[CooperWalker]

Hi all, new to the forum and hoping to find some support/expertise. I have a '74 Honda XL250 4-stroke that was running great about 3 years ago. I lost the ignition keys (don't ask) and haven't started it in about that time. I cleaned the carb, dumped the tank and put in new petrol, changed the spark plug and still can't get it to start. Now... there is spark... the battery seems ok - lights are working, horn etc. and there is spark. I get compression, I have spark, gas is getting into the carb... but it won't start! Is there anything obvious I'm missing? The air filter got a little wet from the rain, would this prevent ignition? I have compression. It's a kickstart, have had difficulty starting in the past but not like this. I'm in LA so no real weather concerns. Any advice or insight is very much appreciated. Thanks.

 

[Easy Rider]

Welcome.
Paper filters sometimes become plugged when wet. Have you tried it without the filter ?

Then, it sounds like you need some starting fluid or propane introduced into the air box to see if that spark you have will actually make it fire a few strokes.
You are using the choke (closed) when trying to start, right ?

Often the low speed jets in the carb are very small and hard to properly clean even if you know where they are.
I think it's likely you have a fuel delivery problem due to some crud still left in the carb.

 

[CooperWalker]

Welcome.
Paper filters sometimes become plugged when wet. Have you tried it without the filter ?

Then, it sounds like you need some starting fluid or propane introduced into the air box to see if that spark you have will actually make it fire a few strokes.
You are using the choke (closed) when trying to start, right ?

Often the low speed jets in the carb are very small and hard to properly clean even if you know where they are.
I think it's likely you have a fuel delivery problem due to some crud still left in the carb.

I will try to start without filter, and possible there is still crud in the carb... Yes choke is closed when starting, it sounds like it wants to start but won't and I end up flooding. I used guitar strings to clean the jets I could find but admittedly there is one in the center that was either not a jet or very clogged, I will try starting with fresh battery charge and no air filter, if no ignition I will remove the carb again and post pictures. Where would I put the starter fluid, in the tank? Thanks.

 

[AloRaptor]

Starter fluid goes in the air intake.:bluethum:

 

[CooperWalker]

Charged the battery, air filter is totally dry, still not starting... does anyone know how many jets this carb has? I removed the floats, there is one jet that unscrews, there's only one other screw that comes loose and it's not a jet. There's a (jet-looking) rod that runs through the center right beneath the bowl that seems to be held in by the metal around it being bent... I will follow up with pictures but any input is helpful. I feel like it's something simple like a jet being clogged since I'm a true novice with carburetors and I may have missed something while cleaning it out. The jet I did clean was clogged shut so it's very possible I missed one... I'll keep tinkering.

 

[Easy Rider]

Where would I put the starter fluid, in the tank? Thanks.

From my previous post:
Then, it sounds like you need some starting fluid or propane introduced into the air box

Don't use a lot.

If it already sounds like it it "trying to fire" maybe you need to modify your technique just a bit.
Try it without the choke.....or with partial choke. And do NOT open the throttle any until it fires good.

How do you know that it "ends up flooded" ? That sounds like too much fuel instead of too little.

And finally, you can't trust an old spark plug in cases like this.

There is a limit to the amount of help others can give you without being there.
Removing the carb just to post pictures of it is probably a waste of time.

At this point, your time might be better spent looking for a replacement carb.

 

[CooperWalker]

From my previous post:
Then, it sounds like you need some starting fluid or propane introduced into the air box

Don't use a lot.

If it already sounds like it it "trying to fire" maybe you need to modify your technique just a bit.
Try it without the choke.....or with partial choke. And do NOT open the throttle any until it fires good.

How do you know that it "ends up flooded" ? That sounds like too much fuel instead of too little.

And finally, you can't trust an old spark plug in cases like this.

There is a limit to the amount of help others can give you without being there.
Removing the carb just to post pictures of it is probably a waste of time.

At this point, your time might be better spent looking for a replacement carb.

True I don't know that it becomes flooded, just seems to get farther from starting after about 20 kicks. I have been opening and closing the choke, adjusting the idle, etc. I haven't tried leaving the throttle closed though I've had it open almost every time. I replaced the spark plug and checked for spark so I don't think there's a problem there. I think the next step will be to try a little starter fluid... I can't think what else to do. You're right that it's almost impossible to figure this out without being there but besides trying to clean the carb again I don't know what else I'm able to do to get it running again. :|

 

[Easy Rider]

I haven't tried leaving the throttle closed though I've had it open almost every time.

That is NOT good technique.
The best plan with a kick-start bike usually is:
Choke fully closed. Kick once or twice.
Open choke about half way and keep going a few more kicks.
DO NOT TOUCH THE THROTTLE until you hear it fire a rev or two.

It's pretty much guaranteed that it won't start with the throttle open.

 

[CooperWalker]

That is NOT good technique.
The best plan with a kick-start bike usually is:
Choke fully closed. Kick once or twice.
Open choke about half way and keep going a few more kicks.
DO NOT TOUCH THE THROTTLE until you hear it fire a rev or two.

It's pretty much guaranteed that it won't start with the throttle open.

I took your advice and kicked it a couple times with throttle closed, key off and gas off. Turned the key, started on the second kick! Really rough idle, I turned the idle down and it seemed content, stalled when I put it in gear. I got it back started a couple times but did not want to stay running. Should I let it idle before trying to ride it to let the fuel work it's way in? I don't want to damage it so I'm writing in before starting it again.

 

[Easy Rider]

I took your advice and kicked it a couple times with throttle closed, key off and gas off.

Well that is NOT what I said.
You need to stop reading things that aren't there......but I'm glad it worked.

Yes, most bikes need to warm up a bit before they will run smooth with no choke.
Most need partial choke to run smoother while warming up. During that time, the idle speed should be a bit higher than normal.

And finally, if you have fresh gas in it, it is time to add a double dose of Berrymans B12 Chemtool in with the gas.
That is two ounces per gallon of fuel.
It might take a couple of days and a couple of warming-up runs to finish cleaning out the carb.

Good luck. Hope there isn't another problem remaining.

 

[CooperWalker]

Well that is NOT what I said.
You need to stop reading things that aren't there......but I'm glad it worked.

Yes, most bikes need to warm up a bit before they will run smooth with no choke.
Most need partial choke to run smoother while warming up. During that time, the idle speed should be a bit higher than normal.

And finally, if you have fresh gas in it, it is time to add a double dose of Berrymans B12 Chemtool in with the gas.
That is two ounces per gallon of fuel.
It might take a couple of days and a couple of warming-up runs to finish cleaning out the carb.

Good luck. Hope there isn't another problem remaining.

You're right - I posted a few places about this bike and it was another member who suggested kicking it without gas or key on. Anyway managed to start it yesterday, idle was very rough, but I should have waited before trying to take it out. Got a little excited. So now I kick it over and no start. Will keep updating, hopefully once the carb has the new fuel worked into it she'll run. Lot of excess gas leaking from the tank, may need to replace the fuel lines. Will check back in when something new happens.

 

[CooperWalker]

Update: Got it started, still idles rough, tried to keep it running but stalled after a couple minutes. I think one of the jets is still clogged, I remember thinking there must be more jets to the carb than the one I cleaned. Exhausted from trying to start it, tomorrow I think I'll take the carb back off and really look for more jets. Hoping there isn't another problem. Any possibility this isn't a jet-related issue and something either starter fluid or chemtool would fix? My only recourse is to rebuild the carb again. Thanks.

 

[Easy Rider]

You still aren't listening.....which is not unusual for some reason.

There likely are some low-speed jet passages inside the carb that you can't see or get to.
A healthy dose of chemtool often gets to these after running for a while.
Also it is possible that you could take the carb apart 100 times with no better results.

There could be a vacuum leak too.

When it is running rough, what happens if you vary the amount of choke you use ??

 

[CooperWalker]

You still aren't listening.....which is not unusual for some reason.

There likely are some low-speed jet passages inside the carb that you can't see or get to.
A healthy dose of chemtool often gets to these after running for a while.
Also it is possible that you could take the carb apart 100 times with no better results.

There could be a vacuum leak too.

When it is running rough, what happens if you vary the amount of choke you use ??

Varying the choke doesn't seem to have any effect at all, certainly doesn't seem to make it easier to start. I will try the chemtool. Trying to listen!

 

[Easy Rider]

Varying the choke doesn't seem to have any effect at all,

If that really means that opening or closing the choke has no effect at all while it is running rough......that's a bad sign.
It probably means that it is WAY too rich, which can be caused by a gasket leak inside the carb or a float set wrong.
When it is running rough, does removing the air filter make any difference ??
I'm about out of ideas.

 

[Aussie Steve]

You mention excess fuel leaking from the tank...not sure what you mean but if the fuel lines are old and crumbling every time you try to start it you may be dragging tiny bits of rubber into the carbs....also if the lines are shot then the tank may have a build up of crud too...as probably any filters do as well.

 

[RjMaan]

I think you should properly tune it and after that you can also check the lubrication. You should also check he coil whether it is fine or not.

 

[RjMaan]

Oh no. I think you should check its spark plug, battery and wiring or still if you are not being able to start it then there are some Honda XL250 Service and Repair Manuals, which would guide you in repairing your bike.