Zama RB-K75 Adjustment

[Echofan]

I should have mentioned I put all new lines, fuel filter and grommet on this unit as well.

Is there an inexpensive version of the air pump out there, other than the one Walbro sells for $70? While I like quality tools, they save time, I don't do this for a living. Actually I've only worked on things that either I bought to have, or my own fleet that needs maintenance. Some people do puzzles in their spare time. I work on a small engine. One project at a time, until I either give up, or it's done. I haven't given up yet.

I've had my eyes on the Oppama tachometer for a while, and that's maybe my next tool purchase. While I've seen the tachometer and the pump in an Echo service toolkit, the kit was well over $400, which at this time for a hobby is a bit high.

I have to figure out this forum, so that I get e-mail notifications when someone responds to one of my posts. I assume that it can be done, I got to dig harder in the setup.

[bgsengine]

The article should have a link to a decent tester (Mightyvac - around $50) - The Echo tester is kit # 91139 we're out of stock at the moment, they can be special ordered though they go for around $90 - The Oppama Tach PET-304 is around $90 ( Ebay example: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 1258322965 ) and the spark tester 99051130023 is around $75

[bgsengine]

I have to figure out this forum, so that I get e-mail notifications when someone responds to one of my posts. I assume that it can be done, I got to dig harder in the setup.

When you go to post a reply , scroll down further to the Options (below submit button) : Notify me when a reply is posted and check that checkbox

[Echofan]

Thanks for the thought, here's an update for anyone that finds this post via google.

The needle lever arm was noticeably high when I pulled the carb apart. Removed needle and cleaned, reinstalled and the level came down. Weird, maybe not freely moving on the lever pin I don't know.

For anyone working on the RB-K75. There is a brass throttle cable assembly piece threaded into the carb. If this is threaded in too far, the bore in the rotor will not fully open. Because this had been "played with" before I got it, I was not sure if there was supposed to be a nut on this brass assembly or not. Initially I had the carb mounted, and then worked with this piece and the throttle cable.

While the carb is off the unit you should install this brass sleeve to the carb body, and check that upon WOT the full bore of the rotor lines up with the bore of the carb.

Appears to start in 2-3 pulls, which isn't bad since it has been used, and I'm not sure what oil mix was used previously. I'm a fan of high quality oils because I've had some equipment apart that's been run way too rich on ashy oil and seen the results. Unfortunately many of my family still buy the cheapest oil mix they can find at the dollar store.

Thanks again-- I spent way to much time on this hoping it was a mixture screw, rather than checking the needle lever... Take it off and check the lever for a loading condition! Lesson learned.

[bgsengine]

For anyone working on the RB-K75. There is a brass throttle cable assembly piece threaded into the carb. If this is threaded in too far, the bore in the rotor will not fully open. Because this had been "played with" before I got it, I was not sure if there was supposed to be a nut on this brass assembly or not.

Yes they typically have a lock nut to lock the adjustment in place.

Initially I had the carb mounted, and then worked with this piece and the throttle cable.

While the carb is off the unit you should install this brass sleeve to the carb body, and check that upon WOT the full bore of the rotor lines up with the bore of the carb.

Also make sure it is not adjusted out too far - with idle stop screw threaded out so it is not touching the throttle rotor there should be a couple mm of slack in the throttle cable , then turn in the idle stop til it just touches, initial adjustment is 2-1/2 to 3 turns in from that point, usually then adjust for proper idle speed (without a tach, at least it should idle steady without engaging clutch)

Appears to start in 2-3 pulls, which isn't bad since it has been used, and I'm not sure what oil mix was used previously.

2 pulls is excellent - prime, choke, pull once , it fires once, take off choke, and fires up at idle and idles smooth - if it starts that way, it's good as a new one.

I'm a fan of high quality oils because I've had some equipment apart that's been run way too rich on ashy oil and seen the results. Unfortunately many of my family still buy the cheapest oil mix they can find at the dollar store.

Good quality mix oil is not that expensive - even synthetic Dolmar mix oil we sell over the counter is under 2 bucks for a 1 Gal mix bottle

Thanks again-- I spent way to much time on this hoping it was a mixture screw, rather than checking the needle lever... Take it off and check the lever for a loading condition! Lesson learned.

Glad you got it going!