J
jake
Guest
power wasnt a big issue either, could get into 6th gear at 100kph easily enough at 8k revs
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J
jake
Guest
Nessism, I checked the fuel in both carbs 3 times, primed each time and tried to start, and checked the fuel quality on each one, there was unfortunately no water or dirt in any of the fuel I drained from both carbs.
The fact that this starting issue developed over a period of months, and with 40,000 miles on the clock, I would definitely check the valve clearances. Spec @ .003” - .005” doesn’t leave much room for error. If those valve adjustments have worn down to where the valves are not completely sealing it could act like a vacuum leak as it could draw some of the exhaust side in when on the intake stroke and blow some out the carb on the compression stroke, both keeping the fuel charge from getting in the combustion chamber. I would confirm/set valve lash.
Compression, spark, fuel. Those are the ingredients to get your bike to run. We have offered suggestions on each of them and you have dismissed them all. I'm out of suggestion unless you are wrong about something. Most of the time when these things occur the problem turns out to be something basic and/or lack of maintenance. Only thing I can suggest at this point is to go back to the beginning and check everything again.
J
jake
Guest
It will definitely be the next thing I will check, I'll keep you updated, thank you for all your contributions so far, I will get back to you all hopefully sooner, rather than later.
Thank you.
Thank you.
J
jake
Guest
well, everything seemingly but fuel... I'd only had the bike since May, and had only been riding it since mid June... I hadn't even clocked 2000 miles on it and everything beforehand sounded/seemed in good nick... There were no funny noises, or misfires at any rev range, and power seemed adequate given its age... I will check valve clearances, spark plug and fuel quality again regardless.
J
jake
Guest
Hi Steve,
I have not checked the valve clearances as I'm still a relatively new home mechanic, I would hope that when I left it into the mechanics when it broke down that they checked the valve clearances, I will double check with them. I am currently away from the bike, and I have a large work undertaking for college etc... please allow me a couple days to check the valve clearances.
I didn't think to check valve clearances, as there was no loss of power, or misfiring... and the bike rapidly deteriorated in the space of a couple days. Further, there is no fuel entering the piston, so I did not think the problem was ignition or valve related. However as I said, I am new to the game, and I know that the members here such as yourself have far more experience than I do.
Would valve clearances stop fuel entirely from entering the piston or stop starter fluid from catching at all?
Thanks.
I have not checked the valve clearances as I'm still a relatively new home mechanic, I would hope that when I left it into the mechanics when it broke down that they checked the valve clearances, I will double check with them. I am currently away from the bike, and I have a large work undertaking for college etc... please allow me a couple days to check the valve clearances.
I didn't think to check valve clearances, as there was no loss of power, or misfiring... and the bike rapidly deteriorated in the space of a couple days. Further, there is no fuel entering the piston, so I did not think the problem was ignition or valve related. However as I said, I am new to the game, and I know that the members here such as yourself have far more experience than I do.
Would valve clearances stop fuel entirely from entering the piston or stop starter fluid from catching at all?
Thanks.
Firstly,
The usefulness of this forum is BEYOND the basics you will find in almost any manual....fuel,compression,spark. You are advised to get a basic understanding of your engine.
Checking your valves will inform you of how your engine functions as a "pump". Valves that aren't closing and sealing won'tallow the pistons to csuck fuel in or pump the exhaust away.
again,
Do not use starter fluid. Put a little gas on the plug or maybe squirt a little gas through the airbox(remove seat and foam filter- turn the bike over with kill switch off to suck some gas in) Your assumption of the manifold rubbers is probably wrong. Leaking manifolds make the bike run very lean in operation but should not affect starting unless there's some really bad leaks that you can plug temporarily-(grease, tape,gobs of rtv...) Starting is a very rich condition on these bikes.
..is highly suspect. These are simple engines ...Perhaps you have "baggage" with these folk or they are not able to help. Find a new mechanic.
If you are going to work on your own bike, you must take the time to do it. You will need some tools beyond the emergency kit the maker included with the bike. The money you "save" fixing it yourself is best invested in tools.
The usefulness of this forum is BEYOND the basics you will find in almost any manual....fuel,compression,spark. You are advised to get a basic understanding of your engine.
the most obvious -fuel supply to the carburetors -the petcock- has been mentioned.
You should find your engine resists being turned by hand in neutral. This is due to "compression" and "vacuum". If there is no engine vacuum or compression, you have a serious problem. Cracked head, failed or severely maladjusted valves, broken rings etc etc...simply fitting your thumb over the spark plug hole is a simple way of "discovering" vacuum and compression....but a compression gauge is much better.
Checking your valves will inform you of how your engine functions as a "pump". Valves that aren't closing and sealing won'tallow the pistons to csuck fuel in or pump the exhaust away.
again,
These bikes don't require throttle plate opened to start. When the throttle-plates are closed, the engine vacuum will be greatest ! that is, the main inlet is blocked and the engine must suck very hard through the idle circuit and the "enrichment " circuit. Given the rest of the bike is ok, A no-start condition suggests these passages and jets are blocked, broken,maladjusted.
Do not use starter fluid. Put a little gas on the plug or maybe squirt a little gas through the airbox(remove seat and foam filter- turn the bike over with kill switch off to suck some gas in) Your assumption of the manifold rubbers is probably wrong. Leaking manifolds make the bike run very lean in operation but should not affect starting unless there's some really bad leaks that you can plug temporarily-(grease, tape,gobs of rtv...) Starting is a very rich condition on these bikes.
Steve
GS Whisperer
Unless someone has modified their bike, that is not possible with a GS. :-k
Turning the kill switch to the OFF position also disables the starter.
Now, ... if the bike has a kick starter, you can kick it a bit, but you don't even have to have the key ON, so it won't matter what position the kill switch is in.
.
J
jake
Guest
Hi Gorminrider,
Thank you for your input, reading over what you said, I will double check again all the jets. I would be very alarmed if my mechanic had anything against me, I'm a new motorcyclist, they're family run, and they put on the new tyres where no one else would touch a bike this old (im in Ireland), also bought all my gear from them.
I am relatively familiar with compression, spark etc... I wouldn't have posted in the forum if I wasn't. Unfortunately I am not in a position to buy new tools let alone pay for transport etc... I bought the bike because it was relatively cheap, and I was told by a couple home mechanic relatives (who have all had a look) that older bikes very rarely broke down.
I thought that the leak may have been responsible as the symptoms preceding the bike breaking down seemed very similar to what I'd read online about vacuum leaks.
Thanks for explaining the operation of the vacuum operated carbs, I had had them mostly apart, however I did not want to take them apart fully for fear of being unable to rebuild them in case the rubber elements were too degraded.
I will recheck, fuel, valves, petcock, and jets
thankyou
Thank you for your input, reading over what you said, I will double check again all the jets. I would be very alarmed if my mechanic had anything against me, I'm a new motorcyclist, they're family run, and they put on the new tyres where no one else would touch a bike this old (im in Ireland), also bought all my gear from them.
I am relatively familiar with compression, spark etc... I wouldn't have posted in the forum if I wasn't. Unfortunately I am not in a position to buy new tools let alone pay for transport etc... I bought the bike because it was relatively cheap, and I was told by a couple home mechanic relatives (who have all had a look) that older bikes very rarely broke down.
I thought that the leak may have been responsible as the symptoms preceding the bike breaking down seemed very similar to what I'd read online about vacuum leaks.
Thanks for explaining the operation of the vacuum operated carbs, I had had them mostly apart, however I did not want to take them apart fully for fear of being unable to rebuild them in case the rubber elements were too degraded.
I will recheck, fuel, valves, petcock, and jets
thankyou
right. Sloppy- but mainly, squirting a little gas in through the airbox before turning it over should give a useful reaction...even if the airbox screen is in the way .Unless someone has modified their bike, that is not possible with a GS. :-k
Turning the kill switch to the OFF position also disables the starter.
Now, ... if the bike has a kick starter, you can kick it a bit, but you don't even have to have the key ON, so it won't matter what position the kill switch is in.
.
Dirty idle jets are very common. Cleaning the bowl and pulling out the jets to clean does not need the vacuum slides disassembled.Otherwise there's few to none rubber o-rings involved until you pull the float needle seat or the idlemixture screws or the bowl drain screw. and usually these are ok anyways- certainly good enough to start the bike while dirty jets are NOT.
Being careful not to tear the bowl gasket is the main hurdle.
https://www.cmsnl.com/suzuki-gs250t-1980-t-united-kingdom-e02_model13417/partslist/FIG-12.html
J
jake
Guest
Hi All,
I know it has been some time since I last was in touch with you all. Although I have still not had the time or other resources to recheck the various items that were mentioned e.g. valve clearances, I was offered a free tow and check by a vintage mechanic... The mechanic cleaned the carbs and returned them to the bike, and the bike started up, he said no bother. I rode the bike back home all in good condition, however within the space of about 3 days the engine died again, I had used it every day since getting it back and didnt have an issue... I haven't been in touch with the mechanic yet as I am in the midst of very tough exams, I hope to be able to get around to him some time in February... In the mean time however I wanted to ask what you guys thought might be wrong with the bike... the mechanic said the bike would continue to run for decades to come and that there were no other problems with the bike... I am truly stumped... If anyone has any further light to shed on why this problem might be recurrent or even what it is would be very much appreciated... I have only been able to ride the bike for 3 months and paid out 1800 for insurance and 1000 for the bike which I was hoping to be able to rely on for more work... I lost my job because it broke down... I dont want to have to end up selling the bike for scrap and losing my license which I paid another 600 for...
Many Thanks,
jake.
I know it has been some time since I last was in touch with you all. Although I have still not had the time or other resources to recheck the various items that were mentioned e.g. valve clearances, I was offered a free tow and check by a vintage mechanic... The mechanic cleaned the carbs and returned them to the bike, and the bike started up, he said no bother. I rode the bike back home all in good condition, however within the space of about 3 days the engine died again, I had used it every day since getting it back and didnt have an issue... I haven't been in touch with the mechanic yet as I am in the midst of very tough exams, I hope to be able to get around to him some time in February... In the mean time however I wanted to ask what you guys thought might be wrong with the bike... the mechanic said the bike would continue to run for decades to come and that there were no other problems with the bike... I am truly stumped... If anyone has any further light to shed on why this problem might be recurrent or even what it is would be very much appreciated... I have only been able to ride the bike for 3 months and paid out 1800 for insurance and 1000 for the bike which I was hoping to be able to rely on for more work... I lost my job because it broke down... I dont want to have to end up selling the bike for scrap and losing my license which I paid another 600 for...
Many Thanks,
jake.
fbody_mike
Forum Mentor
From your last post, I'd assume the tank has a lot of rust or dirt. The mechanic cleaned the carbs and fixed the no run condition but not the cause. Drain all the fuel from the tank into a bucket and see what is in it. if there is particles then you will need to get the tank treated and lined.
I agree ....debris from tank gunking up petcock and carbs. Drain tank and look inside with flashlight
J
jake
Guest
Hi fbody,
The Tank has a very small amount of rust, but I'm not sure dirt's the issue, I had the carbs apart and cleaned them myself twice before sending it in and didn't have any luck, and he said all he used was carb cleaner spray... The bike won't even cough on starter fluid... Good spark and good compression... He mentioned something about a potential blocked overflow passage, but when I asked he said he didn't know enough about the carbs on it, he didn't even have them apart... Rust is definitely something to consider, but the fuel was extremely clean, I've drained in small quantities (and let sit) about 3 cups, no water or dirt... I am puzzled...
The Tank has a very small amount of rust, but I'm not sure dirt's the issue, I had the carbs apart and cleaned them myself twice before sending it in and didn't have any luck, and he said all he used was carb cleaner spray... The bike won't even cough on starter fluid... Good spark and good compression... He mentioned something about a potential blocked overflow passage, but when I asked he said he didn't know enough about the carbs on it, he didn't even have them apart... Rust is definitely something to consider, but the fuel was extremely clean, I've drained in small quantities (and let sit) about 3 cups, no water or dirt... I am puzzled...
J
jake
Guest
I will have another look and will drain the tank and reclean the carbs again... However it might take some time given my workload and the lack of daylight, thank you for your advice.
J
jake
Guest
Hi all,
Thank you for your patience for me to get back to you. I have some good news, I drained the tank entirely and found there to be no rust or water. Then I recleaned and rechecked the jets and carburettor, and put everything back together. Put in a freshly charged battery, refilled with fuel, primed, choke on, and pressed the starter... and lo and behold, the bike started up... fantastic. I let it warm up and took it for an hour spin or so, as all sounded very well. A couple of problems developed throughout the ride however. The ignition system at one point went dead, the headlight high beam/low beam indicator began flickering, then the engine died. The starter motor wouldnt work either, I noted water from the kill switch and put it down to a short. After a little drying the starter worked and all was well. The second issue was power, I didnt have has much power in the bike as I had beforehand, and the sound of the bike could be described as flat, and produced a sound almost like very quiet backfiring. I am not sure what could have caused this. The bike would not start unless on the prime position of the petcock, could this be due to a lack of the required pressure, or petcock failure? The last problem I have is that the battery is discharging throughout the evening, I am not too bothered by this right now, as I just want the bike to run properly so I have put on a switch to cut off the battery completely.
The bike was still hard to start however and I noted that the airbox was not able to fit fully/properly to the carburettors and were placed at an angle, I was going to test for vacuum leaks today, but the battery discharged and is also low on fluids, I couldn't get the bike started. I will be topping it up and recharging tomorrow. Does anyone have any suggestions for more tightly fitting the airbox? The exhaust manifold is scorched (when I got the bike) which makes me think lean mixture alongside poorer power output, but the spark plugs that came on it seemed fine. The battery dropped fluids quite fast from when I last checked it, I am told that it could be due to overcharging, I will check the voltage when I get it started tomorrow, could someone recommend a cheap, durable voltage rectifier if this is the case? If you don't think that may be the cause I would appreciate your thoughts.
I know I may need to order new boots and I found a set on partzilla, however if these boots are wrong, or there is somewhere else I can find them cheaper please let me know, I will have to pay shipping to Ireland regardless. https://www.partzilla.com/catalog/suzuki/motorcycle/1980/gs250t/cylinder-head
I am uncertain how to ensure the airbox is connected properly to the carbs, they dont seem to reach their mark, even with an excessive use of force and with the mounting screws. I would feel more comfortable If I could get that more properly sealed, however I am not sure how to go about this. I have had some suggest plumbers self adhering tape, however I think vulking tape may be stronger. Getting it around the carbs etc... will be a pain in the ass, any suggestions? I'm getting a little tired of having this apart (5 times!).
Thank you for all your help so far, It is indeed much appreciated.
Jake.
Thank you for your patience for me to get back to you. I have some good news, I drained the tank entirely and found there to be no rust or water. Then I recleaned and rechecked the jets and carburettor, and put everything back together. Put in a freshly charged battery, refilled with fuel, primed, choke on, and pressed the starter... and lo and behold, the bike started up... fantastic. I let it warm up and took it for an hour spin or so, as all sounded very well. A couple of problems developed throughout the ride however. The ignition system at one point went dead, the headlight high beam/low beam indicator began flickering, then the engine died. The starter motor wouldnt work either, I noted water from the kill switch and put it down to a short. After a little drying the starter worked and all was well. The second issue was power, I didnt have has much power in the bike as I had beforehand, and the sound of the bike could be described as flat, and produced a sound almost like very quiet backfiring. I am not sure what could have caused this. The bike would not start unless on the prime position of the petcock, could this be due to a lack of the required pressure, or petcock failure? The last problem I have is that the battery is discharging throughout the evening, I am not too bothered by this right now, as I just want the bike to run properly so I have put on a switch to cut off the battery completely.
The bike was still hard to start however and I noted that the airbox was not able to fit fully/properly to the carburettors and were placed at an angle, I was going to test for vacuum leaks today, but the battery discharged and is also low on fluids, I couldn't get the bike started. I will be topping it up and recharging tomorrow. Does anyone have any suggestions for more tightly fitting the airbox? The exhaust manifold is scorched (when I got the bike) which makes me think lean mixture alongside poorer power output, but the spark plugs that came on it seemed fine. The battery dropped fluids quite fast from when I last checked it, I am told that it could be due to overcharging, I will check the voltage when I get it started tomorrow, could someone recommend a cheap, durable voltage rectifier if this is the case? If you don't think that may be the cause I would appreciate your thoughts.
I know I may need to order new boots and I found a set on partzilla, however if these boots are wrong, or there is somewhere else I can find them cheaper please let me know, I will have to pay shipping to Ireland regardless. https://www.partzilla.com/catalog/suzuki/motorcycle/1980/gs250t/cylinder-head
I am uncertain how to ensure the airbox is connected properly to the carbs, they dont seem to reach their mark, even with an excessive use of force and with the mounting screws. I would feel more comfortable If I could get that more properly sealed, however I am not sure how to go about this. I have had some suggest plumbers self adhering tape, however I think vulking tape may be stronger. Getting it around the carbs etc... will be a pain in the ass, any suggestions? I'm getting a little tired of having this apart (5 times!).
Thank you for all your help so far, It is indeed much appreciated.
Jake.
