Losing Accelleration at WOT

[teoteo]

Howdee, I ride a Super 8 125cc, had it for about 6 yrs (mileage so far:38000km) from new. I live in a tropical climate where temperatures rarely dip below 27 degrees C'. I use it mainly to get to work and back (approx.20km round trip, plenty of stop-N-go traffic). Last weekend I took it for a longish (approx.160km) road trip with my wife on board and did lots of WOT at highway speeds (100kmh - 110kmh). I remembered filling up the petrol tank and topping it off some more and when I got back to doing WOT on the highway trying to maintain 110kmh, the scooter surged quite badly. It jerked whenever I tried to get up to 110kmh. But when I slowed down to 100kmh it was fine and it felt like it could cruise all day at 100kmh. I suspected a few things;like valve clearances or a defective ignition coil or cable or spark plug but haven't the time nor the skill to investigate further. Will be doing a long road trip next month with the wife (1200km)and some friends on their small scooters so am just hoping the problem goes away because I topped off the tank with petrol last time.

Anyways, its been mostly great reading all this from fellow S8 owners. Very educational n fun!

Hope Mr Wkreps U get your problem solved soonest! Cheers!

[wkreps]

teoteo,
Sounds exactly what I have going on. Haven't had the time to do what klav suggested with the bypasses but when I do I'll post it up here.

[BettinANDlosing]

Hey Wayne, how does your plug look? That description sounded EXACTLY like lean main jet. These bikes come lean to to pass EPA guidelines. Look at the plug, if its white that's your guys problem. Also will amplify the issue of you have bypassed the emissions system.

[wkreps]

Hey Wayne, how does your plug look? That description sounded EXACTLY like lean main jet. These bikes come lean to to pass EPA guidelines. Look at the plug, if its white that's your guys problem. Also will amplify the issue of you have bypassed the emissions system.

Can I just pull it now or do I need to run it WOT til it acts up then bring it back home to inspect. Plug chopping and inspecting the plug I would be a total rookie at. Never even done it on the lawn mower before.

I was leaning toward the fuel filter cause like the other guy said, I can run it at 90% all day long with no issues. Just thought that extra fuel draw needed for WOT may be hindered by the fuel filter.

[0BARK4322]

Maybe you are at red-line

[BettinANDlosing]

You don't need to do it right after a run, in general if it is white ish is lean. Also there isn't really a rev limiter on the 150's that would cause surging. Over the years your main jet might be slightly plugged. I would see what size main is stock from the service manual, then order one size larger if it's a #110 order #115 etc.

[wkreps]

I cleaned the carb this spring so it shouldn't be clogged and the main jet is a 102 (found that out when cleaning it). I need to get on the stick and get some of this done. Not very motivated at the moment. 

[BettinANDlosing]

I cleaned the carb this spring so it shouldn't be clogged and the main jet is a 102 (found that out when cleaning it). I need to get on the stick and get some of this done. Not very motivated at the moment. 

Order a 105 and and 110 and see what that gets ya. I get all my jets from jetsRus.com they are great and always get it right. Go for the OEM jets, not the "oem equivalent", they will be more accurately sized.