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Old 03-04-2012, 12:23 PM   #1
Navin OP
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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!

Navin screwed with this post 03-04-2012 at 12:44 PM
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Old 03-04-2012, 01:47 PM   #2
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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?

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Old 03-04-2012, 02:40 PM   #3
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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.
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Old 03-04-2012, 06:11 PM   #4
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Thanks!
'definitely want to get that TPS hooked back up, otherwise your timing is going to be off and drivability will suffer...

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Old 03-04-2012, 08:28 PM   #5
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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.
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Old 03-04-2012, 08:59 PM   #6
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TPS theory

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.
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Old 03-04-2012, 09:01 PM   #7
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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.
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Old 03-04-2012, 09:09 PM   #8
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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.

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.
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Old 03-05-2012, 03:31 AM   #9
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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.
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Old 03-05-2012, 09:15 AM   #10
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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.
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Old 03-05-2012, 12:32 PM   #11
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Quote:
Originally Posted by kamanya View Post
The set I bought came with a clamp for the TPS...
Source?

Any pics of this item?

Thanks!

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Old 03-07-2012, 02:58 AM   #12
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Quote:
Originally Posted by ktm950se View Post
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.
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Old 03-07-2012, 08:35 AM   #13
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Ok, Thanks!

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Old 03-07-2012, 06:42 PM   #14
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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!

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Old 03-08-2012, 01:13 AM   #15
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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?

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