atp turbo xs1100

[SeaAtp1100]

End gap is stock, bike just got a hone and re-ring with stock Yamaha rings. Don’t plan on anymore than 6lbs of boost.

[SeaAtp1100]

Setting up the new carb, it didn’t like the fuel pump being on. After a few minutes of being on,gas poured right through the overflow tube and onto the shop floor. Messed with the float setting to no avail until a smaller needle valve solved that problem. While I was at it I got the float bowl extender.

[SeaAtp1100]

[SeaAtp1100]

11.9 afr at less than 1/4 throttle cruise with the leanest needle they make for the hsr42. I hit the straight with 2k catalyzing clear coat (solder won’t stick) once the clear coat cures (tomorrow) i’ll try again

[SeaAtp1100]

It wants a 37.5 pilot. I tried at 35 and it’s a half turn out (too lean)

[SeaAtp1100]

Took the accelerator pump out of the equation for testing purposes by screwing this all the way in

[SeaAtp1100]

The testing continues if anyone is still interested.
ive resorted to drilling stuff with micro drill bits.
made a 55ish pilot and got the biggest accelerator pump nozzle #70 which probably needs drilling
with each increase in pilot size the less this thing falls on its face accelerating from a stop. Also adjusted the accelerator pump to come on immediately from the closed throttle position. Still getting lean spikes at 1/4 to 1/2 throttle roll on 15.9 afr (with a little stumble) then it settles in at 12.9 afr on my meter. Still cruises at 12.1. I thought adding thickness to the straight of the needle with clear coat would solve that but I’m cruising where the jet needle is already at the taper and the straight has cleared the needle jet, so I went back to the richer 97 needle that came with the carb have that in the #2 lean position. Running a 205 main, pegging the throttle at speed I lose rear wheel traction. I think I’m at 12.7 wot though I’m watching the road and not the gauge.

[Mathh]

Still following, still interested . I would not be too worried about the spikes as you're working with a temporary set-up for which you're compensating. Can be anything. You know the problem area so you can get to a dyno without harming the engine. These guys know exactly how to tweak the carb (which is way better than the old one).

[SeaAtp1100]

Think I found a dyno nearby that still takes on carbs. Most places around these parts only deal with efi on newer bikes. Or quote high prices to dissuade you from bringing it to them.

drilled the accelerator pump nozzle to .8 mm, definitely helped roll on. Drilled the pilot to 60ish based on mic’ing micro bits and a mikuni jet sizing chart (I know they are numbered by their flow rate). Getting closer but not there yet.

[SeaAtp1100]

Dyno'ed yesterday on a machine from Mathh's neck of the woods. a dynostar. Tuner was fine with me doing all the adjustments since i've gotten pretty fast stripping that hsr42 down to make changes, i got long tweezers to grab the needle without fully taking the carb all the way off the bike or dumping the fuel out of the float bowl. ( tuner's an old timer with some bonnevile salt flat speed records under his belt ). my road dyno contraption was accurate with the pilot and the main, and let me know the same problem area with the lean spikes, they were confirmed on the dyno.
final settings

55 pilot 2 1/2 turns out
richest mikuni needle (#95) richest clip position
accelerator nozzle drilled out to 1.0mm tuner said it made no difference drilling it from .9 so we most likely maxed out the accelerator pump circuit.
205 main jet.
5-6 psi boost.

still falls on its face accelerating from a stop, i have to feather the clutch a little and its fine. definitely have to adjust my riding style.
a little choppy sounding cruising below 3800 rpm 3rd and 4th gear, cruise at 4-5k in 3rd 4th gear it feels fine, pulls great to redline. I think since the air/fuel path to the engine being longer than the original stock setup, through the carb, over a turbine wheel and around a corner, then through a plenum, we're not gonna have the low end torque off the line as the air fuel hasn't caught up to what's going on at the throttle. That's just going to be the nature of this eccentric turbo setup.

The blue line was the final. If we had started the run at 4k and held it both the tuner and I believe it would have settled in at +-12.5 . accelerator pump is maxed. tuner was surprised that the leaner runs didn't experience any detonation considering how lean it was getting. All done on 93 octane pump gas.

[Mathh]

Well done, looks like you were pretty close. With turbocharged engines the saying is that when you hear detonation it already is too late hahaha. These relatively early kits come with the big F40 Rajay turbo which will always suffer from turbolag below 4k rpm. You can slightly spool up the turbo before take off to get of the line quicker but then you will need a good clutch. The later RC turbokits came with better flowing tubing, better carb and intake manifold but, even better, with the smaller FF25 turbo that spooled up at lower revs. In the kit that I built myself I used the Aerocharger in front of the engine and smaller diameter tubing between turbo, intercooler and intake which resulted in boost at 1500 rpm. But that kit on this bike still looks period and amazing so don't go to wild on it and just enjoy the ride and the occasional burst of power

[DEEBS11]

That is a cool bike!

[Mathh]

btw, just curious: that area with the lean spikes.. is it gone now? And if so, what was the cause?

[SeaAtp1100]

Maybe I should have been more careful about calling it a “spike”. When I was monitoring af on the road I’d notice 16-17 afr quickly rolling on the throttle while cruising. The pink line on the dyno chart shows it was getting up to 16 in the same area where I called it a spike by the graph I know it’s a curve. That’s the difference between a controlled dyno room vs me only being able to glance at af because I have to pay attention to the road and traffic. It was the 4-5k area that we focused on. Switching to the richest needle brought that lean area down (it’s not on the chart) then for the next run putting the clip in the richest position brought it to 14 + until the air fuel starts catching up. The green line was just a run at 1/4 throttle

[SeaAtp1100]

That is a cool bike!

Yes it is. It’ll be leaving my shop and headed to the other side of state, to the owner, by the end of this month. I’m recommending to him to dump all the oil at 400 miles (I did change it after rebuilding the top end). flushing the middle gear, rear gear and forks (dunno when those were done I’ve only checked levels) tires are 09.