Engine bogs at 8k rpm... every gear
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Welcome to the group mate,
If it was running absolutely fine for couple months then something is starting to fail or carb is getting blocked,
What i would do is try a brand new plug, BR9ES if that doesn’t sort it could be your coil pack breaking up at high rpm, Also sure jets are not blocked but if it’s cutting power it is either fuel or spark, so start with a new plug first
Let us know how you get on
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Hi guys, this is my first post here.... I own a dt125r 2002 and it run well and all for like 2 months after i bought it but now it bogs out at 8k it will go to 9k but then it stars like cutting power( the whole bike twitches ) Can anyone suggest help??
Does it run OK at the lower revs building up to 8K? Starts OK?
Does it do the same if you build the revs up slowly at 1/2 throttle, compared to WOT? (wide open throttle)I agree, you should definitely start with the plug, also clean the HT lead and cap. Take it from there…
PS Hi!
Do you have much or any experience with working on engine/carbs, ect?… -
Hi guys, this is my first post here.... I own a dt125r 2002 and it run well and all for like 2 months after i bought it but now it bogs out at 8k it will go to 9k but then it stars like cutting power( the whole bike twitches ) Can anyone suggest help??
@Vcelicka Possibly could be the HT lead as they break own on DTRs causing this exact problem. The actual coil is very good quality so it's well worth fitting a new lead; you can cut off the very top of the coil's outer case where the lead pushes in with a junior hacksaw, pull out the old lead and solder the new one to the coil output for a really good connection. Then re-waterproof using Shoe Goo and electrical tape. Looks messy but no-one can see it under the tank, and you should notice a performance increase as the leads deteriorate over time. Much better option than just buying a new pattern coil as these often have different specs to OEM which can cause other issues. Fit a new NGK cap while you're there, try to get the type that's moulded into a single piece of rubber.
I had a high-rpm misfire once, after trying everything else we replaced the HT lead in the manner described above which took around 1 hour on a summer's day so the engine was neither stone cold nor up to operating temperature when I took it for a test ride. It wheelied out of the driveway without me even trying, and I couldn't believe how much better the performance was at all engine speeds. Made a big impression on me as I was 17 at the time and I'd spent practically a weekend trying to fix the bike and getting nowhere.Also do a carb clean including removing and cleaning the emulsion tube (the brass tube the main jet screws into) as the space between this and the carb body fills with moisture and blocks more and more of the holes so the fuel can't atomise; eventually it just starts four-stroking one day and won't rev out. Check air is getting to it as well from the hose on the right of the carb body just in front of the carb-to-airbox rubber; ultrasonic cleaning is good but you can just blow out every orifice with compressed air/GT85 etc.
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Does it run OK at the lower revs building up to 8K? Starts OK?
Does it do the same if you build the revs up slowly at 1/2 throttle, compared to WOT? (wide open throttle)I agree, you should definitely start with the plug, also clean the HT lead and cap. Take it from there…
PS Hi!
Do you have much or any experience with working on engine/carbs, ect?… -
@Vcelicka Possibly could be the HT lead as they break own on DTRs causing this exact problem. The actual coil is very good quality so it's well worth fitting a new lead; you can cut off the very top of the coil's outer case where the lead pushes in with a junior hacksaw, pull out the old lead and solder the new one to the coil output for a really good connection. Then re-waterproof using Shoe Goo and electrical tape. Looks messy but no-one can see it under the tank, and you should notice a performance increase as the leads deteriorate over time. Much better option than just buying a new pattern coil as these often have different specs to OEM which can cause other issues. Fit a new NGK cap while you're there, try to get the type that's moulded into a single piece of rubber.
I had a high-rpm misfire once, after trying everything else we replaced the HT lead in the manner described above which took around 1 hour on a summer's day so the engine was neither stone cold nor up to operating temperature when I took it for a test ride. It wheelied out of the driveway without me even trying, and I couldn't believe how much better the performance was at all engine speeds. Made a big impression on me as I was 17 at the time and I'd spent practically a weekend trying to fix the bike and getting nowhere.Also do a carb clean including removing and cleaning the emulsion tube (the brass tube the main jet screws into) as the space between this and the carb body fills with moisture and blocks more and more of the holes so the fuel can't atomise; eventually it just starts four-stroking one day and won't rev out. Check air is getting to it as well from the hose on the right of the carb body just in front of the carb-to-airbox rubber; ultrasonic cleaning is good but you can just blow out every orifice with compressed air/GT85 etc.
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Welcome to the group mate,
If it was running absolutely fine for couple months then something is starting to fail or carb is getting blocked,
What i would do is try a brand new plug, BR9ES if that doesn’t sort it could be your coil pack breaking up at high rpm, Also sure jets are not blocked but if it’s cutting power it is either fuel or spark, so start with a new plug first
Let us know how you get on
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Like @HOTSHOT-III said the best Coil pack is the OEM Yamaha one, I couldn’t get my hands on a decent one, but I did trail a few and the best one for me was off yambits, just order a NGK cap for it and screw it on, I’ve not had a single problem with it and starts and revs all the way to 11800 on my rpm and been spot on
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@HOTSHOT-III That is a lot of steps dont you know any ytb tutorial..... your saying i should buy whole new lead and cap for spaark plug?
@Vcelicka This guy has had a go but he's just joining the new lead to a short stub of the old one which might not cure the problem.
https://www.youtube.com/watch?v=jz3pklBtK9o&t=129s
When the coils are manufactured the lead is just a push fit onto a little spike which is the coil output and corrosion can affect the connection here as well as the lead breaking down, hence why soldering makes such a good job of it and sometimes delivers a noticeable performance improvement (the spike sometimes breaks off when removing the old lead but don't worry, just gently clean up what's left of it with a file and solder the new lead to that).
If you don't want to try this just yet you could just trim 5-10mm off the existing lead where it screws into the plug cap as this sometimes helps.
I keep meaning to do a post about this with pictures, will see if I can find time for this
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@SpookDog It runs good to like 7k but even if i WOT it bogs after beeing opens up. I mean i can clean carb but i dont know how to clean HT lead and cap..... but i can for sure change the plug so i will try that
Just wipe them down with a solvent to get any grease and dirt off…
Also look for thin black ‘pencil’ lines on the plug & cap (inside) Carbon tracking can be a nuisance!…You can’t go wrong just replacing the spark plug and cap. If it still has troubles then do the HT lead….
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@Vcelicka This guy has had a go but he's just joining the new lead to a short stub of the old one which might not cure the problem.
https://www.youtube.com/watch?v=jz3pklBtK9o&t=129s
When the coils are manufactured the lead is just a push fit onto a little spike which is the coil output and corrosion can affect the connection here as well as the lead breaking down, hence why soldering makes such a good job of it and sometimes delivers a noticeable performance improvement (the spike sometimes breaks off when removing the old lead but don't worry, just gently clean up what's left of it with a file and solder the new lead to that).
If you don't want to try this just yet you could just trim 5-10mm off the existing lead where it screws into the plug cap as this sometimes helps.
I keep meaning to do a post about this with pictures, will see if I can find time for this
Would a rubber boot, like the one on hard plastic NGK caps slip over the HT lead to coil? Just as an extra layer after sealing. Also do you know if RTV silicone is insulating?…
I’m extra attentive to corrosion since my wires started rotting off the back of the connector blocks!!
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Would a rubber boot, like the one on hard plastic NGK caps slip over the HT lead to coil? Just as an extra layer after sealing. Also do you know if RTV silicone is insulating?…
I’m extra attentive to corrosion since my wires started rotting off the back of the connector blocks!!
…@SpookDog Yes and yes
I've found rubber boots the right size for this in the past, and I think I used to use silicone sealant for this before discovering Shoe Goo. -
@SpookDog Yes and yes
I've found rubber boots the right size for this in the past, and I think I used to use silicone sealant for this before discovering Shoe Goo.Cheers bud!
It’s weird about the wheelie thing. I had my bike do this when I put in a new pilot jet and finally fixed the low rev spluttering and head gasket blowing! It was like an eager little puppy with loads of energy
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Would a rubber boot, like the one on hard plastic NGK caps slip over the HT lead to coil? Just as an extra layer after sealing. Also do you know if RTV silicone is insulating?…
I’m extra attentive to corrosion since my wires started rotting off the back of the connector blocks!!
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@SpookDog does this look good ? https://en.50factory.com/parts news/68749-antiparasites-with-red-wire-ngk-racing-cr2-cable.html Cant found it cheaper
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@HOTSHOT-III @OllieDTR @SpookDog Thanks so much for the help, i just took the cap from the cable an there was little to none cooper left so i cut it little down and cleaned the cap becous it was rusty . I took it around the hood and work absolutely great..... i will buy new plug and cap anyway beacous the rust . Thanks guys
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@HOTSHOT-III @OllieDTR @SpookDog Thanks so much for the help, i just took the cap from the cable an there was little to none cooper left so i cut it little down and cleaned the cap becous it was rusty . I took it around the hood and work absolutely great..... i will buy new plug and cap anyway beacous the rust . Thanks guys
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@HOTSHOT-III @OllieDTR @SpookDog Thanks so much for the help, i just took the cap from the cable an there was little to none cooper left so i cut it little down and cleaned the cap becous it was rusty . I took it around the hood and work absolutely great..... i will buy new plug and cap anyway beacous the rust . Thanks guys
