I believe it's one of the best trimmer or brushcutter due to its solid construction and triple layer carburetor/air intake heatshields. Cheers! VARIETECH
Aussie Aussie Aussie Go! Go! Go!... Great to find someone with a unit identical to mine.. Bastard wont start lol... Well presented, though more comment would have been nice, eg when testing the spark, it only sparked a few times for the number or turnovers of the engine... I would have thought this might deserve a comment. Also, would be nice to rule out the coil by showing what the resistance should be for a good one both 2ndary and Primary. None the less Varietech you did well. Thank you - Sydney
Haha! This is the best comment of the year! Thanks! Yes proud to be Australian. EC, that's a good point to test ignition coil resistance as reference for others while fixing the unit. Thanks for the constructive comment and subscribing to our channel. I will be doing more videos soon. Cheers, VARIETECH
No probs brother. Have an FS250 and a stihl Boss chainsaw. They all worked well for years one after the other, ie year after year, no looking after, no maintenance, except that I am kind to my gear, I treat everything well and do the right thing... usually. It took too many years for the units to become a problem. Every year I was surprised they didn't need anything worked on, alas, has caught up on me at last. Re:FS85R: Seem to have spark, though hence the comment, pulled down the carb & blew the shitter out of it with carb cleaner. Clean new fuel, good spark plug. Bastard still didn't work. Put it down for a month and walked away. Pull rope broke, replaced it, new fuel AGAIN, and it started and ran for a tank juice. never started again. still hunting for the reason the bastard won't frikin start. Spose a diaphragm kit is next.
@@Varietech-AU Hello again Varietech, I'd really like to rule out the coil before I do anything further to the carb. It appears that the coils fail quite regularly. When I test the spark, I do not get frequent spark when the rope is pulled, rather not often and sporadic. Coil numbering:4137 1304 A AD 4137 FS 417. Plug boot to ground measures 1.5Kohm. Tag to ground measures 1.85M ohm. This in itself seems outrageously high, but is quite within range compared to my FS250 and ChainBoss. Their 2ndary windings measure 1.44K and 1.92K respectively and tag to ground is 1.85M and 1.92M ohm. They both run. The FS85R in question doesn't even try to start. Comment? Thanks
Hi.... I have this brushcutter works great until it heats up then it turns off .... new carb was put on but still same problem. ... maybe if you know what could possibly be wrong with it?
In my opinion, the engine stops when it gets hot is possibly cracked plastic spacer manifold, or the piston ring had fused into the cylinder head, or head gasket, ignition coil becomes open or spark plug. Check all those. Thanks for watching and please don't forget to subscribe to support my channel to produce more contents. Thanks, VARIETECH
Thanks for watching our video. I hope you will find this video informative. The number of the kit is on the video description. Just click on the link. Thanks, VARIETECH
Super video @@Varietech-AU .. I followed your instructions and my trimmer runs better.. It still requires slow throttle action though, even since new. Even after leaning the low speed mixture counter clockwise 1/2 a turn, the trimmer wants to stop if you open the throttle to fast, indicating a rich mixture I think.. If you pull throttle slowly, it performs well though. Thanks!
@MrRerod good to know you managed to fix your Stihl. I'm glad you found my content informative. You can allow more fuel mix to air ratio or richer to 2 1/2 turns counter-clockwise and see if it makes a difference. Please share the channel. Cheers, VARIETECH
Hey Varietech, I just rebuilt my C1Q-S69A using the RB-100 rebuild kit. The RB-100 kit came with two small oval shaped pieces. Zama calls them a “Welch Plug”. One is longer than the other. Nothing that looked like those pieces came out of the carb when I first tore it down for a rebuild either. There is one recess area on the needle side of the carb that fits the smaller of the two pieces (part #0005013), but nothing came out of that area when I first tore it apart. Maybe they are for a different model carb? Any help would be appreciated. Thanks!
Most RB-100 kit doesn't comes with the longer oval shaped welch plug including our RB-100 kit. The longer welch plus is normally found on Ryobi ZAMA carburetor on the same spot or location close to the needle. Normally carburetor kit will cover different model of carburetors and not all individual parts can be used for example for Walbro K10-WAT. Do not replace the welch plug unless low jet is blocked and you have the ZAMA ZTK-101 Welch Plug Tool to punch a new welch plug. Thanks for watching our videos. Cheers, VARIETECH
@@Varietech-AU One more quick question for you. What do you set the high speed RPM to for an FS 85? The manual states: Engine cutoff speed (nominal): 10,500 rpm 10,500 RPM seems high. I've really only seen 7,500 rpm max for most trimmers, but this is a lot older so maybe it was different back then.
Interesting, I do not have the intake heat shields. I'm pretty sure I bought the unit pretty early so the shields may have been added to improve or stabilize fuel behavior.
That's interesting. Yes I agree the heat shield will improve or stabilise the the fuel mix. You could possibly add a heat shield using cut aluminium plates. VARIETECH
@@Varietech-AU Thanks for the quick reply! My lovely little FS85 starting spitting oil out the exhaust today and running poorly. Compression was around 95 on only two pulls so pretty good I guess. Plug was fouled so replaced that, dumped the fuel and replaced it. Runs better but still throwing oil which it never did before yesterday. Could that be a crankshaft seal perhaps?
@@nheng6913 This is a full crank engine with two crankshaft seals. Testing the crankshaft seal is not straight forward. You need to perform and vacuum test either on the carburetor intake manifold and block sparkplug and exhaust ports. Leaking crankcase may reduce pushing of fuel into the combustion chamber and accumulate fuel inside the crankcase. Reason for spitting of fuel through the exhaust port when crankcase is filled with fuel and should be just wet or lubricated but not filled with fuel which allow the fuel to push through the ring during down stroke ignition/fire which pushed out though the exhaust.
Thanks for watching our videos. It should work with aftermarket carburetor but it's best to rebuild the original or genuine carburetor if there is no other option. Thanks for subscribing to our channel. We will produce more videos small engine and electronics. VARIETECH
Hi, This type of carburetor has only Hor high revs adjustment aside from the iddle adjustment on the top of the throttle cable circular guide. While I adjusted the H, I keep quick triggering the throttle to find the optimal response when you quickly squeeze the trigger/throttle to make sure it won't bog down then fully squeeze and continue adjusting until fine optimum sweet revs. Confirm if it won't bog down when throttle is quickly triggered and repeat the process if necessary. Since there is no L or low adjustment, only adjust the iddle screw to minimum revs at 300rpm or just low enough the engine won't stall when throttle is released. Thanks for watching our TH-cam videos and subscribing to our channel. More interesting and informative videos to come. Cheers, VARIETECH
I believe it's one of the best trimmer or brushcutter due to its solid construction and triple layer carburetor/air intake heatshields. Cheers! VARIETECH
You can save yourself a few bucks by lightly rubbing a tube of hard chapstick on your gaskets and diaphragms to keep them from sticking and ripping when you take it apart. Almost infinitely reusable.
Has anyone tried this by rubbing the diaphragm and gasket with a chopstick? No luck for me! I've tried it on the hardened diaphragm but it just disintegrate into tiny flakes. I just replaced with a new one. Cheers, VARIETECH
@@Varietech-AU it won't restore a diaphragm but it will keep gaskets from sticking to the body so they don't need replacing. Next time you open her up they come right off in one piece.
One of the best trimmers ever made
I believe it's one of the best trimmer or brushcutter due to its solid construction and triple layer carburetor/air intake heatshields. Cheers! VARIETECH
Best, most thorough video on carb rebuild!
Thanks for watching our videos and found it informative. VARIETECH
Aussie Aussie Aussie Go! Go! Go!... Great to find someone with a unit identical to mine.. Bastard wont start lol... Well presented, though more comment would have been nice, eg when testing the spark, it only sparked a few times for the number or turnovers of the engine... I would have thought this might deserve a comment. Also, would be nice to rule out the coil by showing what the resistance should be for a good one both 2ndary and Primary. None the less Varietech you did well. Thank you - Sydney
Haha! This is the best comment of the year! Thanks! Yes proud to be Australian. EC, that's a good point to test ignition coil resistance as reference for others while fixing the unit. Thanks for the constructive comment and subscribing to our channel. I will be doing more videos soon. Cheers, VARIETECH
No probs brother. Have an FS250 and a stihl Boss chainsaw. They all worked well for years one after the other, ie year after year, no looking after, no maintenance, except that I am kind to my gear, I treat everything well and do the right thing... usually. It took too many years for the units to become a problem. Every year I was surprised they didn't need anything worked on, alas, has caught up on me at last. Re:FS85R: Seem to have spark, though hence the comment, pulled down the carb & blew the shitter out of it with carb cleaner. Clean new fuel, good spark plug. Bastard still didn't work. Put it down for a month and walked away. Pull rope broke, replaced it, new fuel AGAIN, and it started and ran for a tank juice. never started again. still hunting for the reason the bastard won't frikin start. Spose a diaphragm kit is next.
have FS85R/FS250/Chaisaw Wood Boss
@@eruditis Let us know how's you go with fixing your Stihl or after rebuilding the carby with new rebuilt kit.
@@Varietech-AU Hello again Varietech, I'd really like to rule out the coil before I do anything further to the carb. It appears that the coils fail quite regularly. When I test the spark, I do not get frequent spark when the rope is pulled, rather not often and sporadic. Coil numbering:4137 1304 A AD 4137 FS 417. Plug boot to ground measures 1.5Kohm. Tag to ground measures 1.85M ohm. This in itself seems outrageously high, but is quite within range compared to my FS250 and ChainBoss. Their 2ndary windings measure 1.44K and 1.92K respectively and tag to ground is 1.85M and 1.92M ohm. They both run. The FS85R in question doesn't even try to start. Comment? Thanks
Hi.... I have this brushcutter works great until it heats up then it turns off .... new carb was put on but still same problem. ... maybe if you know what could possibly be wrong with it?
In my opinion, the engine stops when it gets hot is possibly cracked plastic spacer manifold, or the piston ring had fused into the cylinder head, or head gasket, ignition coil becomes open or spark plug. Check all those. Thanks for watching and please don't forget to subscribe to support my channel to produce more contents. Thanks, VARIETECH
I have the same FS85 zama C1Q S45 carburetor and problems. I cannot understand the rebuild kit number, and where do you find this information? Thanks
Thanks for watching our video. I hope you will find this video informative. The number of the kit is on the video description. Just click on the link. Thanks, VARIETECH
Super video @@Varietech-AU .. I followed your instructions and my trimmer runs better.. It still requires slow throttle action though, even since new. Even after leaning the low speed mixture counter clockwise 1/2 a turn, the trimmer wants to stop if you open the throttle to fast, indicating a rich mixture I think.. If you pull throttle slowly, it performs well though. Thanks!
@MrRerod good to know you managed to fix your Stihl. I'm glad you found my content informative. You can allow more fuel mix to air ratio or richer to 2 1/2 turns counter-clockwise and see if it makes a difference. Please share the channel. Cheers, VARIETECH
Hey Varietech, I just rebuilt my C1Q-S69A using the RB-100 rebuild kit. The RB-100 kit came with two small oval shaped pieces. Zama calls them a “Welch Plug”. One is longer than the other. Nothing that looked like those pieces came out of the carb when I first tore it down for a rebuild either. There is one recess area on the needle side of the carb that fits the smaller of the two pieces (part #0005013), but nothing came out of that area when I first tore it apart. Maybe they are for a different model carb? Any help would be appreciated. Thanks!
Most RB-100 kit doesn't comes with the longer oval shaped welch plug including our RB-100 kit. The longer welch plus is normally found on Ryobi ZAMA carburetor on the same spot or location close to the needle. Normally carburetor kit will cover different model of carburetors and not all individual parts can be used for example for Walbro K10-WAT. Do not replace the welch plug unless low jet is blocked and you have the ZAMA ZTK-101 Welch Plug Tool to punch a new welch plug. Thanks for watching our videos. Cheers, VARIETECH
@@Varietech-AU Thank you this helps a lot!
@@Varietech-AU One more quick question for you. What do you set the high speed RPM to for an FS 85? The manual states:
Engine cutoff speed (nominal): 10,500 rpm
10,500 RPM seems high. I've really only seen 7,500 rpm max for most trimmers, but this is a lot older so maybe it was different back then.
@@red4e9 10,000 the most for Hi. No harm for 7,500rpm. Low is 300rpm.
Interesting, I do not have the intake heat shields. I'm pretty sure I bought the unit pretty early so the shields may have been added to improve or stabilize fuel behavior.
That's interesting. Yes I agree the heat shield will improve or stabilise the the fuel mix. You could possibly add a heat shield using cut aluminium plates. VARIETECH
@@Varietech-AU Thanks for the quick reply! My lovely little FS85 starting spitting oil out the exhaust today and running poorly. Compression was around 95 on only two pulls so pretty good I guess. Plug was fouled so replaced that, dumped the fuel and replaced it. Runs better but still throwing oil which it never did before yesterday. Could that be a crankshaft seal perhaps?
@@nheng6913 This is a full crank engine with two crankshaft seals. Testing the crankshaft seal is not straight forward. You need to perform and vacuum test either on the carburetor intake manifold and block sparkplug and exhaust ports. Leaking crankcase may reduce pushing of fuel into the combustion chamber and accumulate fuel inside the crankcase. Reason for spitting of fuel through the exhaust port when crankcase is filled with fuel and should be just wet or lubricated but not filled with fuel which allow the fuel to push through the ring during down stroke ignition/fire which pushed out though the exhaust.
Is it possible to order a brand new carb assembly?
FS38 FS45 carburetor will fit on FS85. Thanks for watching our videos.
hi mate any chance i can buy a gasket set and pick it up
How do you fix an on and switch on s Stihl F85
amazing detailed video thanks`1
Thanks. VARIETECH
Very nice video. I replaced mine with a Chinese carb but may rebuild the old Stihl (Chinese probably) for possibly better behavior.
Thanks for watching our videos. It should work with aftermarket carburetor but it's best to rebuild the original or genuine carburetor if there is no other option. Thanks for subscribing to our channel. We will produce more videos small engine and electronics. VARIETECH
Quick question, how do you adjust this specific carburetor with only one screw. ( I am an engine noob)
Hi, This type of carburetor has only Hor high revs adjustment aside from the iddle adjustment on the top of the throttle cable circular guide. While I adjusted the H, I keep quick triggering the throttle to find the optimal response when you quickly squeeze the trigger/throttle to make sure it won't bog down then fully squeeze and continue adjusting until fine optimum sweet revs. Confirm if it won't bog down when throttle is quickly triggered and repeat the process if necessary. Since there is no L or low adjustment, only adjust the iddle screw to minimum revs at 300rpm or just low enough the engine won't stall when throttle is released. Thanks for watching our TH-cam videos and subscribing to our channel. More interesting and informative videos to come. Cheers, VARIETECH
Excellent !
Thanks for watching. Please like, share, and subscribe and get notified for more upcoming uploads.
Do you know if a FS 85x model Stihl is a solid shaft model??
Straight shaft Brushcutters are mainly solid shafts especially Stihl.
@@Varietech-AU Not the FS-56. It has a cable drive inside it's straight shaft. Beware.
@@LafreniereJ thanks for the info.
Why do many heat shields? Crazy is it not only ment to have 1
I believe it's one of the best trimmer or brushcutter due to its solid construction and triple layer carburetor/air intake heatshields. Cheers! VARIETECH
They also add space and further reduces heat to the breather for a weed eater with extremely hard hot use in design.
Good job
Thanks. VARIETECH
Good thank you
Thanks. VARIETECH
You can save yourself a few bucks by lightly rubbing a tube of hard chapstick on your gaskets and diaphragms to keep them from sticking and ripping when you take it apart. Almost infinitely reusable.
Has anyone tried this by rubbing the diaphragm and gasket with a chopstick? No luck for me! I've tried it on the hardened diaphragm but it just disintegrate into tiny flakes. I just replaced with a new one. Cheers, VARIETECH
@@Varietech-AU it won't restore a diaphragm but it will keep gaskets from sticking to the body so they don't need replacing. Next time you open her up they come right off in one piece.