into the cylinder bank which is a machined bore that is not honed to a precise tolerance. The aluminum and sleeve then heat cycle creating the out of round issue of the cylinder. I have taken many new engines apart and bored them to the next oversize due to cylinder inconsistencies.

Is the forged piston better? In my opinion, no not really. Not only are the heavier, they require the additional clearance you speak of due to expansion. Then the poor quality casting of the Wiseco piston will shrink as much as .001 during its life and create more ring wear than the stock piston. Thus is the reason we are able to fit them so tight on the build.

Plus, if you do use the Wiseco piston, make sure you use wrist pin buttons, as the impost circlips dig into the piston to far and allow the wrist pin to get by.

You will not see any performance advantage with the 1195 or 1202 kit, and Yamaha makes a .50mm piston that you might be able to hone right into your existing cylinders.

The cast piston has a much more controlled rate of expansion and will handle the normal performance enhancements of the FJ. If you start getting the compression ratio up, big cams & carbs, then the forged piston becomes a requirement.

When the Wiseco kit had a $275-300 price tag, that was how I build all of my engines. Due to rules changes in the compression ratio and having to cut the Wiseco piston dome .135-150 to get the compression ration down, I am now using stock pistons in all of my builds for the racecar application. The cost is better and I don't have to worry about them shrinking and I don't have to machine the dome off of them.

I am on the same page as Marsh. When I bought my wife's bike last year, it had the same smoking issues at start up. She has put about 3000 miles on it since last year, and since I did not know how well it was serviced it has had two oil changes. We went for a 179 mile ride yesterday and no smoke at initial start up or at and point along the trip.

If you are not sure, change the oil a couple of times and put some good long miles on it, and see if that might be the solution.

Randy - RPM
rpm@swaybar.com

[SlowOldGuy]

I had a smoking on startup when left for several weeks issue with my '85.  Had the head off 2 years ago to replace springs, valves and seals.  No more smoking.

DavidR.

[capitanoinsano]

I was on vacation, thanks for the input!

I am leaning to leaving the cast pistons in there now.  I am not sure I agree with advice I got on the phone from the legend car engine builder.  He told me the valve seals never go out on these bikes.  But more and more I hear of it happening.

Mine won't clear up from a long ride.  I have taken two 1000 mile trips since I got the bike.  The problem was very mild then and only happened when I started it and it was cold outside (30's - 40's, not colder), and it was less smoke.  Now it happens if the temperature outside drops to below 60 (guessing).  If it stays above 70 out I can leave the bike sit for a week and very little smoke.  The problem has gotten worse not better.  But really isn't that bad at all.  I could live with it the way it is.  It never has fouled a plug or even ran funny.  I just worry about it getting alot worse if a valve seal rips when I'm 500 miles from home.  So I better fix it.

There seems to be a maximum amount of smoke it produces and it is a 3-5 second cloud, and not a big one, noticeable but brief.  That makes me think that there is a limit to how much oil is causing the cloud and it's probably due to how much oil can seep into one valve bucket area.  I think Hank Scott (was that his name?) may not have diagnosed this one right, but then again, he didn't see it in person and there is a limit to how good phone support can be.   I think it is a 99% chance it's valve seals.

[Dan Filetti]

I had this same thing happen on an FJ that had been purchased. I
was pissed off at first thinking the same thing that you did...a bad/burnt
exhaust valve seal. Then Klavdy took the bike on a long trip to the 05
Central Rally...after 500 or 1000 or so miles...the problem cleared right up.

I had a BMW K75 that exhibited nearly the same behavior.  In my case, the bike had rough fueling.  I actually spent $350 at the stealer to clean this up and it did not help. -Damn!  What fixed it? a Long ass ride to Iowa (from Philly).  The fueling was 10000% better after that ride, for the at least the 3 years after while I owned it.  I gave the same advice to the guy I sold it to; if it starts acting up, run the crap out of it.

Dan

[fitzsimons53]

hey bud im slightly new here but i have a 89 fj1200 was in a wreck recently and now went street fighter but it has the wiesco bore kit. Runs like a raped ape and i havent had a problem in 10,000 miles the bike has 50,000 miles on it and was recently dyno'd at 167hp. my warm up time is a little longer than used to be but runs very strong! has a few other bolt on's but i ride the crap out of it! i'm prolly the worst person on taking care of a bike but it hasent had a hiccup since the build evan after being flipped in the air! its really tourqy!

[wheels]

its going to be a barmy 40 degrees or (100 f) tomorrow in vic