wont do 55mph!!

[remainincognito]

My buddies XS will not do 55mph. Set timing chain..valves and checked timing. Advance looks fine too. Has pamco ignition. I also took off pox filter and no change. Hes going out of his mind

 

[remainincognito]

Wanted to add that garb jetting is good. Bike will start tight up...idle and tun great but just wont go fast enough. I took for ride it it runs great to about 50ish. You can give it more gas and wants to go more but feels like it'd too high of rev

 

[Grinder]

Does it feel like the clutch is slipping?

 

[remainincognito]

From my time of riding it the clutch did not slip. Crank the gas and bike will lurch forward but feels like over reviving and high gibes.

 

[pamcopete]

Here is a list of things that can hold you back:

Bike goes slow (< 60MPH)

1. Low battery / charging system. A low battery will produce a low ignition voltage at the plugs which is most evident at higher RPM's.
2. Timing. Did you use a timing light to set the timing?
3. Stuck or no advance. When checking the timing with the timing light, did you check for maximum advance at 3,000 RPM.
4. Binding advance rod. Check out this video:

5. Fouled plugs. Did you install new plugs? Check them after you got it running?
6. Plug wire not making contact in the coil. Measure the resistance from plug cap to plug cap to ensure that both plug wires are making contact in the coil.
7. Brakes dragging.
8. Speedo out of calibration. You are actually going faster than 60 MPH! Use your GPS to check the speedo.
9. Tire pressure. Pump up to 32 PSI for high speed.
10. Drive chain too tight. That will rob you of power to the rear wheel.
11. Enricher plunger stuck partially on.
12. Enricher (choke) left on or partially on.
13. Weak or loose advance springs. Weak or loose advance springs cause the advance to use up some of the available movement because you have to essentially retard the advance to get it on the idle advance mark, so there is less movement available at higher RPM's.
14. Timing chain needs adjustment.
15. Cheap or bad gas.
16. Low octane gas.
17. Water in the gas.
18. Partially blocked pet cock or fuel filter.
19. Paper filter that has low flow when the tank is not full.
20. Try a run with a full tank of high octane, fresh, expensive gas.
21. Blocked fuel cap vent.
22. Incorrect sprockets. What RPM are you getting at 60 MPH.
23. Rear tire rubbing on brake rod or swing arm.
24. High wind resistance. Are you a large person?
25. Throttle cable not fully opening the throttles.
26. Blockage in the muffler(s)
27. Dirty or blocked air filters
28. High altitude
29. Very hot air, like 95+F
30. Very cold air, like 32F
31. Low oil
32. Really dirty oil
33. Gas in the oil
34. N/A
35. Cracked carb boots.
36. Hole in carb diaphragm(s)
37. Cheap pods covering air hole in carb inlet

 

[remainincognito]

Can dirty oil really make it only go 50? Going through the list all good so far. Whet should we see on meter when checking resistance from plug cap to plug cap? Mew springs from mikes on advance unit. Cam is coming out 1 to 2 mm while running

 

[Grinder]

I've read bad things about those Mike's advance springs. Do you have the old/oem springs to put on there. Check timing with a light to see if it's advancing all the way or too much. Do a search, here's one post.


http://www.xs650.com/forum/showthread.php?t=17902&highlight=mikes+advance+springs

 

[pamcopete]

Can dirty oil really make it only go 50?

Dirty oil does not lubricate as well as clean oil does so you could have high friction between the rings and the walls of the cylinders which slows the engine down and causes it to overheat. When was the last time you changed the oil?

 

[Phail]

Mine was like that when I first got it. After replacing just about everything it's running really well now.

It was shaking so bad welded parts were breaking off.

After changing the chain, sprocket (18/30), and the exhaust it got much better. After changing out all the electrical (PMA, Pamco) it got much better. After changing out the front forks it got much better.

Now I'm riding 80+ with not too bad vibes. I usually cruze around 65.

 

[remainincognito]

He changed oil last season. But forgot to ask how many miles.

 

[pamcopete]

He changed oil last season. But forgot to ask how many miles.

Two quarts of oil, $8
A bike that runs great....priceless....

 

[alfredo]

Do me a favor, even if you have done this already . . . . synchronize that carburetors. Many people of the forum told me to do this about 100x and I failed to listen. Then one day, I made the homemade manometer, synced the carbs (which were only off like 3-4mm) and the bike would blast up to 75-80 and performed worlds differently. Now, the vibrations you'll get doing those speeds. . . . thats a different story.

 

[jd750ace]

Synch does wonders for vibration as well. I believe I read that people wer cutting a coil off the Mike's springs because they were too stiff. Chime in if I flubbed that one.

 

[Phail]

Oh yeah, syncing is a big help. +1

 

[GreasyC]

You said it feels like it would rev too high if you went faster? What's the tach reading at 55?

 

[coughing skunk]

Synch does wonders for vibration as well. I believe I read that people wer cutting a coil off the Mike's springs because they were too stiff. Chime in if I flubbed that one.

Cutting a coil off of a spring makes it stiffer, not softer.

For anyone who wants to know the physical reasoning behind it please see this post. Some basic physics knowledge is needed to understand the concept, like spring constant and such

 

[Socopunk]

I was having problems with my bike staying up at about 3,000 rpms after slowing down and topping out at about 60mph.

Bought new springs from Mikes. Still a problem. Clipped one ring off. Bingo runs great.

Changed the oil. Bangin' all day at 65.

73' TX, BS38's with no vaccum barbs, I have to synch before nearly every ride. Sometimes half way through.