Keihin FCRs or Mikuni HSRs?

[Mr Kay]

Hi guys,

 

I've got an 1100i motor that will go in my old Le Mans. I'm going to twin plug the heads and have Raceco port and flow them and I'll run a custom ignition system.

I've done away with the injection gubbins as I want to run good old carbs.

Does anyone have experience of either Mikuni HSRs or Keihin FCRs?

I can get an FCR kit especially for the Sport 1100 which will have appropriate jets as a baseline for further tuning or I can buy individual HSRs and start from scratch. The advantage I can see with the Mikunis is that they do a 45mm bore which may suit the free breathing heads better.

 

Does anyone have any personal experiences or recommendations?

 

Thanks in advance

[Guzzirider]

Last thing I heard was that Amadeo at Raceco had stopped working on Guzzis and only worked on kits cars now with Ford motors. Have you spoke to him recently? Is he back doing Guzzis again?

 

He would be the best guy to answer your query re carbs. I think Pete Hindley who raced an 1100 Sport at the Manx GP a couple of years back used Mikunis.

 

Good luck with your project

 

Guy

[Mr Kay]

Last thing I heard was that Amadeo at Raceco had stopped working on Guzzis and only worked on kits cars now with Ford motors. Have you spoke to him recently? Is he back doing Guzzis again?

 

He would be the best guy to answer your query re carbs. I think Pete Hindley who raced an 1100 Sport at the Manx GP a couple of years back used Mikunis.

 

Good luck with your project

 

Guy

Thanks Guy,

 

As you say, Amadeo is mainly concentrating on four wheeled contraptions but he'll still carry out work on Guzzis. He hasn't been particularly forthcoming with advice with regards to carbs , hence the question here.

 

Alex

[1100sport]

For sure the easy route would be to go with Keihin FCR 41 as there already exists a Kit for the 1100 Sport carb. The kit is perfectly tuned and the FCR gives superb throttle response and performance.

 

I have also looked at the Mikuni HSR (typically the 42 looks good on paper for the 1100 2v) and should give very good result as well (they are designed for big HD V2 engine).

 

From a technical POV, the HSR and FCR are pretty similar too altough the FCR are more "race proven" than the HSR.

 

In either case, you'll have to find a solution for the ignition but there are a some options out there.

 

Mathieu

[jcbooghs]

As pictures tell, I notice FCR's on Mr Pete Hindley 's bike! Maybe he raced Mikuni's as well, don't know.

I have swapped my Dell Orto's to Mikuni TMR about 10 years ago. BIG difference! A true improvement.

Much smoother, much shorter, much better.

I've tried some Keihin FCR 41 as well. Very comparable. But in those day's the Keihin's weren't available with choke. And as I was still riding the streets those days I wanted some choke. In that case there wasn't much to choose from. There were also those huge and fat RS carbs. But they just spilled fuel, the slides shattered louder than the engine. I wasn't very charmed with that. So I went for the Mikuni TMR 40.

That newer roller beared flat slide carb is a much better choice than the HSR. They do exist now in 41 too.

 

Some info on the net

http://www.supermoto-racing.de/content/ver...mikuni_tmr.html

http://www.mikuni-topham.de/

http://www.allensperformance.co.uk/

[Mr Kay]

Thanks guys,

 

I've managed to find a price for the FCRs here in the UK - £940 the pair (approx 1100euro) which is a little beyond my budget. I can stretch to £500ish for a pair of HSRs though. Shame really, I love the idea of the roller bearing slide.

 

One of the guys on here is running HSR42s on his bike but suggested that it'd easily run 45s, I'm tempted to try the bigger ones, especially with gas-flowed heads. The old 850 mid-valve engines could apparently happily run 40s (crude dellortos at that) so it should be ok.

 

Ignition won't be a problem, my father is developing a programmable system that will run from the existing camshaft pickup. I'd have to do some messing about in that area anyway to get the most from twin plugged heads.

 

Alex

[Murray]

The FCR's are brillant IMO I've never missed the choke ethier Mukuni's I have heard can be a bit tricky to setup but thats more rumour and innuendo than direct experince.

[1100sport]

Thanks for the info, very helpful.

I have a pair of Dell Orto 41 (instead of Phm40) and that was already an improvement over stock. But I like the idea of moving to flat side carbs. Any recommendation regarding jetting for the TMR 41s?

How did you set your TMR 40?

 

Did you mount them on the oem rubber?

 

Thanks for your feedback!

 

Mathieu

 

 

 

As pictures tell, I notice FCR's on Mr Pete Hindley 's bike! Maybe he raced Mikuni's as well, don't know.

I have swapped my Dell Orto's to Mikuni TMR about 10 years ago. BIG difference! A true improvement.

Much smoother, much shorter, much better.

I've tried some Keihin FCR 41 as well. Very comparable. But in those day's the Keihin's weren't available with choke. And as I was still riding the streets those days I wanted some choke. In that case there wasn't much to choose from. There were also those huge and fat RS carbs. But they just spilled fuel, the slides shattered louder than the engine. I wasn't very charmed with that. So I went for the Mikuni TMR 40.

That newer roller beared flat slide carb is a much better choice than the HSR. They do exist now in 41 too.

[rocker59]

I'm running the Keihin FCR41s on my '96 carb Sport 1100.

 

Bought 'em in a kit from SUDCO here in the USA.

 

The kit was good. Really all I had to do was richen up the idle mixture and it runs pretty darned good. The cables weren't quite the right lengths, but they worked out.

 

The switch to the FCRs instantly changed the bike. Better throttle response, lighter throttle pull, better fuel economy.

 

No chokes, but I've not really missed 'em...

[jcbooghs]

How did you set your TMR 40?

 

Did you mount them on the oem rubber?

 

I would have screw it open to see what jetting is used. When I got the carbs, standard jetting was just quite allright. If you are that far, I will check and let you know.

The carbs are indeed mounted on the OEM (Le Mans 1000 - Sport 1100) rubbers.

Are you going to ride it with the airbox? Because I don't know if they have a fitting solution for this.

The Keihin FCR's do have.

 

About the choke: I think the latest FCR's do have choke too now.

But as been told here none is missing them. As a matter of fact I have eliminated mine too (but I never ride the bike on a cold morning).

 

An idea: if you want BIG why don't go looking for a set of 48mm Honda Firestorm carbs? Just a wild guess, I have no idea if it should work.

[Mr Kay]

Thanks again guys!

 

I've done a little research and discovered that apparently the HSRs do have the roller bearing slides. I think I'll give Allens Performance a bell and see what they reckon.

 

An idea: if you want BIG why don't go looking for a set of 48mm Honda Firestorm carbs? Just a wild guess, I have no idea if it should work.

 

Downdraft carbs I'm afraid.

[Murray]

The orginal rubbers I found were a bit flimsy for supporting a carb without the aid of the airbox at the other end. Went down to the local serious auto store and order a half meter length of fuel delivery hose of the right diameter. From memory it was listed as about 1mm smaller than the actual carb throat but a bit of hot water got it sorted. The hose is rienforced with copper wire to give it a bit more strength can be cut with a stanley knife with a new blade without too much of a drama. From the local hardware store got a four stainless hose clamps (much wider than stock) total cost $20-25 australian with enough for a couple of bikes and maybe a mistake or two while cutting and the carbs don't get that droopy look anymore.

[jcbooghs]

Can you post a pic of that solution, murray?

I don't think about a droopy look with the OEM rubbers.

[Skeeve]

An idea: if you want BIG why don't go looking for a set of 48mm Honda Firestorm carbs? Just a wild guess, I have no idea if it should work.

 

Downdraft; not gonna work.

[bigdog]

Ignitech might be the go for the ignition. They produce an ignition that will work from the original Hall effect sensor.