Makita BP Blower --Sending Myself a $1000 Repair Bill & Kick in the Backside

Discussion in 'Mechanic and Repair' started by GlynnC, Mar 4, 2013.

  1. GlynnC

    GlynnC LawnSite Senior Member
    Messages: 913

    It's a long story, with a good ending! I have a Makita RBL500 backpack blower--one of my favorite pieces of equip. Early last spring, ran it one day to blow off my own driveway, put it away, next time I pulled it out to use--a week or two--dry summer last summer, wouldn't start. This would usually indicate a fuel problem. Pulled plug, shot in a spray of choke cleaner--still didn't get a hit. This blower probably has fewer than 30 run hours. I'm a crazy man when it comes to fuel, 93 octane (no ethanol), Amsoil at 50:1, fuel stabalizer, never more than a couple months old. I'm not new to 2-stroke repair--maintain equip for 3 full time commercial guys, part time LCO myself.

    I worked on this several times over the summer--cleaned carb--diaphram and gaskets all in good shape--carb was spotless. Pulled rope about a thousand times (maybe not so many). New sparkplug, another known working plug, changed fuel lines and filter, pulled muffler--exhaust port looked like new engine, spark arrestor screen clean, and muffler looks new. Tested compression with known good tester--120psi at 2nd pull, almost 150 after 4 pulls. Tested spark with an in-line tester--looked great. Pulled flywheel to see if key had sheared--in perfect shape. Against my better judgement, ordered new carb. a few weeks ago--finally could get it to run--but just barely. Getting tired of reading about this yet--I'm about ready to haul to junk, but just couldn't force myselt to do it.

    Today, I pulled the muffler, reassembled without muffler, pulled rope and it started and ran like crazy--bout scared the cat to death!!! Now I'm excited!! Blew on the muffler with my mouth--couldn't blow thru it--never tried this before so didn't know for sure, blew it out with compressed air, an felt something happen. Tried with mouth again, air moved freely. Reinstalled muffler and it runs great--smoked like an insect fogger for about 15 minutes--probably from all the many times I had tried to start it!!!.

    What stopped up the muffler--remember this happend while stored in my mower building. Not a dirt-dobber, muffler was spotless as far as I could see! I'm happy it's finally running, but I bet I've worked 40 or more hours on this blower. Glad it was my own, and not somebody's I would be charging for repair.
  2. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,188

    The muffler prolly has a catalytic honeycomb in it that might have gotten clogged or dislodged.

    May have been a clogged spark arrestor screen.
  3. GlynnC

    GlynnC LawnSite Senior Member
    Messages: 913

    Not spark arrestor screen--it was perfectly clean and open. I thought it might have something to do with catalytic something in the muffler--but don't understand why this would happen while unit was in storage.
  4. pugs

    pugs LawnSite Gold Member
    Messages: 3,025

    I think that unit was before Catalysts started getting added to 2 strokes. I sold a couple of those but that was like 7+ years ago.

    Did you shake the muffler around after whatever was clogging it loosened up? I am betting it was some type of insect created blockage.
  5. GlynnC

    GlynnC LawnSite Senior Member
    Messages: 913

    I did shake the muffler--obviously something inside, it rattled, but it never came out, probably did after I started it last night--but it was dark.

    In Texas, there's a bug--don't remember what it's called, circle bug or something--it goes inside about anything that has small openings, builds a nest, web, or something, and stops it up. Haven't seen any of those in the Nashville, TN area. But I'm agreeing, it had to be something like that. I'm kicking myself for not checking the muffler early in the process--the symtoms were there, but since the exhaust port and spark arrestor screen were clean, I didn't give the muffler a second thought.

    You're, right, this unit is several years old--but almost new. Don't know the details, bought it off a guy that had a lot of Makita stuff for sale--advertised on Craigslist. Answered ad to buy Makita 14.4v drill, bought it. Also bought a really nice Makita air compressor in pieces--said it kept throwing the breaker and he tore it apart--put it together and it runs perfect--paid $10 for this. Then saw this very clean--looked new--blower. He said he couldn't get it to run, checked comprssion, paid $30, and gave it a new home. The fuel line was not attached to the carb. I'm thinking it had set in his garage for several years, not running.

    Anway, I'm glad it's running, I think I'm more excited to get it going than anything I've ever worked on. I've also promised myself to give mufflers more attention in the future, after all, what goes in must come out!:laugh:
  6. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    The problem is mixing a 100:1 oil @ 50:1!

  7. GlynnC

    GlynnC LawnSite Senior Member
    Messages: 913

    Not to be disrespectful, but I've run equipment with this mix for several years now--never any problems. Clean exhaust ports every time I check. The spark arrestor screen on this unit is at the top of the muffler--just as exaust comes out of the engine. It was perfectly clean. Plus, I don't see how the mix ratio would cause a problem while the blower was setting in the building. I've worked on a lot of equipment, cleaned many plugged exhaust ports and blocked screens, but have not had a blocked muffler--until now (except for a "non-running" trimmer bought at a garage sale--had a dirt dobber nest in exit pipe of muffler).

    I probably will eventually work my ratio up a little, but not while I have 2-stroke equipment still under warranty. I saw on another post where you run Opti-2 at 100:1. A friend of mine in the tree trimming business ran that mix for years in his Stihl saws, then had a fairly new saw melt down. Stihl dealer refused warranty due to fuel ratio. This guy didn't have the money nor the will to hire a lawyer to fight the battle. He now uses Stihl Ultra at 50:1, so that at least the mix ratio cannot be used as an excuse not to honor warranty. A guy who works for him runs his own Stihl saws some of the time. He refuses to use the Stihl mix, now brings his own Opti-2 mix for his saws. I'm a little guy, without volume leverage with a dealer--just don't want to fight the battle. Of course, if this muffler blocks again, it may have a dedicated fuel mix, with higher ratios..
  8. herler

    herler LawnSite Fanatic
    Messages: 5,139

    It doesn't make sense to run a 100:1 oil at 50:1
    I've always ran Opti-2 and Amsoil 100:1

    Never fried one yet, maybe your friend ran straight fuel, that's a likely possibility.
    Of course the dealer asked, what were you running in the fuel?
    And your friend said 100:1 which was the end of that.
    But did he really, or did he run straight gasoline?

    Besides if it fries an engine why would I go to the equipment dealer?
    It's Opti's / Amsoil's problem!

    But I can appreciate the 93 octane
    Last edited: Mar 5, 2013
  9. GlynnC

    GlynnC LawnSite Senior Member
    Messages: 913

    A quote off the Amsoil site "Saber Professional--
    Designed for pre-mix applications as lean as 100:1 ratios or richer".

    I didn't say the saw went down due to a lubrication problem--I said it went down. He was working storm damage in another state, it was a very hot summer, and the saw went down with a fried piston, he suspected it might have been the heat--don't know all the details, just know that Stihl didn't honor warranty on this expensive commercial saw, and he switched to Stihl Ultra oil. And yes, I'm sure he told the truth when ask what oil he was using--this guy is not the dishonest type. (Besides if it fries an engine why would I go to the equipment dealer?
    It's Opti's / Amsoil's problem!
    And this is the reason I run equip at mfg. recommended ratios while under warranty--it always a "not my problem, it's the oil ratio", or "it's not our problem, it's the equip. mfg problem". You run your equip on whatever fuel mix you want to, for me, I choose to follow Amsoil on the richer side as per Amsoil quote above as long as equip is still under warranty.
  10. GlynnC

    GlynnC LawnSite Senior Member
    Messages: 913

    (Originally Posted by american dream
    We run all our two stroke on amsoil at 100:1 and the equipement runs like a scalded dog!)--from another thread

    Echo technical guys still don't think that is a good idea so I am sticking with them. (posted by ed2hess on another thread)

    After 100's of threads on various forums, we know the brand and ratio of 2-stroke mix will be debated for years to come, so this is my last post on this issue for this thread.

    I'm very confident that carbon build up is not an issue on my Makita blower. You know carbon build up when you see it--exhaust port and spark arrestor screen are a mess--not the case here.

    My original intent for the thread was to remind myself, and others, how important exhaust flow is to a good running engine. Shame on me for not finding the problem much earlier in the repair process!

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