Bike wont go over 45mph! Help! need to fix asap!

[garyg199]

Hey guys.

Finally took the bike out for a nice ride that was actually beyond my neighborhood and it won't go faster then 45 mph!!

I don't know what it could be and it'd better not be serious.
I'm thinking plugs or cylinders? At first I thought just my shifting was a little rusty blah blah. But no even in sixth gear with throttle all the way opened it would still evenuslly get up there .

Please tell me what this could be and how to fix it if anyone's run into this before! I need to fix it asap being I drive on a freeway to work daily!

Thanks a bunch everyone.

[rwinn]

I'm new to this forum and learning about these bikes. On my 79 KZ 650 a similar situation and it turned to be air not getting to the carbs intake. Have you tried disconnecting the intakeboots to the air box? In the process of elimination I would start with the easiest 1st. Also any disruption in fuel delivery, then maybe clogged jets. Also may consider engine timing. That's my thoughts.

[JAS6377]

What year, naked or faired, and do you have any mods? That might help narrow it down.

If it is naked, there's a common problem with a vacuum hose that gets too much cross wind and causes fuel starvation. Also, these bikes hate inline fuel filters, as they also cause fuel starvation.

Any other symptoms like bogging, weird idle, etc?

[garyg199]

So it's a fully stock 06 gs500f faired. Has been bogging a tiny bit nothing crazy. Also on my way to work it stalled in sixth gear after having the throttle all the way open..stalled as soon as I let up a bit. Other then that it's fine and it's only been in my hands for a week. Previous owner said he had no problems at all (could be b.s) abd that he was getting to about 40mph in second gear..

I read something about dirty spark plugs and bad coils? I feel like it's something stupid but I don't know enough yet to test things out.

Thanks guys

[The Buddha]

Coils and what not, likely no.
I think you may have a rip in the diaphragm ...

Or you may have a seriously clogged air filter ...

Or no - very bad fuel flow.

Cool.
Buddha.

[garyg199]

Thanks man

How can I start testing those things now though?

Air filter I'm sure I can figure out but I'm real new to bikes so the diaphragm...fuel flow..not sure where to start with those.

Cool. Appreciate it!

[Big Rich]

Just guessing, but the motor rpm's just kind of flatline around 45 mph?

The reason I ask, is because if you hit 45 mph and your rpm's increase with more throttle, than it's your clutch.

[garyg199]

Nope they just kinda stop moving up at that speed:/

[garyg199]

This definitely cannot be just from me being bad at running through the gears either correct? I mean I'm not terrible but I haven't rode in about ten years or so.


Also I was noticing that once or twice on my maybe 25 mile ride home it would just bog down to the point where I would have to pull over...go back down to first..completely stop abd start going again.

Just so weird abd frustrating! Just got this Damn bike and I'm having nothing but problems!!

[Badot]

Try leaving the bike in prime, turn it off for a few minutes, start it back up, then accelerate briskly -- does it still top off at 45? If so, it's a carburetion issue. If you can get past 45 but the bike eventually starts bogging again, it's a fuel delivery issue.

[Nocluejoe]

Have you checked the basics? How does both spark plugs look are they gaped correctly? Do you have full oil in the motor?  Are any gas tank wires pinched ?

Also when you reach 45mph does the motor sound change like its struggling And the rpms drop? 

[garyg199]

@badot-I'm going to try that first thing tomorrow. Finally have a day off so I'm just gonna take everything apart and check everything out.

And @nocluejoe- it does seem like it struggles when I get it to where it won't go any faster..but only sometimes. It's so odd some rides are fine (except it not being able to go past 40-45)
But then out of nowhere I'll run into problems!

Just now on my way home I shifted down to first after a long stretch of backroad and I had to ride the clutch basically for about a mile! Any time I have it has and completely let go of the clutch it would lug and lurch like the throttle wasn't doing anything! But then I pulled the choke out a bit and it just stopped doing that and it was fine again....like...it's a joke lol.

At this point it sounds like a fuel issue I'm guessing? It's just not getting enough power.

I've been reading a lot about people losing cylinders and only having "half power" but like I said I haven't been able to fully work on the bike yet. This is only my second day having it on the road.
Wish I had a go pro so I could just show you guys. I know it's something fixable and not a HUGE deal. Please tell me I'm right?!

Also..this probably doesn't have to do with it but my indicator clusters aren't working either. Thought I'd throw that out there in case it could be relative.

Ah anyway..thanks a lot for everyone's input! Keep it coming because I gotta get this bike solid!

[Atesz792]

You can test if you're running on one cylinder by starting her up cold and keeping your hands on the sides of the cylinders/heads.
Do they warm evenly? If one's staying cool to the touch while you can't keep your hand on the other without being burned, than the colder one is not running. Your spark plug would also appear really wet on that side (supposing it's a spark issue, that is).

[Nocluejoe]

Sounds like a throttle cable thats why it will work on chock have you looked at your carbs recently best thing to do is stop riding it take off your carbs and inspect those

[gsJack]

Having ridden my 02 GS home about 10 miles on one cylinder your 45 mph top speed sounds familiar.  I'd check that out first, my problem was a plug wire loose in the coil.  They are screwed in and then bonded in place and can't be turned if they are OK.  If you can turn it screw it out, cut off about 1/4", and screw it in tight for a good temporary fix.

Loss of a cylinder could also be due to a bad pick-up coil, if you check the spark in the conventional manner of holding the plug with wire on it against the cylinder and cranking engine and it sparks the pickup is working but does not prove plug will be sparking in cylinder under pressure.  When buying a used bike it's a good idea to put a new set of plugs anyway soon as possible, they are cheap enough.

If the loss of a cylinder is a carburation problem then maybe one of our carb gurus can help you, I've put my 180k GS miles on a 97 and a 02 GS without ever touching the carbs, stock all the way.  Been know to say "Don't mess with your carbs and they won't mess with you."

Badot's suggestion above is a good idea to check for a fuel flow problem rather than spark or carb problem.  By the way, a compression check is also a good idea on a newly acquired bike to check it's basic condition.  If you don't have a gage a finger over the hole, crank, and pop check is helpful, no or low compression can result in running on one cylinder too. 

[garyg199]

Awesome all of this is great.

How do I get to the cylinders though? Does anyone have a labeled diagram of the system? I know the plugs on the carb and ya gotta pop the tank off but if you guys know of any videos or have specific instructions that'd be great too.

I'm gonna check the basics out right now..air filter..plugs etc.

Keep it coming tho guys it's very helpful! Thank you!

[Alan_nc]

The 45 mph speed limit is a safety feature for new riders.  After you have put some miles in the bike knows it and runs normal.



..........sorry couldn't help it.......................

[garyg199]

Lolllll if only that were true my friend...

[garyg199]

Just had a neighbor check it out and he says it's the carb. Revving it in neutral and it would go up to about 6-7k but it wouldn't hold it. Goes up and then slowly goes down ....slowly comes back up.

Looked up carbs and I got prices about 77-150 bucks does that sound about right for a 2006 gs500f?

[Nocluejoe]

Why not just repair the carb for half the price