GSX250 Rough Running, Then Non Starting...

[buelligan]

Right this is going to be a bit of a long post, so I apologise now...

Back in 2005 we (a mate and me) started to build a bike ready for when I passed my test. It was already partly chopped, we just finished it. It had a 2 into 1 straight through exhaust fitted, and the standard air box was binned and replaced with twin cone filters. The wiring was chopped about to move things to their new place.

It was finished at the start of January, and I passed my test. It ran well for a couple of months, then on a ride it started firing on 1 cylinder at anything under full throttle. Took the carbs apart and they were all orange and dusty inside, cleaned them up and it was fine again. A few months later the stator burned out, then the plugs had to be replaced, that was around August. Around this time it also wouldn't idle, had to keep blipping the throttle.

I started college in September, and the bike became really unreliable, the first week it was just hard to start, then the 2nd it was hard to start and running a bit rough, by the 3rd week it was a complete bitch to try and ride through the traffic. On the last day of college that week (thankfully), it cut out as I crossed a roundabout at the top of a big hill. I managed to bump start it part way down the hill, and just about got it the last half mile home. As I pulled up the bike died and wouldn't restart, I tried to start it again the next day and it just turned over but wouldn't fire.

I needed a bike for work and college, so my dad gave me an early birthday present, and I started riding a Yamaha Dragstar. So 9 months, and 4000-5000 miles later, the bike was dead, forgotten, and has been parked up since.


Fast forward 8 years, a few bits have been borrowed from the Suzuki for other things, but now I'm tracking them down and want to rebuild the bike for my wife.


I've connected a battery, and the engine still turns over, I've taken the float bowls off the carbs and they look clean enough, taken the tops off and the diaphragms look ok. Theres a bit of gungy stuff around where the diaphragms sit, but not a enough to stop them fitting properly. The slides move up and down freely. I've not yet had a chance to check the spark, and I need to try and get some fuel line to make sure fuel is getting through (its been so long though that I can't actually remember where the fuel line goes, there seems to be 3 possible places?)

Just thought, when I connected the battery and was turning the engine over, black dusty stuff was coming out the exhaust, I took the exhaust off and ended up with a little pile of black sooty stuff on the garage floor:



Anyway, I'm basically looking for any hints or tips at what else to look at?

Hopefully heres a few photos of the bike as it was, and as it is. If anyone wants any of the condition of the carbs I have some, or of other bits, I can easily get some....

Thanks for reading!

[pedda]

Nice chop.

I'd have a closer look at the jets, make sure they are clean. Give it new spark plugs and let it go. Don't care about rust from the zorst. But make sure you don't have any of it in the tank.

Are you running stock airbox or pods?

[katana]

He said cone filters higher in the post - i'd be more concerned with those and a straight through exhaust and no jet changes = lean conditions......burnt out valves! By the way the pipes at the head looks like they blue'd up - they got proper hot. Seems it has never run right and with use has got worse. You can have fuel and spark but without compression it'll never run right or at all!

[buelligan]

I can't actually remember if anything was done re. The jets, I do think I can remember my mate doing something, but not sure if he fitted different jets or what. I've not really got any understanding about rejetting so any help with that would be gladly received. Is there an easy way to check? 

Is is there a way to check for compression without the proper tools that screw into the plug hole?

oh and the pipes were already like that when I got them, they're not smooth any more, gone all rough and lost their chrome. The chrome seems to be bubbling in places, so if I can get the engine running I'll probably treat the bike to a set of stainless pipes.   

The tank was another question I meant to ask. Theres a couple of small patches of surface rust inside the tank, is there a liquid I can pour in and swish around to deal with that? It doesn't look bad enough to cause problems at the moment, but could if it gets worse.

[katana]

Get a manual and check jet sizes against the specs - idle mix screws may just require a tweak, lift the needle a notch and up sizing the main is what is usual - how much is anyones guess! Also make sure floats are set as spec's. You really need to know what compression you've got - any friendly stealer should check it for a drink! - even better if they have a leak down tester would indicate if valves or rings are in trouble!

Tank sealer products are available but I don't think there is definitive proof that they last with the shite petrol we are getting these days - may last a year, maybe less! Best give tank a good swill out and try and keep it full if storing for any extended period. Use a decent filter in the fuel line to the carbs - see the crap it catches!

[buelligan]

Thanks, getting the bike to a local workshop would be the biggest problem with that, but I've had a look and they're not too expensive so could probably get 1 next month. Or a couple of my mates may well have 1, they're both into classic cars, so have a lot of the tools.

I've got a haynes manual, found the section about stripping the carbs so sat at the kitchen table now about to take them to bits and see what jets are in there, I remember setting the floats the first time around. And I always used an inline filter, and will fit another 1, have to say, at the time I never noticed and dirt collecting in the filter.

Think I'll clean the carbs out and see what jets are in them, stick some new plugs in and try and start it. See what happens then take it from there, before I got checking compression and things, just in case it was something simple. i've got a feeling my mate saying he thought it was something electrical, but I don't know what, and we've lost contact since.

Thanks again.

[buelligan]

I went out to the garage to fix the Buell, and ended up spending all afternoon on the suzuki.

I've now taken the carbs apart and used carb cleaner on all the jets, and cleaned up the float bowls, checked the floats are moving freely, as are the slides, diaphragms seem ok, and when blowing into the slot the diaphragms lift the slides. Blown everything through with the air compressor.

The engine turns over quickly, both plugs look a decent enough colour, and are both sparking, not sure what is classed as strong or weak spark though. Fuel in the tank, and is getting through to the carbs, when turning over and putting my hand over where the air filters would fit I can feel suction, but the plugs looked dry when I took them out. I'd expect them to be pretty wet with how long it was turning over. And it wasn't trying to fire at all, so not really sure what to check next?

Check compression? Possible piston rings, valves or similar? Or something electrical? Pickups, coils or something?

Anyone got any ideas? Thanks.

[arnout]

Well.. I know you wrote that fuel is getting to the carbs, but the supply might be poor.. Especially if the chop still uses the stock vacuum controlled tap, this might be the culprit..
But eitherway check presence of fuel in the float bowls (undo drain screw with catch pan underneath and let it flow for a while) and check fuel flow from the tap if the flow from the bowls isn't strong (pull hose from tap and fit different hose to catch tank.. suck on the smaller vacuum hose to operate tap on ON, and also check flow on PRI)

Quick check for compression by comparing compression (via thumb on plug hole method) between the 2 cylinders.. Or comparing suction with the carbs off should give you some indication too (in case of a holed piston)..
Mind accidentally dropping debris down the plug holes or stuff getting sucked into the ports..

I suspect fuel supply might be the issue here though.. So if in any doubt about the tank or tap just use a separate plastic tank for test purposes (and to eliminate this area from the equation)..

[buelligan]

Jan 1, 2015 18:16:17 GMT arnout said:

Well.. I know you wrote that fuel is getting to the carbs, but the supply might be poor.. Especially if the chop still uses the stock vacuum controlled tap, this might be the culprit..
But eitherway check presence of fuel in the float bowls (undo drain screw with catch pan underneath and let it flow for a while) and check fuel flow from the tap if the flow from the bowls isn't strong (pull hose from tap and fit different hose to catch tank.. suck on the smaller vacuum hose to operate tap on ON, and also check flow on PRI)

Quick check for compression by comparing compression (via thumb on plug hole method) between the 2 cylinders.. Or comparing suction with the carbs off should give you some indication too (in case of a holed piston)..
Mind accidentally dropping debris down the plug holes or stuff getting sucked into the ports..

I suspect fuel supply might be the issue here though.. So if in any doubt about the tank or tap just use a separate plastic tank for test purposes (and to eliminate this area from the equation)..

Thanks, the fuel tap does have a place for a 2nd pipe, but on 1 of the tap positions fuel comes out regardless of a vacuum pipe being fitted or not, I guess this is the reserve setting? I'll check the float bowls tomorrow to make absolutely sure there is fuel in there.


Ill try and get some clear fuel line from work when I go back next week so I can rig up a bottle on the handlebars, easy to get to then.


Not sure I can actually get a finger or thumb to the plug holes to check compression that way, I think theres some cooling fins in the way.


Another thing I noticed today was 1 of the exhaust studs isn't actually fitted, 3 of the holes use allen head bolts, and the last has what appears to be threaded bar, rather than a bolt or proper stud, and it doesn't actually screw in. It just pulls out, so that will probably need helicoiling.

[coombehouse]

Don't want to appear negative but ask yourself is it really worth it. TBH gsx250's were not great when they were new & haven't got better with time & this sounds like you might end up throwing money at something with little monetary value. Consider that your dad did you a big favour back then, why not do the same for your wife.
I'll get me coat!

[atshed]

if its what you want then do it. there are plenty of helpful, positive and knowledgeable here . certainly good experience for some basic mechanics if nothing else.

[captain chaos]

plug leads swapped around?

Could be that it's getting fuel, but firing at the wrong time.

[katana]

Jan 2, 2015 7:57:14 GMT captain chaos said:

plug leads swapped around?

Could be that it's getting fuel, but firing at the wrong time.

Wasted spark on a twin? - it doesn't make any difference!

[buelligan]

Jan 1, 2015 23:05:33 GMT coombehouse said:

Don't want to appear negative but ask yourself is it really worth it. TBH gsx250's were not great when they were new & haven't got better with time & this sounds like you might end up throwing money at something with little monetary value. Consider that your dad did you a big favour back then, why not do the same for your wife.
I'll get me coat!

I appreciate that, and I certainly won't be throwing an endless amount at it, I intend on getting sorted on a budget of around £400, even if I have to spend £600, there's not a lot around that I like, for sale at £600. Plus, it's not just about the bike/value at the end, it's something to do, gets me out the house and away from the TV. I've achieved absolutely nothing on it in the last few weeks, but I have really enjoyed taking bits off, cleaning them, putting it back on, finding lights, indicators etc

Ps. The building it for her is a side line really, I decided I was going to rebuild it as a rat/army bike, while I was out in the garage she came out and sat on the bike and said she'd like to do her test and she thought that bike was nice and the right height, not too heavy etc. But I doubt she actually will take her test, and even if she does, I don't think she realises just how hard a hardtail really is, so I'll probably build it as something we both like, then use it for work in the summer....

[buelligan]

Jan 2, 2015 0:28:12 GMT atshed said:

if its what you want then do it. there are plenty of helpful, positive and knowledgeable here . certainly good experience for some basic mechanics if nothing else.

Thanks, it's something to keep me busy, I can't afford big budget rebuilds, and if this does goes wrong and need to be scrapped, then there's really nothing lost as it's worth pennies anyway. I'll certainly be asking for some advice on here though, I have basic knowledge, but could certainly use some pointers, and some dummy level explanations for things!

Jan 2, 2015 7:57:14 GMT captain chaos said:

plug leads swapped around?

Could be that it's getting fuel, but firing at the wrong time.

I did think this.....

Jan 2, 2015 11:02:54 GMT katana said:

Jan 2, 2015 7:57:14 GMT captain chaos said:

plug leads swapped around?

Could be that it's getting fuel, but firing at the wrong time.

Wasted spark on a twin? - it doesn't make any difference!

But I didn't realise this, so that rules that out.... 

I haven't managed to get out to the garage today, but hopefully will have a few hours tomorrow. I've got a nice list of things to try now, battery has been on charge all day, and will stay on trickle over night, a fresh can of petrol is hopefully being brought home by my wife. 

Thanks.