FCR vs. CR

[vecchio lupo]

OK, I have been trolling the net for reviews and opinions on carbs, OMG it's as bad as talking oil and tires. I have exhausted the archives on more than a couple forums, and here is where I stand.

I have an 02 T-100 with a 790cc (duh). I have done the usual, AI, Airbox, pod filters, Emgo free flowing silencers, re-jetted with 138s and I'm pretty darned happy with my B road Bomber. I just keep looking for 6th gear, so I am going up a tooth on the front, I also want to replace the carbs to get every single horse inside the stock 790. Oh yes, I ordered a stage one ignition module from pieman and will install with the carbs.

I have read the FCR vs the CR carbs and 80% of the coherent answers are "39mm FCR Flatslides are the only way to go, don't be stupid, get the FCRs"

So far only one guy said he liked his CRs. I do not want a Big Bore Kit, I don't want stage 2 head work, I am working toward the most sweetest, just right 790 Bonnie I can get. I hear the CRs are too hard to tune and for an extra $350 the FCRs are much easier to manage. I know that for big numbers, the FCR or 42 Mikunis are the thing, but I'm after streetable, well behaved carbs that will net me a few extra horses to offset my gearing change. Let me hear your CR experiences, if you bought FCRs and they work great, I already know that, I'm looking to get real world, city traffic, everyday living with CRs vs FCRs. Yeah I'd like to spend $580 rather that $980 , but I'm not above learning from others.

Thanks

 

[qwenzel]

I bought a set of used CR's and they where jetted just right for me also. So I won't be any help in that dept.
But the power increase is there. I live about 1/2 up a 8% grade hill. Before the CR's only could manage 90 mph. After CR's 100 mph, yea those are indicated speeds, but you can see there was a increase. No I haven't gotten the bike on a dyno yet.

I have no experience with the FCR's, just can't justify the price for them.

 

[Kirkus51]

There's a thread here, which I can't find, about carbs that a guy has put on his heavily modified Bonnie that are mainly for two stroke racing bikes and I'd look at them too. They're very good at at atomizing the fuel/air mixture. Sort of a flat slide type.

 

[vecchio lupo]

Thanks for the input, I've decided to go with CR for price and street manners. The increase will be enough to offset the gearing change. I will not be going into this engine, it will stay a sweet running 790. I thank you for the replies and I will post next week after I install what they feel like.

FYI my Moto history is Italian ( Moto Guzzi, Ducati, Benelli) I checked around the Italian bike scene and for Ducati the FCRs have the strong nod, but guzzi likes round slides. The Italian tuner consensus is a slight advantage to the FCRs but the CRs are a great step up. My BMW friends all say ditch the CV for a round slide unless you get radical, then you need the FCR.

My future is set as I've purchased CRs, I'll let you know next week, so stay tuned.

 

[Flaco]

Rules to live by…

CR 35's are easier to tune, period. Perfect for your 790 set-up application. No accellerator pump… Can't snap the throttle wide open for jack-rabbit starts…
Perfect upgrade though...

FCR 39's are BEST for flowed heads, OS valves, Big Bore strokers…
Do the math…

Flaco...

 

[vecchio lupo]

Thanks Flaco, well stated.

 

[beemerrich]

Rules to live by…

CR 35's are easier to tune, period. Perfect for your 790 set-up application. No accellerator pump… Can't snap the throttle wide open for jack-rabbit starts…
Perfect upgrade though...

FCR 39's are BEST for flowed heads, OS valves, Big Bore strokers…
Do the math…

+1. I'm the guy who defends the CRs at every twist and turn. Great for stock bore bikes and probably give up, oh, a whole HP to the FCRs.

With your bike having 790 cams already, slide carbs are the thing you need to pop the cork at this stage of the game. If you still have a 7,200 rpm rev limit ignitor, an ignitor re-programming is also a good way to spend a couple hundred bones & will let you rev to 8,500.

Cheers,

--Rich

 

[vecchio lupo]

Igniter

I have already parted with my hard earned Dollars to the Pie Man for a stage 1 remap with an 8500 rev limit. Can't wait.

 

[Flaco]

I have already parted with my hard earned Dollars to the Pie Man for a stage 1 remap with an 8500 rev limit. Can't wait.

Good choice!

Carb's, intake manifolds, exhaust, rev limiter and gearing you can't go wrong. And you'll save lot's of dead presidents…
More gold for eye candy, hummm, D9 maybe? Looks make a bike go faster...

Carry on…

Flaco

 

[pz1p]

i believe in the CR's, i run the procom ignitor, have replaced the coil, the 3 items help alot on the performance of my 68,000 mile 790 motor.

 

[strokerlmt]

I had the FCR39's on the 988cc engine. Liked their simplicity but I have to say I am very impressed with the Mikuni's I just installed….
LMT

 

[vecchio lupo]

I'm waiting for my CR's, they were on a 6 week back order, but they are on the way to me now. I hope they arrive for the weekend so I can rip it up. I'll post progress when it happens.

 

[beemerrich]

I'm waiting for my CR's, they were on a 6 week back order, but they are on the way to me now. I hope they arrive for the weekend so I can rip it up. I'll post progress when it happens.

You'll like them. I added 5 RWHP when I installed the CRs in place of the stock corks....

 

[strokerlmt]

Rich…..those "stock corks" aren't very efficientoke:
LMT

 

[vecchio lupo]

We'll gang, I installed my CRs and ran into a tiny snag. The TPUSA billet intakes are 1/4-1/2 inch too short. The carbs interfere with the top motor mount and the petcock, plus they don't seat into the spigots as well as I think they should. I contacted my vendor who said I needed to use stock intakes or purchase a longer set of billet intakes for $200 and I'd be in great shape. In all fairness, he also suggested I slip in the stock spacers as a half measure to get me by. All my issues aside, the bike runs awesome, and I don't over use that word. Throttle response is crisp and strong. It pulls all the way to the top, I have a pie man breathed on ignition module with an 8500 rev limiter. It ran hard, all the way to a garmin indicated 106 mph, and a Triumph speedo indicated 120 (what a joke that in 2003 Triumph couldn't build as good a speedo as BMW did in 1980 for my R100) I feel that it might be a touch under jetted, but I'll sort that out when I figure out my intake situation.

Final word...money we'll spent.

 

[Flaco]

Oh yeah, Shoot!
What I did was use billet intakes for Bonneville America / Speedmaster on my Bonnie's.
They have a different angle (downward from carb's to filters) that make the fit oh so nice that you don't have to mess w/ fitment as you described.
They will then "miss" the petcock and side covers without trimming the side covers...
I sold my billet Bonnie intakes to fund the S/A intakes…
No loss of dead presidents!
Hope this helps…
Allin...

We'll gang, I installed my CRs and ran into a tiny snag. The TPUSA billet intakes are 1/4-1/2 inch too short. The carbs interfere with the top motor mount and the petcock, plus they don't seat into the spigots as well as I think they should. I contacted my vendor who said I needed to use stock intakes or purchase a longer set of billet intakes for $200 and I'd be in great shape. In all fairness, he also suggested I slip in the stock spacers as a half measure to get me by. All my issues aside, the bike runs awesome, and I don't over use that word. Throttle response is crisp and strong. It pulls all the way to the top, I have a pie man breathed on ignition module with an 8500 rev limiter. It ran hard, all the way to a garmin indicated 106 mph, and a Triumph speedo indicated 120 (what a joke that in 2003 Triumph couldn't build as good a speedo as BMW did in 1980 for my R100) I feel that it might be a touch under jetted, but I'll sort that out when I figure out my intake situation.

Final word...money we'll spent.

 

[strokerlmt]

Alright VL……ton plus 6 is a good day ;-)))))):scooter:
LMT

 

[beemerrich]

We'll gang, I installed my CRs and ran into a tiny snag. The TPUSA billet intakes are 1/4-1/2 inch too short. The carbs interfere with the top motor mount and the petcock, plus they don't seat into the spigots as well as I think they should. I contacted my vendor who said I needed to use stock intakes or purchase a longer set of billet intakes for $200 and I'd be in great shape. In all fairness, he also suggested I slip in the stock spacers as a half measure to get me by. All my issues aside, the bike runs awesome, and I don't over use that word. Throttle response is crisp and strong. It pulls all the way to the top, I have a pie man breathed on ignition module with an 8500 rev limiter. It ran hard, all the way to a garmin indicated 106 mph, and a Triumph speedo indicated 120 (what a joke that in 2003 Triumph couldn't build as good a speedo as BMW did in 1980 for my R100) I feel that it might be a touch under jetted, but I'll sort that out when I figure out my intake situation.

Final word...money we'll spent.

For anyone accessing this thread as a resource, know that you can buy longer spigots from Sudco for these carbs that will push the carbs back enough to give the needed petcock and top-rear motor mount clearance.

Cheers,

--Rich

 

[Flaco]

Good info!
I searched on Sudco website and didn't find 'em…
Any link you can provide for us please?
Still in need of stock oil coolers also...:shh:

 

[Texas94fs]

I'll be throwing the FCR39s on with an ignitor reprogram on the bike soon as she's broken in. Then it's dyno time. For stock displacement bikes the CRs are a great improvement.