GS550 rejetting beginnger advice

[TyeGuy]

I have a 78' GS550 with the carbs off due to a blown cam chain tensioner gasket. I figured with the carbs off and it being winter, I'd try to take on installing K&M pod filters and rejetting it. I have the original VM22SS carbs and stock pipes. My thinking was to install K&M filters and rejet, but I also would like to find a new exhaust system (4-to-2, or 4-to-1 if I can find any) in the new future as well.

Question is; would it be easier to rejet for the carbs, and enjoy the summer riding. Then come fall, rejet for a new exhaust? Or should I rejet the carbs for both new filters and exhaust at the same time (seems more difficult). I don't want to bite off more than I can chew.

Thoughts?

 

[Steve]

The question you really need to ask is "How many times do you want to rejet?"

The smart answer is ZERO. Just leave it alone and enjoy the ride.

If you still insist on changing things that force re-jetting, how many times do you want to do that?

By the way, they are K&N filters, not K&M.

.

 

[hillsy]

Do you still have the stock airbox? If so, re-install and enjoy.

 

[TyeGuy]

The question you really need to ask is "How many times do you want to rejet?"

The smart answer is ZERO. Just leave it alone and enjoy the ride.

If you still insist on changing things that force re-jetting, how many times do you want to do that?

By the way, they are K&N filters, not K&M.

.

I?m sure I?m better of not touching it, but if I were to take that plunge.... Anyways....I?d like to eliminate the stock air box and filter, so that?s the main reason, and maybe this is ambutious but it?ll get me to learn about carbs more. If all else fails and my patience runs out. I?ll just go back to full stock

 

[hannibal]

You only want to rejet once so you should install the pods and pipe together.

 

[TyeGuy]

You only want to rejet once so you should install the pods and pipe together.

I found a few links/forums that discuss about how many jet sizes you need to go up/down with for new pods and pipes. But thought it?d be too drastic of a change to make adjustments to. I figured it?d be easier to rejet one modification then rejet again for the second modifications.

The bike starts and runs perfect now, I?m worried if I rejet for both pods and pipes, my fuel/air mixture will be so off it won?t start,, and I won?t know which direction of jet sizes to go in to fix the issue.

 

[Big T]

Direction is easy -up

How far up is the question

Just ride the bike as is, so you can actually enjoy it for a while

Then, make this decision next fall

 

[roeme]

(...)Question is; would it be easier to rejet for the carbs, and enjoy the summer riding. Then come fall, rejet for a new exhaust? Or should I rejet the carbs for both new filters and exhaust at the same time (seems more difficult). I don't want to bite off more than I can chew.

Answer:

(...)

The bike starts and runs perfect now, (...)

Don't f$ck!ng touch it and enjoy summer riding instead.

On a GS550, you'll want to manhandle the airbox or carbs as few times as possible, it's a royal PITA to get out/in. Add the iterative process of rejetting, and you have the recipe for much frustration.

It's involved, it's tedious, it requires a lot of spare time and energy.

Don't shoot yourself in the foot. You're free to, but we've warned you.

 

[Steve]

You only want to rejet once so you should install the pods and pipe together.

Let me fix that for you. :-k

Unless you are a masochist, you don't want to rejet AT ALL.

I found a few links/forums that discuss about how many jet sizes you need to go up/down with for new pods and pipes. But thought it’d be too drastic of a change to make adjustments to. I figured it’d be easier to rejet one modification then rejet again for the second modifications.

The bike starts and runs perfect now, I’m worried if I rejet for both pods and pipes, my fuel/air mixture will be so off it won’t start,, and I won’t know which direction of jet sizes to go in to fix the issue.

Have you read any of the horror stories about rejetting? Almost NEVER do you hear of anyone saying " I just slapped in the new jets and the bike ran PERFECTLY." Rejetting is usually a tedious process of installing the new jets, testing. Making an adjustment, testing. Making another adjustment, testing. Maybe change another jet size, testing. Making another adjustment, testing. After you think you have it perfect, the weather is going to change and you will find that your "perfect" jetting isn't quite right when it gets ten degrees warmer.

Then you put the pipe on and have the "pleasure" of doing it all over. :-\\\

As far as not having the bike start: if you get to that point, you are not jetting correctly. There are four distinct jetting circuits inside the carb. The starting and idling (pilot) circuits are not usually changed. Your bike should start and idle just as well as it does now. The circuits that need to be changed are the needle and main, which control fuel flow at mid- and full-throttle. They need to be changed because you have removed the airbox and the restriction it imposes. At low airflow speeds, typical of starting and idling, the airbox is not a restriction at all, so does not require any rejetting.

It's your bike. You know your tolerance level. You are the one that will have to decide how many times you want to do this.

To make things a bit more interesting, I just noticed your location. You are going to have to travel a bit to do the testing that is necessary when rejetting. You will need to do a few specific runs at mid- and full-throttle, neither of which you will be able to accomplish within the confines of NYC.

Good luck.

.

 

[TyeGuy]

Answer:



Don't f$ck!ng touch it and enjoy summer riding instead.

On a GS550, you'll want to manhandle the airbox or carbs as few times as possible, it's a royal PITA to get out/in. Add the iterative process of rejetting, and you have the recipe for much frustration.

It's involved, it's tedious, it requires a lot of spare time and energy.

Don't shoot yourself in the foot. You're free to, but we've warned you.

I knew taking out the carbs was going to be a bitch, and I experienced it first hand. But if I remove the airbox and filter and move my electronics else, I'll get more room to put in/take out carbs. At least, I'm assuming it would create more room.

 

[Steve]

Yes, you will have more room, but that does not remove the fact that you will likely have the carbs in and out a dozen times or more.

Have fun. :encouragement:

.

 

[hillsy]

Yes, you will have more room, but that does not remove the fact that you will likely have the carbs in and out a dozen times or more.

Have fun. :encouragement:

.

And not to mention you will probably strip a screw or two on the float bowls by the time you get "close" with the re-jetting

 

[bobgroger]

Let me fix that for you. :-k





Have you read any of the horror stories about rejetting? Almost NEVER do you hear of anyone saying " I just slapped in the new jets and the bike ran PERFECTLY." Rejetting is usually a tedious process of installing the new jets, testing. Making an adjustment, testing. Making another adjustment, testing. Maybe change another jet size, testing. Making another adjustment, testing. After you think you have it perfect, the weather is going to change and you will find that your "perfect" jetting isn't quite right when it gets ten degrees warmer.

Then you put the pipe on and have the "pleasure" of doing it all over. :-\\\

As far as not having the bike start: if you get to that point, you are not jetting correctly. There are four distinct jetting circuits inside the carb. The starting and idling (pilot) circuits are not usually changed. Your bike should start and idle just as well as it does now. The circuits that need to be changed are the needle and main, which control fuel flow at mid- and full-throttle. They need to be changed because you have removed the airbox and the restriction it imposes. At low airflow speeds, typical of starting and idling, the airbox is not a restriction at all, so does not require any rejetting.

It's your bike. You know your tolerance level. You are the one that will have to decide how many times you want to do this.

To make things a bit more interesting, I just noticed your location. You are going to have to travel a bit to do the testing that is necessary when rejetting. You will need to do a few specific runs at mid- and full-throttle, neither of which you will be able to accomplish within the confines of NYC.

Good luck.

.

I just slapped in new jets and it ran perfectly. Well, and the rest of the DynoJet kit too. Really. It did....

 

[Steve]

Well, I did say "almost never".

A Dynojet kit gets you pretty close.

.

 

[TyeGuy]

Let me fix that for you. :-k




Have you read any of the horror stories about rejetting? Almost NEVER do you hear of anyone saying " I just slapped in the new jets and the bike ran PERFECTLY." Rejetting is usually a tedious process of installing the new jets, testing. Making an adjustment, testing. Making another adjustment, testing. Maybe change another jet size, testing. Making another adjustment, testing. After you think you have it perfect, the weather is going to change and you will find that your "perfect" jetting isn't quite right when it gets ten degrees warmer.

Then you put the pipe on and have the "pleasure" of doing it all over. :-\\\

As far as not having the bike start: if you get to that point, you are not jetting correctly. There are four distinct jetting circuits inside the carb. The starting and idling (pilot) circuits are not usually changed. Your bike should start and idle just as well as it does now. The circuits that need to be changed are the needle and main, which control fuel flow at mid- and full-throttle. They need to be changed because you have removed the airbox and the restriction it imposes. At low airflow speeds, typical of starting and idling, the airbox is not a restriction at all, so does not require any rejetting.

It's your bike. You know your tolerance level. You are the one that will have to decide how many times you want to do this.

To make things a bit more interesting, I just noticed your location. You are going to have to travel a bit to do the testing that is necessary when rejetting. You will need to do a few specific runs at mid- and full-throttle, neither of which you will be able to accomplish within the confines of NYC.

Good luck.

.

​Thanks for the info about the circuits. I live in Brooklyn and there are some spots where you can open up for a while. I understand what you're saying, but its not like manhattan city blocks.

 

[TyeGuy]

Okay Okay okay. So its a PITA and very time consuming. Lets get back to the original question, and lets say that I was actually mentally prepared for the long haul and still wanted to rejet.

Would it be "easier", more beneficial to rejet both pods and new exhaust system together. OR. Install pods first, rejet properly, then install exhaust and rejet properly again?

 

[Guest]

Do everything at once. No point in going to the hassle of finding the sweet spot once, then doing it all over again to accomodate more changes.

 

[hannibal]

Let me fix that for you. :-k

Fair enough Steve. I'll say it this way: you don't want to rejet more than once.

 

[Steve]

Okay Okay okay. So its a PITA and very time consuming. Lets get back to the original question, and lets say that I was actually mentally prepared for the long haul and still wanted to rejet.

Would it be "easier", more beneficial to rejet both pods and new exhaust system together. OR. Install pods first, rejet properly, then install exhaust and rejet properly again?

To answer your question, I would like to invite you to simply go back and re-read posts 5, 8, 9, 17 and 18. :-k

.