billyt Posted September 1, 2014 Report Share Posted September 1, 2014 Chaps & Chapets Can some one help me with this one? On a normal carb the idle adjustment only affects pure idle and just off the pilot jet. The questions is: on the 2014 Repsol fuel injection system, does the idle screw still act like a standard carb idle screw or does it affect the other parts of the RPM range also. In other words does opening up the idle screw let more air in at more than just low idle type RPM’s? I dont think it does but I want to get some more opinions on this!!! If it only affects idle then how do I get more air in at the higher RPM’s? Mapping? Thanks BillyT Quote Link to comment Share on other sites More sharing options...
oz thumper Posted September 1, 2014 Report Share Posted September 1, 2014 Chaps & Chapets Can some one help me with this one? On a normal carb the idle adjustment only affects pure idle and just off the pilot jet. The questions is: on the 2014 Repsol fuel injection system, does the idle screw still act like a standard carb idle screw or does it affect the other parts of the RPM range also. In other words does opening up the idle screw let more air in at more than just low idle type RPM’s? I dont think it does but I want to get some more opinions on this!!! If it only affects idle then how do I get more air in at the higher RPM’s? Mapping? Thanks BillyT Hi Billy, You are correct the idle screw on the 4RT does not change the mixture at all, idle or otherwise. It is only a throttle stop that alters the stop point on the throttle butterfly. ALL air fuel adjustment is via the ECU mapping. When you say get more air at the top end, do you mean it is too rich and you want to weaken the mixture or do you simply feel it is not revving out fully? Obvious possible causes of restricted air supply are dirty or deteriorated air filter, the foam is very fine and I think that over oiling with a tacky air filter oil may clog the foam, the book suggests only engine oil and that is all I have ever used. My speedway machines use K&N air filters that are much coarser foam and fitted with mesh pre cleanin elements these do require thetacky filter oil to work well. Quote Link to comment Share on other sites More sharing options...
mags Posted September 1, 2014 Report Share Posted September 1, 2014 Billy, You can test the topend (as far as filter oiling holding it back) with a clean but not oiled filter installed. Don't check where dusty though! If it improves its too sticky an oil, or possibly over-oiled? I'm like Oz thumper, just use mineral motor oil (10w-40) for the foam filter. How's the exhaust side of things? You have the big end cone on the muffler? I fitted a large diameter titanium header today. Well... it had a bigger bore than the stock Cota header. Don't know if it would help topend but should improve throttling up from idle. The Repsol might be fitted with a free flow exhaust compared to the one standard model's have? Mags Quote Link to comment Share on other sites More sharing options...
billyt Posted September 1, 2014 Author Report Share Posted September 1, 2014 (edited) Guys thanks for the replies. Here is my issue. I rode a trial Sunday and the bike kept stalling in the sections. I somewhat fixed that (how later). Then on up hill climbs with several rocks to climb the bike would hesitate or get all boggy. The bike was also hard to start sometimes. Caveat to the above issues are the following conditions. It was around 90F Altitude was over 8000ft No air movement as the trials was in a forested area. Dry and dusty. Dry air filter no oil on it. I turned up the idle, that some what took care of the hard starting. Turing up the idle partially took care of the stalling in the sections. The bogging down and sputtering continued on the bigger obstacles. I am now down at approximately sea level today and the bike seems fine. My hypothesis: The fuel injection just could not handle the high altitude coupled with the high temperatures no air flow and in a stagnant forest area. The air filter was somewhat clogged up but I could still see through it when held up to a light. I need more air less fuel at the higher elevations, but how? So now what? I intend to ride more of these higher altitude trials events and it will be hot dry and dusty with little to no air movement? Any suggestions? Edited September 1, 2014 by billyt Quote Link to comment Share on other sites More sharing options...
b40rt Posted September 1, 2014 Report Share Posted September 1, 2014 (edited) Post removed, to many closed minds. Edited September 2, 2014 by b40rt Quote Link to comment Share on other sites More sharing options...
jj65 Posted September 1, 2014 Report Share Posted September 1, 2014 The idle screw does exactly that, nothing else. The bike will be difficult to start if the idle is set too low. Could be a bad plug. I suggest you get a dual map throttle body with a standard set up for sea level and a second map for altitude if that's going to be a regular thing. The throttle body and map should be able to cope with variations in altitude to some degree, but 8000 ft is quite high. I would also try opening up the air vents on the rear mudguard like the factory bikes to get more airflow and use a very thin oil on the filter. Quote Link to comment Share on other sites More sharing options...
jrsunt Posted September 1, 2014 Report Share Posted September 1, 2014 (edited) To increase airflow, remove the flame retarder from the standard filter. The jitsie filter works even better. To help the bike in hot conditions we used to run a CR5EH-9 spark plug. This did help with the spluttering when it was exceptionally hot. If you want a more preventative option than a fix, go for the larger capacity radiator which keeps the overall engine temmperature down. Other than programming the throttle body, there isn't much you can do on the electrics side. Certainly worth doing the filter and plug as it plagued me doing the european rounds, although that was back on the 2005 bike, but I don't think much has changed since then. It may also be worth removing the head breather pipe from the airbox just to get that little bit extra clean air into the system. Edited September 1, 2014 by jrsunt Quote Link to comment Share on other sites More sharing options...
mags Posted September 1, 2014 Report Share Posted September 1, 2014 Billy, I have a TinyTach which is hand held, proximity tachometer for small engines. I was able to set the idle at the recommended 1800rpm by using it rather than guessing. Once set I marked the rim around the slot screw for future reference. See if you can borrow one and set idle rpm? Makes a big difference to starting even when only 100-150 low. Have a peek at www.tinytach.com if you want one for the toolbox... about $47 US Dollars. Mags Quote Link to comment Share on other sites More sharing options...
oz thumper Posted September 2, 2014 Report Share Posted September 2, 2014 Guys thanks for the replies. Here is my issue. I rode a trial Sunday and the bike kept stalling in the sections. I somewhat fixed that (how later). Then on up hill climbs with several rocks to climb the bike would hesitate or get all boggy. The bike was also hard to start sometimes. Caveat to the above issues are the following conditions. It was around 90F Altitude was over 8000ft No air movement as the trials was in a forested area. Dry and dusty. Dry air filter no oil on it. I turned up the idle, that some what took care of the hard starting. Turing up the idle partially took care of the stalling in the sections. The bogging down and sputtering continued on the bigger obstacles. I am now down at approximately sea level today and the bike seems fine. Any suggestions? Hi Billy, John probably has most overall experience with these bikes. I have not ridden at those altitudes on the 4RT's however have ridden several of our summer series trials on calm days with temperatures of 43 C (about 110F) without any similar symptoms. The slightly thinner air will reduce the cooling effect over the radiator (even electric motors are de rated above 10,000 ft due to reduced cooling efficiency), so a radiator with greater cooling area (not more coolant) will assist. However I have not noted this problem at even higher temperatures. I have also not needed to run a harder plug, but is a good idea in high temperatures. Assuming rad fan and pump is normal, I reckon number one culprit is likely to be plug however similar syptoms can be experienced with tight valve clearances and is worth a check. My old 06 became hard to start particularly when hot and was traced to tight exhaust valve clearance, correctly set an instantaneous cure. As John says a two stage map may help, however I have always had to get someone to re programme mine (single programmable throttle body) as I am not that computing savvy. Note John says that the standard mapping should be OK at those altitudes so tends to point possibly to something else not correct, Good luck Quote Link to comment Share on other sites More sharing options...
billyt Posted September 2, 2014 Author Report Share Posted September 2, 2014 (edited) Hi Guys Some more info. You can see by the attached PDF file at the bottom that the idle screw (7) is in fact a not a hard mechanical butterfly throttle body stop but rather a air by pass orifice. It affords an air adjustment from the filter side past the butter fly to the throttle body at idle. If this is true you can then assume that the idle screw definitely only adjust the idle RPM which is necessary for good starting amperage/voltage. I am using a Jitsie filter currently. The idle is sitting at 1875 RPM checked with a Snap On Automotive Digital RPM meter. John suggested running a hotter plug i.e CR5EH-9. The bike comes standard with a CR6EH-9 I will follow the advice of running one step hotter plug (#5 instead of a #6) along with trying to get more air flow into the filter box. JSR Hunt what do you mean by "It may also be worth removing the head breather pipe from the airbox just to get that little bit extra clean air into the system”. Apart from that I guess it is all in the ECU and mapping as it looks at air density, temps, altitude etc and then goes through its algorithm accordingly supplying fuel. I guess it was a perfect storm of high temps, stagnant air flow in the woods, high altitude, and dry dusty conditions. This is a direct quote out of the 2014 Montesa manual "Start Up Recommendations: If using your motorcycle at different heights, bear in mind that you must adjust the idle; otherwise you may have problems operating the vehicle”. So they want you to adjust the idle at higher altitudes, partly due to starting and idling and off idle. That coupled with my bad throttle and clutch control did not help. The bike starts okay at sea level. It is also a 2014. Could the valves need adjusted already? PGM Montesa.pdf Edited September 3, 2014 by billyt Quote Link to comment Share on other sites More sharing options...
mags Posted September 2, 2014 Report Share Posted September 2, 2014 Billy, I checked my valve clearances at 2-3 hrs use on my 2014 and they were spot on. I assume they would be need checking again in about 40 hrs? Chatting with importer here in Australia he has not seen them out from factory... highly improbable to be out at this stage but not impossible. The pipe out of the head is a crankcase scavenge/vent system AFAIK. So technically, dirty air (potentially oil misted air) gets drawn back into engine. Should not be an issue normally, as Honda engineers are pretty good! (wink) Can be an issue if rings/valve guides are worn excessively. Mags Quote Link to comment Share on other sites More sharing options...
jrsunt Posted September 2, 2014 Report Share Posted September 2, 2014 (edited) If you look on your cylinder head cover there is a breather pipe, trace it and it ends up in your airbox! Remove from airbox and blank the hole off with silicone or a bung. Put the breather pipe in your sumpguard. Its best removed from your airbox, as if you fall off and the bike continues to run whilst upside down, you will find your engine oil in your airbox. it may also be the bank angle sensor playing up, they have been problematic in the past. Edited September 2, 2014 by jrsunt Quote Link to comment Share on other sites More sharing options...
billyt Posted September 3, 2014 Author Report Share Posted September 3, 2014 (edited) BR40RT This is a fuel injected bike, there are no jets, and no traditional carb so why would we be closed minded How does changing a main jet discussion play into this scenario when there is no main jet period? Please help us understand? Edited September 3, 2014 by billyt Quote Link to comment Share on other sites More sharing options...
b40rt Posted September 3, 2014 Report Share Posted September 3, 2014 (edited) BR40RT This is a fuel injected bike, there are no jets, and no traditional carb so why would we be closed minded How does changing a main jet discussion play into this scenario when there is no main jet period? Please help us understand? Because a larger main jet ritchens the mixture, your trying to weaken it. Delivery system might be different but principal is the same.Running weak also causes the overheating you describe. Edited September 3, 2014 by b40rt Quote Link to comment Share on other sites More sharing options...
johnnyboxer Posted September 3, 2014 Report Share Posted September 3, 2014 Because a larger main jet ritchens the mixture, your trying to weaken it. Delivery system might be different but principal is the same. Running weak also causes the overheating you describe. I'm at a loss to understand that on a Fi bike Surely you have adjust mixture with a laptop to alter the mapping ? Quote Link to comment Share on other sites More sharing options...
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