Old school meets new school
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I’ve been running Wiseco pistons for 30+ years. Never had one fail, but I’ve had plenty of OEM pistons fail.
I had an issue with my "time capsule" Husqvarna... Original TwinAir filter was degraded. Still can buy them new. Used modern filter oil. Ran pig rich. Jetting was stock and bike was in "like new" condition. Very annoying!
After trying a bunch of stuff and finding out how much Bing charges for jets these days on a whim I bought the TwinAir filter oil kit from Rocky Mountain ATV. (Had some bonus bucks I needed to use or lose.)
TwinAir oil is very thin and must dry for a few hours. When dry, filter is not "sticky" at all. Catches dirt great though. Richness cured. Bike ran like new again. I used the "Liquid Power" original formula.
I use that on our modern dirtbikes, (18' crf450r and 19' ktm sxf 450) and filters are cleaned every other ride. Easy to wash out, easy to re oil and never had a dust passing through issue
I am looking to buy good condition 1969 DT1 gas and oil tanks
1968 DT1 x 2
1998 Kawasaki KX60
I don't know about the design of your model Unifilter or how it compares to stock. I will say Yamaha wasn't stupid... their foam filters... even the strange looking "fuzzy foam" air filters of that era... flowed air very well.
Foam filters can also look brand new, clean, and properly oiled and not flow air properly. The foam itself can go bad... I've experienced this problem with foam filters... one filter was less than two years old!
Last thing I can think of is fuel. Are you running standard pump gas? Or race fuel? I have a friend that decided to run VP C12 because he heard it's a great fuel for racing two strokes... it is... His bike blubbered like hell on it. Went back to pump gas and ran great again.
P.S. Changing the amount of oil mixed in the fuel to "jet" the bike or cure excessive smoke/spooge is not a good idea in my experience. It doesn't work. As was said, reducing the premixed oil increases the available fuel and makes the fuel ever so slightly less viscous so it flows through the jets easier which also increases the available fuel. Less oil in the gas = richer air/fuel mixture. Richer air/fuel mixture = more smoke and unburned oil coming out the pipe.
Using less oil will give the appearance the problem is better... it will smoke less... heck, oil smoke and spooge will stop completely if you go to straight gas... but it will probably seize on straight gas before the residual oil burns out of the pipe.
You can run a lot of oil in the gas without excessive oil coming out the pipe if the bike is jetted properly. I've run 927 at 20:1 with little to no smoke and no spooge dripping out the pipe or sprayed the back of the bike. Bike was jetted well. I've run race engines on 16:1 (not 927 that I remember) with no excessive smoke or oily pipe issues. These bikes like oil... I would not run less oil than 32:1 on 927.
Perfect jetting is for racing... for casual riding I don't like to jet that lean. A little smoke and spooge is fine and as long as bike runs clean... even if it "just" runs clean... I prefer to stay towards the rich side.
formulaz1 wrote: Mark T. Thanks, 90+ pump gas. I will go back to 32:1 per your recommendation, inspect the filter better and try some jetting changes. Ya know, one thing I forgot to mention is no matter how long its been sitting, it starts on the second kick with no choke. Needle and seat is fine cuz I can leave the fuel on and days later nothing comes out the overflow. Could float level cause it to be blubbery from quarter throttle through full throttle?
That tells me it is jetted way too rich. First thing you should do is remove the carb, open it up and get the numbers off the following parts:
1. Main Jet
2. Pilot Jet
3. Needle and clip position
4. Jet Needle
6. Air Jet (if it has one)
Being able to start without the choke is a sign your pilot jet circuit is too rich (big).
Blubbery from 1/4 to WOT is a sign the needle, needle jet and main jet circuits are too rich. Start by raising the clip on the needle one groove at a time and see if it improves. If the clip is in the top groove you need to drop the main jet by one size and return the clip to the middle groove.