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R6 First Gen stalls on idle

5K views 13 replies 4 participants last post by  SMGhost 
#1 ·
Hi,

so I've recently bought an old r6, but in really good condition visually (no scratches). Owner mentioned some problems with engine, but said most likely carburetor related and should be a quick fix. Unfortunately...

When I first got it. It would barely start. You'd have to rev it immediately on start, because it would just stall otherwise and would be PITA to start again. It also had bad performance.

So at first mechanic checked the compression in the cylinders and found that one cylinder was broken. I had to buy a used engine to replace it. It did solve the problem with performance, but it would still stall on low rpm's and when started again would barely run ~2k rpm's on full throttle for a period of ~10 minutes until finally starting to go up.

Then mechanic found that one membrane on cylinder was damaged. So we bought a used carburetor with membrane from same motorcycle we bought the engine from. After replacement. Still same problem, stalls on low rpm's, but atleast starts again much faster.

This was supposed to be a cheap bike for the summer, but half the summer it waited for the repairs, I've spent so much money on it, that there's no way I can sell it now and I'm still left with non fully functional motorcycle.

I'm not really good with mechanics, but maybe anyone of you had seen or experienced a similar problem and have suggestions what might be wrong and what to check (and how) first?

Sorry for the long post.

TL;DR; Engine stalls on low rpm, don't know what's wrong, need help :)
 
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#3 ·
Thanks for your reply mavrikno

Apparently mechanic did clean the carbs and synced the throttles. He said that he checked with idle screw, which is ok and if it's a coil problem, the engine would have problems on higher rpm's, which it doesn't. We bought new sparks and that didn't helped.

I'm not sure what and where jets are. Is there some easy way that I can check them myself?
 
#5 ·
So I asked the mechanic and he said that jets are ok. The bike revs ok, but yeah if I let it idle, sometimes it dies immediately, sometimes after a couple seconds, few times even a minute or so.

There are few other indications:
- If I stop and the bike still hasn't died on idle and I turn that lever on left handle bar, that is supposed to up rpm's, motorcycle dies.
- After bike has stayed for a while, I turn it on and put my hand behind exhaust, I can see black particles pilling up.

Could one of these issues indicate fuel pump problem?
 
#7 · (Edited)
Wouldn't increasing idle cause a lot more of fuel consumption? I know the screw on the side, but where are the pilot screws?

I'll try to make a video in few days time, to show the problem.

For now, mechanic checked fuel pump ant it was showing 35 kPa pressure, so we had it lowered down to ~15kPa. After that we could see some improvement. Engine started to idle for longer and for the first time I was able to stop on neutral near a traffic light. Unfortunately it still dies after driving some time and leaving it on neutral to idle. It also dies if I keep it on idle and pull the choke lever.

Motorcycle also has an aftermarket exhaust. Could this be an issue?
 
#9 · (Edited)
@yamahacrazy, yeah, this does seem strange to me too. I no longer trust the mechanic. Will probably try to get carb sync tool and do the syncing myself:)

So I made a video that shows the problem at the end: https://www.youtube.com/watch?v=I0mv32cc7YQ

Development so far. With idle screw I was able to set netural at ~1000-1500 rpm's so it stays there and I'm able to stop on neutral. Current issue I experience is that if I reach more than 90 degrees celsius (>200 fahrenheit), the bike would stall again and I would have some more trouble trying to start it up. So it seems the temperature indicates some sort of trouble.

I bought fuel system cleaner and filled it in this morning in hopes situation would get better.

I've currently think that problem might be related to vapor lock, breather hose or fuel pump itself (which I'm planning to buy used from other bike).

Is my thinking rational?:)
 
#11 ·
Ok, I want to say you definitely need to sync your carbs.
That should help start up and Idle.
Also, have you tried using the choke to start the bike? That should help with initial start up.
As for the over heating, you should check to see:
1. You have enough coolant.
2. Thermostat is opening.
I hope it has never gotten too hot... That can cause a lot more problems...
 
#12 ·
@mavrikno13764, thanks for the suggestions. I'll try getting ahold of carb sync tool and look what's the situation myself. I'll try figuring out how to check coolant and thermostat and do that too. It didn't get much hotter that I showed and today was unusually hot day in my country, but hey, now I know there's a fan somewhere :D I did tried starting with choke when it's cold and it did start immediately. So now my problem seems to be with overheating and stalling idle when engine is hot. Hope to fix this soon, apart from all the problems, it's a really nice bike :)
 
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