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Message started by realdeal on 07/13/05 at 05:36:08

Title: Need Help - Bike wants to stall for first 10 min.
Post by realdeal on 07/13/05 at 05:36:08

First, let me say hello all! I purchased my first motorcycle, an '87 savage a few weeks ago. I absolutely love it! Fits me like a glove.

However, i've been having one particular problem. When i first start the bike, it runs fine for a few mintues. Don't need a choke or prime to start it . . . it starts right up. But, after about 5 minutes, it starts to bog down and will die. It will not just idle. I have to keep on the throttle to keep it from dying. I've turned up the idle, which helps a bit, but doesn't fix the issue.

During this time, the exhaust appears to be a little smokey and black. Not a ton of smoke, just seems like a little more than normal.

After this 10 - 15 minute period, the bike seems to warm up or something, and runs perfectly. Idles with no problem. I can ride it for hours and hours with no issue.

Any ideas what could be causing it? My best guess is that it's running super rich or something. In fact, one time i even saw a little gas dripping when i keep it just barely idling enough not to stall. Also, more than once, I just took off and rode with it like that (since I have the throttle on it will run okay). And, 10 minutes or so into the ride, it seems to kind of buck and sputter for a second or two, then the power comes back on, and she runs perfectly. Almost like something was sticking in the carb and finally became unstuck.

Any ideas?

Thanks in advance!

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by Reelthing on 07/13/05 at 06:19:25

Welcome aboard and welcome to the world of Mikuni constant velocity/variable venturi carbs - yes it sounds like something is hanging in the carb with very high odds on the round carb slide. When it floods out as you describe it's going up and pulling the needle out to open the main jet and hanging on the way down so it doesn't close the main jet. The tube this slide operates in is very close tolerences and the least bit of dirt build up will cause this situation.

Several ways to address this - some folks swear a little (about 2 caps per tank i think) of marvel mystery oil will clean it and prevent this. Another way is to pull off the black rubber intake tube and spray the slide with a little carb cleaner and push it up and down a few times.

- I am not one of these, but it may be worth a try if your not up to wrenching.

I think you need to pull the slide, clean it and the tube it operates in with say electric contact cleaner, change the air filter (might want to grease the back side of the airfliter seems to seal better that way) and make sure the clamps on the black rubber intake tube are tight.

You can do this with the carb on the bike by pulling the seat and tank - which will give you a chance to look over the workings - and of course since you in there might as well do the carb spacer mod - unless you 87 has the 3 rings on the needle then you can just move the snap ring down 1 notch.

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by realdeal on 07/13/05 at 08:31:29

Sounds like an excellent place to start. Thanks a bunch for the advice. I'll give it a shot this weekend. I'll keep you posted as to my progress.

Thanks!

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by Reelthing on 07/13/05 at 08:35:56

if you do pull the slide/diaphram be real careful with the stock phillps screws - head strips out very easy - if you can find them - most hardware stores carry them - replace these with 4 cover screws and 4 on the bowl cap with allen head stainless m5's

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by Reelthing on 07/13/05 at 10:00:48

One other school of hard knocks tip - if you are going to work on anything around the carb or perhaps anything within 10 feet - place a shop towel on the starter - you see that gap between the starter and crankcase ? - that is a dropped item blackhole - anything small that you do not have a spare of , dropped with in 10 feet will be sucked in there !

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by Greg_650 on 07/13/05 at 22:17:57

I will help.

How is the bike doing now? Spare no details. What do you do and what does the bike do?

I want to know, from saddle to startup, what happens. And I warn you, I will pick it apart. Okay?

Greg

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by realdeal on 07/14/05 at 06:07:51

I probably won't get a chance to work on it until this weekend. I'll be sure to respond and let you know how it goes (and take pictures, if applicable).

Thank you to everyone for the advice!

Here's my plan of attack:
- remove tank
- take apart carb enough to clean it and do white spacer mod
- clean carb
- reassemble

I'll let you know how it goes!

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by Greg_650 on 07/15/05 at 06:46:59

realdeal wrote:

In fact, one time i even saw a little gas dripping

Where?

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by realdeal on 07/19/05 at 06:10:37

Alright . . . the saga continues.

I finally found some time to take the carb apart last night. Not to happy with what I found. There are 2 screws at the top of the float. 1 of which was stripped!!! There was no getting that thing out. Doh. No white spacer mod for me. :(

The other screw must have loosened up over time and had backed all the way out! It was just laying in there. Sheesh.

So, I put that screw back in, cleaned everything up with some carb cleaner, and reassembled.

No luck. Still had the stalling problem. So, I decided to adjust the idle mixture screw. Turns out it also must have worked its way loose . . . it was out over 5 turns.

Here comes the fun part. As I turned in the screw, it definately ran better and stopped stalling. In fact, it runs best with the screw all the way in!

If I'm not mistaken, it shouldn't run at all like that, right? I don't recall if that's an air screw or a fuel screw, but here is my new theory.

I'm assuming turning the screw all the way in makes the bike run rich. So, I'm thinking there is an air leak (at the manifold?), that's allowing air to get in where it shouldn't.

Any thoughts?

Thanks in advance!

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by savage_joe on 07/19/05 at 07:58:55

Realdeal, I also have an 87 and I do not recomend that you do the white spacer mod with the stock jetting as it will be way too rich. That mod is for the leaned out 95 and later bikes.
My bike will also idle with the mixture screw all the way in, our carbs have more passages than the newer ones do.
I believe that turning the mixture screw in (fuel screw) leans out the idle mixture. I had the same issue with mine, at 3 turns out it would start up with no choke but once warm it would not want to idle at all. I can get mine to idle pretty good at just under 1 turn out from fully seated.
I am still trying to find the best setup for my 87, and unlike the newer ones I am finding myself too rich instead of too lean. This may explain the blackish smoke as mine does it too.
I will stay in touch with what works for me, and keep me posted to as I do not see many people on here with the older "pre-EPA" carbs, which look the same, but are not the same. Best of luck...Joe

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by realdeal on 07/19/05 at 08:11:29

Joe,

Thanks for the reply. I'll definately keep you posted. I have a buddy who is a motorcycle mechanic . . . i'm going to have him look at it soon. Maybe he'll have an idea.

Like yours, even with my idle screw all the way in, I still get a little black smoke when the throttle mostly open (indictating a mixture too rich). It's weird.

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by Savage_Rob on 07/19/05 at 08:23:19

Your carbs do run richer than our later versions by design.

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by savage_joe on 07/19/05 at 08:25:15

It's not all that weird. I have been tinckering with bikes, atvs, and snowmobiles for years now and I have seen a change. The thinking in the past was better rich than lean as lean will burn up an engine......then the EPA said wait a minute, what about emmisions...which is probably why the savage was in the us from 86 to 88, then it finally came back in 95 and it was all leaned out to meet some kind of EPA thing.
I am going to try and do a few WOT plug chops to see if I may have to use a smaller main jet or not.
My bike (and from your description) and your bike are too rich from the sounds of things.
I am going to try and figure out which main jet is best and then go back to the other circuits after that.
Indeed, lets keep each other posted as it sounds like we are already in the same boat.
Best of luck..Joe

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by savage_joe on 07/19/05 at 08:28:43

Also to note, with the screw being stripped out in the slide, are you sure the plastic spacer is in there still, could you see it down the center hole?
I did try a 1/2 spacer and it was way too rich, put the spacer back in and I'm much closer now. I was going to either lean out the main (depending on plug readings) or try to lean out the needle by shimming the plastic spacer some.
I will keep you posted. Joe

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by Savage_Rob on 07/19/05 at 09:26:24

The difference is definitely the result of emissions regulations.

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by realdeal on 07/20/05 at 05:52:04

Okay . . . I started her up last night. It's definately running better, but still has a tendency to stall in that period just after it starts to warm up but before it gets all the way warmed up.

I also noticed something else. When I'm sitting in neutral and crank on the throttle, it doesn't snap back down to idle . . . it kinda slowly drifts back down to idle. There is a second or so delay between the position of the throttle and the speed of the motor.

I decided to study the diagram of the carb, when I discovered something disturbing. I appear to be missing the spring I've shown below.

Am I losing my mind? The 87's are supposed to have this spring, right? Could this be my culprit?

http://wam.umd.edu/~neila/carb.jpg

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by savage_joe on 07/20/05 at 06:35:00

My 87 has the spring, something tells me your's should too. Joe

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by realdeal on 07/26/05 at 05:44:47

okay, I got the new spring for my carb in the mail yesterday and installed it last night (see above in this thread for an illustration of which spring). Definately made a difference. Seems to have more power and run a lot smoother.

Unfortunately, it didn't seem to completely cure my stalling problem. Right after I installed it and started it, it ran fine until it started to warm up (same as before). Once the temp started to rise, it was trying to idle, but woudl die out after a minute or so. I decided to take it for a spin. I hopped on the bike and drove it, and it idled just fine. Drove it for 30 min. or so with no problem.

There is one weird thing about it, though. If i'm crusing up to a stop light and pull the clutch (remove the load from the engine), the RPM's will go way down to the point that it almost stalls. Then, it quickly builds up RPM's again until it reaches idle speed.

Any ideas what would cause this?

Title: Re: Need Help - Bike wants to stall for first 10 m
Post by klx650sm2002 on 07/26/05 at 10:57:22

Sounds like idle mix is a bit rich, if it were slow dropping to tickover it would be lean.

Clive W :D