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Discussion Starter #1
Hi Guys,

I am getting sick of this bike now! It has a few problems which i believe to be related and want to get these sorted but now sure where to start.

Firstly to start the bike i have to use a switch between engine temp sensor wires then the FI light comes on obviously as im cutting off the sensor but then itll fire up straight away but sit at like quite high revs 4-5. Then when its warm after a couple of mins i can flick the switch back off. (Ive replaced the engine temp sensor, still same)

Secondly sometimes when riding usually in second gear itll jerk and drag back but soon as you pull clutch in and out itll be back to normal

Thirdly today when going up a steep hill at 30 MPH in second gear again it started jerking like no tomorrow like it was struggling to get up the hiil soon as back on flat it was fine.

And Finally i got on the bypass and it would not go past 73mph..

Any advice/help would be greatly appreciated, can't really afford to take it to a garage right now.

Thanks
Scott
 

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Suggest you start by reading my treatise on "Voltage Dropping" on the repair forum, then voltage drop first your ECM power, ign, and ground leads, and THEN check your sensor wires/connectors, ECM connector for damage, etc. If replacing the sensor didn't fix the problem then it either has wiring damage or the ECM is damaged internally.

That's unlikely if the bike runs at all.

You're asking for help doing diagnosis that generally requires an electrical expert. I only give you about a 30% chance of succeeding, ASSUMING you REALLY study and learn about voltage dropping.

And whose, ahh, "genius" idea was it to install a switch and put a dead short on the temp sensor leads? That ALONE could have fried the ECM circuitry dedicated to reading the sensor?
 

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Your middle finger gives an extra added touch to this particular post
Thanks Hawk. That means a lot to a sensitive new age guy like myself... I don't mean to be a prick but I feel I either need to tell a guy like this how it REALLY is or else just ignore his cry for help...
 

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Greatest Member Ever
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Hi Guys,

I am getting sick of this bike now! It has a few problems which i believe to be related and want to get these sorted but now sure where to start.

Firstly to start the bike i have to use a switch between engine temp sensor wires then the FI light comes on obviously as im cutting off the sensor but then itll fire up straight away but sit at like quite high revs 4-5. Then when its warm after a couple of mins i can flick the switch back off. (Ive replaced the engine temp sensor, still same)

Secondly sometimes when riding usually in second gear itll jerk and drag back but soon as you pull clutch in and out itll be back to normal

Thirdly today when going up a steep hill at 30 MPH in second gear again it started jerking like no tomorrow like it was struggling to get up the hiil soon as back on flat it was fine.

And Finally i got on the bypass and it would not go past 73mph..

Any advice/help would be greatly appreciated, can't really afford to take it to a garage right now.

Thanks
Scott

Scotty... What you just posted is absolutely useless. On your bike, a coolant sensor switch failing would not stop the bike from starting. Nor would it affect the top speed. You'll need to give us a more accurate description of what is happening.
 

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Thanks Hawk. That means a lot to a sensitive new age guy like myself... I don't mean to be a prick but I feel I either need to tell a guy like this how it REALLY is or else just ignore his cry for help...
Well then Wade, at least tell the guy THE TRUTH. The Hyousong (SP) GT250's ecm does not monitor the coolant. Therefore, the coolant prob is not the prob. Hawk was just saying exactly what I'm saying now... If ya got nothing nice to say (read: HELPFUL) then say nothing.... Geez...

Jack
 

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Well if it's not an engine coolant sensor then ( most likely ) what is it? Why don't you post something helpful Jack instead of just critiquing the fact that I don't know that bike doesn't have a coolant temperature sensor .

My guess is that the fuel injection light coming on indicates a problem and not that it's ready to run .

The OP ( original poster) needs to go back to basic diagnosis and see if it won't start because it's lacking fuel or lacking ignition.

That can be done in 30 seconds with a spark plug tester and a can of starting fluid.
 

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Well if it's not an engine coolant sensor then ( most likely ) what is it? Why don't you post something helpful Jack instead of just critiquing the fact that I don't know that bike doesn't have a coolant temperature sensor .
He asked for more information, which is about the only logical thing to do at this point. :)
 

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Discussion Starter #9
Wow guys sorry, only asking for a little bit of help not for people to bite my head off!

The bikes cooling system is an oil radiator, it doesn't have coolant or anything like that.

The sensor in question is a sensor that goes into the engine near the barrel to measure the temp to adjust the air fuel mixture.

Im not too sure what other info is needed? Fuel is getting into the chamber and it is sparking just seems to be incorrect air fuel for when its cold like if it had a carb youd put the choke on to temporarily adjust air fuel well basically thats what the switch is doing...
 

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So this switch is something you added to trick the FI system? Is it only on cold starts that you have to use it?

I know only a very little about FI - I own an air cooled VW with a Bosch system, but that's it. The symptoms you described sound consistent with a lean condition. Shorting the sensor wires could be dumping a full rich mixture into the bike, which helps get it started. Just a guess. Those temperature sensors can go bad in the VW world, and are pretty cheap.

The biggest issue with FI seems to be vacuum leaks - air getting into the intake system which isn't being measured by the FI system - hoses, o-rings, etc leaking.
 

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If I wanted to fake out A coolant or an intake air temperature sensor (not that there's much difference between the two) for added starting enrichment I would put it in a bucket of ice and measure the resistance at 32° or less and substitute a resister for that value with my switch rather than dead shorting the two signal lines together which is a great way to destroy an ECM permanently
 

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He asked for more information, which is about the only logical thing to do at this point.
If Jack wants to ridicule me because I don't know that particular bike has an intake air temperature sensor instead of a coolant temperature sensor (even though they perform virtually an identical function) why don't you stay out of the argument that ensues instead of climbing into the middle of it?

And he didn't ask for information he stated that my contribution was worthless

By the way I concur with another poster's comment that unmetered air bypassing the mass airflow sensor is quite likely a cause of the OP's drivability problems and starting problems -- which he should confirm with a can of starting fluid / ether.
 

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Because I agree with him: If you can't say anything decent or you don't know enough about working on his type of bike to try to help the guy, why don't you keep silent? Making judgmental comments and telling him he probably can't fix it doesn't help him out, and doesn't contribute in a positive way to a new member's experience on this forum.
 

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I saw a request for help that nobody else had replied to. Not Jack not you. I chose to at least try and outline the situation to the OP and the degree of difficulty. You know as well as I do when beginners try and repair their bikes it's not all rainbows and unicorns. Especially when they turn to unpaid "experts" on the inner tubes who don't know a CTS from an IAT. ;)
 

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Wow guys sorry, only asking for a little bit of help not for people to bite my head off!

The bikes cooling system is an oil radiator, it doesn't have coolant or anything like that.

The sensor in question is a sensor that goes into the engine near the barrel to measure the temp to adjust the air fuel mixture.

Im not too sure what other info is needed? Fuel is getting into the chamber and it is sparking just seems to be incorrect air fuel for when its cold like if it had a carb youd put the choke on to temporarily adjust air fuel well basically thats what the switch is doing...
The reason we're asking more questions is that without the bike in front of us it can sometimes be hard to understand exactly what it is you have going on. Sometimes even the terms we all use get confusing as well. No one's trying to bite your head off, they're just trying to understand you and your issue. CmonStart has a ton of experience working on bikes, and Jack is a professional bike mechanic that has forgotten more about Asian bikes then I'll ever learn. Wade is an electrical engineer, (but has less then stellar social skills apparently.)
 

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Original: Wade is an electrical engineer, (but has less then stellar social skills ...

ReWrite: Wade is an accomplished EE who worked extensively on automotive electronics for over 30 years. He holds several ASE certifications and helped design some of the original digital electronic fuel injection units for Robert Bosch. He holds two patents. He has written for innumerable auto technology magazines about diagnosing and debugging ECM's and other problem modules including Motor, Motor Age and Master technician for whom he was an editor. He taught automotive electronics at San Juan College most of which applies directly motorcycles as well. He may come across as grumpy now and then but he'd give you the shirt off his back and is always looking to help others experiencing problems with their bikes' electronics. He has contributed several valuable articles to this forum including diagnosing no start and no crank conditions as well as voltage dropping inoperative circuits

So now that I've outlined my credentials I apologize for my original post which was a little gruff.
 

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Sorry, I had to. Really, I couldn't help it.
 

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So this switch is something you added to trick the FI system? Is it only on cold starts that you have to use it?

I know only a very little about FI - I own an air cooled VW with a Bosch system, but that's it. The symptoms you described sound consistent with a lean condition. Shorting the sensor wires could be dumping a full rich mixture into the bike, which helps get it started. Just a guess. Those temperature sensors can go bad in the VW world, and are pretty cheap.

The biggest issue with FI seems to be vacuum leaks - air getting into the intake system which isn't being measured by the FI system - hoses, o-rings, etc leaking.
This ^^^^^^ Just because it is sometimes the easy solution....That fixes things
I am not a guy to talk to about FI, but only want to add the shadetree solution to diagnose air leaking into the system. Any place like a rubber connection that could suck air in is sprayed with carb cleaner. If the engine speed increases, you have air leaking into the system.

Now if you buy a 70's vintage Honda, I might have a little knowledge of things learned the hard way.... I might also add that voltage drop testing and a few tricks of my own found a hard to diagnose problem I was having

As far as the arguing goes, Are you guys gonna behave, or am I gonna have to call Moni?

And, wow, I was just gonna mention that pretty much any of these guys would take the time to give you the shirt off their back even though they might have a few words with each other, but it looks like Wade got there first.

Anyway,Scottie,welcome to the forum!
 

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I'm here, I'm here. Did somebody call??? LOL!!!!!


Hey Scottie. Welcome to the Forum. I think all the guys just need a hug today. We really are just like one big family...arguments and all. Most folks learn a lot from the Forum. Stick around and join in the fun!

Honestly, folks on the Forum really do try to help others. Some come across a little harsh at times, some come across as total lunatics at times and some come across really straight laced and to the point. Either way, we always need new members to post so we'll have more to think about and talk about.
 

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Well if it's not an engine coolant sensor then ( most likely ) what is it? Why don't you post something helpful Jack instead of just critiquing the fact that I don't know that bike doesn't have a coolant temperature sensor .

My guess is that the fuel injection light coming on indicates a problem and not that it's ready to run .

The OP ( original poster) needs to go back to basic diagnosis and see if it won't start because it's lacking fuel or lacking ignition.

That can be done in 30 seconds with a spark plug tester and a can of starting fluid.
Wade... Buddy... Pal... The OP is NOT experiencing a no-start prob. The bike does start and run. But not properly. Moni is right. We need not have the OP thinking we are biting his head off. I know all I want is to help him, but I can't help him if his description of the problem is not understandable. It has fuel, it has spark. His prob seems like it might stem from this (SO far) mis-identified sensor/switch. All I'm trying to do is to get more info so that maybe I can help him. Unfortunately, all my experience with Hyosung is with the GT650. I would think the 250 wouldn't be that far off. That said:

Scottie... You need not apologize for our bad manners. I am Sorry if we all gave you bad vibes.... We ALL want to help you. Even Wade... You can dress him up, but he's totally socially unacceptable!! LOL...


Ok...

This component you speak of... is it a sensor or an actual switch that you can control? Your description kinda indicated that it is a switch that may have been installed as a sidestep to what was supposed to happen?? If your Hyosung has been altered from stock, I need to know this!! As Wintersol said...

What really has to happen here is quite simple.. we need to find out how to access the FI error codes on your bike. Once we do that, we can try to determine what will be the correct path to take to make your bike run right.

I will research the info needed and get back to you. That you can count on!!!

Jack
 
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