r100 jetting adv.

[45disco]

i have search with no luck.. i have a r80 converted to a 1000cc. i have 32 bings. the U.S. jetting i have heard is lean. if any running 32s on a r100, what are u jetting them too. stock, 45 idle, 2.66 needle, 135main, 3rd position needle.
i have heard, the better jetting is 48 idle, 2.68 needle, 145main,

the bike is set now to 45 idle, 2.68needl, 145main, 3rd position.. seams to run ok, haven't put many miles on it, will do about 600mile this week.

3000 ft to sealevel, highest is 6kft altitude.

 

[richie moore]

put it on the dyno its the best way to do it. ps lean is good.

 

[Rob Farmer]

My 78 100/7 runs 32mm carbs.

Jetting is

Main Jet - 150
Needle jet - 2.68
Needle is - 46-241
Needle position - 3rd from top
Idle jet - 45

I have a 33/11 bevel box on it and it pulls without a glitch.

What year is your bike? What size valves have you in there?

 

[45disco]

My 78 100/7 runs 32mm carbs.

Jetting is

Main Jet - 150
Needle jet - 2.68
Needle is - 46-241
Needle position - 3rd from top
Idle jet - 45

I have a 33/11 bevel box on it and it pulls without a glitch.

What year is your bike? What size valves have you in there?

i have an 83 r80g/s(euro) with a 88 r100rt topend. valve are 42 and 40, with 32 bings. i have it jetted to the 78 standard except for a 145 main. the compression ratio is supposed to be 8.45.1 which is better than the r100gs(us spec @ 8.2.1) this is the cause of the jetting dellema. i just don't want to be too lean or too rich

i have the 37:11 bevel drive...

i did the conversion to get as much torque as i can for two up and loaded.

 

[Rob Farmer]

The 88 Euro RT standard jetting should be (according to Haynes) and as you mentioned.

135 main
2.66 needle jet
46-251 needle on 3rd notch from top
45 Idle jet

So you're probably too rich on the main jet for the altitude.

I treated myself to one of these air fuel meters. Not cheap but worth it's weight in gold

 

[45disco]

need one of those air/fuel meters.

so i should keep the 2.68 needle jet, put the stock 135 back in and leave the idle at a 45 pilot(stock)..

i just check the pugs from my ride which did not get past mid throttle(needle jet) and the pugs seemed to be brown/grey (electrode) and light black(not wet) on the rim and base of the contact.

 

[45disco]

ok. i am going back stock except for the main.. i have been told by some one that has done this tuning, he said that the bike pulled harder after after 5k on a 145main. he thinks a 140 would be better but did not have one.. he tuned with and air/ fuel meter and found that the mid was still a bit rich so he shimmed the jet needle a bit in the 2cd clip, so about a 2.5 clip position and found this to be with in the range.. he is at sea level so mine will be a bit rich till i come down off the mountain. 3300ft. he also had stock exhaust and filter.


cheers

 

[MattW]

I treated myself to one of these air fuel meters. Not cheap but worth it's weight in gold

Ooh - that's nice.

Do you have to weld a connection point on your exhaust to mount the sensor?

(trying hard to resist the temptation to look how much they cost...)

 

[pete.keys]

i have search with no luck.. i have a r80 converted to a 1000cc. i have 32 bings. the U.S. jetting i have heard is lean. if any running 32s on a r100, what are u jetting them too. stock, 45 idle, 2.66 needle, 135main, 3rd position needle.
i have heard, the better jetting is 48 idle, 2.68 needle, 145main,

the bike is set now to 45 idle, 2.68needl, 145main, 3rd position.. seams to run ok, haven't put many miles on it, will do about 600mile this week.

3000 ft to sealevel, highest is 6kft altitude.

I have the same spec bike as you (except mine is dual plugged as well) I am impressed by the overall engine set up (done by Andrew sexton) it is running on 45 2.64 needle and 145 main. Every time I have been inspired to change anything it runs worse so I put it back.

From the plugs it looks like mine is running very lean - although it uses a lot of fuel for some reason.

I really don't know what the difference in jets is .. I should probably find out

Well when I say running - its broke at the moment but thats another matter/thread

 

[Rob Farmer]

Ooh - that's nice.

Do you have to weld a connection point on your exhaust to mount the sensor?

(trying hard to resist the temptation to look how much they cost...)

You can do but I bought the optional bracket to fit in the end of the exhaust, the only down side to this is it picks up a little reversion every time you change gear. It's the same set up and sensor they use for the dynos though. The wideband sensor is a Volkswagon Audi item.

£225 for the basic kit but that is also a full odbII reader for diagnosing faults with your car.

It's a chunk of cash but if you're messing about with older bikes and cars it's very useful and saves a lot of guess work. The only downside is top speed runs, you can't beat a dyno for these.

 

[MattW]

You can do but I bought the optional bracket to fit in the end of the exhaust, the only down side to this is it picks up a little reversion every time you change gear. It's the same set up and sensor they use for the dynos though. The wideband sensor is a Volkswagon Audi item.

£225 for the basic kit but that is also a full odbII reader for diagnosing faults with your car.

It's a chunk of cash but if you're messing about with older bikes and cars it's very useful and saves a lot of guess work. The only downside is top speed runs, you can't beat a dyno for these.

Ta Rob - I'll have to have a word with Santa

 

[45disco]

I have the same spec bike as you (except mine is dual plugged as well) I am impressed by the overall engine set up (done by Andrew sexton) it is running on 45 2.64 needle and 145 main. Every time I have been inspired to change anything it runs worse so I put it back.

From the plugs it looks like mine is running very lean - although it uses a lot of fuel for some reason.

I really don't know what the difference in jets is .. I should probably find out

Well when I say running - its broke at the moment but thats another matter/thread

i ran mine with stock jetting except for a 145 main. for a trip 800miles, fully loaded 41l panniers & two up. my plugs looked ok, however i did notice it running a little crisper when the outside temp was better than 45 and not damp. elevation seemed ok to 5k ft. i got around 36mpg in very windy conditions. i did like the power and torque well worth the little more vibration.

 

[Sean Kelly]

Hi

I have an Andrew Sexton twin-plug, 1000cc with 800 heads. It's a while back so I can't remember what jets/sizes are in there but..... a run on the dyno after fitting the new motor showed it was running rich around the middle throttle settings. One clip on the needle was too lean so we shimmed it a half clip and good-to-go. Economy was improved. If you re-condition the carb with new parts then settings will move around.

Sean