How much smoke is too much smoke?

[skipevans]

Hey all. I'm familiar enough with jetting RZ350s back in my roadracing days, but have never really rode two strokes on the street, and am wondering if the amount of smoke my 87 2ME (Canadian 2MA) is putting out is too much, perhaps indicating it's running too rich. It runs pretty well, a bit sluggish down low when cold (2k to 4K RPM), and there is a flat spot between 4K and 5K at steady throttle opening. But overall it runs well.

I checked that last condition by slowing opening the choke at about 5K when it lurches slightly, thinking if it was too lean at that point it would smooth out with the choke richening the mixture, but that wasn't the case: with just a little more choke the engine about died. So I think it is a bit rich there.

When it first starts there's a steady stream of smoke puffing out both pipes that floats a good half block down the street, and at stop lights there's always a steady stream wafting behind the bike as well as a stream following behind when pulling away.

Also, I cleaned the outside of the silencers completely yesterday, and after a few short rides then and one today, there is a drip of oil out of the hole at the tip, running down the very end of the opening of the silencer, so I'm watering if liquid oil deposits there indicate too rich a mixture overall.

I'm not unhappy with the way it runs generally, as I said a bit sluggish down low when colder, a mild flat spot at 4-5K, but it pulls very hard with more open throttle positions all the way up to redline.

Of course, if it's safer on the engine I'd rather leave it a bit rich than lean it out too much, but if the above information leads anyone to believe I'm clearly running too rich I'd like to perhaps drop the needle jet one setting go a bit leaner on the main jet. Does that sound like a safe adjustment?

Any opinions, advice would be greatly appreciated.

[calgap]

Skip,

Have you checked the colour of the plugs?

Or done a plug chop?

Cheers,
Chris

[Fotis]

it shouldnt dip any oil from the silencers... Its rich! TRy lowering your needle one or two steps

[Martin77]

Surely the first thing to check is the oil pump (I presume you're not running it on premix?), the slight flat spot at around 5000 on low throttle openings is perfectly normal, especially with differant pipes fitted.

So, check the oil pump settings (cable adjustment and minimum stroke) before doing anything to the carburation.

[skipevans]

"Have you checked the colour of the plugs?"

Oh, geez, I have been away too, too long. Yes, I'll check the plugs.

Skip

[skipevans]

The shop readjusted stuff since the engine was rebuilt. Leaned out the pump setting and dropped the needle jet. Made a world of difference!!! Flat spot is gone, runs smooth all the way up from the lower revs to the top, and a lot, lot less smoke!

Both of the suggestions here: oil pump adjustment and need jet setting were spot on, just what the mechanic decided to do.

But there is still a small bit of oil coming out the very tip of the silencer, perhaps because inside the baffling is still soaked from being too rich??? What do you think?

[teezer250]

But there is still a small bit of oil coming out the very tip of the silencer, perhaps because inside the baffling is still soaked from being too rich??? What do you think?

Yes,you will still get oil coming out due to the excess that has built up inside over the time it has been run previously,i wouldn't worry about it and just give it a wipe now and again.

[skipevans]

Yeah, thought about all the build up from it running rich, so I think I'll dump out the baffling and repack them.

[Northland]

Some brands of oil will never burn dry at the exhaust tips.

AMS oil.......Interceptor blend had so much end can spoo, you could oil the hood of the car behind you at stoplights if you cleared out the pipes GP style at the green light !!   

[skipevans]

Aha! That's the brand I've been running because the mechanic recommended it highly at the shop.

What other brands would spew less gunk?

[joey car]

bel ray Si7, used it in my rz 350 for years, low smoke , j.c. 

[Northland]

Z1 is all I use in the roadgoing injected bikes.


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