Need technical advise/help from a pro !!

[CapeRace]

Hello..I'm relatively new to this forum and have a question that may be stupid but here goes. I purchased an 81 GS100GLX with an aftermarket exhaust that was in bad shape. I just replaced it with a V&H 4/1 and am concerned about jetting. I have no idea what size the current jets are,if they are stock,etc. What damage can I do by running the bike with the new exhaust. The bike starts normal and runs really well after a brief warm up and has tons of pull. The plugs are clean with no signs of running too rich,etc. As well it has the stock airbox (lid is on). Should I go through the cost of having the carbs redone...please I need some advise from the pros here.

[Nessism]

Carbs are not hard to deal with; paying someone to monkey around with them is a recipe for frustration unless they are familiar with the BS Mikuni's, it's much better to just learn to deal with them yourself.

As for your bike, you might be okay with just a simple main jet bump, and shimming the needles. Pretty simple work. Of course this assumes the carbs are clean in the first place and have fresh O-rings installed.

I suggest you drop Chef a PM and ask his opinion - he's super knowledgeable about rejetting and can even rebuild your carbs if necessary.

[bwringer]

Soooooo.... what color are those spark plugs?

[Guest]

Soooooo.... what color are those spark plugs?

Exactly. You need to do some plug chops and read the plugs at the various throttle openings. That will tell all.

[Guest]

Is this an 1100, 1000 or 100?
I do believe this motor came stock with
115 main jet
40 pilot jet
With the 4-1 pipe I'd go
122.5 main jet
42.5 pilot
shim the jet needle by removing the plastic spacer and replace it with two Radio Shack washers that are the same size as the washer under the clip.

[blowerbike]

why do anything if it runs well?????

[Billy Ricks]

If it already had an aftermarket exhaust there is a good chance a jet kit was installed if the PO did the job right. Look at the front of the carbs on top of the throats and see if there are any caps over the mixture screws. The slide needles will also have 5 clip positions if a jet kit was installed.

[Guest]

why do anything if it runs well?????

Shoot, I didn't even read all his post. Just assumed since this is the techy section.

New advice
If it ain't broke don't fix it.

[blowerbike]

Shoot, I didn't even read all his post. Just assumed since this is the techy section.

New advice
If it ain't broke don't fix it.

[Steve]

On the other hand ...

maybe he isn't running it hard enough to get into the mains.

Stock jetting works quite well at lower throttle openings.

.