gearing

[78GS550]

im looking for advice on sprokets for my 78 gs550 and i was thinking of adding 2 or 3 teeth in the back but i dont know what kind of results im goin to get and i was wondering if ne gear experts could help me any help is greatly appreciated im lookin for some better acceleration but not lose all the top end also

[chef1366]

If you want huge take off improvements lose a tooth on the counter sprocket (front) but you will wind out at highway speeds. I jumped up two teeth on the rear and it has better take off and I'm not winding it out on the highway.
Cheap torque.

[78GS550]

do i need to get a bigger chain then and will it still line up properly with the front by adding two teeth in the rear and would that drop my 1/4 mile times thank you for the help

[chef1366]

I didn't have to change the chain links but you might.
Why are concerned with the 1/4 mile on a 550? Did a friend of yours get a new bike?

[rphillips]

As a general rule 3 up on the rear would be about the same as 1 down on the front. You can hardly notice 1 up on the rear, you can clearly notice 3 up in the rear.

[78GS550]

im racing in a school thing in may and i want it to beat my teacher on his stock harley

[SqDancerLynn1]

That would be cool to beat your teacher's Harley with a bike 1/2 it's size. Go practice your take offs somewhere private maybe 20 lbs in the rear tire. If it launches ok leave it,if it bogs drop 1 in the front. Get seated as far forward as you can to avoid wheelies

[78GS550]

alright thank you for the advice ill try it but i was wondering if i drop a tooth in the front will i need to get a different chain or will it be alright

[bradleymaynar]

I would think that may depend on how much adjustment travel you have left in the swing arm. The more teeth you add to the sprockets, the more likely you're going to need a longer chain.

Brad bt

[Nicholaschase29]

If you drop 1 or 2 teeth in the front, you may get away with just sliding the wheel back, if push comes to shove, you just need to pop a few links out.

[KEITH KRAUSE]

I'm no expert at gearing and its exact effect on your 550 1/4 times, but based on the replies and previous chat I've had with you, I'd probably compromise and try 2 more teeth on the rear. You don't want to wind out too soon and give that Harley a chance to pull you in.
Sometime in May? Get that jetting right. I've given my best guess at the jetting, but it's not always realistic to expect it to be spot on the first try. It may take some tinkering and the jetting will be more important than the gearing change.

[78GS550]

yeah im working on that jetting trying little runs down my street seeing how it acts with it i have a 1/4 mile marked off so i dont my own little tests and it seems to be working pretty good

[KEITH KRAUSE]

OK. Without a Dyno, the best way to test for each jetting circuit is...full throttle for the mains, 1/3 for the jet needles, and minimal/steady throttle for the pilot circuit. Just enough throttle to cruise about 35 in 4th/5th gear for the pilot.
Chop off and get plug reads. Plug reads are more accurate after you vacuum synch the carbs. You should be able to feel any lean symptoms such as surging or rich symptoms such as a bog but sometimes things are subtle and you need to trust the plug readings. If the bike is tuned in preparation for the re-jet you'll be able to trust the reads and KNOW that any problem is the jetting and not something you skipped that effects the jetting. For one thing, a carb bench synch only prepares the bike for the vacuum tool synch.
I know you may have limited time but the rest of the bike needs to be checked/tuned to insure the jetting is accurate and easier to adjust. Typically, the valve clearances should be set correctly, then the ignition timing/advance timing, then the side air screws are set using the highest rpm method. After this, THEN you vacuum synch. Of course, the carbs must be clean/float levels correct, the manifold o-rings should be replaced when the carbs are off and manifold condition checked to avoid intake leaks, points (if you still have them) clean/not pitted and gapped correctly, good condition/correct heat range plugs, etc.
Also, I forgot to mention, REMOVE the two floatbowl vent lines and leave the ports open. This is to avoid fuel starvation when running pods. Your VM carbs are finicky about this and it's a requirement in jet kit instructions such as Dynojet.

[RacingJake]

I got a 78 GS550 and it's been certified by the Maricopa police dept. for being one fast little 550 :twisted:

Go with a 14 tooth upfront and I just kept the oem 50 tooth on the rear. It's cheaper to get the 14 tooth around 20 bucks and most likely your old chain will still work as long as your not at the max adjustment now.

Best bet is to practice you launch, giving it lot's of gas as you slip the clutch, get more aggressive until it's starts to wheelie then just back it off a notch and try to launch at that pace. Try to get use to laying on the tank with your chest, the more weight you can get forward the harder you can launch and say stuck down as your going down the big end of the track cause you'll pick up a few more mph's.

And go get that Harley......ps sounds alittle fuuny coming from a Harley guy like me too :???:

[78GS550]

thanks for the help i appreciate all of it and maybe some day i would be able to come down and see ur 550 im prolly road tripping cause its time for a long ride