Quote: have you factored in the fact your speedo might be inaccurate now?
I'm riding a stock 89 LS 400 chain driven with 17-48 sprockets and I'm getting just over 125 kph (77mph) my speedo is out by round 5%
reads 100kph but doing 110kph ish
Yeah. I'm using an app called strava it has gps. Mines off by 10 mph over 50 mph. On bike it reads 65 mph which gps shows my top speed at 75 mph.
Quote: reads 100kph but doing 110kph ish
Posted by: Gary_in_NJ Posted on: 10/10/17 at 13:45:51
How many miles on the engine? Have you done a compression test?
Unless you are trying to ride at max speed at idle, the idle mixture will do nothing to effect operations at or near WOT. What jets do you have installed and what position is the needle?
Almost 15k. Had it at 13k 1 year ago. I haven't cracked open the carb. Its been running good ever since I got it.
I've just been messing with the idle screw around low rpm and backfiring.
Read the screw will help a tad to the main jet. Just feeling it out and seeing what difference does it make and practicing before the jets I ordered from here come in.
Quote: by: justin_o_guy2 Posted on: 10/10/17 at 14:44:15
How big are you?
Got a windscreen?
Bags?
Drag bars or buckhorns?
And what size rear tire?
How it's jetted matters.
Speedo is driven by the transmission.
Designed to Report the speeds that a given RPM in a given gear would create using the OEM gearing and the rear tire circumference. They usually report a higher than accurate speed. By replacing the tire with a taller sidewall they are pretty close. Changing the front sprocket diameter to rear sprocket diameter ratio and you get higher speeds without the speedometer knowing about it.
The low horsepower motor can only shove so much stuff down the road at speed. We do some gearing change not for speed, but to decrease the RPM at highway speeds.
6th 190lbs. No bags on right now. No windscreen either.
Drag bars. Stock tires. Its actually a 17/41. I've read some on here ride at 80-90 mph. I just wanna get up to 70-80 and hold it there.
It hiccups for a sec at 75 and then I back off at to 70.
Quote:
Posted by: Dave Posted on: Yesterday at 03:42:04
Yep......use a GPS or PhoneApp to check speed, as your speedometer doesn't read correctly once you start fiddling with the final drive ratio (pulleys or sprockets). The stock 23/68 gearing is 2.9565, your current 17/43 gearing has a ratio of 2.5294. That is a change of 16% - so ignoring any speedometer error you may have........a speedometer reading of 70 mph will now be a ground speed of 81.2 mph.
And.........with the current gearing you have it is very likely the engine can't wind up enough to get your top speed in high gear. The 25/65 gearing I have on my bike has a ratio of 2.6000. I have a modified engine and I can't get to my top speed in high gear - and neither will you. If I want to go "full speed ahead" I have to do it in 4th gear - but the taller gearing allows for very nice highway cruising in 5th gear, as my engine is only turning about 4,000 rpm at 70 mph.
That's sounds like it could be that and I don't like it haha.
I really should open up the carb and go up a size little by by little. This bike came from Illinois and then Ohio before that so I wanna assume that the main jet is on the smaller said because of the weather. What a jet kit that's tuned well get me another 5-10 mph?
Thanks to all of you that replied :thumbs up: