Keihin FCR review on a SE 950

Wasn't sure what to expect but I needed to get some non CVs on here as the stutter/judder bump stalling was getting to be dangerous despite adding a fuel pressure regulator that controlled it to a large degree. I use my SE for off road 99% and always at race speeds. With harder use it would just lose all connectivity at the throttle to carb and blubber. Not good when you need a boost of power or are skimming whoops at 70.

First impression? Dead off idle to I'll guess about 2200-2500 RPM when it gets into a hit that might be a problem if you aren't ready for it. I guess I'll be covering the clutch a bit more in nasty slow stuff. The CVs with H2W prefiltered jetting were awesome in this regard, buttery smooth.

Mid is absurd now, and the top feels the same on the street. From my first street ride to just see how they are I know I could bald my rear Teraflex in under 60 seconds with the same throttle twists the CVs would tolerate. Should be fun, maybe not for everyone but fun regardless.

I'll post again after I get her off the tar.

Thanks to H2W for both my original CV jetting and a good deal on these FCRs!

Greetings,
2 questions if I may...

Did you attach the TPS to the carbs, and if so, how?

What's the coldest temp you tried starting the bike in, and how was it to start without a choke/enrichener system?

ktm950se

TPS deleted from the wire harness right now, garage was 50+ degrees F. Wasn't that hard to start, took a long time to prime with my vac FP the first time. After it was it started easily the first time. A few days later.. probably 6-7 attempts with 3-4 throttle pumps between each and a slight surge of the AP to keep it alive for 15 seconds after it really caught.

Thanks!
'definitely want to get that TPS hooked back up, otherwise your timing is going to be off and drivability will suffer...

ktmhk53

Hmm, I've read up on it and there seem to be a few theories on that. So far I think I just feel the AP coming on that step up the fuel/snap. Driveability above (wild guess here) 2400 RPMs is spot on and damn strong. The CVs were smoother from that point but didn't have the response or boost these have.

Do you have the FCRs and what were your observations regarding the before/after TPS? Is what I described what you felt? I'll have to search that TPS thread again, I almost recall there was no real difference the rider described but I may be wrong. Maybe it started easier?

I still need to get them into some nasty repetetive stutters to be sure the flooding/stalling is gone. I still have the FPR in it and so far it revs to the limiter no problem. I may be able to dial in even less fuel from the pump. The little boost I described I can live with or I'm sure, tune out later.

Shamelessly copied from another thread;

FOR 950 CARBS - the Throttle Position Sensor, TPS, sets the ignition advance. The ignition set the advance based on Engine RPM and Throttle Position. This is called a 3D Map, 1. RPM, 2. TPS, 3. Ign Advance.

When you turn on the ignition, the small computer in the ignition looks for a 'referance voltage' to determine if the TPS is in range. The voltage should be 0.5-0.6 volts when the throttle is shut. You should always have the throttle shut when turning on the ignition.

This referance voltage is set at the factory at engine idle. BUT, if the idle is turned down during the break-in period, then the referance voltage may be wrong! You may need to reset the TPS after the engine loosens up and the idle position is different. I've seen several 2006 950 Adventures with a too low voltage of 0.38 v. These had a bad surge around 3000 rpm. Reseting the TPS usually fixed it without re-jetting.

If the ignition doesn't see this voltage during start up, it may not set the advance correctly and you'll get a surge between 2000-3800 rpm. This acts just like a lean carb condition. It can be masked by richening up the carb low speed mixture screws or low speed jets, but you'll get poor mileage and a weak low rpm throttle response. If the TPS is dirty or worn, you can get the same erattic behavior.

The workshop manuals show how to set this. I'd recomend to try a resultant voltage very close to, but below 0.6 v. Check it several times by turning off the ignition and make sure you still have the same voltage when you turn it back on. Make sure it tracks voltage smoothly as you open/close the throttle. Any jumps, dead spots or other flaky action means you need a new TPS.

Another;

Do you still have the throttle sensor hooked up? Have you checked the voltage? This sets the ign advance and you'll get flaky idles, hard starting and surges about 2500-3500 rpm. Between the Yellow and Black wire it should read 0.5-0.6volts, ign on, throttle closed.

I have none of the negatives with it unplugged from the harness. No surge, starting I think will be something I need to get a ritual for. I may need more throttle twists to prime it. Idle is dead flat and perfect response.

Another;

...TPS was used in conjunction with 2/3 gear sensor to retard timing for noise emissions purposes.

I have a feeling this one may actually apply. I had adjusted my idle sometimes a few times a day with CVs when it went from cold to hot during a ride. I doubt my TPS was right from a few hundred miles into ownership and I never suffered any of the possible problems listed above that could be potential results. :huh

Who knows? I'm pretty jetting sensitive, I have been spending too much time jetting perfectly good bikes with JD kits and hours of test & tune to get them right. The hit I'm describing is from 1/16' throttle to a hair above it. Not unmanagable, just noticable power increase that stays that curve thru the midrange.

Well, I'll be able to chime in here in a month as I am refreshing my 950 with 39mm FCR's. The set I bought came with a clamp for the TPS so we can compare notes. Along with offroad, I use mine a lot in technical as well as touring.

I too was battling over rougher stuff, 10 - 20 seconds of whoops and it was nearly unrideable. I had to rev it out with the clutch in to clear the carbs.

I was having it die completely in some extreme situations while racing a scrambles and said ENOUGH!

It was much better with the FPR but it was limited to about 80% in race/agressive riding in stutters and whoops where the CVs could still get confused. I'm racing this weekend so trial by fire! I'll report my findings.

Source?

Any pics of this item?

Thanks!

ktm950se

I bought them like that second hand. So not sure where he got it from. Will get photo's soon.

Ok, Thanks!

ktm950se

Tried starting it today with 4 throttle twists, would catch then die a few seconds later. After 8-9 tries the battery was getting tired. Great. Where is the kickstarter again?

No choke may prove to be a problem, or the TPS, though it started well the other day and idled smooth pretty quickly. More tomorrow, I was hoping to test it on the MX track then.

EDIT: 30 minutes later it started with no throttle twists so I guess 4 was too much! 2 attempts had it easily idleing along. Good news for tomorrow!

While easy TPS fitment is not built into these carbs, others have done it, and I have a drawing of the bracket required, so this would not keep me from doing the conversion.
The lack of an enrichment/choke system is another matter.
Until there's a fool-proof way to start the bike in cold temps (down to 20F) and not drain the battery, I'll reluctantly keep the CVs...

What temps are you trying to start your bike in Navin?

ktm950se

I think I flooded it last time I had a problem. 2 pumps today at 60 f and it held idle right away, one try.

The bike was on the track today. Had a problem with stalling under braking, needed a bit of throttle to restart. Turned up the idle until it went away or I figured to ride around it. Needs more time to see if it is still there.

The power is explosive, like a full on built up 450 SX bike, it just barks now. Good and bad I fear, but it gets your attention!

The stalling in choppy stuff seems to be gone.

Testing got cut short by a newly revalved shock that is leaking oil and a missing rubber bottoming snubber. It starting bottoming hard after about 15-20 minutes then kicking so I pulled off only to find that mess. No more riding till next week.

Found the house smelling of fuel, dug in with a flashlight and the screws just above the accell pump are leaking, shooting fuel out with a throttle twist but dripping the rest of the time. The fuel was pooling between the cylinders, a line of gas down the left side cases and evaporating before hitting the floor. Glad I caught it before it blew the house up with fumes at the furnace in the next room! BOOM! :eek1

Sudco tells me those are drilled/tapped to install the leak jet and were supposed to be epoxied in. OK, someone missed that step. Epoxy drying as I type, check this if you get these carbs!!!

This has been a love hate relationship with these carbs. With the CVs I had higher speed impact induced fluttering/stalling, with the FCRs it stalls into corners and with the clutch in in low speed, idle level junk. On the street or in the driveway it is fine.

Today was the second time I needed to be towed out of the woods. A combination of the shitty stalling and the crapola Shorai battery which after about 6 starts just clicked the starter. I'll give these one more going over but right now I give them a huge thumb down. My higher speed stalling is gone but this is just as bad.

Very frustrating, back to square one!

I loved riding my 950 ADV with FCR41's
the midrange hit was absolutely incredible
I built a baffled cold air intake waterproof heat resistant carbon fiber air box using phenolic HR aircraft resin like a quality exhaust heat shield
the roar was awesome , it had that big V-8 resonating vacuum
fuel mileage was about the same as my CV's maybe better
I had them dialed perfectly
after a lot of tinkering they were very reliable and ran absolutly perfect .
.....that is IF I could get it started on a cold morning

and thats a big IF to deal with when adventure riding solo

its not a very good feeling to crawl out of a tent and see frost on the seat and wonder IF, I like to keep my If's under control




at 60 degrees F and under it was throwing dice to get it to start without killing a battery
sometimes it would start OK other times forget it , and thats after trying every ritual possible
other times no problem at all especially above 60 F, in summertime they were excellent
once they got started they were good for the rest of the day , as long as you dont let the motor metal get cold
and the $140 battery will go to trash if killed too may times, they just do not survive too many draining s and recharges

So reluctantly , after about a year of fun, dependability outweighed the awesome performance factor so I sold them

I dont have a lot of good to say about Sudco . I live within range and used to visit there often to get retail carb parts for my various bikes and the cringe factor of having to deal with their attitude became too much to bear
When I asked about them providing FCR's with a choke for the 950's It was as if I may as well have been asking the boss for a raise, all I got was know it all attitude and a turned back
If Sudco would take their head out of their rectum and listen to riders then maybe they could come up with some decent products at competitive prices, like jetting kits for example, but all that would take real world hands on R&D, something they have no clue about
hope that didnt break any forum rules, I am just pissed that the FCRs dont have a choke or I would still have them , in fact I would consider buying some again, especially if Sudco was not involved

If you want to sell them put me in line
I know how to get them dialed for everything but cold starting and thinking about giving it another go
I must have taken mine off al dozen times to get them dialed just right , I tried every jetting range, different needles and pump squirt timing durations, even experimented with the Honda CRF450 pump rods
I found that compared to a single, the 950 likes a lot of pump squirt and the float level is critical,and the slides need to be adjusted to open at precisely the same time, there is also a balance point for air/fuel ration between at idle slide opening(idle adjustment screw), and the pilot fuel screw .
If you were close by and could bring it by I am confident could get it running tops for you in a about 2-4 hours

I am considering fabricating an old tech cable operated butterfly choke with spring loaded bypass door like the old 70's Keihins had , or possibly an electric solenoid actuated enrichment system using fuel injectors in the intake stream
and I have enough HT phenolic resin left over to build another CA intake box

hope you get it sorted Navin they are a lot of fun and well worth the effort , espescially if just riding out of the house in fair weather all the time