Author Topic: No power, stuttering, backfiring after 5 km ride (Read 4375 times)

devilears · « **on:** September 30, 2006, 02:32:12 PM »

I'm having serious problems. I recently discovered that my bike loses power if I open the throttle fully above 8k rpm in the higher gears after a lot of trying stuff trying to figure out what is wrong, I discovered that my fuel mixture is too rich due to a too big main jet. Or at least that`s what I think. Unfortunately I haven't gotten time to fix that. But as I was driving home today my bike suddenly started to lose all power and started backfiring and just stuttering along. It sounded like it was only running on two cylinders and wouldn`t do anything. The bike then died when I pulled the clutch and wouldn`t start again. Luckily I was going downhill and I tried runstarting the bike, still nothing. After about the tenth or fifteenth try it started again, ran fine for about 100 metres and started losing power again. Luckily I was almost home and just made it before the bike died again. Is this somehow linked to my rich condition or is something else causing this problem? It sounds like maybe the bike isflooding, and that`s why I'm losing power, so it could be because I'm running rich. But I can`t understand why it only started doing this now. It`s been almost two/three weeks that I've been riding with it like this without having any problems like this. So far it has only been the power loss in high rpm in high gears. Now suddenly this happens.

What do you guys think? Any help would be appreciated.

Thanks

sclay115 · « **Reply #1 on:** September 30, 2006, 05:25:38 PM »

While not a fueling problem, my bike had similar starting/sputtering issues, turned out to be the spark plug wires. I ran through the entire machine to find that my wires weren't pressed into my caps fully in the 2&3 cylinders. Causing it to run ok at times, but when called upon for higher loads, it would miss like crazy. So like I mentioned, not related to fuel, but something to look into. Especially since you mentioned that it was running perfect before and all of a sudden went to heck. Fueling issues to me seem to be apparent from the get go, not a gradually increasing problem. At least from my experience as of late.

Steve

andrewsw · « **Reply #2 on:** September 30, 2006, 06:18:39 PM »

my bet is you are flooding due to either 1) a stuck float (not likely), 2) a bit of dirt stuck in a float needle valve (highly likely), or 3) bad or improperly seated o-rings in the float assembly (common B4 problem).

You've been mucking with the carbs, right? that's sure to cause these problems if you aren't careful. Pull the carbs, pull the float bowls, pull all the floats, replace the o-rings since you're in there (search this site for links to the proper rings), blow out the float valves, put the floats back in properly, adjust the float level since you're there. You've already got 'em open so you might as well put in the right main jets, and put it all back together.

Have you been running on reserve? sometimes that'll suck in the muck from the tank, so check that as an option too.

This used to be a common occurence on my '91 as the tank was rusting inside. I had to pull the carbs every week or so to fix it...

my .02, wait for others to chime in as well.

devilears · « **Reply #3 on:** September 30, 2006, 07:22:37 PM »

Thanks guys. I`ll try that, unfortunately I'm a bit busy at the moment, work and exams all at the same time. Will do it as soon as I`ve got time. Just have to try and see where I will be able to get the o-rings and the jets cause I live in South Africa and all the b4`s here are grey imports. Luckily there`s a lot of them around so it shouldn't be a problem to get the parts. If anybody else has any other ideas or agree with the above said please let me know. All help is much appreciated!!!

interfuse · « **Reply #4 on:** October 01, 2006, 01:26:43 AM »

1. Richness

If it's a richness problem, pull the air filter and see if the bike runs better. If the problem goes away with the air filter pulled get your bike rejetted by someone who knows how. If it's still acting up see 2.

2. Electrical

Figure out what cylinders are firing and what ones aren't (lightly touch the headers and guage what ones are the hotest... obviously be careful and don't burn yourself, and if you do don't blame me!). If you're having problems with 1 & 4 or 2 & 3 then its mostly likely an electrical problem with one of your coils.

It could be that the wires going to one of your coils are intermittently losing connection. Try jiggling the black and orange wires going to the coils, if it starts runnng good again after do that you know that's your problem.

PitterB4 · « **Reply #5 on:** October 01, 2006, 08:52:36 AM »

I'm going to bet on electrical. First, a spray bottle of water works better than fingers for testing the pipes.

Like Interfuse said, if it's cylinders on the same coil, check the wires that feed the coils. They're not very sophisticated connections and can come loose.

devilears · « **Reply #6 on:** October 01, 2006, 12:04:16 PM »

So I tried starting it again today, nothing!

It cranks and every now and then it sounds like something wants to happen, but to no avail, nothing happens. Motor is turning and that`s all, After trying for a while I felt the exhaust header pipes and only one of them (nr.2) is starting to get hot, the rest are still ice cold. So I guess it can't be the coils or wiring to the coils beacuse then either 2 and 3 must be hot, and 1 and 4 must be cold or vice versa? Gues I'll just have to pull the carbs, get them cleaned, rejetted and replace the o-rings. Am I correct or is there something I`m overlooking. Thanks for all the help!

devilears · « **Reply #7 on:** October 01, 2006, 04:22:00 PM »

Update on my problem. I tried starting it again, had the same problem as last time. Except this time pipes from 1 and 2 started to get hot. Tried using the choke, sounded like it wanted to start but still nothing(usually it starts easily without the choke). I then picked the bike up from it`s side stand and tried it again with the choke, now pipes from 1,2 and 3 started getting hot. Eventually it started, but only running on 3 cylinders, number 4 was still cold. After letting it run a while it started sounding better and number 4 also started getting hot and it was running fine. Let it run for about 2-3 minutes without any problems, revved it up a couple of times, it kept running without any problems. Now this is very strange to me, cause if it was flooded wouldn`t using the choke make matters worse? And while it was on the side stand only pipes from 1 and 2 would get hot, the side that leans towards the bottom, thus according to me the side that would be more prone to flooding because its lower down, and only when I picked the bike up did no. 3 also start getting hot, and when I started leaning the bike towards the right, leaning number 4 to the bottom it also started getting hot and firing. Anybody got any ideas what this means or what could be causing this?

This problem has really got me baffled now. I just don't know what to do anymore

Thanks for all the help so far. Just hope I can figure this thing out.

interfuse · « **Reply #8 on:** October 01, 2006, 04:38:36 PM »

Okay, sounds like you're having fuel delivery problems. Things to check:

1. It could be as simple as "tank lock" or "vapour lock" did you recently fill the fuel tank up to the max? Google it, you'll get a better explaination then I could write.
2. Fuel tap vacuum line - that it's connected tightly with no leaks. -- to test this you can turn the bike on prime, if it runs on prime then you've got a problem with the vacuum line)
3. Fuel filter, not clogged (there's one in the tank, and possibly and inline filter if someone installed one)