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 2 Stroke Carb Rebuild Kits 
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Location: Bothell
Joined: Sat Sep 12, 2015
Posts: 4843
Ok --- so I used my leaf blower on Sat with no problem... until the end -- tried to restart it again while it was hot and it wouldn't start.... heard some bubbling/gurgling come from the carb/muffler somewhere ---- not good - thats happened before. Thought I'd let it sit - tried it again on Sun only to find a puddle of gas underneath and unable to start it..... Yeah, I take that as a sign its time to replace the gaskets and the diaphragms again..... I think its been about 5 years since the last time.

So I go searching for rebuild kits.... thank god I was smart enough to write down the P/N for the kit in the manual. Looking thru for price and # of parts in the kits to compare.... I find two different types of kits --- one that has all black diaphragms like this one ---

https://www.amazon.com/Zama-Genuine-GND ... B00THR412K

and the other that has the black/blue/whitish diaphragms like this one ---

https://www.amazon.com/Stens-615-218-Ga ... 3189&psc=1

Anyone know what the difference is between the black - blue - whitish diaphragms is???
The black and the blue ones appear to be pretty identical --- I assume they are just different types of rubber???
The whitish ones seem to be slightly different - with most notably a hole missing compared to the blue and black ones. I am assuming that the whitish ones are a similar material to the tan ones that have a fiber reinforcement that came in a kit for my Walbro carb --- I never used it, opting for the black rubber one instead - it worked so I didn't do anything more, but saved it for a replacement for when the black one gives out.

I assume that the tan and whitish ones are more of a plastic (mylar or PVDF) rather than the rubber type of the blue and black ones....??? Would a stiffer diaphragm mean one of the pressure hole would not be needed?

Anyone have more knowledge about these rebuild kits than me?


ETA ---- If I start looking for a rebuild kit RB47 instead of a gasket/diaphragm kit GND18, I see fewer parts in the kit but I see some with back and some with blue --- none that have both....?....?

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Plan B is actually repeating Plan A.... it just involves much more alcohol.

Of the ten voices I hear in my head, only three keep telling me NOT to shoot....
Do I go with the majority or common sense?


Mon Apr 25, 2022 12:29 pm
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Location: Bothell
Joined: Sat Sep 12, 2015
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So.... I ordered that kit and it got here in 2 days --- got it installed yesterday. Turns out the whitish diaphragms were actually just a clear plastic and wrong for my carb -- no suprise. The blue one that i expected to be blue rubber actually turned out to blue plastic too --- I wasn't expecting that. I opted to use the black rubber one since that is what was in there before.

I really don't think that the diaphragms were the problem now --- the ones I took out still looked pretty good. Thankfully, I ran across a YT vid showing the rebuild.... There was mention that if the metering needle lever is set wrong, it could cause leaks --- just like I was having. I checked the lever height before disassembly and it seemed to look good. Then I recalled that the last rebuild I actually got the rebuild kit instead of the gasket kit --- I didn't bother replacing the spring or the needle since the originals seemed fine..... But I did notice that the original spring was noticeably shorter than the one in the rebuild kit. So, since I had it apart, I decided to replace them now --- damn those little springs are a bitch to work with and keep in place....

So its back and running now! Happy to keep the old tools running. I'll have to see if I still have issues with gas leaking like I did, but I'm hoping the new spring and needle have taken care of it.

But I'm still confused and wondering about these plastic vs rubber diaphragms.... I almost wonder if you are supposed to use BOTH in there to help support the flapper valves ?..?..? Or will the plastic work just as the rubber....? At some point I will have to switch out the rubber for the plastic ones and see if/how they work.....

_________________
Plan B is actually repeating Plan A.... it just involves much more alcohol.

Of the ten voices I hear in my head, only three keep telling me NOT to shoot....
Do I go with the majority or common sense?


Sat Apr 30, 2022 8:06 am
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Location: Nampa, Idaho
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Real Name: Rick
Too bad I read this thread a little late.
Last summer my Honda lawnmower started running like crap: slow to not wanting to run at all. I forget what year it is but I knew it was carb related.
Thoughts while on the ceramic throne. A) should I rebuild the carb back better? B) what about replacing the carb altogether? * let's see what fleabay has to say...

Plan B won! A brand new collaburator was a whopping $12 that came with everything. So simple a caveman could do it.

I had that sucker changed out in 20 minutes just taking my time. (after ten minutes of getting the damn thing up on the workbench. I hate bending over)
It started up on the second pull and runs like a raped ape now.

Moral of the story - buy a new carb!
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Sat Apr 30, 2022 8:54 am
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Location: Kent
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I kinda disagree with buying china carbs. The quality is pretty iffy, sometimes you can never really get them dialed in. This is especially important on 2 strokes as too lean will cause engine damage.


Sat Apr 30, 2022 9:08 am
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Location: Bothell
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I always hold the option of a new carb close --- it can get really close in price between a GND/RB kit and a new carb.... but yeah, I hear the chineesium carbs can be hit or miss. Its always a gamble as to what HIPA adjustment screws they have as to whether or not you can adjust it - I had to buy one for the leaf blower (21 spline)..... I was always drawn to the ones that come with the tool, but they are always more $.

I'm feeling kinda good for going with a Sten GND kit this time around instead of the Qazaky one I got last time - I always assumed that the materials were pretty standardized, but who knows. I think the Sten was the same price as the Zama tho.... I like the fact that I would get two pump diaphragms.

I'm thinking my real problem was the spring on the metering needle tho.... will see how long before it starts leaking again --- hopefully it will be many years so that I forget what I've done.....

The weedwhacker is starting to act up again.... I may be due for another K10WAT soon...

Gotta say --- there is a nice sense of pride to keep these things running..... I know so many people that pitch them at the first sign of a gas leak, not starting or poor performance. Pretty sad.


You'll like this --- I got everything reassembled and put some gas in to fire it up.... push the primer bulb..... no gas pumping thru..... tried to start and it sputtered a couple of time - promising. I realized that I got the tank and the purge lines crossed, so I was just pressurizing the tank..... Popped the lines off and gas was just streaming out of the line!!!! Of course I pulled the wrong line off first. That stream of gas just poured right down into the carb..... so ANOTHER round of pulling the plug, drying it and trying to clear the crankcase of gas. When it did fire up - right away - it was blowing all sorts of oil out the muffler..... What a mess.

_________________
Plan B is actually repeating Plan A.... it just involves much more alcohol.

Of the ten voices I hear in my head, only three keep telling me NOT to shoot....
Do I go with the majority or common sense?


Sat Apr 30, 2022 9:53 am
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Location: Kent
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Sound like you're ready to graduate to motorcycle carb rebuilding soon, the FCR on my 450 had a few more parts than anything I've delt with previously...


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Sat Apr 30, 2022 11:19 am
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Location: Snohomish Co
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I'm on the fence about any chink carb too... I had to buy one for my badass old troybilt tiller since the old carb was a ball of rust when i bought it, but i forgot to drain the carb last winter and got a corroded up mess this spring, with a stuck needle. I cleaned everything but the bowl gasket fell apart. $10 for 5 rebuild kits from amazon(just incase) and back up and going. I'm also going to start hitting the local farm/feed for ethanol free gas for my jerry can in the future to prevent this stuff

Try to keep everything as original as possible because new stuff is junk


Sun May 01, 2022 8:17 pm
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This summer I will try and salvage this jetski carb...


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Sun May 01, 2022 9:02 pm
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Location: Bothell
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Wow --- you like a challenge - don't you.....
Hope the rebuild kit is extensive...

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Plan B is actually repeating Plan A.... it just involves much more alcohol.

Of the ten voices I hear in my head, only three keep telling me NOT to shoot....
Do I go with the majority or common sense?


Mon May 02, 2022 9:16 am
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If you think ethanol is hard on cast aluminum carb castings, wait till you see what it does to chineesium alum pot metal carbs.


Mon May 02, 2022 1:53 pm
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Thought I'd throw this in here.....

So - something strange popped up this weekend..... I was doing some weed whacking for my neighbor.... I started off with his echo unit --- worked ok, but didn't feel as comfortable to swing as my poulan and I was really missing the power of the 32cc over the 25cc ---- it was REALLY thick grass and weeds thigh to waist high. He said to use his stihl premix in the can.... it ran fine in my poulan.... but after the second tank, I noticed the idle had dropped to the point of stalling out. I was just using mine last week without any issue with my 85 gas with cheap 2 stroke oil..... Does running factory premix 93 octane tend to mess with the idle if its not set up for it? I bumped the idle up to finish up the yard and still have ~ 1/2 a tank left --- I'm curious to see what happens when I go back to my gas......

_________________
Plan B is actually repeating Plan A.... it just involves much more alcohol.

Of the ten voices I hear in my head, only three keep telling me NOT to shoot....
Do I go with the majority or common sense?


Sun Jun 12, 2022 2:31 pm
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Octane is essentially a rating of how easily the fuel will ignite. If using higher octane in a lower compression engine, it will make less power and increase emissions. However too low of octane for the compression ratio will cause detonation, which will result in engine damage.

I would wager a weedeater is just fine on regular or even lower...


Sun Jun 12, 2022 8:01 pm
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Location: Snohomish Co
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I see you are in bothell, snohomish co-op has ethonol free fuel... i'm not sure if anyone closer does. I'm going to fill my jerry can for the last 'till, mow, and weed-eat of the season.


Sun Jun 12, 2022 9:02 pm
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My weed whacker and leaf blower run just fine on 85 ethanol gas with cheap oil.... no problems for 20+ years. I fully expect to replace gaskets and diaphragms every 5-7 years --- I figure its the trade off for using cheaper gas with ethanol. Honestly, I wonder if using ethanol free gas would make any difference to that.

I was using the neighbors premix canned gas just because of the gas prices --- I ended up using the better part of 3/4 gallon in 8 hours of full tilt weed whacking. I was just caught off guard by how the idle dropped so low using 93 octane gas... I think the reason my neighbor buys the canned gas is because he just picked up a new Stihl chainsaw --- I've heard rumors - and my brother confirmed it - that Stihl will void the warranty if you don't use their oil... and I've also heard they will extend the warranty if you use their premix. Seems like it would make sense for a chainsaw that doesn't get used very often, but it seems REALLY expensive for weed whackers and blowers that get used a lot to me. I usually go thru ~2 gallons of mix gas a year for my own yard work... and right now --- thats running ~$10/gal with the oil.

_________________
Plan B is actually repeating Plan A.... it just involves much more alcohol.

Of the ten voices I hear in my head, only three keep telling me NOT to shoot....
Do I go with the majority or common sense?


Mon Jun 13, 2022 9:35 am
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Location: The banana belt of MT
Joined: Wed Dec 30, 2015
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Real Name: Brian
Ive rebuilt Quadra-bogs (Quadrajets) in the past in the 70s but never 4 stroke stuff.

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Mon Jun 20, 2022 3:39 pm
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