RunRyder RC
WATCH
 1 page 224 views POST REPLY
HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › YS 120SR air bubbles
08-02-2018 03:51 PM  80 days agoPost 1
dweb4

rrNovice

Maryland

My Posts: All  Forum  Topic

Hello I'm noticing air bubbles in the short fuel line going from the regulator to the carb. I've tried re-tuning, going leaner, richer and still getting air bubbles. The motor runs good but I notice the inconsistency due to the air in the line. Anyone got any suggestions as how to remove them. I have other YS motors from .50 to this one and I never notice air bubbles in the short fuel line before. Thanks

PM  EMAIL  GALLERY  Attn:RR  Quote
08-02-2018 04:50 PM  80 days agoPost 2
JLF92677

rrApprentice

Southern California

My Posts: All  Forum  Topic

Check all 4 regulator assembly bolts are tight (do not over tighten.) If so, check or replace gasket between crankcase and regulator assembly and also check or replace fuel line between regulator and carb.

PM  EMAIL  GALLERY  Attn:RR  Quote
08-02-2018 05:14 PM  80 days agoPost 3
datidun

rrElite Veteran

N Ireland

My Posts: All  Forum  Topic

Not sure what is causing that as never had a YS engine but to prevent it from effecting engine, I would put on a bubbless fuel filter, maybe slight vibration coming from something.

PM  EMAIL  GALLERY  Attn:RR  Quote
08-02-2018 05:31 PM  80 days agoPost 4
ticedoff8

rrKey Veteran

Morgan Hill, CA. USA

My Posts: All  Forum  Topic

I've used YS motors for the last 8 years
All the ones I've used had that regulator on them (60, 91, 96 & 120)
Check all 4 regulator assembly bolts are tight (do not over tighten.) If so, check or replace gasket between crankcase and regulator assembly and also check or replace fuel line between regulator and carb.
^^^ +1

You should also check the regulator's diaphragm for proper fit and integrity (no pin-holes and no gaps around the seat).
EG: I bought a used YS engine where the seller had used a petroleum based after-run oil.
This caused the diaphragm to expand in diameter about 0.5mm. So it wouldn't / couldn't fit back into the diaphragm seat correctly for reassembly.
If I had forced it, there would have been a gap around the seat.
That would have allowed the crankcase pressure into the fuel stream.

Not sure what is causing that as never had a YS engine but to prevent it from effecting engine, I would put on a bubbless fuel filter, maybe slight vibration coming from something
The bubbles are between the regulator and the carb. Not the tank and the regulator.

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

PM  EMAIL  GALLERY  Attn:RR  Quote
08-02-2018 06:21 PM  80 days agoPost 5
dweb4

rrNovice

Maryland

My Posts: All  Forum  Topic

Ok, thanks I'll check all the screws, regulator and diaphragm. I brought the motor from another flyer and not sure what was used to maintain it. I know from the all the YS motors I run there is never been air bubbles in that fuel line.

Also I have a extra regulator from a YS 91SR that ran strong all the numbers match the 120 should I just change them out?

PM  EMAIL  GALLERY  Attn:RR  Quote
08-02-2018 09:15 PM  80 days agoPost 6
JuanRodriguez

rrProfessor

The Villages, Florida

My Posts: All  Forum  Topic

I would just do what has been suggested before parts swapping.....

Been there, done that and old enough to know better.....

PM  EMAIL  GALLERY  Attn:RR  Quote
08-02-2018 11:32 PM  80 days agoPost 7
ticedoff8

rrKey Veteran

Morgan Hill, CA. USA

My Posts: All  Forum  Topic

I would just do what has been suggested before parts swapping.....
^^^ +1
This gives you an idea of the "root cause" of the issue rather than "I swapped parts and it is all fixed".

But, the regulators are the same.
The 91 & 120 carb's bore and barrels are different. So those are not interchangeable

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

PM  EMAIL  GALLERY  Attn:RR  Quote
09-24-2018 03:39 AM  28 days agoPost 8
Dr.Ben

rrMaster

Richmond, VA, USA

My Posts: All  Forum  Topic

I just saw this in passing. I flew for YS years back but with the same basic regulator assembly. Several 61's, 80's, and 91's. All of mine got tiny air bubbles in the short line. Big bubbles may be problematic and should be chased as suggested. Little ones are not uncommon and not problematic.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

PM  EMAIL  GALLERY  Attn:RR  Quote
09-26-2018 05:34 AM  26 days agoPost 9
zonker

rrApprentice

South Jordan, UT USA

My Posts: All  Forum  Topic

I’m having a similar issue. The air bubbles are small in the short tube. When I first spool up the engine runs great for 1/4 tank but then it starts to run really rough and I start to see little air bubbles in the line. I bought this 120sr used. I replaced a bunch of parts including the diaphragm and gaskets. I haven’t even really been able to fly the heli because of the bubbles. I’ve done everything listed in this forum to fix it but it’s a no go so far. I suspect the previous owner messed with the little adjustment screw on the regulator. Would that cause these kinds of issues

I found this on another thread on Runryder: https://rc.runryder.com/t61094p1/

EDIT: The culprit was the adjustment screw a little silicon on top of it and the air bubbles are gone.

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 224 views POST REPLY
HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › YS 120SR air bubbles
 Print TOPIC  Make Suggestion 

 6  Topic Subscribe

Monday, October 22 - 11:53 am - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

The RC discussion world needs to consolidate. RR is now one choice for that. Its software is cutting edge. It hosts on-topic advertising. Help RR increase traffic buy making suggestions, posting in RR's new areas (sites) and by spreading the word.

The RunRyder Difference

• Category system to allow Rep/Vendor postings.
• Classifieds with sold (hidden) category.
• Classifieds with separate view new.
• Answer PMs offsite via email reply.
• Member gallery photos with advanced scripting.
• Gallery photo viewer integrated into postings.
• Highly refined search with advanced back end.
• Hosts its own high end fast response servers.
• Hosts thousands of HD event coverage videos.
• Rewrote entire code base with latest technology.
• No off-topic (annoying) click bait advertising.
Login Here
 New Subscriptions 
 Buddies Online