I got a good deal on a 86 250R a few months ago. Bike ran wonderful- Then, I put a FMF Fatty pipe and matching silencer on and low end power totally went away(the "snap" off idle was gone) and the bike now runs very rich on 22:1 at less than 1/2 throttle, but leans out after 1/2 throttle and runs like a raped ape. I am thinking this is a slow circuit problem, I messed with the needle clip position without much luck. This is my first 2 stroke bike, but not first 'wheeler, so I have the tech skill- but no ideas which way to go for a tune up, questions:

1. What ratio premix should I be running? (current 22:1)
1.a. what brand oil, what grade gas?
2. Could I go up to a hotter grade plug? (plug is wet from a power kill jetting test for plug color)
3. Who has jets, slow and main, for a stock 86 carb?
3.a. is it worth messing with this carb, get a flatside instead?
4. could it be another problem that I am missing? I checked my air filter and run with a modified 'box lid- its ok!

Im out of ideas, But I love this bike! Any Help? Thanks-

Bulldog250R

 

oil mx is way to rich run any good oil 40:1 what altitude are you, should just have to go up a couple sizes on main.

 

thanks for the response 344PV! Im always under 2500 feet, I live near the Mississippi River in Iowa and dont go too far to ride. I looked at your "R" in your profile- Very Nice Bike! [img]i/expressions/face-icon-small-cool.gif[/img] How did you get your silencer to mount up high underneath your fenders? Mine is in a bind unless I mount it to the lower hole on the frame with a spacer. I will lean out my premx and check my main jets. Thanx again![img]i/expressions/face-icon-small-happy.gif[/img]

bulldog

 

i have had a few pipes on it over the years they have always mounted the same.

 

Question for 344PV. The stock mix is supposed to be 20:1 right? I have been running Klotz supertechniplate at 20:1 and it seems to run well. I too have a pipe, silencer, and reeds but with the stock bore. At what point should you start using 40:1? Is it based on type of oil? I can understand running the 344PV (by the way how do you like that upgrade? I am Arctic Cat Green with envy) may require the leaner mix, but what makes you go so lean for a stock motor with a couple bolt on's. I am not trying to knock you, I just would like to have a reasonable discussion. Everyone seems so paranoid (myself included) about getting the mix just right. What are your thoughts?

 

good question, not to pile on, but I thought that sounded a little on the lean side- but this is my first 2 stroker- i defer to the wisdom of experience...

 

20:1 was the factory's way of playing overly safe, 20:1 fouls plugs if you lug around, less oil has nothing to do with upgrades i have run redline or amsoil 60:1 even 80:1

 

ask around most 2 strokes run 40:1 with any kind of 2 stroke oil (plus its cheaper)

 

I have been seeing more people say 40:1. I guess I don't do much lugging around [img]i/expressions/face-icon-small-blush.gif[/img]) [img]i/expressions/face-icon-small-happy.gif[/img] The guy I bought the trike from was an Amsoil distributor (apparently its pretty easy to get into that racket) and he ran it at 100:1.

Its just real hard to go leaner when you have to pay more for being too lean. I have always played the too rich is better than too lean scenario. At least it usually costs less to be too rich (i.e. pistons vs. plugs). I'll probably stay at 20:1 unless it starts running poorly and fouling plugs. Time will tell.

 

with more oil you are leaner air to gas, your only rich gas to oil ratio.