Hey guys, my first post here. I just bought a Hyper 939 and rode it 1300kms home from the North of Thailand. The bike is incredible to ride, but it seems the throttle is insanely sensitive and I have a bad misfire especially around 4-5000 RPM that gets progressively worse the longer I ride it. Got to the point where I was cruising at 100kph and it just spits a flame every now and again. I changed the standard exhaust for a race pipe, it's just made it more prominent. Am I missing something? I was wondering if it was the fuelling, bit it was doing this when it was completely standard. Nothing else has been fiddled with. Any ideas would be greatly appreciated. Cheers
Welcome and enjoy. I own a Hyper 821 the throttle is probably the same as yours but you get used to it after a while. Can't help you with misfire never experienced that with mine. Changing the pipe will probably have aggravated things as you would typically need the fueling changed with the pipe, but that doesn't explain the problem you had to start with. Probably worth a visit to the dealer if that isn't too far from you... Sorry can't be of more help. Be careful out there.
Hey mate, yes the bike is awesome, but I'm sure I've got some fuelling issues somewhere? The throttle is very twitchy but the more I ride it the more I'm going to get used to it. I'm wondering if it's the air temperature sensor or something, it was bad with the standard exhaust, and I've only put a slip on pipe, so no dramatic change really...
So I've just ordered a Booster plug, let's see if that helps things at all, definitely can't do any harm from what I 've read.
I looked at a booster plug a year or so ago, but in February last year when I took the motard for its service they updated the ECU and that smoothed out the fueling to the extent that decided to give the booster plug a miss In my view the 'science' behind the booster plug is sound and it certainly can't do any harm. Do let me know how that works for you.
Booster plug should be here today or tomorrow, also ordered the SC project S1 with servo flap delete, I think that should change the low speed jitters too, stunning bike I must want it to run smoother.
Ok, go out and order a Booster plug immediately. What a huge difference it makes. So much better low speed control. I still have some misfire at 4-5000rpm though, but it's much much better. Fitted the SC-1, pretty anti social to be fair, but I live in Thailand so it doesn't matter. Now waiting for the servo delete plug, then onto air filter and fuel mapping.
So, quick update, I've now ordered the standard rear shock, as mine is too low can you believe it. Also have a K&N air filter coming, along with a Star Ace carbon racing air box modification. Should be looking at a 10hp increase with all the mods done, and also a much much smoother power delivery and no misfire at all. Let's see how the next 10 days go.?...
I got the SC can from the importer, but I might sell it and buy the high level one. My girl is pretty annoyed with it haha. The Booster Plug was straight from Denmark, fastest delivery I've ever seen. Awesome upgrade, forget about a power commander you won't need it.
I also installed a booster plug last year, with the intention of resolving a lean spot around 6K - 7K rippems there was no immediately noticable effect at this rev range, however as time went on the lean spot has become noticably less, even at constant revs, 85mph, cruising on m-ways, where i used to noticed most. Not sure i'd describe this as mis-firing though, more like power surging, almost like it was being starved of fuel, which it may well be, as part of the closed loop O2 sensor emisions thing (no idea, really) perhaps the most notable effect, as mentioned previously in this thread, was the behaviour at low revs, MUCH smoother, easier to manage round town and launching out of lower speed corners. I always found the throttle to be a bit binary, on/off, with the booster plug, things are less jerky all round. one downside though, the plug absolutely batters the MPGs, side effect of running rich i suppose. fuel light now comes on anywhere between 70-90 miles depending on the enthusiasm of the ride
I've found that in neutral my engine warning light comes on at 4500rpm and it won't actually rev any higher. When riding it'll go way past that, but in neutral, it just sounds like it's hitting a limited...
