Gs250t not starting

[rwms71]

Hi

i was given a gs250t a while back and did a full strip down and rebuild, but I have only had it started briefly.

I have checked the timing and valve clearances and do not think there are any sticking.

there is a spark, and fuel is getting to the carbs. The carbs have been stripped and cleaned by hand, not dipped or ultrasonic bath. There is fuel in the bowls.

there is compression, but not checked with a tester.

battery is new and got good charge

the plugs are dry when cranking so am I right in thinking either the carbs are still blocked or there is not enough compression so it is not sucking fuel in or the timing/valves is still wrong?

Tried dropping a bit of fuel down the carbs and also through the spark plug hole and cannot get it to even briefly run..

Any thoughts on what to try next...

 

[Guest]

The carbs have been stripped and cleaned by hand, not dipped or ultrasonic bath.

Any thoughts on what to try next...

Yep.

Dip the carbs.

Can't tell you how many times we see shortcuts being taken, we can only say that every shortcut taken is just another oportunity to do it over and do it RIGHT.

 

[rwms71]

Unfortunately don't have an ultrasonic bath and in the uk chem dip is not available, plus the cost for getting it professionally done is prohibitive too. Also why is lemon juice so cheap in the US... You can't buy a gallon tub of it here and a small bag of lemons here is twice the cost...

 

[ukjules]

I think you need to check the entire petrol route.
Tank - is it clean inside.
Petcock - status ?
Clearly petrol is not getting to engine.

Try an external tank ? I use one that hangs from
Joist that takes tank out of equation.

You got to pull the carbs and strip down
fully , clean , blow out crap and replace.
I am having massive issue similar with my gsx 250 !

I never have issues with my bigger bikes but
my gsx 250 is a nightmare and over the last
few weeks have cleaned the carbs 10 times.
My 550 and 750 are simple and text book by comparison
and never had these odd issues.

I on my gsx have used cold start , it will start
the bike and seems to set the petrol movement
process going.

Pull em off and clean again , only take an hour and half !

 

[Gorminrider]

It should fire once or twice with a little gas down the plug holes, super-clean carb or not. You had it running before, you say. Something basic.

It is just an air-cooled engine. If you have compression/suction, then perhaps it is sucking air around the intake gaskets. Very common on these. It will be hard to start if there is way too much air....
Otherwise, I agree the most common mistake is a not-thorough cleaning of carbs- especially jets. The idle jet and main jet need removal. The proper working of the enrichment "choke" is maybe second....then floats and their valve needles. Doing it twice is not uncommon! especially if they were in bad shape when you first got the bike and "stuff" is coming loose in the passages.
The spark is usually pretty reliable, if you see one, but it needs to be at the right time and strong.

 

[rwms71]

Got the think started now.. Re did the valve clearances and rechecked the IN and EX cam shafts were set up right. Also soaked, boiled and checked the carbs, I suspect it is the starter passages must have been still blocked.. Now need to get it running smoothly.. Don't have a strobe or carb sync tools so bit stumped

 

[ukjules]

A quick question - you say yo soaked and boiled your carbs !

what did you soak them in and what did you boil them in ?
I have never done this and wandered how beneficial it is

 

[rwms71]

I soaked all the small parts in carb cleaner and boils the carb bodies in water and lemon juice.

Tried starting the bike again next day and it's back to not catching again... So I am back to square one. Am looking out for a cheap ultrasonic cleaner on eBay, or may get a litre of acetone (about ?9 on Amazon) and see if soaking in that helps.

the bike died when I pushed the choke in after running for about 5 mins and it did not like Being revved too much while on the choke. Not sure what to try next

 

[ukjules]

All i know is you must not give up ....

Bare with i am having this issue with my gsx 250 and my gpz750 r and am making progress.
Ill post asap.

 

[rwms71]

Got an ultrasonic cleaner and stripped and cleaned the carbs again... And the bike is running again... Fingers crossed it will keep going..

 

[ukjules]

Did i tell you my issue which seemed similar to yours and caused me to clean the carbs over 10 times, swap coils, CDI units,
plugs caps, plugs, clean tank ... and endless tuning ended up being the pickups connector to the main harness near the seat.
I had looked at tank venting, vacuum pipes, inlet rubbers, mixture ...............................

the bike displayed every possible sign of fuel starvation , every sign possible but when all of a sudden it stopped sparking totally
i started to seriously wiggle some wiring.
I found if i pressed the connector box (from the pickups) it would spark .
I cleaned , took it for a run and it is perfect.
I need to sort this connector out , remove pins and clean and make more secure.

Just thought id say i with mine i was convinced it was the carbs and blockages.
It almost cracked me ! Hope yours keeps going !

I drove mine over the quantock hills today and it was like being 18 again when i had one ! ... almost.
the joys of a 250 is not to be laughed at.

 

[rwms71]

Bike MOT'd now and on the road, but.... Having a bit of a problem with clutch adjustment.. Both ends are at full adjustment and it still seems too long...

 

[ukjules]

I boiled my kwak 750 carbs in a solution of water and lemon juice for 30 minutes. it was just simmering.
so a couple bottles of lemon juice from morrisons added to the water.
After i then cleaned them with a can of carb cleaner spray , then blew them out with my diving cylinders.

Jets and that i just soaked in carb cleaner and prodded about with weld rod cleaning wires to be sure
holes were clear.
I have never used a ultrasonic bath , never needed to - might have been lucky.

What is the status now with the bike ?

 

[rwms71]

That sounds roughly like what I did with the boiling in water/lemon, but 3 cleans still did not do it for me. The ultrasonic did the job in 30 mins..

I re-adjusted the clutch cable so had a bit more adjustment left to play with, but the cable I got must be an aftermarket that is not as short as an oem.

Bike is still running OK since the MOT and clutch tweak.

 

[harth]

Are you guys still running with stock petcocks? Mine isn't holding fuel back when the bikes off and floods the carbs. Have you replaced these with a manual petcock or is there a source for oem replacement?

Note: The gasket kit they advertise doesn't include the gasket that's causing the issues.

 

[rwms71]

Yes mine has original petcock which has no problem. I have to source parts from cmsnl and the entire unit is 90 euro's..

 

[Guest]

I found the problem with the fuel tap is the viton O ring on the prime screw fails & allows fuel past