R900/6 Rich Mixture

[PhilScrivano]

I just completed a valve adjustment on a 76' R900/6. The plugs apear to be running rich. The exhaust confirms this. What is the best way to approach a rich mixture on the 900? I am wodering if there is a needle jet adjustment or if I should be looking for the next step in heat range for the plugs?

Phil Scrivano

[cjack]

I just completed a valve adjustment on a 76' R900/6. The plugs apear to be running rich. The exhaust confirms this. What is the best way to approach a rich mixture on the 900? I am wodering if there is a needle jet adjustment or if I should be looking for the next step in heat range for the plugs?

Phil Scrivano

Was is always rich while you owned it? Then I guess maybe someone changed the needle setting. Maybe not. First, I would check my carb floats first. Make sure they are where they belong and are not too heavy (they get heavy from soaking up something over the years). Then make sure the diaphrams are not torn or stuck to the side of the carb where they reside. Then maybe look at adjustment choices.

[PhilScrivano]

The carbs are most likely in bad shape. I will take a look.

Thanks,

Phil

[jgr451]

I think if you have the rare R900S( as opposed to the more common R90S),I think your problem could be 10 times too many cylinders...lessee now,that would be 20...

:stick

:type

[vanzen]

Many situations can cause a rich condition: A dirty air filter could do it.
Enrichener(s) that don't fully disengage. Float(s) that sink. Worn jet needle(s) or needle jet(s). Improper needle position. Torn diaghram(s).
Incorrectly adjusted idle screw(s)...and that's just some of the carb issues to consider AFTER the valves, timing, and ignition check out.

[mthelmet]

Owning a R90/6 1974 model, if the carbs have not been overhauled in say 5 yrs. they are due. A good cleaning and check as everyone suggested are in order. Will make a much better running machine. Spring is a long way off, so take your time.

Get an old cookie sheet from the kitchen, when the other half isn't look, line with old towel then go at it. Slow an easy.
LOL

[carockwell]

For all practical purposes, reading the spark plugs would be a poor way of determining if your mixture is correct. I used to dyno tune cars for a living and I never found that reading plug and exhaust colors was even close to accurate. Lean cars ran black, or rich cars ran white, and everything inbetween. Give your bike a compete tune up and check tht everything is stock. With a bike the age yours is, and a lot of unknown past history, try and find a shop that can dyno your bike and give you the air/fuel ratio chart for it. Then you get to know for sure what is going on.