Bogs down at high speed

[webslappy]

I recently purchased a '07 s200 with 2700 miles and it runs great except when I hit over 85kph, it randomly bogs down. It feels like the belt is slipping or something because it loses power but just for a split second and then returns to fill power. It periodically does this at higher speeds. At low speed, it doesn't happen at all.  Any idea what's going on?  Thanks for the help.

[Tromper]

I ran into similar for a few different reasons
- Overheating (in 100 F weather)
- Plug blow out, kinda intermittent.
- Flat spot on rollers (fixed by switching to DP sliders)

I also had a low speed issue due to a cracked vacuum tube, & would bog due to lack of air flow when I overfilled the tank and got going on a hill just wrong

[webslappy]

I thought about flat spot on the rollers and considered swapping them out. What do you mean 'plug blow out'?

[Tromper]

The DP sliders were an overall upgrade anyway so I highly recommend 'em.
I ran stock weight, but for my riding at the time, knowing what I know now, I would have tried 1g lighter.

By plug blow out I mean the gap had gotten wide enough on the plug that it was starting to have issues at high speeds.
I was riding mostly highway with the bike topped out all the time.
Since getting to the plug was a bit of a PITA, I had a fresh one ready when I pulled it apart, but I could have just re-gapped the old one for one more round.
Since you should probably at least check the valves anyway it won't hurt to replace yours while you're there.

I thought about flat spot on the rollers and considered swapping them out. What do you mean 'plug blow out'?

[webslappy]

Thanks for the reply.  I'll swap out the plug and roller weights to see if that helps.  I searched and found that the S200 weights are 14g. Is that correct?  If so, I'll get 13g DP.

[Tromper]

I think 14g was what I used, but to be honest it's been a while.
I'm also not dead sure what gain you'll get but around here I'd give it a shot since if you're not going up you're going down in this area.
I suspect you'll stop top out ~60mph (real, not indicated) in the flats, but you'll get there with a bit more pizzazz.  Might negatively impact your MPG a bit too.  Might not, not really sure.
I got a pretty consistent 60MPG on mine, & I was not gentle.

Beyond that, if you haven't done it consider a solid carb cleaning.  I had a local guy who's great with small engine carbs go through mine, I believe he upped the main jet a bit as well as cleaning it up & tuning it.  I can't say it was a huge impact but it was noticeable after 6k miles of whatever I could find to put in the tank.

[big blue]

I agree with Tromper on the Dr Pulley sliders giving a performance boost. I installed them in my Like 200i (same engine) and got better pull off the line and actually gained top speed due to the fact that the sliders ride higher in the variator. The stock roller weights were 14g and I went with the 13g per Buggy Parts Northwest recommendation from whom I purchased the sliders.

[cleanerman]

webslappy

Did you get your bogging down problem fixed?  What was the cure?

Scarlett is doing the same thing.

Thanks.

[webslappy]

cleanerman -

The scooter is at the mechanic now.  He's replacing the petcock, cleaning the carb and swapping out the roller weights.  I'll report back when I get a final resolution

[cleanerman]

Thanks, I'll stay tuned.

[cleanerman]

Well, I may have cured most of my "missing" problem at high cruise speeds.  Reading the owners manual as well as info on the internet, I was under the impression I should be using high octane gas.  Well, duh, looking under the seat I find a very clear label that said use 87 fuel.  I switched. 

Almost immediately, first tank, my bogging, surging or missing was greatly reduced.  On tank 5 of regular, branded gas now and is running so much better.  Every now and then, when cruising between 55-60, straight and level, it will "miss" but nothing like it used to.

Next I will change the spark plug and check the valves.  Other than this little problem, Scarlett runs like a champ.

[Tromper]

Only had to use high octane on highway running (WOT) on a 100 F day.  Might have been a bad batch of regular on the prior fillup but it did settle down on premium.  Before that I was getting some ping.

The usual routine with the Asian bikes is that the manual say 90 octane, but that's RON, not AKI (R+M/2).  90 RON is about 87 AKI.  Thus the confusion.

[cleanerman]

I changed the spark plug and I still get an occasional "miss" or "cough" while cruising above 85 clicks.  Acceleration is smooth and without hesitation from zero to max speed.

Just wanting to do one thing at a time so I know what the fix is, so next is valve check.

I need a rainy day.

[Tromper]

Next time hit 'em when you hit the plug.
This was honestly the easiest valve set I have ever had to do once the plastic was off.

I changed the spark plug and I still get an occasional "miss" or "cough" while cruising above 85 clicks.  Acceleration is smooth and without hesitation from zero to max speed.

Just wanting to do one thing at a time so I know what the fix is, so next is valve check.

I need a rainy day.

[cleanerman]

webslappy

Any luck with your bogging down problem yet?