Carb question

[Mebob2 8]

What should I do in this case? Don’t want to make it worse .  Diaphragm looks in decent shape but stuck pretty good . Inlet gas line fitting is plugged, will inlet fitting come out or does diagram have to be sacrificed.  
   I can find lots of carb info but couldn’t find anything on the inlet fitting.

 

appreciate your thoughts

 

tks, Rob 

[factory 487]

The little brass part is a check valve, which is often stuck, here is a quote from @Wallfish in a thread last month about the same part;

On 2/17/2020 at 1:20 AM, Wallfish said:

No. DON"T use carb cleaner in it. It's a check valve with a rubber type of flapper inside and carb cleaner will swell it closed and locked. Hopefully I'm not too late.

BTW

Typcally you can push it open with the flat end of a paper clip or better yet the butt end of a drill bit that just fits inside but you gotta go easy and feel for it. Then try and blow through it to see if it's loose. Once loose you can use something that won't swell the rubber. I've been using citris degreaser for cleaning my engines recently and it disolves that old 2 stroke oil pretty good. Never tried for that but if you can keep pushing that stuff through eventuality it should clean it. then check the valve by blowing the other way and you should'nt be able to. then go back and blow and hopefully you're all set.

When all else fails, drill a hole through it using that drill bit you tried with earlier. That's what I had to do after carb cleaner

 

I've had one stuck too, at the time I had access to a large industrial ultrasonic cleaner which eventually cleaned the fuel/oil residue from it.

The brass check valve is a press fit, I wouldn't recommend trying to remove it.

 

David

[Wallfish 698]

Drill it out. You can't really tell if you got it or not with the old diaphragm still stuck on there and the ball check valve under it not cleaned. The ball will most likely be stuck in the hole it sits in preventing any testing or airflow.

If that diaphragm is stiff at all it will need to be replaced. Use a razor blade to remove it. Start where your thumb is in the pic above right near that hole. Once started it will easily come off and you can save it if it's good.

[factory 487]

There is also a possibility that it may use the later diaphragm arm with the rubber seal, instead of the ball bearing under the diaphragm arm.

 

David

[Mebob2 8]

The diaphragm is very flexible when you touch it, no signs of being brittle. But I think your right the only way to be confident it’s truly cleaned out is to take it off. I don’t mind getting a new diaphragm I was just trying to rush things along a bit. I got points cleaned , adjusted and got a nice spark back so was getting anxious to see if it would fire up. Got a little aux. fuel supply geared up. I want to clean polish tank before I put back on. 
   I attached a pic of some parts that came with them, are they even any part of these tiny tigers?

[factory 487]

Those are "press fit" diodes, they look similar to those used in the alternator part of the Tiny Tiger, which are used to rectify the AC generated from the alternator windings to supply the low voltage DC for battery charging.

 

Do those have a part number on them?

 

I've no idea why these diodes in my Tiny Tor have two different colors in the center, the picture also shows extra holes for the diodes to fit into, those are only used if one fails.

 

Also available in "gold-plated rust" finish in my older Tiny Tiger.

 

David

Edited April 13, 2020 by factory
Extra Info

[Mebob2 8]

[Mebob2 8]

So just so I get this right. I removed the diaphragm, seems to be ok. I took out the diaphragm arm and it’s like the one you posted. Now for the brass fuel inlet fitting. I can blow through or suck air through it. Cleaned , soaked it the best I can with citrus type cleaner. Now it’s suggested that I drill through the inlet hole in the fitting to clean it out? Is this correct? I don’t quite understand what’s inside the brass inlet fitting and hole drilling it won’t destroy it?

  Again appreciate any help

 

tks, Rob  

[Webhead 95]

It's like a rubber flapper inside the brass fitting, hence the reason you should not use harsh solvents. If working correctly, you should be able to blow through one side, but not the other, in essence, a check valve. Drilling it out and eliminating the check valve is what we do if soaking and cleaning it does not work, or if we don't want it to cause problems down the line. The early ones did not have them and they are a nice feature, but not necessary. The rubber tipped lever is another story....I'll let someone else elaborate.

[Wallfish 698]

2 hours ago, Mebob2 said:

I can blow through or suck air through it. Cleaned , soaked it the best I can with citrus type cleaner.

If you can blow air through it you're good to go. It was explained in that quoted section above that you can drill it if all else fails

[Mebob2 8]

Ok, understood. I see my previous post said “I can blow air through it” it should of said “ I CAN’T blow air through it” , I see why you guys were likely confused by my question.

    After a lot of soaking and cleaning with, paper clip, drill bit, thumb tack I still can’t get air through in either direction. I will drill it out.
 

Thanks guys. 

[Fishnuts2 22]

I have the same valve on my saw and ended up drilling through it.  I mistakenly removed the valve body from the diaphragm cover, and was able to replace it by heating the cover in a toaster oven. Things went back easily and sealed up.

I now have another project with a 13B motor and the same check valve on the carb.  Gonna try cleaning with ultrasonic before the drill and see what happens.

What is the purpose of the check valve anyway?  Perhaps works to prime it easier?

[Wallfish 698]

Those check valves were just another "Band Aid" they put on to try and help. Those carbs are the weak link on these engines and they should have just scraped them long before and did a completely new design. The check valve's purpose is to keep fuel flowing in only one direction and it "checks" it going the other direction.

[factory 487]

20 hours ago, Webhead said:

The rubber tipped lever is another story....I'll let someone else elaborate.

 

The older engines used a ball bearing for the valve under the diaphragm arm, this would often get gummed up with stale gas/oil mix, they even recommend replacing the ball bearing instead of trying to clean it, but at least you can still get ball bearings as they are a standard part.

 

The redesign uses the rubber seal on the diaphragm arm, these seem worse than the ball bearing as they no longer seal due to gas/oil mix and/or ageing badly. Unfortunately the seal was sold with the carb repair kits, same as the brass valve only being available in a new carb diaphragm bowl assembly, I can't help thinking one reason they did this was to generate more parts sales.

 

The diaphragm arms with rubber seal are very difficult to find now, if it's bad you could replace the carb parts with the older versions (i.e. the carb bowl bottom half, a ball bearing & the older diaphragm arm).

 

David

 

P.S. Avoid using any gas that contains ethanol for the fuel mix for these engines, look for ethanol free (non-oxygenated) gas instead, it may be harder to find, but it should cause less problems with stale gas, swelling of rubber seals and corrosion from it attaching moisture.

[factory 487]

On 4/13/2020 at 11:59 PM, Mebob2 said:

 

OK thanks for that picture, that is a Motorola 1N3491R diode rated at a maximum of 50 volts at 25 amps (date code week 49 of 1973), the 'R' in the part number indicates the polarity being anode to the case. This seems to have suitable ratings for the Tiny Tiger charger circuit and is the correct polarity.

Note: This component is now obsolete, any for sale will either be new-old-stock or relabelled parts.

 

Question is why they are with the Tiny Tigers, could it be possible they were returns that never got repaired? The manual does mention that they can get damaged if the battery is connected the wrong way round.

 

David

[Mebob2 8]

Thanks for the info Dave and you brought up my exact question when you first mentioned they were diodes. Why 4 spare?

hmmmmm. You mentioned battery  being hooked up wrong way around , as clean and new as they appear to be I noticed a tiny mark on the side of one generator, first thought when I seen it was a electrical burn mark, as if positive lead touched case. I don’t know how much it would take to burn out a diode. 

    On another note, I got my check valve working. Between soaking in wd40, Zep citrus HD degreaser, drill bit , paper clip and air pressure. I finally ever so gently got it moving, then open but very stiff. Kept at It every few hours. At first As hard as I could blow I could hardly get a squeak through it. A little can of compressed air would blow through no problem and still seal in opposite direction. Now I can blow through it and can’t suck through it. Not super easy but not bad. I’m assuming they have to move super easy. It seems that the rubber could be slightly swelled (As mentioned) but it’s getting better. I’m going to stick It in boiling water for a minute or two, might shrink rubber just a touch. 
   Again I appreciate you help, tremendous insight and conversation.

 

tks, Rob

[Mebob2 8]

Just a little follow up to the previous post. I now have the check valve opening and closing. I can blow through it but i can’t suck through it. It takes a little bit of blow pressure to open but not cheek busting. A paper clip doesn’t just fall through the valve but just a slight touch of pressure will open it. So I’m not sure if its operating well enough to use without drilling. I know it’s not to big of a deal to just put together. I’ll wait a bit to see if someone has a thought.

 

thanks 

 

 

 

 

[Wallfish 698]

Having it clean and working should work. The diaphragms don't pump fuel very hard but I have had a couple questionable like yours and they worked. But also had some that didn't.

[Mebob2 8]

I’ll get carb assembled and try a test pump before I put it on. Does any body ever run a thin smear of gasket sealer around the outside edge of diaphragm just to make sure it’s air tight ?

[Wallfish 698]

No, it will seal.

[Mebob2 8]

Very good 

 

thank you 

[Mebob2 8]

Hi guys!! I’m pretty excited. I got carb back together, diaphragm assembly together and carb on. Hooked up gas line to carb and little hanging bottle with mixed gas 24-1, sae30 HD as instructed on side of gas tank. First push of primer button and gas went up the tube, very surprised how far it actually moved, about 5 pushes took it up 16” of gas line. It doesn’t have the exact Spark plug in it but all I have right now. No fuel tank on it or exhaust. I gave it a couple extra primes after fuel reached carb. Put choke on, second pull it kicked!! A few more pulls, monkeying with choke a bit, kicking a bit more each time, it started!! It seemed to want to take off and rev up pretty  quick so I just shut  it down. Just to be safe.  I wasn’t really sure where throttle was. Anyway pretty nice to see it run, it might never run again, I don’t know but I’ll get right plug, finish cleaning it all and put completely back together. Then try it again. 
   A couple things though. 
   Should I go with a different gas mix?

I have 2 stroke STIHL mix, not synthetic.

  I attached 2 pics, the older O&R has a little filter in gas tank on end of fuel intake. The one I’m working on now has nothing on fuel intake.  What options do I have for this one, I obviously need something, correct? In the pic you can see a hard drop of oil on bottom of tank, the tube is about 3/16” above it. 
 

  Thanks again 
  

Edited April 17, 2020 by Mebob2

[CNew 404]

Awesome, glad you got it running- always a great feeling!

I’ve been using a 32:1 mix with Stihl and it seems to work fine. I’ve also had decent success using a little in-line filter called a “crap trap” made by a Sullivan for RC applications. Just do a google search for Sullivan crap trap and it should come up, usually about $7-8.

[Wallfish 698]

They run at 6300 rpm so they they do rev up. No throttle control on a TT, they just run full blast but look at the side of the carb and you should see where the governor vein connects to the carb. Make sure that's connected or will rev up to a grenade

[Fishnuts2 22]

I think the best fuel mix for these little engines is the alkylate premix fuel you buy in home improvement stores or small engine shops. It stays fresh for a considerable time longer than regular pump gas. I was skeptical at first but now use it in all engines smaller than 40cc.