Getting my son's bike running better

[adidasguy]

#5271

If for wet clutch, it should be OK.
Try checking your clutch cable adjustment. Maybe it is too tight.
The WIKI has a tutorial on clutch adjustment.

Owners manual says API of SF, SG, SH or SJ
JASO of MA
Not to use "energy conserving" oils or oils with friction modifiers.

Not sure how the Kawasaki oil stands against the Suzuki owners manual. No idea what "SL" or any of the API letters mean. Someone else should know.

[iclrag]

#5271

If for wet clutch, it should be OK.
Try checking your clutch cable adjustment. Maybe it is too tight.
The WIKI has a tutorial on clutch adjustment.

Owners manual says API of SF, SG, SH or SJ
JASO of MA
Not to use "energy conserving" oils or oils with friction modifiers.

Not sure how the Kawasaki oil stands against the Suzuki owners manual. No idea what "SL" or any of the API letters mean. Someone else should know.

For future reference

According to the American Petroleum Institute (API), SL motor oil grade is used in gasoline engines in automotive vehicles made in 2004 or earlier. SJ motor oil is used in gasoline engines made in 2001 or earlier. Both grades can be used in any older car that requires earlier motor oil grades SA through SH.

[adidasguy]

#5272

I was reading from the GS500F 2008 owners manual. "SL"? Go figure what the manual says. A new 2008 bike specifying SF-SJ.
I vote to check the clutch adjustment.

[salamander]

I vote to check the clutch adjustment.

Only time will tell, along a test drive (but it's raining today, so not likely), but it looks like the clutch adjustment faction wins.  Although the clutch cable play had been adusted before this whole project started, one thing I forget to mention was that all of the fuel lines were replaced during the first go around with the bike, and it's likely the cable is routed a little differently.  When I checked the cable play based on AdidasGuy's suggestion, it was tight with none of the play I had in it before.  It's been readjusted and I'm hoping the slippage problem goes away.

Thanks.

PS: Day 3 with no extra gas in the oil -- I'm about ready to call that problem over.

[salamander]

What I'd like to do is put the new left footrest on the bike and use the old one's rubber to replace the torn rubber on ther right one.  Before I start ripping out fingernails trying to get the rubber off, is it even possible to do or are there any tricks to doing it?

For what it's worth, I'm going with 'no' it's not possible, or at least not worth the trouble.

[knowles]

its glued to it, i had to cut mine off in peices, so no not worth it.

[salamander]

Good to know I'm not just a 260 lb weakling  .

[knowles]

IF he wasn't ridden much it might be that hes not shifting hard enough, and the gear is only half in or out. unless you run it out of oil, or put the wrong kind in, or the thing comes apart, the clutches or really over built for this bike. its basically the same clutch as On the SV 650.

[salamander]

IF he wasn't ridden much it might be that hes not shifting hard enough, and the gear is only half in or out. unless you run it out of oil, or put the wrong kind in, or the thing comes apart, the clutches or really over built for this bike. its basically the same clutch as On the SV 650.

He's really just started riding, and has been doing more than short practice rides in the neighborhood only the last couple of weeks since he got his actual permit.  Even so, he only mentioned the slipping problem since we changed the oil at the start of last week, so I think he's got the hang of shifting gears.  The timing of the problem's also why I was asking about the oil earlier.  Turns out the clutch cable was tight and we adjusted it, so that may have been it instead of the oil.  I tried to talk him into taking the bike out today for a 10-20 minutes ride, but he already had other plans.  So, I'm still waiting to see if the problem's fixed.

Thanks.

[salamander]

The weather finally cleared enough for the roads to dry out so I took the bike out myself for the first time since we started working on it (my son had been doing all the test rides before this).  I rode ~10 mi and did everything I could to get the clutch to slip -- accelerating with the rpm's up around 5-6k on level ground and on gentle hills -- but nothing like my son described, so I think the cable adjustment did the trick.  Thanks, AdidasGuy.

The bike responds much better to throttle, now.  When I open the throttle starting at ~4k rpm, there's no hesitation, no bogging, and the bike accelerates pretty smoothly.  But, even though I weigh in at around 260 lb, I still think a 500 should be able to accelerate better than this one's able to at the moment.  For lack of a better way of describing it, the acceleration is smooth, but not 'crisp'.  After looking through some other threads here and some other sites, I'm thinking this sounds like a rich mixture kind of thing.  We re-jetted to 40/140, but still have stock exhaust, so rich would make sense to me.  Please correct me if I'm wrong, or if there are other things I can check on.

One other thing that I did notice on the ride was that on a straight stretch I was maintaining ~55 mph and the bike started to buck a bit.  I headed to the gas station and filled it up thinking I had hit the spot where I needed to switch to reserve.  I went back out on the highway and it was still doing the same thing -- after maybe 10-20 seconds at speed, it started to buck a little and it would stop if I slowed and backed off the load on the engine.  I''m guessing fuel starvation, but again, if there any other possibilities, please let me know.

Thanks.

[RossLH]

Check the orientation of the carb vent. If some turbulence is blowing up into the tube on the highway, it'll cause the engine to stumble.

[salamander]

Check the orientation of the carb vent. If some turbulence is blowing up into the tube on the highway, it'll cause the engine to stumble.

We replaced the stock airbox with a lunchbox filter, but I still have the hose going over the top of the filter and just to the backside of it (so it's just below seat bottom level).  I also have a small cylindrical filter in the end of the vent hose to try to cut down on turbulence.  Does that sound like an okay positioning for the vent hose?

Thanks.

[RossLH]

That should be fine. If you're worried about it being rich, pull the plugs and take a gander at them. If there is soot built up on them, you'll want to cut back the fueling.

[salamander]

My son took the bike out for a while this afternoon.  As soon as it cools off a little more, I'll pull the plugs and let you know how they look.

[salamander]

That should be fine. If you're worried about it being rich, pull the plugs and take a gander at them. If there is soot built up on them, you'll want to cut back the fueling.

The plugs currently in the bike have been in for ~120 mi, since the initial carb cleaning.  The first ~30 mi of that was put on before I adjusted the floats to stop an overnight leak of fuel into the left cylinder (and into the oil sump), but the remainder have been post-float adjustment, which I think is right but need to get a better-sized piece of clear tubing to confirm.  I just pulled them, and both look similar -- a little bit of light brown to one side of the of the electrode hook, and the rest of the insulator white, almost like new, but no sign of blackness or even dark brown.  Assuming 120 mi is enough, I'm surprised -- maybe I'm actually running a little lean, or on target.  The new jet sizes (40/140), washers (1 on the needle) and turns out on the pilot air screw (2.5 from closed) were blindly set from the re-jetting matrix on this site for a K&N lunchbox filter and stock exhaust.

Thanks.

[RossLH]

Brown is a good color. A white electrode would indicate a lean condition.

[bombsquad83]

He's talking about the insulator being white, which is ok.  As long as you are happy with with the performance with no hesitation or flat spots, then I would say that your jetting is good.

[salamander]

Check the orientation of the carb vent. If some turbulence is blowing up into the tube on the highway, it'll cause the engine to stumble.

We replaced the stock airbox with a lunchbox filter, but I still have the hose going over the top of the filter and just to the backside of it (so it's just below seat bottom level).  I also have a small cylindrical filter in the end of the vent hose to try to cut down on turbulence.  Does that sound like an okay positioning for the vent hose?

Thanks.

Either I misread your question, or just wasn't paying close enough attention, but what I described to you was the crankcase vent, not the carb vent  .  Starting from the T-connector at the carbs, the vent hose runs up and over the top of the air filter, then down, ending near the rear brake cylinder.  And, it does NOT have anything in the hose end -- the hose just stops and is open.

[BockinBboy]

http://gstwins.com/gsboard/index.php?topic=60976.msg705284#msg705284

A link regarding the carb venting issues with the wind.

This is my bet on your 55+ mph stumbling problem.

- Bboy

[bombsquad83]

Check the orientation of the carb vent. If some turbulence is blowing up into the tube on the highway, it'll cause the engine to stumble.

We replaced the stock airbox with a lunchbox filter, but I still have the hose going over the top of the filter and just to the backside of it (so it's just below seat bottom level).  I also have a small cylindrical filter in the end of the vent hose to try to cut down on turbulence.  Does that sound like an okay positioning for the vent hose?

Thanks.

Either I misread your question, or just wasn't paying close enough attention, but what I described to you was the crankcase vent, not the carb vent  .  Starting from the T-connector at the carbs, the vent hose runs up and over the top of the air filter, then down, ending near the rear brake cylinder.  And, it does NOT have anything in the hose end -- the hose just stops and is open.

I agree with jester.  Having the carb vent tube all the way back there will cause crosswind stumbling.  It should terminate somewhere that will be out of the wind.  In the stock set up, it terminates behind the airbox between the airbox and the battery, and is held there by a clip.  I think jester routed his over the battery and terminated it behind the battery box...I think.