View Full Version : Misfire and popping on Trail 650

05-10-2007, 08:11 AM
I have just bought a Trail 650 and it is due for its first service next Monday. The trouble is that when I am in a low gear on the over run with throttle off I get a considerable amount of popping and misfiring. Hopefully the dealer will be able to fix this but in order to appear to be at least slightly knowledgeable in front of the dealer could anybody tell me what the trouble may be. Any help would be greatly appreciated.

05-10-2007, 08:29 AM
My bike does this too. If i'm going down a hill, say, in 3rd gear at 20mph and off the throttle it pops from the exhaust. I kinda like it!!:burnout:

05-11-2007, 04:25 AM
Yeah, AFAIK, all Pegaso's do that, mine included, so it seems to be normal.

05-11-2007, 05:01 AM
Thanks for your replies Rodrigo and G-Man, nice to know that I am not alone.
I'll be more polite to the dealer now!

05-13-2007, 03:27 AM
My does that too, but lately it's really loud .... :bond: .... I believe the air filter must be replaced or cleaned....

05-13-2007, 07:44 AM
Mine does it, I kinda like it too!!

06-13-2007, 05:13 AM
My trial does the same. The popping from the exhaust is fine (I quite like the sound as well), but its the missfire/coughing that bothers me. I just had the first service, hoping this would clear it up, but no change at all. Surely the missfire/coughing business is not normal? Its only at lower throttle openings/revs and spoils an otherwise great engine. Any comments very welcome.

06-13-2007, 06:54 AM
The coughing you mention is well know on another forum, for XT660X and XT660R's. The forum is called
Look out for the `Kev mod' This involves changing the CO2 and other settings using the bikes on board computer.
I will post the code to enable you to get to these settings tonight :)
Saying that I actually live with mine as it is at the moment.


06-13-2007, 08:31 AM
Thanks Keith you're a star. I changed the tick-over so that it was a little faster and I think that may have helped.

06-13-2007, 01:32 PM
According to a guy who was following me t'other day it spits out unburnt fuel when popping too, just need an igniter on the back of the pipe then!!!

06-13-2007, 01:48 PM
Try this link for the KEV MOD
Again this is meant for the XT660 Yam, but as its the same motor it should work OK.
Code is 25973
There is a link here somewhere which gets you a PDF copy of eh aprilia workshop manual


06-13-2007, 04:26 PM
Looks interesting Keith, but I think I had better wait until the warantee has expired before fitting (he sells a complete kit as well on Ebay). Whilst on the subject have you any idea what the ideal CO setting is? Mine has been set at 10 by the dealer.

06-16-2007, 03:49 AM
Since putting the cans on and doing the air box mod my bike has transformed. It's loads smoother on light throttle. It never was really jerky and snatchy like some of the bikes are (from what i've read on here). My Co setting was at 15 when i checked it and coz the bike went ok i just left it alone.

As for the popping now the cans are on. On light throttle, just enough to be holding it on neutral throttle when sitting at a constant 40mph say it's great. Lets out little pops and bangs then every so often BANG, it lets out a beauty!! Or if i accellerate way quite hard up through 1st, 2nd, 3rd but short shift up at 4000rpm, when i roll off it always bangs or cracks really loud.

06-16-2007, 07:16 AM
I have been looking at what you guys have said about the airbox mod, and I will do this for sure - just for the better sound if nothing else!!! Whether it helps with the "coughing" remains to be seen. When you talk about the Co settings, I guess this is something you can change yourself only the strada - not the trial?

06-16-2007, 08:02 AM
I'm sure it's adjustable on both bikes. It's in the setting menu. You put in a code to to access that setting. Check through past posts. The code's been put on here a few times and there are a good few threads on CO.

It's the blanking of the box part of the mod that makes the biggest difference. Cutting the intake pipe shorter, or removing it totally didn't do too much. I removed mine, but i'm gonna put it back in (i've shortened it a good bit) to quieten it down a tad.

06-26-2007, 06:04 AM
Thanks G-man - what a helpful bunch of guys you are!


07-02-2007, 07:02 AM
Hmmmm, moved the CO settings from 15 to 20 (which seems to be the popular choice here), but to be honest, I don't think it made a heap of difference. I have a almost run the bike in now, so will take her for a thrash to clear her lungs soon, then off with the resonator box!