Need help adjusting throttle on a 2-stroke

Ron-P · #1 01-10-2010, 09:34 PM

The engine runs perfect except I can only reach 24 mph and the throttle is maxed out. I need to adjust the linkage so I can open her up more but not sure how. Help!

MB-Monkey · #2 01-10-2010, 10:08 PM

speed increases with break in giv e it some time. Also take off the air cleaner and look to see of the slide is opening all the way. 24-30mph is what most of these engines do.

Cannonfish · #3 01-10-2010, 10:15 PM

Ron, one solution might be to shorten your throttle cable just a tad, while leaving the cable housing the same length. If the problem you are having is that the slide in your carb isn't opening up fully, this will fix it. Check out these instructions from a very knowledgeable forum member: http://motorbicycling.com/f39/norm-s...able-9010.html. If that doesn't work, then you can always just trim a bit of the cable housing off to bring everything back to the same relative length again.

Something to think about, I don't know the details of your set-up, but if it's a brand-new engine and a stock kit, then 24 mph might be getting close to the max that you're going to get out of it - unless you've added engine modifications or a smaller (like 36-ish tooth) sprocket...

marts1 · #4 01-10-2010, 11:08 PM

Your jokin aren't you.

**BarelyAWake** · #5 01-11-2010, 05:31 AM

Perhaps not - between the unknown accuracy of the OP's speed quote and the fact that most stock motors really do top out at roughly 30mph-ish there's a good chance that all the above info is dead on.

**2door** · #6 01-11-2010, 12:32 PM

Quote:

Originally Posted by Cannonfish

Ron, one solution might be to shorten your throttle cable just a tad, while leaving the cable housing the same length. If the problem you are having is that the slide in your carb isn't opening up fully, this will fix it. Check out these instructions from a very knowledgeable forum member: http://motorbicycling.com/f39/norm-s...able-9010.html. If that doesn't work, then you can always just trim a bit of the cable housing off to bring everything back to the same relative length again.

Something to think about, I don't know the details of your set-up, but if it's a brand-new engine and a stock kit, then 24 mph might be getting close to the max that you're going to get out of it - unless you've added engine modifications or a smaller (like 36-ish tooth) sprocket...

Please don't try shortening the throttle cable until you've determined if the slide is opening all the way. If it is then shortening the cable will accomplish nothing.
Remove the air cleaner, look down the throat of the carburetor and twist the throttle to wide open. The slide, the cylindrical thing you see moving up and down, should move up and expose a slender brass needle. If the slide moves upward at least a half inch then it is probably moving as far as it is designed to move. As has been said above, 24 mph prior to full break-in isn't that unusual. As the rings seat and compression goes up you'll experience a gradual increase in performance. There are other factors involved that will effect your top end speed. Rider weight, rear sprocket size, fuel mix, etc. Give your motor a chance before attempting modifications to the stock configuration until you have a complete understanding of the mechanics involved.
Tom

Ron-P · #7 01-11-2010, 08:55 PM

Awesome, thanks guys. The bike has close to 75 miles on it now and it's been upwards of 35+ so I know it can go faster. I had the entire thing torn down to replace a broken engine mounting bolt. I'll pull the filter off and take a look at the carb before I do anything.