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Are you certain that the float height is correct at 16mm? Find your model/size (Mikuni?) carburetor and look for the float height spec, it is very, very important, because the bike will act as you say also - (dying after several minute/seconds) - when the float height is maladjusted; There might not be enough fuel in the bowl and you simply 'run out of fuel'.

I hate to beat a dead horse but, Float heights vary tremendously between model/sizes so do not think you can get away with finding a 'close match'. Be certain of your findings and then leave it at that height. In other words, do not fool with the float height once it is set to a correct level and do not change it arbitrarily in search of the correct mixture.

Also, When the bike is running,
Have you tried adjusting the pilot jet screw above and below 2 1/4 turns to see if the idle RPM raises to a maximum value at idle?

Is the plug 'Clean", not wet, DRY. A color off of white may be seen but the plug should be completely dry to fire correctly, and will suddenly die if it becomes wet fouled almost instantly. I would use a step hotter plug than recommended until you iron these issues out, There is no sense fighting a cold plug at idle.
 

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Discussion Starter #22
The float setting I used is from my Clymer manual. The carb is a Keihin. Since I'm not sure if it is the stock carb I will have to do some checking.
 

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Off the subject but, sounds stupid...did you check the coolant level ...assuming it a newer 250R.

You said that after 5 mins. of running it would shut off.

If the coolant was low then, the motor would overheat. Being that you said...you held your hand on the cylinder and it wasn't hot.

If you had a low coolant level, The cylinder may be warm..not hot being that the coolant isn't transferring the heat to the outer part of the cylinder but causing the piston to expand at a greater rate than the cylinder can compensate for.

When the motor has been running for the 5 minutes and bogging down to a stall, did you check for spark, compression when this occurs?

It almost sounds like you need a "top end" rebuild...piston-rings-top rod bearing and gaskets. check the reeds while you have it apart.

When the motor is cool, it runs but when warm...it shuts down... being that you have spark, fuel...thinking...tear the top end down. have a look.
 

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Discussion Starter #25
Yes, I checked the coolant and it is at the correct level.

I did two compression checks on the bike with in the last couple of days. One when the bike was cold because I could get it to run and got a reading of 163 psi. the second reading came two days ago when we managed to get the bike to run for about 5-10 minutes and that reading was 165 psi.
Cold: 163 psi Warm: 165 psi

The other day when I did the cold compression check, I pulled the reads out and looked them over really good; while with the human eye they looked good no cracks, chips, splits, and they appeared to be making a good seal, but after putting a little fuel around the edge of the reeds to see if they were making a good seal; it showed that the reeds are not completely sealing. That being said I think that's just saying they will work but I definitely need to get some new ones soon.

While I had the reeds out I did take a peek at the intake side of the piston which did not have any sign of anything more than normal wear. In fact it almost looked like a brand new piston. I know that is a small section of one side of the piston and the rest of it could look like crap but I thought I would just mention that.

As far as the carburetor goes I thought and was told that it was a Keihin PWK 35mm, but today I figured out that I actually have a Keihin PJ 34mm carburetor. The good news here is that the float and needle setting are the same for the two carbs.
 

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Discussion Starter #26
Yes mgty3whlr, I'm leaning that way myself; but I do have to try everything I can think of first. I am married and the wife might put a stop to the repair of this bike if I tell her that cost to soon.
 

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(Isn't it true) If it was the stator, it would not have spark, which the engine has, according to the first post.
I would mess with the float level, raising it 3mm higher. You can always go back.
 

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Discussion Starter #29
So I was just doing some more web searches on this issue and ran across this video which is the same thing my bike is doing. There are some differences like he has a new rebuilt motor. His answer was to just replace all of the electronics. It worked, but I don't have the budget for that.

https://www.youtube.com/watch?v=Z-fs7L1w1QI
 

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Do you have spark or not when this no-run condition exists?
 

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Discussion Starter #31
Sorry about the late response, but I did something stupid and that I new better than to do that created another issue that I had to stop and fix before I could continue.

Ok, Yes we had spark.

Update on the last couple of days; I decided to pull the hole wiring harness out of the bike and start testing thing pretty heavily by warming things up, wiggling wires, and doing continuity test on every single wire, connector and joint. After about an hour of messing around with the cut up, rewired, bubble gum, and paper clipped mess, I tossed it aside and went and found a good harness that hasn't been altered. Then I got back to testing thing and found that there was a weak spot in the wire right at the connector for the stator that would make a good connection until it got moved, shaken, bumped, or wiggled just right to lose contact. Now that I have fixed the connector I can put everything back into the bike and give her a try.
 

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That is really good that you are fixing the wires; I mean, it helps eliminate 'false' problems, but it still doesn't explain why you would have spark and the engine would not run.
My thinking is that you would not have spark if the connections (at the stator) were "bad".

Anyway, I hope it works out, but,
If it still won't run, and you have spark, and the CR was 160 psi, we need to have a closer look at that carb. Good luck.
 

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C'mon....Get that Donkey Fixed !! Inquiring minds wanna know ! LOL! JK!
 

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Discussion Starter #34
Donkey!.... What now my donkeys broken, well damn that the third time that dang donkey has broke this year so far. Some body fetch me my gun!! I'll fixed that problem right now.... LOL
 

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Discussion Starter #35
Ok, got all the electronic back in the bike. Good news is I was able to get the bike to start and run for a few before it died on me. But I am able to get it to restart back to back. The bike while start right back up as long as the choke is on but it wont stay running. So with the electrical issues fixed it's back to the carb we go.

Just Checked my fuel flow again from the tank I can fill a 2 liter bottle about half way in a minute. I also just got done cleaning the carburetor really good as some people have suggested I should give the carburetor another look. Tomorrow I'm going to shoot down to my local dealer and pick up a new chunk of fuel line and a couple new plugs. Drop the carb back into the bike and see what happens.
 

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1) Raise that float level 3mm higher. It sounds like the float level is too low. You are running out of fuel.

2) Get a new, or clean the old, idle or pilot jet (whatever it is called on a Kenhin)

3) Get a couple of plugs that are a hotter heat range, I would start with 2 ranges hotter, B6ES
you will not hurt a thing, but it will at least eliminate fouling from the equation. Remember the plug should be white, or a shade
of white, Not black, or oil fouled. If the plug is oil fouled then a hotter one will alleviate that. If it is black - too much fuel.

When you get the bike to run good (and you tell us) then fool with finding the correct heat range for your riding style.

By the way, In NGK that would be a lower number,
When I fool with adjusting the idle circuit, I use a B5ES,orB6ES, instead of the recommended B8ES (which is way too cold anyway for my engine) Play with the heat range till you get the plug to look the way it should.
-Wet/oil fouled plugs needs hotter heat range.
-Scorched white needs a cooler plug.
Combustion chamber temperature determines necessary spark plug heat range.
 

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Discussion Starter #37
IT'S ALIVE!!!!

It fired right up today only took three kicks and it stayed running. Still won't idle with out some one just resting thumb on the throttle. That could be the because of the slop in the in the thumb throttle or from what I have found on the web that could be the all famous trait of the keihin PJ carb. Which ever it is I think I can get it to idle with a little more tweaking here and there.

The good news is it runs; and my step son and I believe it runs better than it ever has since I've owned it.
 

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Awesome !! it's prob. gonna need some more carb tweaking. Or you might have an air leak, might be the reed cage gasket...from pulling it off a couple of times.

Take a can of Carb. cleaner and mist it around the carb boot, reed set-up and see if the idle changes. but you want to make sure you don't get the spray near or on the air filter/air box as it will pick up the vapors and throw you a curve ball with the idle change.

If it is lean and there is a vacuum leak, spraying around the intake, will show a leak because the idle will change while spraying.

Give that a shot once you get the carb float and pilot jet set-up. You might hafta bump the idle up on the carb to keep it running while spraying around the reed boot.

Joe
 

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Discussion Starter #39
Ok, for mgty3whlr what did it take to get it running again.

1) Replace the wiring harness so I had something that wasn't hacked up to work with.
2) Fix the partly broken wires on the stator and clean the stator ( it looked like it had been sitting out in the elements for years ) so that I had reliable spark.
3) Readjust the floats, ignoring the book and all listed measurement. Went with the tried and true method of float seem level with the float bowl lip/base.
4) Apparently one of the most important things was figure out the setting for the starter/choke valve on a keihin PJ carb ( which is as close to exactly in the middle of the threads as possible. Just in case some one else needs know).
5) Joining this web site to have people to shoot ideas back and forth with. Really wish I hadn't wasted my time joining 3wheelerworld. As a matter of fact I still haven't been approved to post there yet and I joined them a day before joining everything2stroke.
 

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Discussion Starter #40
Yep, will prob do that in the next couple of days, but as for today I think it time just to relax and take a break from motorcycles for the rest of the day.
 
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