Two things you don't need on your 2 stroke.

Discussion in '2-Stroke Engines' started by upshifter, Jan 1, 2009.

  1. upshifter

    upshifter Member

    After market parts can be good and they can be bad. I've had experience with various 2 stroke engines in motorcycles, chain saws, lawn mowers, weed whackers, model airplanes, pumps, generators, and other things, for about 50 years or more. Yes, I'm older than dirt.

    FUEL FILTERS: I won't use inline fuel filters on a 2 stroke. I've seen them ruin engines. 2 Strokes use the fuel mixture to cool the engine. not just feed it. If the engineers that designed the engine would have thought in-line fuel filters were necessary they would have used them, or recommended them. They don't; because if the fuel filter becomes partially clogged, the engine will keep on running, but running hot and lean, the kiss of death for those engines. I've seen motorcycle dirt bikes seize from a partially clogged fuel filter. The in-line after market fuel filter is just one more thing in the chain that can potentially harm the engine. There is no need for an after-market in-line fuel filter.

    CYLINDER LINERS: Those are not a step forward on a 2 stroke, they are a warmed over idea from the past when we still re-bored engines and installed over-size pistons. Like I've said before, BMW stopped using cylinder liners and went to chrome bores, "Nikasil", in 1981. Chrome on Aluminum is a hard surface that conducts heat away better than liners, and it saves weight. Even if the liner was a good idea, it would cost more than a new engine just to get it re-bored and fitted with a piston. I've seen new cylinders selling for about $24.00. If it fails, then slap a new piston and cylinder on it. Don't waste your money. Parts are cheap, labor is expensive.

    (Also, don't believe the BS, Barbara Streisand, that you read on the internet about BMW Nikasil. I rode BMW for 15 years, about 100,000 miles, and never had a problem with Nikasil; and I never met a person who did, nor a mechanic that had seen a Nikasil failure.")

  2. srdavo

    srdavo Active Member

    interesting thoughts.....

    about the fuel do I keep crud out of my carb???

    My Russian 2 strokes have steel sleeves & they are notorious for that makes since!!
    Are BMW's 2 stroke?????

    and can we keep Barbara Streisand out of this? :smilielol5:
    Last edited: Jan 1, 2009
  3. BSA

    BSA Guest

    Yeah but chrome liners get ruined if your engine seizes up. Take your point though.

  4. Skyliner70cc

    Skyliner70cc Active Member

    Disgree on the fuel filter. The tanks are pretty rusty and flake off gunk all of the time. The manufacturer puts a mesh fuel filter in the petcock assembly but it clogs easily and blowing it out while on the road with fuel in the tank is something I've done and don't wish to repeat.

    For my 2 strokes, the built in petcock strainer gets removed and I install a fuel filter inline. Most of HT riders are also HT builders and we have a keen ear for when our engine is running differently. A noticeably higher idle speed or snappier response or sluggishneses if you were already a little lean from fuel starvation due to a partially clogged filter would not go unnoticed by most folks.
  5. upshifter

    upshifter Member

    You won't care if there is crud in the carburetor or not if the engine seizes. Many bikes have a fuel strainer in the carburetor input line, usually at the fuel shutoff valve.

    The GasBike engine kits I just bought are no exception. There is a fuel strainer mounted in the shutoff valve, that's bad enough. Why buy another one? When I put gas in a bike, I never pour the last little bit from the gas can into my bike's tank because most crud and water, if any, are at the bottom.

    BMWs are 4 strokes, but the Nikasil process cylinders are the same for 2 or 4 stroke engines.

    Fuel filters, cylinder liners, and other stuff make good advertising, but that's all.

    Two stroke engines that run hot are usually using the wrong heat range spark plug, or running too lean. If the engine develops a small air leak, it can run lean and seize the engine.

    If you're not sure that the gasoline is clean, get a funnel with a filter, or place a coffee filter in your funnel and filter it as you pour it into the tank. Also, Coleman has a small funnel with a reusable filter for their gasoline lanterns and stoves.

    I never put gasoline into a bike unless I'm absolutely sure it's clean; I put the dirty gas in the lawnmower, and forget it. If it runs, I cut the grass, If it doesn't run, I go take a nap, or work on my bikes. LOL
  6. srdavo

    srdavo Active Member

    true statement
    this is the 2 stroke forum & you brought it up.

    I am not against learning.... but i will stick with my inline filter.
  7. upshifter

    upshifter Member

    Skyliner, I've been restoring old bikes for years. I buy a kit and coat the gas tank with plastic, and it never rusts again. Living near the beach, everything rusts quickly.

    The plastic fuel tank kit will repair several small tanks. It comes with a rinse that removes any flaky rust. The next step is to put the acid "conditioner" or "Etcher" in the tank and all the rust wil be neutralized. Then rinse the tank and dry it. After that, put the liquid plastic in the tank and move the tank around so the plastic coats everything. Then you let the tank dry for a day or so. Once it's coated it is fixed for good.

    I haven't had any need for a fuel filter other than the one in the carburetor or the fuel valve.

    But, they sell plenty of them, so they can't be all bad. But, I won't use them.
  8. srdavo

    srdavo Active Member

    I appreciate the info.
    the older Grubee 2 stroke kits, came with a standard, lined fuel tank. The newer kits (non-grubee) I have seen are cruddy.

    A lot of us here, Skyliner70cc included, have been building these bikes for several years. We have some credentials , too.
    No one has reported any problems with an inline filter.
    Last edited: Jan 2, 2009
  9. graucho

    graucho Active Member

    I also have been using inlines for years. I do like threads that make me scratch my head
    for a few minutes. If your statement is true, maybe ive been lucky since I buy a ten
    pack on ebay and change them early spring and mid summer. I also try to buy them clear
    if they have them in stock so I can keep an eye on things.
  10. spad4me

    spad4me Member

    I buy the biggest clear inline filter I can find in a year I have gone through 4.
    The old fuel tanks in the local gas stations are contaminated with water, dust, urine and rust.
    I have replaced a fuel regulator on my sons truck $96.00,
    a fuel pump in my van $396.00. Because of the seasonal monsoon flooding the gas station fuel tanks.
    a new fuel filter is cheap insurance.
  11. Skyliner70cc

    Skyliner70cc Active Member

    THe HT kits aren't worth spending $$ to line the fuel tank. I'm for cheap and a 2.99 filter works just fine with me as long as I ensure the tank is full of fuel, it won't rust :)

    BTW, if you insist on lining your tank, save some $$ and use phosphoric acid in the form of tile/grout cleaner from Home Despot. It is the same as Yamaha fuel tank cleaner but cheaper.

    BTW, I agree Nikasil is a great and last forever! Chrome is pretty durable too and ABC lined cylinders (aluminum brass chrome) in a ringless 2 stroke model rc engine seem to last forever as long as the engines are run hard and not allowed to idle forever or run at low throttle settings.
  12. duivendyk

    duivendyk Guest

    Take your pick,lean conditions due to fuel starvation can be a killer,whatever the cause, without a filter in the fuel line the carb is more likely to get clogged up.These little engines are run pretty hard and without forced cooling prone to overheat.The best thing is to run them on the rich side.The Coleman filter funnel is a good idea.
  13. fetor56

    fetor56 Guest

    Personal preference...i'll stick with my inline filters & steel sleeves,but by all means u go ahead & run what ya want.
  14. Tinker1980

    Tinker1980 Guest

    I use an inline filter on my MB, I removed the one from the petcock. I also ride a '77 Husqvarna dirt bike, and I wouldn't dream of running that thing without it's inline fuel filter - the tank is only 3 decades old, and Bing 54 carburetor parts aren't exactly common. Nor are pistons (Wiseco - $165) or rings. After you've had to fabricate parts for something because the guys at the motorcycle shop said the right thing didn't exist, you start taking some precautions.

  15. Old Bob

    Old Bob Member

    IMHO a lot depends on application of the engine.

    Where you can get inexpensive replacement parts that don't get performance modifications, using the chrome bore cylinder is probably the way to go.

    On racing RC boat engines the cylinders are highly modified, a complete engine with carb minus mounts and exhaust runs $600 for a modified $200 engine.To rebuild it, it costs nearly as much.(over $450) Because the cylinder has to be replaced and ported.
    The steel sleeve favorite among the rc boat racers has even greater performance than the chrome bore engine and only costs $125 to rebuild.
    Because the parts are manufactured to the same specifications the power is nearly identical to the original, where as the hand ported cylinders vary from engine to engine by a noticable degree.

    As a note on filters, if the engine you are running uses a Walbro diaphragm carb is has a very fine screen in the inlet, using and inline filter will help avoid having to pull carb off engine and take it apart to clean the screen when it gets clogged.

    Like Tinker1980 I have a couple of vintage dirtbikes, clean fuel and clean air are a must.
  16. ibdennyak

    ibdennyak Guest

    If you're not sure that the gasoline is clean, get a funnel with a filter, or place a coffee filter in your funnel and filter it as you pour it into the tank. Also, Coleman has a small funnel with a reusable filter for their gasoline lanterns and stoves.

    Ha, coffee filter...why didn't I think of that!!! Great tip
  17. It does get me thinking. Would two stroke oil mixed in with your gas clog up some filters enough as to where just the gas passes and less than the desired amount of oil?
    A lot of us buy automotive filters that are designed for 4 stroke engines and not necessarily designed for 2 stroke oil.
    If I remember right back when I was tinkering with Diesel engines there are fuel filters out there that are designed for gasoline but NOT for diesel fuel because when it gets below freezing it can actually clog some filters. They made different filters for those.
    I'm thinking especially with our cold weather could we in fact be starving our engines of oil when we pass it thru our filters?
    Maybe we need to look into inline filters designed for diesel fuel. Of make sure our tanks are absolutely clean and pass our gas thru coffee filters that won't deteriorate with gas.
    I love threads that get me thinking!
    Last edited by a moderator: Jan 2, 2009
  18. POPS

    POPS Member

    Got me thinking too...Of the many motorcycles I've owned, 2 stroke and 4 stroke....NO fuel filters!...Just screen on peticock in tank and in bowl on peticock??????.......Hummmmmmm.....POPS
  19. So maybe just a fine METAL screen to trap particles that may clog the carby.
  20. POPS

    POPS Member

    Large...I would tend to agree with you...Maybe something like Pablos (SBP) filter and I also agree with you about a paper filter filtering out oil!!!! Never thought about that but I believe it has a lot of merrit!!!! Look at a used auto oil filter... Any oil in there!!! Good thinkin Large...POPS