Got the lemon running

F-Type

Well-Known Member
Messages
265
Location
Gothenburg - Center of the Universe
Hi guys, I'm back!

Did you miss me? Ha-ha, bet you didn't even notice I was gone :)

Is there anyone around here any more, or is Octane stone dead now?

In any case, as you may remember. I was fighting a lot with my octane engine trying to get it running. Checked everything about the engine, compression, carb pump pulses, etc, only to conclude it was in mint condition. Same thing with the carb, checked everything, did leakage tests, pressure tests and stuff, tried it on another engine (bigger leafblower engine) just to conclude that it was in mint condition. Still, the engine wouldn't run.

So now, the engine has been put aside for quite a while. In the end my conclusion was that there really isn't anything wrong with either the engine or the carb. It is the combination of the two that is all wrong, and that is why so many more than me have problems. With a bit of luck, you get it running, for a while, sometimes, -ish.

Too big a carb on too small an engine. Simple as that. The Walbro WT-668 used on the Octane has a 15.88 mm bore, which is big even for an engine twice the size of the octane, and in general recommended for 50cc+ engines. Bigger bore/venture gives more power, people say, but it's not like there are no other differences, otherwise everyone would use bigger carbs, no doubt. It comes with the drawbacks of flooded engines (check) and extremely sensitive on carb tuning (check) for instance.

In any case, if this is the problem, somehow somewhere I should be able to get my Octane running with this carb, even if it is tough finding the tuning that will work.

One other thing I have been on about before is the air restrictor in the filter, or between the filter and the carb. Why on earth would anyone wanna restrict the air? Well, if you put on an oversized carb ... ... ... (yeah, it is really so incredibly stupid, what where they thinking?)

Also, what I noticed, by chance, when experimenting with limiting the airflow even further, was that the air restrictor is not symmetrical, it can be put in no less than four different ways, add to that the two different ways you can put the little t-shirt shaped sorry piece of plastic "fly" under the restrictor, you get 8 different ways of putting it back. I wonder how many Octane owners managed to get that back in the correct position every time. Because, what I noticed was, that it makes a difference, a difference of go or no go, one way or the other. How many of you realized that, 8 different ways, only 1 correct. Yup.

And, in the end, funny enough, I managed to get my engine running, when the low speed needle was set to 1 & 1/10 turn out, not 2 & 7/12 or whatever the updated manual stated.

Now, the problem I had, and still to some extent have, is to get idle speed down. I am probably running a bit lean, and if I turn the low speed out further, the engine stutters and stops. However, when the engine heats up, I can adjust out / down a bit to what seems like a more normal idle rpm. And guess what, the low speed needle then ends up close to 1 and 1/4 turn out. Now, go read the original manual, not the updated one. Yup, there we go again, recommended low speed needle setting 1 & 1/4 turn out. It's in the f*cking manual. But not the updated one, that HPI said you should use if engine won't run. But it'll only work in that setting once the engine is hot. Cold, 1&1/10 is what works. On my engine, yours could be different!

The combination of this engine and this carb, band-aided with a f*cking air restrictor on the air intake, is probably the worst piece of poop engineering I have seen in my entire life. And I have seen a few things. Now, the engine is fine, and the carb is fine too. But not the two together, and the air restrictor confirms that.

Well well. You might say, if you, against all odds, remember that I have said several times before that I found the problem and got the engine running, so why believe me this time? Well, first of all, I didn't jump to conclusions this time. It's been three days. Ever since I got the engine running the first time three days ago, it hasn't failed me one single time. Not one. Also, there is no "magic", no odd additions or changes. Back to basics. Everyting back to original, everything at factory setting, properly fitted. Only carb adjustments, nothing else.

Cold it starts after 3-4 pulls. Once started from cold, it will start again on the first pull, every single time, without exception. I've been through half a tank in three days, (not much I know) but running on the bench half a minute - minute a time, it makes a hell of a difference compared to before when a long run was 5 seconds, and rare. Now I can stop and re-start, with confidence.

Now, my main recommendation to anyone with an octane on the shelf, get a smaller carb, I'd recommend a Walbro 9,5 mm. I haven't had the chance to test one myself, but I bet it will be a hell of a lot easier getting that to run with the engine, than the stock WT-668 which is made for a lot larger engines. (LIke my leaf blower which runs a lot better with the octane walbro carb than with its own china-crap-carb I can tell you).

Well, that's all for now! If there is still someone out there, listening on the "Octane"-channel, at least say Hi, so I know you're there! :)

Thanx!
 

NightFlier X4.6

Well-Known Member
Messages
1,158
Location
Ohio
I'm happy you found a band-aid big enough to fit the octane lol. Never owned one I've heard tooooo many horror stories. If I ever found one for a steal I might give her a try but doubt it.
 

F-Type

Well-Known Member
Messages
265
Location
Gothenburg - Center of the Universe
Ok, so, today I did what I have been thinking about for a while. I replaced the carb for one with a smaller bore/venturi, a Walbro WT-300A. The engine started right away and was easy to adjust to a nice and stable idle. BIG DIFFERENCE.

I have only tested on the workbench so far, so have no idea how it will run in the car, though.

But in any case, using a carb that is more of a matched size for this size engine definitely made a huge difference. Certainly something to try for anyone having start-stall issues.

THough the WT300A is not the best choice, no primer, no choke and gas lever on wrong side. I just tried that one because I had it. There are other alteratives that would be a better choice to replace the stock WT-668 straight on.

And of course, no air restrictor or anything alike was needed ;)
 

desertbasher

Member
Messages
6
So with the 300A not being the best , what would you recommend? Anything off the top of your head?
 

Mark Walters

Well-Known Member
Messages
144
Location
Alsip, ILL
Hi guys, I'm back!

Did you miss me? Ha-ha, bet you didn't even notice I was gone :)

Is there anyone around here any more, or is Octane stone dead now?

In any case, as you may remember. I was fighting a lot with my octane engine trying to get it running. Checked everything about the engine, compression, carb pump pulses, etc, only to conclude it was in mint condition. Same thing with the carb, checked everything, did leakage tests, pressure tests and stuff, tried it on another engine (bigger leafblower engine) just to conclude that it was in mint condition. Still, the engine wouldn't run.

So now, the engine has been put aside for quite a while. In the end my conclusion was that there really isn't anything wrong with either the engine or the carb. It is the combination of the two that is all wrong, and that is why so many more than me have problems. With a bit of luck, you get it running, for a while, sometimes, -ish.

Too big a carb on too small an engine. Simple as that. The Walbro WT-668 used on the Octane has a 15.88 mm bore, which is big even for an engine twice the size of the octane, and in general recommended for 50cc+ engines. Bigger bore/venture gives more power, people say, but it's not like there are no other differences, otherwise everyone would use bigger carbs, no doubt. It comes with the drawbacks of flooded engines (check) and extremely sensitive on carb tuning (check) for instance.

In any case, if this is the problem, somehow somewhere I should be able to get my Octane running with this carb, even if it is tough finding the tuning that will work.

One other thing I have been on about before is the air restrictor in the filter, or between the filter and the carb. Why on earth would anyone wanna restrict the air? Well, if you put on an oversized carb ... ... ... (yeah, it is really so incredibly stupid, what where they thinking?)

Also, what I noticed, by chance, when experimenting with limiting the airflow even further, was that the air restrictor is not symmetrical, it can be put in no less than four different ways, add to that the two different ways you can put the little t-shirt shaped sorry piece of plastic "fly" under the restrictor, you get 8 different ways of putting it back. I wonder how many Octane owners managed to get that back in the correct position every time. Because, what I noticed was, that it makes a difference, a difference of go or no go, one way or the other. How many of you realized that, 8 different ways, only 1 correct. Yup.

And, in the end, funny enough, I managed to get my engine running, when the low speed needle was set to 1 & 1/10 turn out, not 2 & 7/12 or whatever the updated manual stated.

Now, the problem I had, and still to some extent have, is to get idle speed down. I am probably running a bit lean, and if I turn the low speed out further, the engine stutters and stops. However, when the engine heats up, I can adjust out / down a bit to what seems like a more normal idle rpm. And guess what, the low speed needle then ends up close to 1 and 1/4 turn out. Now, go read the original manual, not the updated one. Yup, there we go again, recommended low speed needle setting 1 & 1/4 turn out. It's in the f*cking manual. But not the updated one, that HPI said you should use if engine won't run. But it'll only work in that setting once the engine is hot. Cold, 1&1/10 is what works. On my engine, yours could be different!

The combination of this engine and this carb, band-aided with a f*cking air restrictor on the air intake, is probably the worst piece of poop engineering I have seen in my entire life. And I have seen a few things. Now, the engine is fine, and the carb is fine too. But not the two together, and the air restrictor confirms that.

Well well. You might say, if you, against all odds, remember that I have said several times before that I found the problem and got the engine running, so why believe me this time? Well, first of all, I didn't jump to conclusions this time. It's been three days. Ever since I got the engine running the first time three days ago, it hasn't failed me one single time. Not one. Also, there is no "magic", no odd additions or changes. Back to basics. Everyting back to original, everything at factory setting, properly fitted. Only carb adjustments, nothing else.

Cold it starts after 3-4 pulls. Once started from cold, it will start again on the first pull, every single time, without exception. I've been through half a tank in three days, (not much I know) but running on the bench half a minute - minute a time, it makes a hell of a difference compared to before when a long run was 5 seconds, and rare. Now I can stop and re-start, with confidence.

Now, my main recommendation to anyone with an octane on the shelf, get a smaller carb, I'd recommend a Walbro 9,5 mm. I haven't had the chance to test one myself, but I bet it will be a hell of a lot easier getting that to run with the engine, than the stock WT-668 which is made for a lot larger engines. (LIke my leaf blower which runs a lot better with the octane walbro carb than with its own china-crap-carb I can tell you).

Well, that's all for now! If there is still someone out there, listening on the "Octane"-channel, at least say Hi, so I know you're there! :)

Thanx!
Hi guys, I'm back!

Did you miss me? Ha-ha, bet you didn't even notice I was gone :)

Is there anyone around here any more, or is Octane stone dead now?

In any case, as you may remember. I was fighting a lot with my octane engine trying to get it running. Checked everything about the engine, compression, carb pump pulses, etc, only to conclude it was in mint condition. Same thing with the carb, checked everything, did leakage tests, pressure tests and stuff, tried it on another engine (bigger leafblower engine) just to conclude that it was in mint condition. Still, the engine wouldn't run.

So now, the engine has been put aside for quite a while. In the end my conclusion was that there really isn't anything wrong with either the engine or the carb. It is the combination of the two that is all wrong, and that is why so many more than me have problems. With a bit of luck, you get it running, for a while, sometimes, -ish.

Too big a carb on too small an engine. Simple as that. The Walbro WT-668 used on the Octane has a 15.88 mm bore, which is big even for an engine twice the size of the octane, and in general recommended for 50cc+ engines. Bigger bore/venture gives more power, people say, but it's not like there are no other differences, otherwise everyone would use bigger carbs, no doubt. It comes with the drawbacks of flooded engines (check) and extremely sensitive on carb tuning (check) for instance.

In any case, if this is the problem, somehow somewhere I should be able to get my Octane running with this carb, even if it is tough finding the tuning that will work.

One other thing I have been on about before is the air restrictor in the filter, or between the filter and the carb. Why on earth would anyone wanna restrict the air? Well, if you put on an oversized carb ... ... ... (yeah, it is really so incredibly stupid, what where they thinking?)

Also, what I noticed, by chance, when experimenting with limiting the airflow even further, was that the air restrictor is not symmetrical, it can be put in no less than four different ways, add to that the two different ways you can put the little t-shirt shaped sorry piece of plastic "fly" under the restrictor, you get 8 different ways of putting it back. I wonder how many Octane owners managed to get that back in the correct position every time. Because, what I noticed was, that it makes a difference, a difference of go or no go, one way or the other. How many of you realized that, 8 different ways, only 1 correct. Yup.

And, in the end, funny enough, I managed to get my engine running, when the low speed needle was set to 1 & 1/10 turn out, not 2 & 7/12 or whatever the updated manual stated.

Now, the problem I had, and still to some extent have, is to get idle speed down. I am probably running a bit lean, and if I turn the low speed out further, the engine stutters and stops. However, when the engine heats up, I can adjust out / down a bit to what seems like a more normal idle rpm. And guess what, the low speed needle then ends up close to 1 and 1/4 turn out. Now, go read the original manual, not the updated one. Yup, there we go again, recommended low speed needle setting 1 & 1/4 turn out. It's in the f*cking manual. But not the updated one, that HPI said you should use if engine won't run. But it'll only work in that setting once the engine is hot. Cold, 1&1/10 is what works. On my engine, yours could be different!

The combination of this engine and this carb, band-aided with a f*cking air restrictor on the air intake, is probably the worst piece of poop engineering I have seen in my entire life. And I have seen a few things. Now, the engine is fine, and the carb is fine too. But not the two together, and the air restrictor confirms that.

Well well. You might say, if you, against all odds, remember that I have said several times before that I found the problem and got the engine running, so why believe me this time? Well, first of all, I didn't jump to conclusions this time. It's been three days. Ever since I got the engine running the first time three days ago, it hasn't failed me one single time. Not one. Also, there is no "magic", no odd additions or changes. Back to basics. Everyting back to original, everything at factory setting, properly fitted. Only carb adjustments, nothing else.

Cold it starts after 3-4 pulls. Once started from cold, it will start again on the first pull, every single time, without exception. I've been through half a tank in three days, (not much I know) but running on the bench half a minute - minute a time, it makes a hell of a difference compared to before when a long run was 5 seconds, and rare. Now I can stop and re-start, with confidence.

Now, my main recommendation to anyone with an octane on the shelf, get a smaller carb, I'd recommend a Walbro 9,5 mm. I haven't had the chance to test one myself, but I bet it will be a hell of a lot easier getting that to run with the engine, than the stock WT-668 which is made for a lot larger engines. (LIke my leaf blower which runs a lot better with the octane walbro carb than with its own china-crap-carb I can tell you).

Well, that's all for now! If there is still someone out there, listening on the "Octane"-channel, at least say Hi, so I know you're there! :)

Thanx!
Hi I'm still here. I'm going to try what you did to your. I'll let you know how it goes
 

rcHero11

ooo that was a squirrel yo...
Messages
11
Hey F-type, Mark, and everyone else lurking around. After leaving the hobby due to divorce and selling off nearly everything, I somehow still have my octane lol. The reason being it was hiding in my brother's house, great =).

So 2 days ago, I was like oh hell let's see if it starts up as is. That said after sitting 2 years at my bro's house, but it worked fine back then as stock.

Charged the stock batteries but realized hpi ones were toast. Got some venom 1600 hump packs charged those up, put the fuel from 4 years ago (I know I'm bad lol, gave that gas a good shake), and started pulling.

Thing fired up no problems on 7th pull after 3 choke ones and shot out of the garage like the road runner cartoons and started to crush the bushes. I had to adjust the throttle arm and trim, but that was it.

Ran the truck for 1 hour straight driving and popping wheelies it was fun (got rid of all that old gas mix). I'm just blessed this octane was not 1 of the lemons. Originally, the first octane I got was the lemon, but my local hobby store took care of me and dealt with hpi directly and got me my current truck.

In other words, my original replacement truck has been working ever since. I think now I'm going to make a custom body for it.
 

Savaholikk

New Member
Messages
2
Hi guys, I'm back!

Did you miss me? Ha-ha, bet you didn't even notice I was gone :)

Is there anyone around here any more, or is Octane stone dead now?

In any case, as you may remember. I was fighting a lot with my octane engine trying to get it running. Checked everything about the engine, compression, carb pump pulses, etc, only to conclude it was in mint condition. Same thing with the carb, checked everything, did leakage tests, pressure tests and stuff, tried it on another engine (bigger leafblower engine) just to conclude that it was in mint condition. Still, the engine wouldn't run.

So now, the engine has been put aside for quite a while. In the end my conclusion was that there really isn't anything wrong with either the engine or the carb. It is the combination of the two that is all wrong, and that is why so many more than me have problems. With a bit of luck, you get it running, for a while, sometimes, -ish.

Too big a carb on too small an engine. Simple as that. The Walbro WT-668 used on the Octane has a 15.88 mm bore, which is big even for an engine twice the size of the octane, and in general recommended for 50cc+ engines. Bigger bore/venture gives more power, people say, but it's not like there are no other differences, otherwise everyone would use bigger carbs, no doubt. It comes with the drawbacks of flooded engines (check) and extremely sensitive on carb tuning (check) for instance.

In any case, if this is the problem, somehow somewhere I should be able to get my Octane running with this carb, even if it is tough finding the tuning that will work.

One other thing I have been on about before is the air restrictor in the filter, or between the filter and the carb. Why on earth would anyone wanna restrict the air? Well, if you put on an oversized carb ... ... ... (yeah, it is really so incredibly stupid, what where they thinking?)

Also, what I noticed, by chance, when experimenting with limiting the airflow even further, was that the air restrictor is not symmetrical, it can be put in no less than four different ways, add to that the two different ways you can put the little t-shirt shaped sorry piece of plastic "fly" under the restrictor, you get 8 different ways of putting it back. I wonder how many Octane owners managed to get that back in the correct position every time. Because, what I noticed was, that it makes a difference, a difference of go or no go, one way or the other. How many of you realized that, 8 different ways, only 1 correct. Yup.

And, in the end, funny enough, I managed to get my engine running, when the low speed needle was set to 1 & 1/10 turn out, not 2 & 7/12 or whatever the updated manual stated.

Now, the problem I had, and still to some extent have, is to get idle speed down. I am probably running a bit lean, and if I turn the low speed out further, the engine stutters and stops. However, when the engine heats up, I can adjust out / down a bit to what seems like a more normal idle rpm. And guess what, the low speed needle then ends up close to 1 and 1/4 turn out. Now, go read the original manual, not the updated one. Yup, there we go again, recommended low speed needle setting 1 & 1/4 turn out. It's in the f*cking manual. But not the updated one, that HPI said you should use if engine won't run. But it'll only work in that setting once the engine is hot. Cold, 1&1/10 is what works. On my engine, yours could be different!

The combination of this engine and this carb, band-aided with a f*cking air restrictor on the air intake, is probably the worst piece of poop engineering I have seen in my entire life. And I have seen a few things. Now, the engine is fine, and the carb is fine too. But not the two together, and the air restrictor confirms that.

Well well. You might say, if you, against all odds, remember that I have said several times before that I found the problem and got the engine running, so why believe me this time? Well, first of all, I didn't jump to conclusions this time. It's been three days. Ever since I got the engine running the first time three days ago, it hasn't failed me one single time. Not one. Also, there is no "magic", no odd additions or changes. Back to basics. Everyting back to original, everything at factory setting, properly fitted. Only carb adjustments, nothing else.

Cold it starts after 3-4 pulls. Once started from cold, it will start again on the first pull, every single time, without exception. I've been through half a tank in three days, (not much I know) but running on the bench half a minute - minute a time, it makes a hell of a difference compared to before when a long run was 5 seconds, and rare. Now I can stop and re-start, with confidence.

Now, my main recommendation to anyone with an octane on the shelf, get a smaller carb, I'd recommend a Walbro 9,5 mm. I haven't had the chance to test one myself, but I bet it will be a hell of a lot easier getting that to run with the engine, than the stock WT-668 which is made for a lot larger engines. (LIke my leaf blower which runs a lot better with the octane walbro carb than with its own china-crap-carb I can tell you).

Well, that's all for now! If there is still someone out there, listening on the "Octane"-channel, at least say Hi, so I know you're there! :)

Thanx!
Admittedly, I haven't run into these issues YET because I just got 2 of them in trade and have yet to run them but, I enjoyed reading this post ! I'll post on here in a few days about how my test run goes 😁

Ryan
 

Vmansavage

Active Member
Messages
96
Location
Cumberland MD
Hi I am getting a octane in the very near future and your post are very helpful and if I have any issue I will be deff using ur post and all the other great people on this forum hope I don’t have any major issues with the octane cuz even brand used there not very cheap but ya gotta pay to play so they say lol
 

Jam Racing 1

NPTB MONITOR & Master of the known Universe
HPISF Staff
Messages
4,652
Hi I am getting a octane in the very near future and your post are very helpful and if I have any issue I will be deff using ur post and all the other great people on this forum hope I don’t have any major issues with the octane cuz even brand used there not very cheap but ya gotta pay to play so they say lol

There are MUCH BETTER rigs out there than the Octane, Losi makes a true 1/8 gasoline powered truck that is 10 times what the octane is...... so unless you have lots of time and experience I would steer clear of that one....
 

Vmansavage

Active Member
Messages
96
Location
Cumberland MD
I have lots of exsprience with 2 stroke motorcycle engines and with small engines and carbs I really like hpi n the Losi is only a 5cc engine if I am not mistaken I am really torn between the two lol
 

Vmansavage

Active Member
Messages
96
Location
Cumberland MD
Hi was wondering what carb would be best to get get to step down from stock carb thanks for all the info and help really glad I am a member and found this forum Merry Christmas
 

Vmansavage

Active Member
Messages
96
Location
Cumberland MD
Should b getting octane soon would like to know what carb would b best to get if I run into issues I have looked at a site that sells walbro carbs and typed In 9.5 mm but nothing comes up any help will be greatly appreciated
 

Vmansavage

Active Member
Messages
96
Location
Cumberland MD
Seem like good truck to me but I am still a newbie I have researched a lot about them and all the problems and how to fix em I am actually looking foward to running my octane soon as weather breaks why did you give up on yours seanthemechanic???
 

Blackie287

Member
Messages
16
Location
Horicon, WI
Hi guys...well if I have anything to say about it, the Octane scene won't ever be extinct...I just acquired my third one, although have yet to get them out. Busy with other projects already started, but rest assured, the Octane will be a focal point of my efforts once some of the MGTs, LSTs, & a cpl Savages I have are sold. I recently re-entered the hobby in a big way in May 2017 after being on the sidelines for a few years. What immediately struck me was the demise of the nitro Monster trucks, virtual disappearance of reverse capability in anything nitro, & of course the emergence of brushless power. So I went on a reckless, frantic buying-binge that lasted until, well, the present.... Currently 19 MGTs of various types, 11 Savages (including an XL Flux), 8 LST 1/2s (including among the LAST two NIB XXL2 .31 trucks on the internet) And some nitro 4-TECs, NTC3s that I rebuilt, although I was never really into touring cars. It was more the fact that so many of the cool nitro vehicles were being rapidly discontinued. So yeah, I have an addiction....and I need an INTERVENTION......but not today though, haha. As stated in other posts, most of these are fun projects that will eventually be sold. I will keep a collection of nice ones although I want to be careful that I leave myself some good bashers, not just shelf-Queens
 

Blackie287

Member
Messages
16
Location
Horicon, WI
I had been running an XL with an LRP .32 quite a bit till bad weather hit, but have not gotten to run the Octanes yet; one has never seen fuel at all yet, the other two had been run by their previous owners with apparently little problems; the one has reportedly had 4 tanks run thru it & the one I just got has had about 2.5 gallons run thru it with no complaints. Again, this is word from the previous owners; I've been busy with completing a project now but will definitely report on when I get the Octanes rolling
 

Big dipper

Member
Messages
18
Wow I felt the same been buying a rebuilding the old nitros half the battle is finding the parts here is a part of my current collection 6269
 

Blackie287

Member
Messages
16
Location
Horicon, WI
^^Indeed a Righteous effort..!!^^ Yes, finding key parts is only gonna get harder. The money I recover from the trucks I do sell is gonna go right back into stocking parts for the ones I keep.
6275
This is the Octane I just picked up. Has 2.5 gallons of GAS thru it :) (per previous owner) Cant wait to get it out. Just gotta love the weather we've been having in the midwest here... Will report on how it runs. Post a vid if I can.
 
Top