Progress!!! 1978 GS1000E Restoration/Performance Rebuild

[philosopheriam]

Thanks again for all of the replies - random question: does anybody know if the stock needles in the RS carbs are viton tipped?

[Guest]

An amazing restoration. Congratulations on your hard work, attention to detail and beautiful bike!

Cheers!
K

[steve murdoch]

According to this chart from Jetsrus they are metal tipped not viton.

https://www.jetsrus.com/needle_valve_float_bowl_gasket/needle_valve_and_float_bowl_gasket_mikuni.html

About half-way down the page.

[Guest]

Such a beautiful restoration, Congrads!

[growler]

It was such a pleasure to sit back and watch this restoration. Not only did you document it, but with detail and excellent photos too. Much appreciated. Now go have some fun on that thing!

[philosopheriam]

According to this chart from Jetsrus they are metal tipped not viton.

https://www.jetsrus.com/needle_valve_float_bowl_gasket/needle_valve_and_float_bowl_gasket_mikuni.html

About half-way down the page.

Thanks Steve - the plan for this weekend is to pull the carbs, check all the float heights, check the needles/seats for gunk, and re-enable the accelerator pumps.

I'm debating replacing the needles with viton-tipped ones, as I have access to an entire assortment of them in different sizes/lengths.

[philosopheriam]

Well, I think I just made my first minor mis-step - I have my pilot fuel screws set at 2 turns out. According to the documentation on the RS series from Mikuni, the adjustment range is from 1/4 to 1/2 turn, no more.

See page 2 or 5

http://www.mikuni.com/pdf/rs_app_parts_lists.pdf

Without thinking, I have been looking at the HS40 tuning manual from Mikuni, which outlines general tuning procedures for their carburetors. The adjustment range for the HS40 is 1/4 to 3 1/2 turns. Stupid me...

When I pull the carbs this week, I will reset the screws to 1/2 turn and see how she idles. If she still runs lean I may have to up the size of the pilot jet from a 17.5 to a 20

Derp...

[philosopheriam]

Update, 5/27

Installed a #20 pilot jet and set the pilot fuel screw to 1/4 turn. Checked all of the float heights and set them to a hair under 18mm (spec is 17mm +-1mm) Enabled the accelerator pumps and have them coming on at just over 1/4 throttle and ending at 3/4 throttle. Replaced all of the bowl vent lines and fuel tank drip line to Tygon. Added a pair of Motion Pro quick disconnects to the fuel lines for ease of removing the tank. While I was setting the float heights, I cleaned the needles and seats really well - I'm happy to report that I no longer have any weeping through my bowl vent hoses.

Took the bike out for a 10mi ride today and all I can say is WHOA!!!! Had her up to around 55 going through some industrial parks and around town. 1st and 2nd gear roar, and my butt can barely stay planted in the seat when I nail the throttle. The sneezing through the carbs that I described in my earlier post is 90% gone, and the #20 pilot jet helped immensely - I am going to open the pilot fuel screws an 1/8 turn and see what happens, hoping to eliminate the sneezing completely. After I test this, I tweak the accelerator pumps a but and have them come on a tad sooner and see what effect it has on the throttle response. I have a sneaky feeling I may need to raise the needles by one slot, but I am going to leave this for last, as I am more concerned with the pilot system and performing a vacuum sync first. Can't wait to take her for another spin tomorrow!

[Guest]

Great news, I bet that ride felt pretty damn good.

[Guest]

Is that your breather return K&N sitting above the carb filters?

[Nessism]

Dyno carb tune? I'd break in the engine first but verification of the mixture would be good.

[philosopheriam]

Is that your breather return K&N sitting above the carb filters?

That's my crankcase breather - made a small bracket to mount a filter and ran a hose to the valve cover. Have pics buried somewhere in this thread :-)

[philosopheriam]

Dyno carb tune? I'd break in the engine first but verification of the mixture would be good.

I need to research a shop with a dyno out by me (Aurora, IL) - that would be the best way to tune this beast. If the exhaust had a bung in it for an O2 sensor, I'd contemplate using a wideband monitor to tune it...

[philosopheriam]

Great news, I bet that ride felt pretty damn good.

It did - every time I go out I push the bike a bit harder, then stop, then check for leaks/loose bolts/problems, and then continue again. Next ride will be out on the highway so I can open the throttle a bit more

[80GS850GBob]

I need to research a shop with a dyno out by me (Aurora, IL)...

Let me check with the guys from the cruise nights....I'll get back to you.