FBF Pistons

[Guest Ian Mottram]

Hi

T170 has had some work done this winter.

i have fitted FBF pistons and Standard size stainles valves which are currently running well on the original exhaust and fuel mapping, and will have to stay like that untill more funds are raised.

 

(all measurements are approx to give aguide)

 

FBF piston weight 1.4lbs

Guzzi piston 1.6lbs

(includes gudgen pin)

 

compression before 125

compression after 140

 

I found that the valves were wildly off the correct settings also the carb ballance was miles off. so much for dealer service.

 

Intake should be .1

mine were left .15 right .1

 

exhaust should be .15

mine were left .6 right .25

 

Fitting the valves was very easy and even though i had not had the engine appart before i did one side including valve replacement and grinding in approx 8 hours

 

The pistons i fitted the rings oiled them and slid them into the sleave then with one gudgeon retaining clip fitted i slid the sleave down the studs onto the crank and fitted the pin and retaining clip replacing the gaskets etc. this may not be the approved method but worked very well.

 

The valves are a bit more off a job but only because it takes a lot of effort to bed the valves in.

 

I have done 100 miles since and it is running very well much more linear power and more noticeable is how much quicker the revs pick up can`t wait to finnish running it in, if it ever stops snowing.

 

The exhaust i have left original other than removing the end cap and cutting the exhaust back to the cap looks much better and thats the only reason i have done this.

 

I removed the unused bracket behind the oil cooler which is approx .4lb.

 

the mirrors are now indicator mirrors and the original indicators have been replaced with some very good fitting,with some chopping, side lights.

 

The rear end has had a complete rework but with the size of the legally required number plate does not look that much smaller.

I ,have used a cut down mudguard extender off my old BMW r1100s

fitted new tail light re-fitted original indicators,numberplate and relector.

 

I found the suspension settings when i got my bike were so far off they were dangerous

The damping had over forty clicks, when i reset that i found the sag was over 25mm obviosly the rebound was also off.

 

don`t assume the dealers are doing these things its your life make sure you stay safe, check your settings or find someone that can.

 

see u out there Ian

Sheffield UK

[Guzzirider]

Hello Ian

 

I am glad to hear your FBF pistons have made a difference- I have some on the way (as soon as my brother in law returns from Puerto Rico) and am saving up for some head work and oversize valves which will be done by Hobbsport.

 

I am not too far away in Huddersfieild- will probably bump into you one day at Snake Pass!

 

regards

 

Guy

[helicopterjim R.I.P.]

You may find that a PCIII with the map from FBF wakes up your bike even more. I am glad I put the pistons in my bike and the PCIII made it work better.

[Greg Field]

Consider also that bigger valves may not be the way to go.

 

Dr. John told me the best combo is the larger injection system of the Sport motors with the smaller valves of the Calis. Much better port velocities for more torque and power.

[dlaing]

I found that the valves were wildly off the correct settings also the carb ballance was miles off. so much for dealer service.

 

Intake should be .1

mine were left .15  right .1

 

exhaust should be .15

mine were left .6  right .25

 

81054[/snapback]

I wonder if the setting slipped off on the left exhaust valve???

That could really throw the throttle bodies out of synch.

In any case, the numbers being off that much indicates someone messed up.

However I did find my numbers shifted around much more durring the first 10,000 miles, but now when I check(at over 30,000 miles) I rarely find even one valve out by more than 0.04mm

You may consider using looser valve tappet settings.

I don't know if stainless steel has different thermal expansion properties.

Every one has a different opinion about valve clearance:

 

Clearance specs (I think this is the US spec, but it could just be an outdated spec from older guzzis and almost everyone considers it too tight): intake: 0.002" (0.05mm), exhaust: 0.004" (0.10mm)

 

Clearance specs (rest of world, but also what appears in the US owners manual): intake: 0.004" (0.10mm), exhaust 0.006" (0.15mm)

 

I like mine set to 0.006"(0.15mm) intake and 0.008"(0.20mm) exhaust.

 

RaceCo recommends 0.008"(0.20mm) intake and 0.010"(0.25mm) exhaust

 

Looser valves tend to produce a stronger idle and I presume a little more low end power.

I presume tighter valves will produce slightly more top end power

One person claimed to get better fuel efficiency after tightening the valves to I recall the .10/.15mm

Looser valves run cooler at the seats but rattle more, and may wear the valve train more.

Tight valves have a narrower safety margin, and are more likely to burn.

I imagine if you get a TuneBoy or a PCIII you can reduce the chance of burning valves by running a more appropriate rich mixture.

With the increased compression, I would be concerned that you are now running hotter and leaner. But in the UK at this time of year, the air will probably keep you cool.

[Guest Ian Mottram]

I wonder if the setting slipped off on the left exhaust valve???

That could really throw the throttle bodies out of synch.

In any case, the numbers being off that much indicates someone messed up.

However I did find my numbers shifted around much more durring the first 10,000 miles, but now when I check(at over 30,000 miles) I rarely find even one valve out by more than 0.04mm

You may consider using looser valve tappet settings.

I don't know if stainless steel has different thermal expansion properties.

Every one has a different opinion about valve clearance:

 

Clearance specs (I think this is the US spec, but it could just be an outdated spec from older guzzis and almost everyone considers it too tight): intake: 0.002" (0.05mm), exhaust: 0.004" (0.10mm)

 

Clearance specs (rest of world, but also what appears in the US owners manual): intake: 0.004" (0.10mm), exhaust 0.006" (0.15mm)

 

I like mine set to 0.006"(0.15mm) intake and 0.008"(0.20mm) exhaust.

 

RaceCo recommends 0.008"(0.20mm) intake and 0.010"(0.25mm) exhaust

 

Looser valves tend to produce a stronger idle and I presume a little more low end power.

I presume tighter valves will produce slightly more top end power 

One person claimed to get better fuel efficiency after tightening the valves to I recall the .10/.15mm

Looser valves run cooler at the seats but rattle more, and may wear the valve train more.

Tight valves have a narrower safety margin, and are more likely to burn.

I imagine if you get a TuneBoy or a PCIII you can reduce the chance of burning valves by running a more appropriate rich mixture.

With the increased compression, I would be concerned that you are now running hotter and leaner. But in the UK at this time of year, the air will probably keep you cool.

81102[/snapback]

 

When i striped the heads down i found heavy black sooty build up that i had not expected on a 2,500 bike which would suggest it is already running very rich.

The splitfire plugs i had fitted had only been in for 1,000 miles and were very black as were the originals. The splitfire plugs raised the tickover by approx 300 rpm.. i warmed the engine then fitted the new plugs and retested.

[TX REDNECK (R.I.P.)]

Your problem is the Splitfire plugs

 

It's the same marketing gimmick that got people to buy more razor blades by putting two - then three!- in a single razor head. Technical reports (search online) show the V splits really don't have any significant difference for power. Remember: the spark only jumps from one spot - one electrode - at any time. Plus with a split plug, the spark has more opportunity to arc instead of connecting in a straight path to the other (central) electrode.

I'm not sure if the "platinum" coating helps either because it's really just a very small, very thin coating. You'd have to have a lot more to make it seriously effective.

Simply cleaning the plug and setting the gap regularly will probably work as well. And check the wires, too.

And you may want to check the lawsuit against Splitfire here. www.ftc.gov/os/1997/9702/splitfir.htm and here www.miata.net/garage/splitftc.html

 

While your picking up some new plugs get some Slick 50 too