Ucvmn
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Hi, this doesn’t seem to end, hahaha. Here are the pictures. I think the bike is running rich. I don’t know why.
The bike has a large fuel hose and fuel filter, spark plugs changed 3 months ago, coils tested, stator tested?, plug caps tested, new air filter, new oil and oil filter, carbs with new jets and cleaned, and no vacuum leaks…
At low to mid rpm, it has plenty of power, but when it gets to high rpm, the bike becomes jerky.
Hi, this doesn’t seem to end, hahaha. Here are the pictures. I think the bike is running rich. I don’t know why.
The bike has a large fuel hose and fuel filter, spark plugs changed 3 months ago, coils tested, stator tested?, plug caps tested, new air filter, new oil and oil filter, carbs with new jets and cleaned, and no vacuum leaks…
At low to mid rpm, it has plenty of power, but when it gets to high rpm, the bike becomes jerky.
Ladies and gentlemen, I am pleased to inform you that the problem is officially resolved.
I cut the snorkel from the air filter, and now the bike runs perfectly. It just needed a bit more air. Thanks to everyone for your help. Now, I just need to fix the dashboard.
According to my wiring diagram, the green wire connects the CDI with the pickup coil. I don’t think the bike could run at all without that connection.
Do the front and rear spark plugs have the same color? If yes, and they are sooty, you can remove the air filter to conduct a quick test run to see if the problem is a rich running condition (which is the case for me).
@laserbeam, did you properly tighten the wire to the HT caps? You need to twist it clockwise to tighten it.
Also, you can test the HT caps with a multimeter, as I did in this thread.
I’m happy with that top speed, especially since the engine runs smoothly at high RPM.
Now, since I shouldn’t use the bike without the air filter, I will try a K&N to see if it does not reduce airflow too much. So, the engine running rich is due to the 125cc intake, isn’t it? Because everything else is “stock” for a 250cc engine (main jets and pilot jets). Well, the exhaust headers and muffler are the 125cc ones.
Another problem that I have to solve is the tachometer. I will see what I can do about that.
I think we are close to making the bike run perfectly. Thank you very much for your help.
In Spain, we have a product called “Tankerite” and also “Restom”.
Another option is to use phosphoric acid; you have to mix it with water. I don’t remember the proportion. When there’s no oxide left, you have to clean the tank to ensure no phosphoric acid is left, and then conclude with a hydrocarbon-resistant epoxy resin.
I have news. Today, I tried testing the motorcycle without the air filter, and without it, there’s plenty of power at high RPM. I reached 140 km/h smoothly.
Does this have something to do with the airbox or something? Do 250cc motorcycles have a different airbox than the 125cc ones?
P.S.: The air filter isn’t old, and I’ve only used it for a few kilometers.
The needles are in the middle position and the main jets are 92.5 – 95, pilot jets 20 2.5 turns. Air filter is almost new, i bought it from here. Is the 125 – 250 air filter different?
Hi, this doesn’t seem to end, hahaha. Here are the pictures. I think the bike is running rich. I don’t know why.
The bike has a large fuel hose and fuel filter, spark plugs changed 3 months ago, coils tested, stator tested?, plug caps tested, new air filter, new oil and oil filter, carbs with new jets and cleaned, and no vacuum leaks…
At low to mid rpm, it has plenty of power, but when it gets to high rpm, the bike becomes jerky.
77 mph was the top speed of the 125cc engine (under the same road conditions, wind, etc…).
I will try to remove the spark plugs to upload a photo. Also, I will make a video of the idle. If I give it full throttle and release in neutral, the RPM hangs above idle and then “stabilizes”. If I give it a little throttle and release, the RPM drops below idle and then “stabilizes”.
What kind of signal does the dashboard receive? Can I replicate that with an Arduino or something similar to test the dashboard?
Hi, the bike was stored for 2 months. I was very busy due to work and study.
This week, I had a little time to change the chain and sprockets to the 250cc ones and tested the wiring from the CDI to the front coil and from the front coil to the dashboard (up to the blue connector). The tester gave me a reading of 0.1 ohms. However, the tachometer still doesn’t work.
I tested the bike and it still jerks at full throttle and top speed (only reaching 123 km/h). If I release the throttle slightly, say from 100% to 95%, the bike gains a little more power and reaches 127 km/h. The idle remains unstable.
I forgot to remove the spark plugs and take a photo.
Also, I tested the stator:
Yellow wires in all combinations: 0.6 ohms.
Blue and green wire: 133.3 ohms.
I had a similar problem a while ago. The manual said 17 mm, but the bike stopped running.
In this forum, Marcel told me to set it at 7 mm, and he was right. The bike came back to life.
PS: my engine was a 250cc
Okay, Try this… Take out the spark plugs and show me ? Are you also using standard CR8E ? (I hope so) Next , remove dashboard ==> Remove fairings ==> Remove tank ==> Follow the “BLACK & YELLOW” wire from dash board to front coil = check for any ohms It should go from 0 omhs to infinity 9999999999 ohms = If it stays zero, harness is broken somewhere and dash board is not able to read signal from front coil. Also check black yellow wire from front coil to rear CDI unit = check for circuit is complete with your meter ? When your bike is running =-==> Check under bike for “sparks” escaping the ht wires on the coil (coil damage) Soon = we may need to replace your stator and regulator again , but i cannot remember if i send you Stator & Regulator for you 125cc a long time ago and you need new parts for a 250cc now ?
Yes, I’m using CR8E spark plugs.
A few weeks ago, I bought a regulator from you along with other things, but not a stator.
Today I went out to test the bike, and I don’t know, the fuel filter seems to fill up, and it empties regardless of the circumstances. The idle is also very bad. Sometimes when I come to a stop, the bike stalls. And to top it off, the tachometer only shows 0, I’ve lost the tachometer.
The video:
If the revs did not change. That is good. Make sure the airbox is not leaking on top of the carbs.
I come with good news and bad news.
The bike has started, you were right, 17 mm isn’t correct. When I opened the carburetors, there was no gasoline at all, so it’s no wonder the bike wouldn’t start. I set the floats to 7 mm and checked all the vacuum lines again, and they’re not leaking anything, absolutely nothing. I also cleaned the carburetors as you suggested.
I cleaned the spark plugs as much as I could and checked the ohms with a tester for the black plug cap, HT wire, and the terminal pin.
Here are the values:
(BLACK PLUG CAP) R – 8.76K Ohm; F – 9.58K Ohm.
(HT WIRE – GROUND) R – 6.05K Ohm; F – 5.54K Ohm.
(TERMINAL PIN – GROUND) R – 0.2 Ohm; F – 0.3 Ohm.
I started the bike and it felt weird, the tachometer was acting strangely and stayed at 5000 rpm even though the bike was idling. I rode it for a while, then stopped to check what was happening: I touched the rear exhaust manifold, and it was hot, but the front one was cold. At that moment, I remembered that I hadn’t connected the terminal pin of the front cylinder coil, so I connected it on the street by reaching between the radiator and the cylinder, and the bike started running smoothly again. However, the tachometer still didn’t work properly. I think I might have damaged the tachometer because it still does the initial check, but when I start it, it doesn’t show the rpm, it stays at 0.
The idle is bad (like before), and I still don’t have power at high RPMs. It doesn’t go over 110 km/h at full throttle in fifth gear (it still has the transmission from the 125cc). The fuel filter is still almost empty.
I don’t know what else I can do. Should I give up?
PS: I’m going to attach a video that I recorded before this adventure so you can see what the idle of the bike looks like.
Alright, tomorrow I’ll set the float height to 7 mm and give the carburetors a thorough cleaning.
I’ve installed size 20 pilot jets and 92.5 + 95 main jets on the carburetors, yes. I’ve also replaced the intake manifold o-rings (I bought them from you along with other things, and I’m happy with the purchase, thank you).
The intake manifolds have cracks on the outside, but I don’t see any cracks on the inside. I’ve also conducted a test by spraying brake cleaner on the intake manifolds while the bike is idling, and the idle didn’t change. Is this a reliable test?
Thank you very much for your help.
I assume as it’s a 250efi engine & yours was a carb bikes your using the carbs from the 125?
Check your float height , after every ride on my carb bike = the big filter is usually full. Or your float needles are jamming causing some internal engine slow leak of fuel in to cylinders = Your manifolds will be “wet” inside as a hint. Also open “OIL FILLER CAP” ( on the clutch cover) and sniff inside hard. ==> If you smell fuel => change oil before riding again. Can you also clean your spark plugs , go for a short ride => wait to cool down => Take pictures of spark plugs so we can see the mixture ? Simon also has the EFi 250 motor, he knows if the fuel system is too rich or too lean,. Pictures of spark plugs will help OR It could be electrical! (Coils? Stator unit?) (Since stator is also part of ignition system = high revs , more pulses to cdi , cdi talks to coils to spark the plugs. , dashboard tells you how much RPM engine is doing
Today I came back from the garage feeling defeated. The bike won’t start anymore.
Firstly, I removed the spark plugs, and they were black, indicating that the engine might have been running rich.
- I checked the float needle, and they seemed fine.
- The float height was very off. They were at 8 mm and should be at 17 mm according to the manual. I adjusted them as the manual instructed, but I didn’t check the fuel height. Is it important?
After all that, I tried to start the bike, but it wouldn’t start. When I engaged the starter, it made an attempt to start but didn’t go any further. During the starting attempt, the fuel filter only filled to about 5%.
Could this be due to the starter jet, main air jet, and the 125 slides? Because according to the manual, they are different between the 125cc and 250cc models.
I’m thinking of buying second-hand carburetors from a 250cc. I don’t know what to do.
P.S.: I opened the oil filler cap and smelled it, but it didn’t smell like gasoline.
