Backplate and pullcord question.

Welcome to RCTalk

Come join other RC enthusiasts! You'll be able to discuss, share and private message with other members of our community.

Register Log in

JimmyJamNitroFan

RCNT Rookie
Messages
19
Ok so I started noticing after I had taken my backplate and pull cord assembly off and put it back on that the pull cord had a dead spot in it sometimes. Like it would just have no resistance at all for a few inches and then would catch and other times it wouldn’t be there. I Andes up taking the pull cord off and when I did the hex head on the back of the back plate that inserts into the hex part of the pull cord assembly just pulls right out now. Like I can pull it right out and put it back in. It still works to turn the engine over when the thing is seated correctly in the pull assembly but I think my dead spots are coming from it moving freely in and out of the back plate so sometimes it is catching and turning the engine over and others it is just not seated and not doing anything. So this thing should not be able to be pulled out like this correct? So why is it and what do I need to do to fix it?
Thanks in advance!!
 

D3MON

RCNT Addict
Messages
1,123
Location
Missoula MT
RC Driving Style
Bashing
Ok so I started noticing after I had taken my backplate and pull cord assembly off and put it back on that the pull cord had a dead spot in it sometimes. Like it would just have no resistance at all for a few inches and then would catch and other times it wouldn’t be there. I Andes up taking the pull cord off and when I did the hex head on the back of the back plate that inserts into the hex part of the pull cord assembly just pulls right out now. Like I can pull it right out and put it back in. It still works to turn the engine over when the thing is seated correctly in the pull assembly but I think my dead spots are coming from it moving freely in and out of the back plate so sometimes it is catching and turning the engine over and others it is just not seated and not doing anything. So this thing should not be able to be pulled out like this correct? So why is it and what do I need to do to fix it?
Thanks in advance!!
think that sounds like a prime example of a One Way Bearing (also called OWB) going out, you can clean it by removing it and soaking it in some brake cleaner and then using a Q-Tip and spinning it inside the bearing.
what engine is this on?
sometimes it just gets loaded with oil from spent fuel because the backplate bushing is not sealing as well as it should be, though there should be some sort of lube for the bearing itself.
 

JimmyJamNitroFan

RCNT Rookie
Messages
19
think that sounds like a prime example of a One Way Bearing (also called OWB) going out, you can clean it by removing it and soaking it in some brake cleaner and then using a Q-Tip and spinning it inside the bearing.
what engine is this on?
sometimes it just gets loaded with oil from spent fuel because the backplate bushing is not sealing as well as it should be, though there should be some sort of lube for the bearing itself.
It is an SH .18. I wondered if that’s what it was because I’ve read about the owb on different threads. So you’re saying I can clean and lube it and keep using the same one?
 

cbaker65

Hardcore RCNT User
Messages
3,043
Location
Kern county ,Calif.
It is an SH .18. I wondered if that’s what it was because I’ve read about the owb on different threads. So you’re saying I can clean and lube it and keep using the same one?
Is the O-way saturated with fuel? If so ,then the back plate bushing is probably wore out ,so the bearing
is already getting plenty of lube!....LOL

Just clean it am put it back on!
 

olds97_lss

RCNT VIP
Supporter
Messages
18,990
Location
Dekalb, IL
RC Driving Style
Bashing
Is the O-way saturated with fuel? If so ,then the back plate bushing is probably wore out ,so the bearing
is already getting plenty of lube!....LOL

Just clean it am put it back on!
I think the SH28 uses an internal OWB. So it's always saturated with fuel. However, if you put a truck away without running the engine until it's dry, the fuel that sits in the crank case evaporates and leaves a heavy oil on the OWB needle bearings, then they don't move freely and grab/release the starter shaft like they should.

I found with engines that run an internal OWB that it's always best to run the engine unti the fuel is gone out of the lines. Even if I break the truck, I empty the tank, then run the engine while blipping the throttle to consume all the fuel in the line until the engine dies. Then I put a few drops of ARO down the glow plug hole and in the carb, then crank it over a few times with the front of the engine facing the ceiling, which helps get the ARO into the OWB so it's coated with that instead of the castor oil in the fuel. Seems to work well for me even after having engines sit all winter. Now it's just something I do after running them.

All that said, to clean the OWB well, you need to take the starter housing off, backplate off, then soak the OWB in some DA. I usually then twist enough paper towel so that the OWB spins onto it relatively snug, then soak the paper towel with DA and spin the OWB on the towel forward/backword to work the crud out of the bearing race. Then a drop of ARO on it when I put it back together.

Eventually, the OWB will need replaced and when you replace it, replace the starter shaft as well. Both the bearing and shaft wear down, so replacing only the OWB will only get you a half life as the shaft is already worn.
 

JimmyJamNitroFan

RCNT Rookie
Messages
19
I think the SH28 uses an internal OWB. So it's always saturated with fuel. However, if you put a truck away without running the engine until it's dry, the fuel that sits in the crank case evaporates and leaves a heavy oil on the OWB needle bearings, then they don't move freely and grab/release the starter shaft like they should.

I found with engines that run an internal OWB that it's always best to run the engine unti the fuel is gone out of the lines. Even if I break the truck, I empty the tank, then run the engine while blipping the throttle to consume all the fuel in the line until the engine dies. Then I put a few drops of ARO down the glow plug hole and in the carb, then crank it over a few times with the front of the engine facing the ceiling, which helps get the ARO into the OWB so it's coated with that instead of the castor oil in the fuel. Seems to work well for me even after having engines sit all winter. Now it's just something I do after running them.

All that said, to clean the OWB well, you need to take the starter housing off, backplate off, then soak the OWB in some DA. I usually then twist enough paper towel so that the OWB spins onto it relatively snug, then soak the paper towel with DA and spin the OWB on the towel forward/backword to work the crud out of the bearing race. Then a drop of ARO on it when I put it back together.

Eventually, the OWB will need replaced and when you replace it, replace the starter shaft as well. Both the bearing and shaft wear down, so replacing only the OWB will only get you a half life as the shaft is already worn.
Thanks for the information. You seem to have way more knowledge than me so I thought about starting a new thread but I’ll go ahead and hit you with this before I ask the community as a whole. So as I said this is my first nitro engine so going into it I did a ton of research and feel like I did the break in process atleast correctly or a fair consensus of what most people say to do is what I did. But there is still no substitute for experience and I may have done something wrong but feel like I pretty much safely broke her in. It ran great through the break in process which I had to do over a two day period due to time constraints and it ran great the second day and I was in heaven as I was getting to finally feed her some more throttle and see what she could do. Well I didn’t get to go out for a couple days and the next time I went out it didn’t want to start and when it did it idled crazy high. Tires spinning like mad and I’m still learning about everything at this point so I didn’t know what to do so I gave up to do some research. Long story short I ended up sealing the engine and the clutch spring had wear on it and I thought that may be my issue. I did show the owner of a local shop and he said no that it’s probably my bearings and sold me some new clutch bearings. I put it back together and tried again and it seemed to help a little at first but not long it was right back to high idle. I ordered a new set of clutch shoes and spring and when I opened it back up the spring had broken. Ok so that’s my issue I think. I put the new spring and shoe on ( didn’t really need new shoes but what the heck ) and hey it’s a lot better. For a little while and soon it’s rught back to the same issues. Revving and idling really high and now am barely able to start it without giving it a lot of throttle trim such in turn make engages the clutch like crazy til I can turn it back down and now it’s just dying after I turn the trim back down and put it on the ground and run it for 30 seconds to a minute. I can get it restarted but it’s the same process everytime and I have played with the needles trying to lean it down thinking it’s getting too much fuel and killing it but no matter what I do it just dies. I try to preheat it hoping when it’s warm it will run long enough for me to tune it but no joy. Admittedly I have never tuned a nitro engine but I would think if I start at factory settings it should run long enough for me to tune it. I did use 15% nitro with a higher oil content to break it in and switched to 20% after and that seems like when all my problems started and a lot of people say to break them in with the fuel you are going to run it on for life or whatever so maybe I should try to switch back but I don’t think that’s gonna solve all my issues. I am worried that all this high idling early in its life is ruining or has ruined my engine and that’s why at this point I can barely get it started without giving it tons of air and fuel. I mean a few times right after I started it the thing was going so fast it changed gears on the block before I could get the trim turned down. Ok sorry for so much info but I need help and i May just start a new thread but thought I’d put this here for now and see. And it’s a lot I know but if you demon or anyone else can give me a tip on even one of these issues it will help a lot or even let me know if it sounds like my engine is a paper weight now. So to summarize:

High idle and practically am taking my throttle linkage and idle screw and trim as far on the low side as I can go to slow it down.

Hard to start without opening the carb up pretty dang far and then having to turn it down to get it anywhere near a normal idle wich I don’t ever really get to.

Dying after about a minute.
 

D3MON

RCNT Addict
Messages
1,123
Location
Missoula MT
RC Driving Style
Bashing
just a quick list to check off the list first,

idle gap, confirm you have this set to about .5-1mm from the widest point to the edge of the venturi (carb throat)
i would start with maybe a 1/4 turn leaner than factory break in specs for the HSN only.
confirm that your controller trim is set to hold the carburetor closed against the idle screw i.e. if you apply brake it wont close the carb any further than the .5-1mm (see gap above)
try spinning the flywheel with your fingers, you want to feel it get alot of resistance right when the piston is getting near the top of the travel (if there is very little resistance to none that would signify a burnt engine. also what temps where the engine reaching when breaking in and what break in method did you use? there are a few out there.
as far as swapping fuels, alot of people run lower nitro percentage and higher oil for break in, a few companies have a "Break in fuel" that they sell, i have switched back and forth on fuels without problems before, i try not to as much as possible, but that is for already broken in engines, for break in imo it is completely fine to use a "Break in Fuel".
as for it revving and driving the wheels, that is what the clutch should be doing, if it was driving the wheels at idle that would be a clutch issue as that means the springs are not strong enough to hold the clutch shoes in.

it almost sounds like there is a air leak somewhere, id go through the engine backplate, and head to confirm all is tight.
fuel line is still connected from carb to fuel tank, and exhaust to fuel tank in corresponding locations.

always frustrating especially just getting into nitro when tuning issues happen. its so worth it when it gets back to working order though!
i still think myself to be pretty newbie to nitro especially with the plethora of issues that can arise, but alot of experienced knowledgeable people here!
 
Last edited:

JimmyJamNitroFan

RCNT Rookie
Messages
19
just a quick list to check off the list first,

idle gap, confirm you have this set to about .5-1mm from the widest point to the edge of the venturi (carb throat)
i would start with maybe a 1/4 turn leaner than factory break in specs for the HSN only.
confirm that your controller trim is set to hold the carburetor closed against the idle screw i.e. if you apply brake it wont close the carb any further than the .5-1mm (see gap above)
try spinning the flywheel with your fingers, you want to feel it get alot of resistance right when the piston is getting near the top of the travel (if there is very little resistance to none that would signify a burnt engine. also what temps where the engine reaching when breaking in and what break in method did you use? there are a few out there.
as far as swapping fuels, alot of people run lower nitro percentage and higher oil for break in, a few companies have a "Break in fuel" that they sell, i have switched back and forth on fuels without problems before, i try not to as much as possible, but that is for already broken in engines, for break in imo it is completely fine to use a "Break in Fuel".
as for it revving and driving the wheels, that is what the clutch should be doing, if it was driving the wheels at idle that would be a clutch issue as that means the springs are not strong enough to hold the clutch shoes in.

it almost sounds like there is a air leak somewhere, id go through the engine backplate, and head to confirm all is tight.
fuel line is still connected from carb to fuel tank, and exhaust to fuel tank in corresponding locations.

always frustrating especially just getting into nitro when tuning issues happen. its so worth it when it gets back to working order though!
i still think myself to be pretty newbie to nitro especially with the plethora of issues that can arise, but alot of experienced knowledgeable people here!
I always start with making sure my idle gap is set correctly at about 1mm but can never get it started like that, always have to open it up significantly to get it started then bring it back to 1mm ish. And it still engaging the clutch but not real real bad. Doesn’t always move when on the ground but sometimes it does. But it I tend to agree that maybe the prong isn’t strong enough. I broke it in with the pretty standard method of 5 tanks but I really did 6 or 7 to be sure with the lower nitro content but the first five tanks I went from quarter throttle first tank just blipping it gradually increasing my throttle amount and duration each tank and last tank I still didn’t go all out on the throttle. Probably by tank seven I was just running it as I would now after break in. Oh and letting it cool down between each tank. As for current temps it’s never getting above about 140 a 150 degrees which i think is because I am running so rich because at this point I can’t keep it running long enough to lean it down and if I just set the needles leaner it doesn’t seem to want to start at all. I took it apart and sealed the engine everywhere I could including the carb and all the hoses are in good condition and even zip tied all of them except the one going to the exhaust just to make sure there is no air getting around the ends. Maybe a pinhole somewhere but I haven’t tried changing lines altogether. Maybe I should just to eliminate that. It has quite a bit of pinch on the piston and sleeve when I spin the flywheel so I don’t think that part is bad so I may just be looking at a tuning issue but I’m about to take it apart and clean the engine. I want to look at the piston and sleeve anyway and I will know I’m starting over with no funk in her at all. So we’ll see. Thanks for the info. ?
 

cbaker65

Hardcore RCNT User
Messages
3,043
Location
Kern county ,Calif.
I always start with making sure my idle gap is set correctly at about 1mm but can never get it started like that, always have to open it up significantly to get it started then bring it back to 1mm ish. And it still engaging the clutch but not real real bad. Doesn’t always move when on the ground but sometimes it does. But it I tend to agree that maybe the prong isn’t strong enough. I broke it in with the pretty standard method of 5 tanks but I really did 6 or 7 to be sure with the lower nitro content but the first five tanks I went from quarter throttle first tank just blipping it gradually increasing my throttle amount and duration each tank and last tank I still didn’t go all out on the throttle. Probably by tank seven I was just running it as I would now after break in. Oh and letting it cool down between each tank. As for current temps it’s never getting above about 140 a 150 degrees which i think is because I am running so rich because at this point I can’t keep it running long enough to lean it down and if I just set the needles leaner it doesn’t seem to want to start at all. I took it apart and sealed the engine everywhere I could including the carb and all the hoses are in good condition and even zip tied all of them except the one going to the exhaust just to make sure there is no air getting around the ends. Maybe a pinhole somewhere but I haven’t tried changing lines altogether. Maybe I should just to eliminate that. It has quite a bit of pinch on the piston and sleeve when I spin the flywheel so I don’t think that part is bad so I may just be looking at a tuning issue but I’m about to take it apart and clean the engine. I want to look at the piston and sleeve anyway and I will know I’m starting over with no funk in her at all. So we’ll see. Thanks for the info. ?
It sounds like a air leak just like Demon said ,that's why your not getting a tune no matter where you set your needles!

A leak could be any where ,not just in the hoses!
A leak could appear on a faulty fuel tank seal ,head screws can be loose ,carb could be leaking at the fuel
inlet ,or ,pressure tube from the muffler to the tank plugged!

Check for wet spots ,like around the cylinder head an fuel inlets ,check the fuel tank pressure!
 

olds97_lss

RCNT VIP
Supporter
Messages
18,990
Location
Dekalb, IL
RC Driving Style
Bashing
Also check the gasket for the header. THat gets beat up pretty good over time and a lot of pipe pressure can be lost right as it exits the engine which can cause poor tuning.

Whenever I need a refresher, I go over these:
Paris Tuning PDF - my site

Which is about once a year as I don't drive nitro nearly as much as I used to.
 

D3MON

RCNT Addict
Messages
1,123
Location
Missoula MT
RC Driving Style
Bashing
Also check the gasket for the header. THat gets beat up pretty good over time and a lot of pipe pressure can be lost right as it exits the engine which can cause poor tuning.

Whenever I need a refresher, I go over these:
Paris Tuning PDF - my site

Which is about once a year as I don't drive nitro nearly as much as I used to.
Always forget about exhaust leaks lol
 

olds97_lss

RCNT VIP
Supporter
Messages
18,990
Location
Dekalb, IL
RC Driving Style
Bashing
Always forget about exhaust leaks lol
Yeah, it's worse on some than others. The savage is pretty bad for it since the pipe is fully suspended in air and flops around when jumping. Usually not so bad on buggies/truggies as the pipe usually rests on the chassis. I got tired of the coupler/gaskets going bad quickly on my savage and made a little L brace out of 3/8" steel rod so that the center of the pipe rests on it. I put a piece of hose over it so it wasn't metal on metal. Has worked out really well. Now I only replace gaskets one in a great while.
 

JimmyJamNitroFan

RCNT Rookie
Messages
19
It sounds like a air leak just like Demon said ,that's why your not getting a tune no matter where you set your needles!

A leak could be any where ,not just in the hoses!
A leak could appear on a faulty fuel tank seal ,head screws can be loose ,carb could be leaking at the fuel
inlet ,or ,pressure tube from the muffler to the tank plugged!

Check for wet spots ,like around the cylinder head an fuel inlets ,check the fuel tank pressure!
I feel ya. I’m aware it can be anywhere, I mention the fuel lines because it was the last place I can think of that I haven’t checked or took some kind of measure to seal aside from the zip ties on the connections. But I’m thinking you guys are right. I’m going to seal everything good again when I put it back together after I clean it, get new lines just to be sure there is no pinholes, check the tank pressure and everything else you mentioned. Tighten everything as tight as I can safely tighten it and see what happens.
 

Harrison worrall

RC Newbie
Messages
3
Ok so I started noticing after I had taken my backplate and pull cord assembly off and put it back on that the pull cord had a dead spot in it sometimes. Like it would just have no resistance at all for a few inches and then would catch and other times it wouldn’t be there. I Andes up taking the pull cord off and when I did the hex head on the back of the back plate that inserts into the hex part of the pull cord assembly just pulls right out now. Like I can pull it right out and put it back in. It still works to turn the engine over when the thing is seated correctly in the pull assembly but I think my dead spots are coming from it moving freely in and out of the back plate so sometimes it is catching and turning the engine over and others it is just not seated and not doing anything. So this thing should not be able to be pulled out like this correct? So why is it and what do I need to do to fix it?
Thanks in advance!!
Check this video for more imformation
 

JimmyJamNitroFan

RCNT Rookie
Messages
19
So just thought I’d update. I took the engine apart, cleaned, re sealed everything tightened everything, replaced all hoses. The collar around the high speed needle seemed more loose than it should be so I tightened it. So after all that she’s running like a top. So probably had an air leak somewhere which I always suspected but just didn’t think of a few of the areas cbaker mentioned so thanks for that! Now my front breaks aren’t working so she does a 180 everytine I hit the breaks. So that’s the next fix lol. But thanks to all who helped!
 

olds97_lss

RCNT VIP
Supporter
Messages
18,990
Location
Dekalb, IL
RC Driving Style
Bashing
The collar around the high speed needle seemed more loose than it should be so I tightened it. So after all that she’s running like a top.
That was likely your issue, if your meaning the HSN housing that holds/pinches down on the banjo fitting where the fuel line connects. If that's not tight, it sucks air, a lot.
 

Similar threads


Top