FCR's fitted some questions

[Kenny]

Mine on Kevs dyno gave 76 with std carbs The dyno pro dyno's are more accurate than Dynojet ones and can read 8-12% lower than a dynojet dyno. Im suprised he didnt show you my curve on his Screen. Ive got to go back there sometims and set my FCR's up properly.

[SDN]

I'll post the curve up



I think this is how you do it - Keep forgetting

[SDN]

Red curve was with Db Killers fitted

[Con Rod]

does not make sense to me that you should get more power with the baffles in as they would restrict air flow.

However, if you are already running lean, restricting the air flow would have the effect of richening it up, which might explain that you have more power with them in.

My guess, as an amateur, (albeit an amature who has spent a lot of time looking into this stuff) is that you are running lean

I suspect if you take your plugs out and have a look, they will be white.

How did you go about setting up the carbs?

[SDN]

does not make sense to me that you should get more power with the baffles in as they would restrict air flow.

However, if you are already running lean, restricting the air flow would have the effect of richening it up, which might explain that you have more power with them in.

My guess, as an amateur, (albeit an amature who has spent a lot of time looking into this stuff) is that you are running lean

I suspect if you take your plugs out and have a look, they will be white.

How did you go about setting up the carbs?

Did them by feel / sound - Dyno bloke said they were spot on and look at the fueling grap fuel is spot on,

[bagmaker]

150 or 170 mains?
I thought the go was around 170?

[SDN]

150 mains and fuelling is spot on, i just have end cans on the exhaust, running with a foam ram air filter - I expected to be running bigger jet than 150 - but you can't argue with the fuelling graph

[Con Rod]

Did them by feel / sound - Dyno bloke said they were spot on and look at the fueling grap fuel is spot on,

The dyno run is done through the gears on wide open throttle though.So main jet only.

What did Kev, "Dyno Bloke" do when you brought the bike down? Sounds like he just put it on the dyno, took your 25quid and that was it, I mean I dont want to sound negative but given your result compared to others, and the very different main jet size I am questioning if he was any help.

You say the bike was running like a pig, you fiddled about a bit and then took it to the dyno and had managed in fiddling about with it to get a spot on set up. Which is unlikely.

In my experience you cannot set carbs up by just feel and you cant take shortcuts if you want get it right (which I learned the hard way).

getting the jetting right jet at wide open throttle is step one.

you still have the needles, float height etc.

Plugs chops are tried and tested and easy and effective means of testing your settings on different throttle openings and there is some good information here:

http://www.factorypro.com/tech_tuning_p ... gines.html

and here:

http://www.factorypro.com/tech_tuning_p ... gines.html

but i am sure some searches on here and google could turn up some good tips for setting the FCRs specifically

[SDN]

Being as I was a professional mechanic for a number of years and am a time served engineer with 30 years experience and am still working as a professional engineer, I have a fair idea of setting machinary up. I used to mess about with carburettors all the time on four and two strokes in my younger days.


I spent a long time on needle setting and main jet before I had a set up which felt right - using the factory pro guide on FCR's, my issue was the strange issue I had with the tank on /off.

Kev did four dyno runs at full throttle, he also did different throttle openings revs etc, in all I was there a couple of hours - bargain for £25 in my book. He told me that the settings were spot on. On the road the bike fuels smoothly, doesn't bog down hesitate or have any other glitches

BTW Kev has offered to do a dyno day for this frum if anyone is interested £10 a run with a wagon selling bacon butties and tea - If that is anyones bag?

[Con Rod]

weird though, why do you reckon you are getting a better result with the baffle in than out?

The question I would be asking is why, what do you reckon, and are your plugs giving you any indication?

[SDN]

God knows, gas analyser wouldn't go in with baffles in so fuel analysis was without them fitted. The final run with baffles in was for him to show me how much the baffles were strangling the engine. We were both totally baffled! when we saw more power on last run with baffles in

Kev the Dyno operator said in his experience you do not get a decent smooth curve if there are major issues with fuelling.

I have abit more fiddling to do and have big bore headers to fit, so will ride over for another go when I have fitted the exhausts

[SDN]

God knows, gas analyser wouldn't go in with baffles in so fuel analysis was without them fitted. The final run with baffles in was for him to show me how much the baffles were strangling the engine. We were both totally baffled! when we saw more power on last run with baffles in

Kev the Dyno operator said in his experience you do not get a decent smooth curve if there are major issues with fuelling.

I have abit more fiddling to do and have big bore headers to fit, so will ride over for another go when I have fitted the exhausts

BTW Plugs are fine - rich tea biscuit shade, maybe I'm down on compression, possibly rings? I know my bike drings oil like it's going out of fashion. Still pulls very hard and will rip past 120mph with no trouble so suggests it's not too lame.

[Con Rod]

hmmm valve clearances maybe.

doesn't explain the better result with the baffle though. Presume your air filter is clear.

anyway let us know what it is when you figure it out

[Dav]

Wow, a mechanic with 30 years experience who used to mess about with 2 and 4 stroke carbs all the time makes posts like this?
"

I don't have any sort of manual for my carbs, for the low throttle circuit, is there a fuel and air screw, or or fuel screw and slow air jet?

From my quick look, I can only remember one adjustment screw, which comes through the bottom of the float bowl

I believe that screwing this in will make the 0 -1/8 throttle leaner?

If I am outside 1 - 2 turns out then conventional wisdom is that slow running jet is wrong - correct?

You're welcome for my earlier advice, thanks for your non-response

[SDN]

I think you will find my response earlier in the post if you read back