I’m considering changing the standard injectors on my 748R for IWP189’s off an 848, with the objective of improving the lower rpm fuelling issues that just won’t go away. Has any other 748R owners tried this? If so, are they just plug and play, or do I need a modded eprom to compensate? Any help or advice would be gratefully received
I’ve had the bike for 15 years now and it’s always suffered with coughing and spluttering on a steady throttle and more annoyingly coughing when opening the throttle on corner exit. I had the bike to JHP many moons agoand they set it up with one of their eproms and it improved it a little, but John said back then that the injectors didn’t help in that they tend to spit the fuel as opposed to properly spraying it. I’ve faffed about with just about every eprom I can get hold of and still I have the same issues
My friends 748r was similar, we were told ‘that’s how they all are’ then my mate got motorapido to sort it out, and they managed to get it to a point where you could barely notice an issue! They struggled as they had to use an old computer and his chip for some reason didn’t want to load new tables etc so I think they had to do some other stuff. Long way of saying it can be sorted with the standard bike, but maybe need a dealer who fancies it! Wilf just admits he loves the 748r and was super geeky with it, fair play
When I had the bike to JHP that’s prety much what I was told too, they had my bike rigged up with a remote tank and showed me how the injectors didn’t properly spray the fuel which leads to pooling on the closed butterflies, John then showed me some injectors they had on a test bench that properly sprayed the fuel. He said back then that if merelli made one with the required parameters to suit the748R it would be a massive improvement. I’m going back to before the 848 was manufactured and so the IWP189 didn’t exist then. What he said has stuck lingering in my mind since, and I’m sure I’ve read that the 848 injectors will do the job. The 748R is a pig of a motor if it’s not set up properly, and getting somebody who has the ability and patience is the key to Nirvana, apart from the fuelling niggles it’s a lovely thing, especially on a good A road with long fast sweeping curves. Mine hasn’t seen much use over the last few years for various reasons, but with the state of things at present I have a little more time to play around than usual so I thought I’d ask the question
Talk to cjs in Bristol he will advise, also louigi moto are in the same building so rich might have some info too.
The injectors will go straight on and work (spray pattern appears much better), and on my bike which is fitted with R type injection system it actually idled and revved at standstill without the slight hesitation present on the standard injectors. I didn't have the time to get it set up properly so I took them back off again as the bike is only used on the track but I could see it as a worthy upgrade for a road bike. The originals do work perfectly at WOT.
That sounds promising, I haven’t actually got the injectors yet, just thought I’d try and get as much experience info first before parting with any hard earned
yeah I’ve seen it too, where the fuel basically dribbles out the injector rather than spraying, although MR did suggest getting them cleaned professionally before going down the 848 route. I think the 848 ones ultimately would be an upgrade but I’m sure there was some reason it wasn’t super simple, possibly to do with mapping, my memory fails me
Especially at 9 mins in on the double apex before the straight... I bet your injector was coughing and splitting a bit there Paul...
You can turn the tank around and refit the fuel pipes, this will allow you to run the engine and watch the injection. At idle and small throttle openings the injection spray just hits the throttle butterfly, and the fuel then runs down the inlet in large drops. I'm always amazed the engine actually runs like this. Obviously at full throttle the butterfly are edge on to the fuel and it doesn't get a chance to catch. The multi hole injectors didn't seem to do this when I experimented.
That’s exactly what John Hackett showed me many moons ago, but back then there wasn’t an alternative multi hole injector that would work on the 748R
I imagine this is why bikes like the 959 and 1299 use twin injectors as the top ones only spray on much wider opened throttles
I fitted the purple injectors to my bitza 748rs engine in my track and for a while, ran the eprom for the 50mm half system quite successfully. When I did the full monty 853 conversion, it had a Power Commander 3 to get the running absolutely right. PC3 lasted about 3 track days before developing an intermittent fault so got binned but I was lucky enough to find an eprom off this forum which suited the set up really well. I’m in the process of putting the 748R back to road trim and am planning to keep the 848 injectors with the 50mm half system. As @Phill748 says, the eprom is real old school electronics now so writing a new one is supported by a very limited number of people. Andy
