700cc test report

Hello thomas,

I am very curiious for the Hp ?? Because I have also a 700cc kit.

I think other will be interested also for torque in Nm??

Greetings Madero

RE: RWHP

someone else tried that 43.8mm before thomas - one of your countryman. he also struggled to carburate it correctly....

good luck with that mate!

regards

Taffy

throw some knobbie tires on it 8O

RE: Re: RE: RWHP

thats why you have to jet down. i'm on a 145MJ.

you'll get there!
i bet they do a damn good mikuni for the harley! but the mikuni is a bloody nightmare to set up on the atomiser tubes.

regards

Taffy

Cheerio Lads!
I´ve been using a 50mm Lectron for quite some time now and I´m very happy with it. Once you´ve got it "jetted" it never needs adjusting to altitude or temperature, due to its strong fuel pickup signal. I have had problems with vibrations causing bubbles in the float bowl, but after installing a support that has never bit me again.

I´m thinking of trying out the 105mm kit, but I need lighter 40mm intake valves first. My 53gr stainless valves are floating at 8300rpm.

testing testing 1 2 3

Taffy,

you advise to jet down when using an engine with a larger displacement, please can you explain this? Is this also a possibility in combination with a larger diameter of the exhaust pipe? I've heard similar from an other sidecar team that, when using a lambda probe to fix the carburetor, a smaller MJ was the result. The only modification was the larger exhaust pipe. I had to increase the MJ to have the engine running better but it was clearly too rich, very confusing. Now the exhaust is modified, smaller diameter at the first part, and I had to decrease the MJ size.

Regards,
Stephan

hi stephan

are you on a sidecar cross outfit?

i learnt when i was 20 in 1981 that if you change the exhaust (more open) or the inlet (less resistance) that the jetting goes up. after that it goes down as you port it, tune it, cams, compression, ignitions, etc etc. more air is going through the same hole so it must be going quicker!

the air speed goes up with the larger displacement or a higher state of tune. you can even say: as the BHP goes up if you like.

as the air speed goes up the signal across the atomiser gets stronger in an INCREASING ratio.

if you ever did air spray painting at school you'll recall that the paint came out in fat globules if you blew gently but if you blew hard it came out as a fine mist. the engine can't burn fat globules of fuel, it can only burn the fine mist. so the faster the air, the harder it pulls and the finer the mist that comes out.

you then reach a point where there is the restriction of any given engine and on the husaberg its the carb and the exhaust valve sizes. so because of this i would expect a 550/650 all to be jetted pretty much the same.

however, in another engine with bigger carbs and ports to suit a 650 more than a 550 i would expect to see a clear difference in jetting but always DOWN for the bigger engine.

jetting and exhaust systems are very difficult.

you should see that the carb and exhaust free the engine and therefore the surges of mixture that had become one continuous stream and required a lower jet has now been freed up and goes back to start, stop, start, stop. this means the jetting goes back up.

i can barely remember 1981-85 but my pantah went 142 to 158 with no air filter and a 2 into 1 exhaust. from then on for three seasons the jetting came down until i was on the smallest MJ that dell orto made. a 135MJ!!!!!

time for 41mm malossi's methought!!!

regards

Taffy

drillling carbs

hi all
would like to know what carb you have drilled a FCR or the delorto
i have taken my FCR 41 a part and there doesn't seam to be enough meat to drill it out to 43.5
any help ?
Cheers Matt

picts off fcr 41 drilled

thanks man
that is very help full . would you happen to have a picture or 2 so i can see what t supposed to look like
cheers Matt

RE: picts off fcr 41 drilled

Hi Thomas,

Do you bore the carb offset or on centre?
What inline air cleaner do you use instead of the factory one?

Cheers spanner

RE: Re: RE: picts off fcr 41 drilled

Thomas,
The JBS big bore kits do they have a plated bore?

Cheres spanner

RE: Re: RE: picts off fcr 41 drilled

in regards to the carb, you can bore the carb larget than 43mm. The centre part that your talking about that you grind with a dremmel can be bought with the larger size. Ive done this on my atv and its awesome. Any of the large atv engine guys do it, like sparks racing, ct racing in cali, or www.nmotiontechnology.com. or do a search on yfzcentral.com.