New Top Speed: 90mph??

thezidane

New Member
Hi guys,

I just hit 1000 miles on my RC today at the track. After the first couple of sessions I noticed a significant drop in power in the higher gears 5/6. If I redline 5th, then shift up to 6th it barely changes the power output. i can get up to about 78-80 in 5th and then barely manage to hit a top speed of 90mph (no redline, about ~7k rpm) down the straight. There was an older post on here that never had a solution to top-end power loss. Any ideas on what could cause this? I have no warning/engine lights coming on and engine temp is within normal limits. Any speculation would be appreciated, thanks!
 

jjtard

New Member
This may sound strange,,, but check your throttle assembly first. My bike was acting similar one day and noticed the whole thottle assembly was rotating on the handlebar even though the screws were fully tightened....good luck.
 

Diploman

New Member
Are you certain your chain is well-lubed and not binding at any spots? The OEM chain is not famous for high quality or durability. A high quality chain will reduce frictional losses and probably add several MPH to your top end.
 

thezidane

New Member
This may sound strange,,, but check your throttle assembly first. My bike was acting similar one day and noticed the whole thottle assembly was rotating on the handlebar even though the screws were fully tightened....good luck.

Throttle assembly is tight on my bar but my idle doesn't sound great. Almost sounds like it wants to cut out. Not sure if it is related to top end power loss. Now thinking I may have lost 6th gear. I am wondering if when I am "shifting into 6th" I am actually just stuck in 5th, which is why there isn't any power difference between 5/6th gear. I think the ECU thinks I'm in 6th gear but I'm actually in 5th which is why I'm topping out around 7000-7200 rpm but never get the red light to turn on...anything think this reasoning makes sense?
 

Ryanthegreat1

New Member
Have you every adjusted the valves? Tight valves will cause a power loss. A burnt exhaust valve from running too tight will also cause power loss.
 

thezidane

New Member
I have not adjusted the valves. do you have any recommendations for someone to go to for that type of work around the Seattle area? Wondering if this issue may be covered under warranty but I can't find my warranty book....
 

Ryanthegreat1

New Member
Sorry, don't have anyone to recommend in that area. I do my own service in Olympia.

A valve adjustment would not be covered by warranty, it is a normal maintenance thing that should have been done at the 600 mile mark. But it might not be the valves so it might be a warranty thing.
 

Rcdan

New Member
I have heard the plug wire can get loose. I believe it happened to a long term test bike for one of the magazines.
 

ReidMcT

Active Member
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In addition to my battery remark in another thread, you should consider replacing the spark plug boot with the much better one offered by Gray Area on this forum. Even if it does not solve this problem, it will prevent another one.
 
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