IBA4rt

3500 ML7 013

The engine is great, and the cycle part too, my intention was to leave both motorcycles, the 4rt and the 300 GP, but the boxes are terrible, they always break no matter what and it is rubbish to have to open the entire engine for a design ****ty. I'm already psyched up so I rebuild, and in the process I put in the piston and all the bearings and seals of the engine, the primary shaft and the two broken sprockets.

Yes I know the gas gas. I have a 2014 racing that I repaired last year and I only had to change the ****ty half moon bearings. everything else was perfect. In my 2020 GP which I bought new and I have changed the oil (Nils clutch trial) every three months since I bought it, I have found the unpleasant surprise of having a broken pinion, and the primary one damaged, with some notches made possibly by the grind an idler, since an idler has disappeared from that bearing. hence my question. These bikes are getting worse, the materials are horrible. I will fix it and sell it since I have a Honda 4rt 301 that I bought precisely to escape these problems. What I did not expect is to have to undertake this repair on a motorcycle that is 4 years old and well maintained from minute 1.

Well, after detecting a piece of metal on the magnet of my 2020 txt 300 gp, I opened the motorcycle and the result is a broken primary shaft sprocket. The half-moon needle bearings were beginning to break and have produced some very slight marks on the inside of another pinion and the primary shaft itself. The truth is that it seems like garbage design and bad materials. My question is, will changing just the bearings be enough or since there are brands, should I replace the primary shaft and the two pinions?

Well, problem solved. After going crazy checking a thousand things, the fault was in the coil. First I thought it was the temperature sensor but I had made the measurement incorrectly, in ohms, when the parameters of this sensor are measured in Kiloomhios. After checking that this sensor was ok, I focused on the coil, it gave a high resistance at 20 degrees, 42 ohms. I went to my Honda dealer and the bike is new, they gave me the new coil, I mounted it and after two days of testing in different conditions the bike is perfect, now idling stable without backfires and it no longer turns off. I hope my little ordeal can help someone in the future. By the way, I love the motorcycle, it's a ****ing tractor 😁

On the other hand, I wonder how a defective sensor or installation can be on a completely new motorcycle. 😤🥴

Well, although I haven't tried it yet, I have no words to thank you for the approach you have given me. Apart from having all the logic, I just picked up the manual and it specifies how to check the sensor from the control unit connector. I have tested all the parameters in this panel with a tester and more or less all of them correspond to the parameters except the temperature sensor that, by placing the tester on the pins indicated on the connector, does not return any data, there is no resistance or continuity. I have checked the sensor connector itself and everything looks normal, so one of two, either I have a sensor failure or I have a failure in the electrical installation since the formal way to check it is not in the sensor (from which, by the way, three cables come out, no only two).

Now I understand it, because it makes perfect sense. I understand that the sensor (since I don't have another one to test) if I measure the resistance as specified in the manual, I can know if it is defective, right? Can you think of another test to find out if that is the fault without changing the sensor for another one? thank you very much for helping me.

good morning. thanks for answering. I don't understand what you mean when you say that it acts as a choke. Could you expand a little more information? When the motorcycle makes these explosions and the idle fails, I notice a lot of gasoline smell, so I don't understand what you mean by that choke function of the temperature sensor, but it could be related since when the motorcycle fails the common pattern is that the fan never stops and the engine temperature, however, is normal because I have measured it. I mean there is no over temperature.

I recovered the post although I considered my problem solved after changing the fuel, which I had published in another thread, I have managed to isolate it and the closest thing I have found is what is proposed in this thread. My 301 starts well when cold and starts well when hot. After doing several tests, regulating idle speed, restarting the ecu, checking possible engine air intakes, air filter... I have managed to detect the following: I start the bike and after having adjusted the idle speed to around 1800 rpm, I let the bike warm up at idle until the first fan starts. I start using the motorcycle and it runs perfectly, the fan activates in alternating cycles with rest. But always, after 30 minutes of using the motorcycle, the revolutions begin to drop and fluctuate when you release the gas. When this happens, it lets out a sputter through the exhaust as if there were an ignition problem. If it accelerates it works perfectly until you release the gas and this malfunction begins. When it gets to this point it smells a lot like gasoline and the fan never stops. If you stop the engine, it starts fine again but starts failing again. The engine is allowed to cool for at least an hour and both the engine and the fan return to normal operation until about 20 or 30 minutes pass again, at which point it begins to fail again. I don't understand what's happening. I think that something electrical fails when it reaches a high enough temperature but I can't detect what it is.

Exactly the same thing happens to me, I have a friend with a 2017 300 RR who barely maintains it, he doesn't take much care of the bike and I think he has never adjusted the idle speed in his life and the bike runs like a clock and at the lowest idle speed. than mine. These 301s from what I see, for whatever reason, which I suppose has to do with the 3-segment piston and increased compression, are much more critical.

I live in the Canary Islands and here there are still about 25 or 26 degrees during the day, so I understand that the fan should work harder. Coming from 2t, I thought it was excessive until I checked the engine temperature. My bike came limited and when I put the exhaust open with the injection body that it had originally, the P61, the bike worked very poorly, it stopped and it smelled like gasoline. I have mounted the P71 body, which is the one that Honda indicates to delimit the 301 2024. The bike with this ECU was already working well but I suppose that the spark plug, as I posted in another thread, was already charred from running it with the other ECU. I suppose it was a combination of bad gasoline and a damaged spark plug. With the tank with BP 98 and a new spark plug, it works perfectly and the fan cycles are now more regular. I suppose that when the temperature drops more, here it doesn't drop below 15 degrees, the fan will act less.

hahahaha here in Spain there are many gas stations from different networks, and no matter how much they say 98 octane, you can see that they are of poor quality. They have recommended BP or Repsol to me, which come from the same place as they have informed me. It seems that at the moment everything is requested.

Well, it seems that after changing the fuel as recommended, for 98 BP fuel, the motorcycle runs better, maintains a stable idle and now the fan cycles are more regular, the electric fan stops more times and the work cycles are more shorts. From what I see, this bike is very critical of gasoline and today there are many gas stations with ****ty and bad fuel. From now on, only BP. I have measured the temperature with a laser and the cylinder head never exceeds 65 degrees, the cylinder reaches 70 and the water pump cover is above 60 or 65 degrees, as is the radiator. I made these measurements with at least 10 fan cycles so it seems that everything is correct. Anyway, I'm going to use Fulch Silkolene Mac Cool coolant, which I always use on my motorcycles and it works better.

Did your spark plug look like this when your bike wasn't working properly?

The oil level is perfect. The carbon is dry. I have changed the gasoline and left the idle screw as marked at the factory. Now it seems to keep the idle stable. Right now I don't have a tachometer to measure rpm.

thank you very much again. I'm going to do what you tell me. I will keep you informed. thank you very much again.

thanks for responding. I had read that the optimal idle speed was 1800 rpm. Right now I don't have a tachograph but I estimate that it will run around 1800 rpm but it works irregularly, on the first burst of gas it smells like gasoline and after 2 hours of use this is what the spark plug looks like. I have been told that some of the 2022 and 2023 models came with a fuel pump problem that prevented them from starting hot. There is even a scam about it. Mine starts well when cold and hot, my problem is unstable idle and backfires more when it's cold than when it's hot. I understand that your motorcycle, with the idle speed above 2000 rpm, has a stable idle speed without failures? With those revolutions don't you have the electric fan running all the time? Mine is another thing that I detect, that the fan is activated practically all the time and has very long cycles.

I return to the topic since I have a similar problem, the bike is new, 301 model 2024, delimited with a race kit with exhaust without catalyst and P71 ecu. The bike starts more or less well when cold and hot (first or second kick) but it has a hard time maintaining the idle speed, especially when cold, with irregular idling and backfiring. The operation is correct, the motorcycle runs well but when you release the gas the idle is erratic with some backfiring. It smells a lot like gasoline. I have removed the spark plug in the state that I provide in the image. totally black. I have regulated the idle speed and it regulates it regularly but it fluctuates erratically with some backfires and desynchronization of the idle speed regime. I have changed to 98 gasoline with 5 percent ethanol, there is no other in my area. any ideas?

My 301 is 2024. I know it is a trials bike. I have had several, all 2 strokes. I tried cooling it on speed 4 today to see if with air flow the fan worked less. but no, only when it is idling does it rest but in very few intervals. 90 percent the fan is working. It seems a bit excessive to me but since I have no experience with this bike I don't know if it is normal. What surprises me most is that once it starts it barely stops and the cycles are very long. is it normal?

Good night. My 301 is the first 4-stroke trial bike I have owned. I'm somewhat lost. Once the bike warms up, the electric fan starts and is on 90 percent of the time. Even on the road going in 4 speed it stays on. When I stop and the engine is idling, the fan stops for a short time and starts again. The periods are very long and continuous. is this normal? The motorcycle has the coolant level, it does not expel it and there is no high temperature in the radiator hoses but the fan is running almost all the time.

Yes, what I need is to know / investigate how I separate that 2ed part from the front installation, since visually it seems all united. In the manual it looks different, on the bike it seems like everything is the same installation. At the moment I don't know how to separate it.

Yes, the ones on the back are easy to remove, but in theory, on the front there is another installation overlapping the main one that can be dismantled. I can't tell the truth apart.

Good morning. I'm sorry if something is not understood well since you are using a translator. I wanted to ask, my 301 has come with all the electrical installation and homologation kit installed. I'm removing everything that's left over. The motorcycle comes with a lot of electrical installations and looking at the manual that was dismantled, there are two installations that I could theoretically eliminate since they are for elements of the approved version. specifically parts 28 and 29. Has anyone removed them? is it complicated? Extracting the deposit I am not able to differentiate them from the main installation.

Por si le sirve a alguien. Mi montesa 301 2024, tras montar el escape abierto va mal, huele muchísimo a gasolina y el ralenti es inestable y termina parándose. Esta moto requiere la centralita race P71. La P61 no funciona sin sonda lambda y catalizador.