Colortune and jetting

[cdanter]

Hey everybody! Just bought an awesome 1980sg from Bruce in Minnesota! She is in showroom shape but as some of you might have read in past posts Bruce gave her up due to a broken case! Well I am happy to report I welded her up and she purrs like a kitten! I am however concerned that her left two cylinders are running a bit lean as those two pipes are blueing. Her right two pipes are barely golden which I feel is not such a bad thing. I have spent several hours reading the jetting tips and posts related to bluing and jetting. My game plan at this time is to replace the intake boots for general purposes, inspect all the carbs checking for float height and jetting. From my conversations with the P.O. I have pretty much concluded that with only 17,000 miles, "North Star" as I have named her(Minnesota, her former home, is also known as "the North Star State") has had no more than routine maintenance. I am curious as to were is the best place to purchase a colortune. I am also open to all of the excellent advice you good people provide. I am really greatful and consider it a great privilidge to be a member of this fine organization. After all if it were not for this group "North Star" would never have come to my attention. I am even now hoping to join a Rally sometime in '05. My other project, named "Blue Bear" is a long way from completion. But now I have an excellent ride. Thanks for all you have done! Chad

[don07tncav]

Chad,
Nice to hear you got the problem fixed on that bike. I live a couple of hours North of you so PM me if you're up this way riding!
Don

[John]

Wow! Sounds like he's trying to butter us up with all the nice things he said about us.
The intake boots can be repaired by applying some Plasti-Dip to them with a small paint brush. It will flow out really well if you are in a warm area, and the product is warm. That will save you about a hundred bucks. You didn't mention what type of exhaust is on the bike...OEM or aftermarket. That will change the way the engine breathes. So will changes in the intake tract. Foam filter vs. paper, individual filters instead of the OEM airbox. As for the jetting, there seems to be some difference in opinion there too. My 80SG had different size jets in it when I bought it in 91. The outer cylinders have 110's and the innner ones have 120's. Or at least that's what the Clymer manual says. The 80 G model has 120's 115's. I've got the carbs from a 78E on mine right now, and I have 140's in them. The K.I.S.S. theory, ya'know.
You need to post some pics of it on your site, so we can all see it though.

[cdanter]

North Star is 100% stock! I plan on getting some pics of both North Star and Blue Bear up real soon! I am not worried about the 100 bucks well worth it! After all She is twenty five! She deserves it! Hoping a little tuning will solve the bluing! I am just not sure why just those two cylinders but I will resolve it!

[Pat Kelly]

I replaced my carb boots about 2 years ago ($100). They are now cracked.
Spray some carb cleaner or WD 40 around the carb boots while the bike is idleing. If the idle changes (stumbles or increases) then you have a leak. If not the the boots are fine and the plasti-dip will be cosmetically acceptible depending on your skill.
Colortune assists in setting your air/fuel misture. Jetting is best done by reading the plugs or following the advice in the "tech tips" section.

[cdanter]

Here is a pic of 'North Star" ! She is a beauty! Also a pic of the bluing! Thanks! Chad

[randy]

WHOA!

17,000 mi and completely stock?!

If I were you, I wouldn't fool with the jetting until you find out why you're not gettin enough fuel to #1&2. Such as:

Clogged petcock screen?

Pinched petcock vacuum line?

Shredded petcock / octopus vacuum lines?

HTH

Randy

[cdanter]

I need to add fuel delivery to my inspection! Thanks Randy! I had not planned on rejetting unless it was the absolute last thing left. I just feel that a good carb clean and inspection may find a small issue. I don't believe this bike has ever had the tank off! I am not sure but I dont want to do alot of riding until I am sure I am not doing any damage! But you got me thinking now! Being that both of those cylinders are fed with the same fuel delivery I may be somehow starving that side a little! Thanks for the input! Chad

[skids]

The other thing that is common to #1&2 head pipes is its down-wind hardware. Make sure that the exhaust system is airtight from the head gaskets all the way to the end. It is possible to have a cracked weld, holes in the muffler, or a crapped-out baffle. Sometimes you can tell that the baffle is shot because it will rattle when you bump it with the side of your fist. If the muffs are removable, take them off and hold them up to the light to look through them. You should not be able see clear through tem and if you can, the baffle is completely gone.

Originally posted by randy
WHOA!

If I were you, I wouldn't fool with the jetting until you find out why you're not gettin enough fuel to #1&2. Such as:
Clogged petcock screen?
Pinched petcock vacuum line?
Shredded petcock / octopus vacuum lines?
Randy

[cdanter]

I would have never thought of that! Now that you mention it, after I repaired the case on this bike I went for a few short rides and noticed a rattle coming from the left rear. I did not think that it was anything serious and was going to investigate later. May be more important than I thought!

[Pat Kelly]

Exhaust leaks also sometimes show themselves by a 'popping' sound in the exhaust note when deccelerating.

[John]

I would look at the fuel line downstream from the octopus. There may be an obstruction/kink in the hose supplying the lean carbs. A restricted petcock shouldn't cause a fuel starvation problem. I have removed my octopus a long time ago, and the way I have the fuel lines plumbed, I can can feed all four carbs from just one petcock. I do it all the time, and most of my riding is done at 70-75 mph. Correct me if I'm wrong, I've never had the octopus apart, but doesn't the fuel feed into a small chamber, then is routed out to the carbs, or is each inlet port dedicated to an outlet port?

[cdanter]

Hey everyone! Just wanted to give an update on what I found today while examinig North Star's fuel system. Check out these pics!





I believe I am going to replace all the fuel lines with something that feels more like fuel line than vacuum line!

[pathfinder]

Tygon

Go for the Tygon Yellow lines on the fuel and also add those little fuel filters inline. They are a tapered clear plastic cone with a copper colored filter inside so you can see what they are catching. The way to route them is petcock on right feed carb 1 & 2 on the left, then left petcock to 3 & 4. That way they wont get kinked. Just don't make them too long or they will.

[cdanter]

Thanks Pathfinder! That confirms it! I was debating on fuel line choices and had already decided to criss cross the sides. Was also planning to add the in-line filters too! So now I just need to find some clamps that i am happy with!