Jet kit and petcock questions for my 81 450

[David.Seth]

So I have an 81 450L, and I'm going to start working on it in the next couple weeks. I'm running into 2 issues though.

First is that I want to replace the original petcock with a new one, but all I can find are rebuild kits (well, I did see a whole new assembly at BikeBandit.com , but I've heard from a few people that its not a reliable site). Are the rebuild kits good enough, or should I just get a new one from bike bandit?

Second thing is that since my exhaust is not stock, its running really lean. So I wanted to get a jet kit for my bike. But everywhere I look, I can't find any that would work on my carbs (BS34SS). At the DJ website, there kit will only fit an 83. I did find this kit on Ebay, but I don't know how reliable it is... So my question is, what are my options for jet kits? Do I just use a universal? Will other year kits work in mine? Or could I buy some used carbs from an 83 and jet that? (and if I did do that, would the 83 carbs fit mine?)

I guess worse case scenario is that I just get some new stock exhaust, but that seems like it would cost a lot more then just jetting a carb.

Anyone willing to give some advice to the novice?

[almarconi]

I've never had good luck with petcock rebuild kits. Try z1 enterprises for a new petcock. You can also try partshark or babbits online they sell oem parts.

If a jet kit is not available, mikuni jets are available for a few dollars each. If you are running aftermarket exhaust with a stock airbox, I'd bump the main up a couple of sizes and shim your needles. When you buy jet, purchase a couple different sizes. Once you install the jets, you can do plug chops to see if you need to make any changes.

[David.Seth]

I've never had good luck with petcock rebuild kits. Try z1 enterprises for a new petcock. You can also try partshark or babbits online they sell oem parts.

I tried Z1, they only stock the rebuild kits for my bike. But partshark had it, and cheaper then bike bandit. so thanks for that tip!

If a jet kit is not available, mikuni jets are available for a few dollars each. If you are running aftermarket exhaust with a stock airbox, I'd bump the main up a couple of sizes and shim your needles. When you buy jet, purchase a couple different sizes. Once you install the jets, you can do plug chops to see if you need to make any changes.

Ah, didn't realize I could buy the jets individually. Is there a good source for mikuni jets? Just checked z1 and they didn't have them. Also, not to sound like a dumb, but... what are plug chops?


Thanks for the info though, I really appreciate it.

[almarconi]

Mikuni jets from z1 enterprises (yours should look the same, BS34 are used on the GS1100)

http://www.z1enterprises.com/SearchResult.aspx?All=True&KeyWords=mikuni%20jets

Also look here

http://www.jetsrus.com/

Plug chop (same principle for our motorcycles)

http://scootrs.com/tech.cfm?tip=plugchop

[David.Seth]

Ah, well, I guess I should have used the search function at Z1 I kept looking at the parts offered for my bike specifically. Oh well, thanks again.
So on Z1's site, all I see are main jets. Do I only need to replace the main jet? Or do I have to change out the others as well?


And now that I see the plug chop method, I will definitely try that.

Thanks again for your help!

[almarconi]

Do I only need to replace the main jet? Or do I have to change out the others as well?

About the only other one you would need to change might be the pilot jet but I seriously doubt it. I keep spares in case I damage one when removing it. You would want to increase your pilot jet if you were still lean at idle and your mixture screw was like 4 turns out. Then you might want to go up one size on your pilot but for your situation you should be fine with the stock pilot.

If you haven't done it yet, check your valve clearances. If these need to be adjusted then you will need to readjust your carbs anyway. I usually adjust the valves, set the idle mixture with a colortune (or highest idle method), and then vacuum sync the carbs.

Before jetting make sure your carbs are properly cleaned. If the carb o-rings are original, replace them. I believe your engine also has carb intake o-rings which should also be replaces (they leak when they get old). They are the ones between the block and the carb holder.