Bonneville America Forums Forums Technical Forums Performance Mods Too lean can't get rich$$$

I've been havin so problems with the bike I had the jetting and carbs set up perfect then now all of the sudden it runs super lean bleach white plugs I had #48 pilots 150mains thruxton needles 1 shim kawi springs about 2.75 turns on the mix screws I've put 160 mains in and still lean put 170 mains in still lean pulled the carbs off tonight completely tore them down didn't find anything all clean and working fine does anyone have any ideas P.S. I'm 300 feet above sea level and have drag pipes with tuning washers

Fuel feed restriction?

What throttle range have you been mostly running?



You can see here where the jets and needle work. If you haven't been on it hard the mains won't improve the rich/lean condition much. Besides, a sudden change implies other influence like a leak past the air filter or maybe even a vacuum leak at the manifold or dry rotted squirrel condoms. Something is getting more air into the system without drawing fuel along with it.

With the federally subsidized ethanol we are forced to burn now, the plugs will not look like the color of Halle Berry left buttock cheek* anymore when the carbs are adjusted correctly. Plug indexing is not so fine a tool anymore. A hint of colour is more the norm. That and decel popping (or the lack of).

*Monster's Ball "Make me feel good" she swooned to Billy Bob. Great scene for an R flick.

make sure you are not pulling in air somewhere else, cracked or loose 'squirrel condom' cracked or loose intake manifold or boot.

and if ethanol mix gas, that is going to help much.

do you have access to an A/F meter that way you know what you really have. Or get the bike on a dyno.

BTW is the engine running hotter than it used too? Or same?

I'm running non ethanol gas and no vacuum leaks it's run fine ive got a friend work at jerry's triumph they have a sniffer might see if I can borrow it

What's your float level,,,,,,,,,,,

If it dropped(lowered)it will run lean,,,,,

Why all of a sudden my theory is the answer? ,,,,,,,,,,,,,,

If the float is cracked,,,,it would sink(adding more gas),,,,,,,,,,,,,,(wrong direction)

The needle seats(rubber) have no signs of wear(grooved ring) that their hanging up?

I've checked the floats they don't have ant gas in them float level is good Needle and seats are good too

diaphram cracked/offset on one of the carbs?

I figured it out I put another shim in it and it fixed it I thought I already had 2 only had one got 155s back in it might drop to 150s thanks for all the help guys I was about to take her to the back forty and put her down the little graph thing helped ive got one buts there's always that one thing you forget or over look Still don't know way it leaned out all of the sudden might be because of the HEAT

Here is another one that shows the same thing.

Your set up sounds as though it would be on the rich side.

Those charts of course don't account for defects/malfunctions...