Help me tune Hudy FX K5 DC engine - modified by The Nitro Shop
10-01-2016, 01:27 AM
#1
Help me tune Hudy FX K5 DC engine - modified by The Nitro Shop
Ok I've installed both of these bad ass engines in serpent SRX8's..
One has the factory FX pipe, the other a little tiny bit louder Nova Rossi pipe. the header looks almost identical.
I've read the manual, watched video's etc.. but nothing seems very simple and clear on how to tune these modified motors. I have 1/2 gallon of break in through each and although still a bit tight they are ready!
using 30% O'Donnell fuel. I have a temp gun and they are running way rich now at about 210F - they bog badly, and sometimes even lose power if you give it full gas for 2 sec! I think that may have been too lean.
This motor has four screws - high speed, low speed, idle, and a mixture screw that the manual says to avoid but my cousin insisted on adjusting a little by leaning it out 1/8 turn.
- I've taken everything back to super rich factory stock - how do I begin??
Thanks, Jeff Check - Dearborn, MI
One has the factory FX pipe, the other a little tiny bit louder Nova Rossi pipe. the header looks almost identical.
I've read the manual, watched video's etc.. but nothing seems very simple and clear on how to tune these modified motors. I have 1/2 gallon of break in through each and although still a bit tight they are ready!
using 30% O'Donnell fuel. I have a temp gun and they are running way rich now at about 210F - they bog badly, and sometimes even lose power if you give it full gas for 2 sec! I think that may have been too lean.
This motor has four screws - high speed, low speed, idle, and a mixture screw that the manual says to avoid but my cousin insisted on adjusting a little by leaning it out 1/8 turn.
- I've taken everything back to super rich factory stock - how do I begin??
Thanks, Jeff Check - Dearborn, MI
10-01-2016, 01:42 AM
#2
You should call me ! probably be much easier to teach you how to tune over the phone as opposed to posting on a forum !
what glowplug are you using
what clutch are you using ?
what size carb insert ?
what is your engine experience ? are these your first engines ?
also on a Hudy FX 1/2 gallon is probably nowhere near enough to be broken in.... also depends on the breakin method...simply idling will not come anywhere close to loosening up one of these engines !
Never tune by temperature !
what glowplug are you using
what clutch are you using ?
what size carb insert ?
what is your engine experience ? are these your first engines ?
also on a Hudy FX 1/2 gallon is probably nowhere near enough to be broken in.... also depends on the breakin method...simply idling will not come anywhere close to loosening up one of these engines !
Never tune by temperature !
10-01-2016, 01:52 AM
#3
glow plug, the ones you provided I think they are P3 - same as the X3 ones in the FX engines. I have two extras you provided also. I have ran with both and they both seem great. I also bought two more p3's and ordered two p4's.
Keep in mind, I've barely tried to tune this at all. it just went so random and badly I put a halt to it!
Factory SRX8 serpent clutch. seems fine, much like a snowmobile it needs to generate RPM before getting going functioning properly I think. brakes work well also.
factory carb size insert, I didn't look in the box for another one. I use the hot blanket to get it started still since pinch is still a little tight. idle is off, not bad but too high. low and part throttle are almost non existent. full throttle seems ok but weak as I said, either Smokey rich or lean, where it died after a couple seconds! never got over 220F so I barely even worked it.
Thanks for responding!
PS. I have been following the manual about 1/2, 2/3, 3/4 then full throttle through different tanks leaning out by 1:00 every tank so it has some full throttle on it, not much though - maybe max 3 seconds at a time on a limited basis.
10-01-2016, 03:20 AM
#4
Maximo, I didn't want to bother you about something this fundamental.. Especially since this has nothing to do with your excellent engine work and everything to do w a nitro noob! figured I would get by with the crowd sourced answer! i'll call you for sure tomorrow if you have a few min.
glow plug, the ones you provided I think they are P3 - same as the X3 ones in the FX engines. I have two extras you provided also. I have ran with both and they both seem great. I also bought two more p3's and ordered two p4's.
Keep in mind, I've barely tried to tune this at all. it just went so random and badly I put a halt to it!
Factory SRX8 serpent clutch. seems fine, much like a snowmobile it needs to generate RPM before getting going functioning properly I think. brakes work well also.
factory carb size insert, I didn't look in the box for another one. I use the hot blanket to get it started still since pinch is still a little tight. idle is off, not bad but too high. low and part throttle are almost non existent. full throttle seems ok but weak as I said, either Smokey rich or lean, where it died after a couple seconds! never got over 220F so I barely even worked it.
Thanks for responding!
PS. I have been following the manual about 1/2, 2/3, 3/4 then full throttle through different tanks leaning out by 1:00 every tank so it has some full throttle on it, not much though - maybe max 3 seconds at a time on a limited basis.
glow plug, the ones you provided I think they are P3 - same as the X3 ones in the FX engines. I have two extras you provided also. I have ran with both and they both seem great. I also bought two more p3's and ordered two p4's.
Keep in mind, I've barely tried to tune this at all. it just went so random and badly I put a halt to it!
Factory SRX8 serpent clutch. seems fine, much like a snowmobile it needs to generate RPM before getting going functioning properly I think. brakes work well also.
factory carb size insert, I didn't look in the box for another one. I use the hot blanket to get it started still since pinch is still a little tight. idle is off, not bad but too high. low and part throttle are almost non existent. full throttle seems ok but weak as I said, either Smokey rich or lean, where it died after a couple seconds! never got over 220F so I barely even worked it.
Thanks for responding!
PS. I have been following the manual about 1/2, 2/3, 3/4 then full throttle through different tanks leaning out by 1:00 every tank so it has some full throttle on it, not much though - maybe max 3 seconds at a time on a limited basis.
There is quite a bit to learn to tune these and its probably not something that is going to come too quickly when you don't have a existing reference point of the tuning cues your listening for.. IMO one of the best things you could do is take your car to the local track and have one of the guys give it a quick walk thru, there are quite a few really good guys who race in Mn. that would be more then happy to help you get rolling.. There are soo many little things that you have to be aware of that initially its very wise to have the hands on help of someone who's experienced. Sadly these engines can be quite sensitive and easy to hurt if you don't have a reference point to work from. Are you familiar with any local tracks ? maybe your close to one of my Team guys !
10-01-2016, 05:41 AM
#5
Its never a bother !
There is quite a bit to learn to tune these and its probably not something that is going to come too quickly when you don't have a existing reference point of the tuning cues your listening for.. IMO one of the best things you could do is take your car to the local track and have one of the guys give it a quick walk thru, there are quite a few really good guys who race in Mn. that would be more then happy to help you get rolling.. There are soo many little things that you have to be aware of that initially its very wise to have the hands on help of someone who's experienced. Sadly these engines can be quite sensitive and easy to hurt if you don't have a reference point to work from. Are you familiar with any local tracks ? maybe your close to one of my Team guys !
There is quite a bit to learn to tune these and its probably not something that is going to come too quickly when you don't have a existing reference point of the tuning cues your listening for.. IMO one of the best things you could do is take your car to the local track and have one of the guys give it a quick walk thru, there are quite a few really good guys who race in Mn. that would be more then happy to help you get rolling.. There are soo many little things that you have to be aware of that initially its very wise to have the hands on help of someone who's experienced. Sadly these engines can be quite sensitive and easy to hurt if you don't have a reference point to work from. Are you familiar with any local tracks ? maybe your close to one of my Team guys !
So far it was just leaning on the high speed needle. Finally it got fast, then went too far it stopped smoking and wouldn't peak rev. Then back rich.. then give up.
10-01-2016, 11:18 PM
#7
Thanks for the heads up Frank! Neil from the Nitro Shop was very helpful explaining the basics of my tune parameters. his key point, I need to work with a local tune pro even if I think its tuned well.
when you say it hides a rich bottom end, is there any way to lean out just the bottom or does it all get controlled by the high speed screw?
when you say it hides a rich bottom end, is there any way to lean out just the bottom or does it all get controlled by the high speed screw?
10-02-2016, 06:42 PM
#8
Update: using the simple principles provided by Neil and reading the Huddy FX engine book my cousin and I were able to tune our buggies very well at least so far.
They are very fast, do not bog, and idle for days. (20min at one point w/o a stall).
we focused on setting idle ref. point at 0.5mm, made sure that under full throttle there was still some of the slide visible looking down the carb barrel. made sure we had the 0.5 to 1mm gap between braking and throttle directions on the servo. Items that needed changing.
1. was running horribly rich - first we did trials with the large needle and got that closer (leaning out 1/12 turn at a time, checking sound, tepms, etc.
2. leaned out the low speed needle significantly, that stopped the part throttle bogging and also corrected the idle.
3. leaned out the mixture screw by 1/4 turn.
4. i'm still finishing break in so its a bit rich still and until its warmed up has a slight bog..
Hope when I see the tuning pro it will be improved even more!
Advice appreciated.
They are very fast, do not bog, and idle for days. (20min at one point w/o a stall).
we focused on setting idle ref. point at 0.5mm, made sure that under full throttle there was still some of the slide visible looking down the carb barrel. made sure we had the 0.5 to 1mm gap between braking and throttle directions on the servo. Items that needed changing.
1. was running horribly rich - first we did trials with the large needle and got that closer (leaning out 1/12 turn at a time, checking sound, tepms, etc.
2. leaned out the low speed needle significantly, that stopped the part throttle bogging and also corrected the idle.
3. leaned out the mixture screw by 1/4 turn.
4. i'm still finishing break in so its a bit rich still and until its warmed up has a slight bog..
Hope when I see the tuning pro it will be improved even more!
Advice appreciated.
10-03-2016, 09:03 AM
#9
Update: using the simple principles provided by Neil and reading the Huddy FX engine book my cousin and I were able to tune our buggies very well at least so far.
They are very fast, do not bog, and idle for days. (20min at one point w/o a stall).
we focused on setting idle ref. point at 0.5mm, made sure that under full throttle there was still some of the slide visible looking down the carb barrel. made sure we had the 0.5 to 1mm gap between braking and throttle directions on the servo. Items that needed changing.
1. was running horribly rich - first we did trials with the large needle and got that closer (leaning out 1/12 turn at a time, checking sound, tepms, etc.
2. leaned out the low speed needle significantly, that stopped the part throttle bogging and also corrected the idle.
3. leaned out the mixture screw by 1/4 turn.
4. i'm still finishing break in so its a bit rich still and until its warmed up has a slight bog..
Hope when I see the tuning pro it will be improved even more!
Advice appreciated.
They are very fast, do not bog, and idle for days. (20min at one point w/o a stall).
we focused on setting idle ref. point at 0.5mm, made sure that under full throttle there was still some of the slide visible looking down the carb barrel. made sure we had the 0.5 to 1mm gap between braking and throttle directions on the servo. Items that needed changing.
1. was running horribly rich - first we did trials with the large needle and got that closer (leaning out 1/12 turn at a time, checking sound, tepms, etc.
2. leaned out the low speed needle significantly, that stopped the part throttle bogging and also corrected the idle.
3. leaned out the mixture screw by 1/4 turn.
4. i'm still finishing break in so its a bit rich still and until its warmed up has a slight bog..
Hope when I see the tuning pro it will be improved even more!
Advice appreciated.
10-08-2016, 12:36 AM
#10
Got it to the tuning expert Mike League.. initial tuning is now very close. He thought I was a little bit lean based on the engine sound when wide open and took I think 2hrs out of the high speed to richen it a touch. The too lean sound we were looking for was essentially a running away of the engine a little bit as opposed to it holding a nice peak rpm. so its a tiny bit slower now at the very top end but more reliable hopefully. It was not overheating at all before but there was a slight wildness at the top on long pulls. Although it never even hit 230F - it was 72F that day.
In addition, we leaned out my low speed significantly like 6hrs and then adjusted my idle screw to match (idle screw seems too easy to turn according to Mike). it has a very nice stable idle. I'm liking this engine a lot and it impresses everyone who see's it run. i'm sure a lot of that is the mods done by Neil.. this bitch is FAST. Thinking about the new FX K3 engine because it has 3 ports vs 5 ports, and a square bore to stroke ratio vs my current setup with a long stroke.
Due to changing weather i'm going to be taking an hour out of the high speed screw as it gets cooler outside and starts to run lean. in the winter race series indoor (50F) peak temps need to be at 220F post race not the 260F seen in the summer time. however, indoors on a small track with 7-10min races it needs to be run lean to be competitive. so its a fine line. cant wait to get another one of these engines done by the Nitro Shop as a spare.
Feedback appreciated. thanks, Jeff Check
In addition, we leaned out my low speed significantly like 6hrs and then adjusted my idle screw to match (idle screw seems too easy to turn according to Mike). it has a very nice stable idle. I'm liking this engine a lot and it impresses everyone who see's it run. i'm sure a lot of that is the mods done by Neil.. this bitch is FAST. Thinking about the new FX K3 engine because it has 3 ports vs 5 ports, and a square bore to stroke ratio vs my current setup with a long stroke.
Due to changing weather i'm going to be taking an hour out of the high speed screw as it gets cooler outside and starts to run lean. in the winter race series indoor (50F) peak temps need to be at 220F post race not the 260F seen in the summer time. however, indoors on a small track with 7-10min races it needs to be run lean to be competitive. so its a fine line. cant wait to get another one of these engines done by the Nitro Shop as a spare.
Feedback appreciated. thanks, Jeff Check
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