jetting

[mikeweyandt18]

i have just finished my chopper project and started it for the first time last night. it ran like shit, which i am not supprised, the carbs need some help. i have installed pod filters, and made a one off exhaust. the exhaust is about 3 feet long and has 4 inch baffels in them. they are split so one on each side of the engine. i am looking for someone who can give me a quick idea of what jets i need. it is a 1981 650, i know that i will need to get new needles for them because they dont have adjusments. i just want to get this thing on the road, i dont mind if it runs a little rich, i just want to be able to ride it already. thanks for the help.

 

[kopcicle]

Hi I just finished my yard art for the summer and was wondering if I should paint it pink or blue to go with the house ...

A little more information please .
year make model
size and year of carb
gearing
type of ignition
what dia primary and estimated length measured from the exhaust valve
current jetting
are the valves adjusted
is the dwell/timing spot on
are you holding your mouth right
what color is the bike (very important as red is faster)
are you a republican

I'd love to help but do you have any yard art and what color is it ?

~kop

 

[grizld1]

5twins and I wrote it in the Carb Guide, but here it is again; when you screw with the intake and/or exhaust and your bike runs like crap, don't go asking for recipes, because there aren't any. Either learn to tune or take it to someone who knows how and be ready to part with significant money. Get started here: www.amckayltd.com/carbguide.pdf .

Hey, Dennis, re. the yard art, what's up with pink OR blue? You're thinking in terms of a false alternative, my man. Use both colors in a paisley pattern; you'll be the envy of the neighborhood.

 

[BigJimmyW13]

5twins and I wrote it in the Carb Guide, but here it is again; when you screw with the intake and/or exhaust and your bike runs like crap, don't go asking for recipes, because there aren't any. Either learn to tune or take it to someone who knows how and be ready to part with significant money. Get started here: www.amckayltd.com/carbguide.pdf .

Hey, Dennis, re. the yard art, what's up with pink OR blue? You're thinking in terms of a false alternative, my man. Use both colors in a paisley pattern; you'll be the envy of the neighborhood.

Griz, when are y'all going to do a carb guide for Dellortos?!

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[grizld1]

That's not gonna happen, Jimmy. Right now I'm running Mikuni TM36/68 4-stroke flat slide pumpers, and I have two different variants of the TM33/8012 4-stroke flat slide pumpers to play with when I feel like experimenting with them. The round slide Dellorto pumpers would be a step backward in terms of technology, and they have some design features I don't like--cable pull slides instead of bellcrank, separate accelerator pumps, no adjustment for AP actuation without changing slides, no easy capability for disabling AP's during transition testing. Somebody else will have to take that project on.

 

[BigJimmyW13]

That's not gonna happen, Jimmy. Right now I'm running Mikuni TM36/68 4-stroke flat slide pumpers, and I have two different variants of the TM33/8012 4-stroke flat slide pumpers to play with when I feel like experimenting with them. The round slide Dellorto pumpers would be a step backward in terms of technology, and they have some design features I don't like--cable pull slides instead of bellcrank, separate accelerator pumps, no adjustment for AP actuation without changing slides, no easy capability for disabling AP's during transition testing. Somebody else will have to take that project on.

I tried. :-D

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[5twins]

There is a general tuning guide for the Dels both available to purchase in booklet form or free on-line. It's a general tuning guide just like the Sudco manual for the VMs and not 650 specific. I used it to help understand and tune my Moto Guzzi carbs but you really need a baseline to start from, just like with the VMs. When I finally found the Euro jetting specs for my carbs, I had that. All you can hope is that the baseline provided in the MikesXS set is good or close to good and then take it from there.

http://www.thisoldtractor.com/gtbender/dellorto.htm

 

[mikeweyandt18]

ok so you need more info. i can do that
it is a 1981 xs650
stock carbs (34 mm Mikuni )
stock gearing
electronic igniton. stock
the exhaust is 45" long and is 1.5 inch pipe
i belive the curent jets in it are stock. the bike was stock when i got it, and i dont think the the guy i bought it from did anything to it.
the timeing is good, the valves have been adjusted and are good.
my mouth is closed due to the fack that i dont like to eat bugs
the bike is blue, with a silver frame, (will post a pic when i can)
and i am no fucking republican

as for your yard art, you can never go wrong with green and gold
(green is for the money, gold is for the hunnies)

hope you got all you need.

 

[5twins]

I would start one up on the pilots and 2 up on the mains. Set the mix screws about 3 turns out to start. I haven't found the need to resort to different needles yet.

 

[mikeweyandt18]

thanks
i will try that and go from there.

 

[grizld1]

Hey Jimmy, if you want pumpers for the XS650, why use those archaic Dellorto roundslides? For a little bit more you can get a pair of Mikuni 34 mm. 4-stroke pumpers set up for the XS650 here: www.mikuni-topham.de . The last quote I saw on those was $700 for the whole kit, shipped to the US. It's likely a little less now, as the dollar has moved up some against the Euro. Don't look for them over here: Mikuni America doesn't see fit to let us have the 34's.

That whole Radial Smoothbore 4-stroke series, which includes the HSR carbs for Hardlies and the RS sport bike carbs (sold in banks of 4 only), is as advanced as carburetor design got before evolution was frozen by the advent of EFI. Tuning is a walk in the park, very little guesswork is involved.

If I'd known about them before I bought the TM36/68's, I'd have bought the 34's from Topham's--it would have come to about the same money, and would have saved a lot of fabrication work. If you're looking for a quality performance carb set, that's what to have.