BSA B50 -500 APG Build

[Koncretekid]

I decided to re-assemble the motor in the frame to fit the new parts before painting.  The new HSR42 Mikuni fits great, and the throttle will be easy to hook up.  I added an oil filter on the return line.  Then I made up the new exhaust with two optional exits.  The first is a short megaphone, tuned to widen the power band down to shift point.  The second is a simple 90 degree turn-out with no megaphone, designed for maximum rpms only.

[coloradodave]

50 more day until Speedweek, are you gonna gave it all ready to go?? looks great and we look forward to the competition.

[Koncretekid]

50 more day until Speedweek, are you gonna gave it all ready to go?? looks great and we look forward to the competition.

Actually, Dave, only 19 days until Loring, which is my goal.  I probably won't make it back to Bonneville until BUB, because that's when my pit crew of one returns, and we also like to take in the Bonnevile GP at Tooele.  I do so hope to get to Speedweeks sometime, to meet all the interesting people I have heard from on this forum.

Incidentaly, I do have a question for anyone reading this -- I bought a Koso narrow band air/fuel gauge, but lost the instructions.  I seem to remember that they wanted me to mount the sensor 19" from the head pipe connection.  This would put it too close to the exit, as the entire pipe is only about 22" long.  Can anybody enlighten me as to the best place to mount the sensor?

Tom

[WhizzbangK.C.]

When I was researching this same question a couple of years ago, the preferred answer seemed to be to mount it in an extended bung closer to the the exhaust valve. The thinking being that it would still get a good sample of the exhaust gas, the extension would help to prevent overheating the sensor, and it would be farther from the outlet so less likely to give skewed readings due to fresh air pulled up into the pipe by exhaust pulses.

I never did follow this advise myself, the result being multiple burned up sensors and readings that I never did trust. 

[Koncretekid]

Thanks, Ed
I managed to get a copy of the instructions and the measurement from the head is supposed to be 20cm, or about 8".  I will try this, but I'm worried about the leaded gasoline.  I seems as though the lead will foul the sensor.  I'm wondering if any of the fuels offered do not contain lead. VP makes such a fuel that would work for my CR, but they aren't bringing any to Loring.  I'll have to  check the BUB site for Bonneville.
Tom

[Koncretekid]

I checked the BUB site and found that there will be an unleaded gasoline available - ERC-MUL/A, but it only has an octane level of 101, as compared to the leaded fuel that I used in my road race motor which has a CR of 12.5 or so, of 110 ((R+M)/2).  My current compression ratio measures 11.7, so is this octane level (101) high enough for my motor? At Loring, I don't know what I'll do, except maybe  just make a couple of tuning runs and them remove the sensor.  Any other ideas out there?
Tom

[MC 1314]

They also have 3 104's, don't know if that helps.
Here is the link:       http://www.ercracingfuels.com/sxs1.htm
Bob
 

[fredvance]

The mul/a should be more then adequate. When I was running my production motor, 13-1 compression, I ran the mul/a. Are you going to run gas class? If not VP has some good oxygenated gas around 100 octane. A lot of people, me included, have run a gas with too high octane. The higher the octane the slower the gas burns. At 4200ft elevation you will, effectively, lose about 2 points of compression.

[wobblywalrus]

I use an oxygen sensor with leaded gas.  The reason I get away with it is I use it for a very short time.  Just long enough to get the readings I need.

[Koncretekid]

Sounds like the mul/a will be sufficient with my CR at Bonneville, so I'll be OK there.  At Loring, I don't see any non-leaded alternatives.

Wobbly,
After you make a couple of runs on leaded gas, do you take the sensor out, or just turn off the power to it?  Mine is only a 2 wire sensor, so I guess it is not heated.  Don't know what turning off the power actually does -- maybe just turns off the leds in the gauge??  Anyway, I can certainly remove it and use the plug supplied if necessary.
Tom

[wobblywalrus]

The o2 sensor bung is shown in the photo without the sensor.  I remove the sensor or switch to unleaded gas after gathering the data I need with ethyl.

My manual says "An unpowered oxygen sensor will be quickly damaged when exposed to hot exhaust gases."  I always keep the power on when the sensor is installed.   

[Koncretekid]

Wobbly, thanks for the heads up.

More photos -- oil tank, shift linkage crossover to left foot shift (because Honda wheel is right side brake and I don't like cables.)  Also, my catch can tribute to Katie and Will, eh! (Aren't we lucky here in Canada to have the Royals visit!! I wonder if Will ever had a chance to ride a BSA? I should invite him.)

[wobblywalrus]

Try a muffler at the track, if needed.  Straight pipes on my A-65 Spitfire gave a lot of power over a narrow rpm range.  Often I could not keep the bike in the power band during the shift from third to top.  This was a major problem with bumpy cams, large ports, and tall gearing like we use for LSR. 

My solution was to use the standard BSA Spitfire mufflers.  They were minimal, as mufflers go.  The Norman Hyde toga mufflers for the modern Triumph Bonneville are similar - straight through glass packs with no internal baffling.  The mufflers softened the pressure wave intensity in the exhaust system and they broadened the power band.  It was easier for the bike to climb from third to fourth and I went faster.

Some folks do this with megaphones.  One of my friends used "shorty" mufflers.  I used the BSA mufflers cause that was all that I had to work with. 

[saltwheels262]

k kid,

re: the first picture posted july third.

     is there enough clearance at the top of the clevis for the linkage
to " swing" and engage the gear?

franey

[Koncretekid]

Saltwheels,
Very observant of you!  I actually had to put the clevises in the mill and round the top and bottom of the slot, mainly at the transmission lever, which you cannot see in this photo.

Meanwhile, I took the exhaust system, linkage, and oil tank in for final welding.  My primary welder was not available on account of taking off for a couple of weeks for his daughter to show her horse.  How inconsiderate of him; he didn't even tell me he was going.  So I used a different welder, but I guess I forgot to tell him this was for my motorcycle and not my tractor.  So he migged all the joints and they look like crap!  I'll have to grind and sand them, which is something I don't do with good welding. 

I also had to revise my side covers and their mounting tabs because I couldn't turn the bars!

Only 10 more days.

Tom