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Registered
1991 VT600 VLX
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61 Posts
Discussion Starter #21 (Edited)
Another update.

I took out the carbs, and set the float level to spec (7 mm). Rear carb was off by a fraction (~7.5), and to my surprise - front was also off to leaner side at ~8.2. So if I am not mistaken - the front was already running a little leaner due to the float sitting lower in the bowl. I don't get it.

I also took out the choke valves to make sure they move ok - which they do. Gave the cables a drop of oil and put it all back.

And well - it didn't idle as before, had to turn it up a little. I can feel a little moisture coming out of rear cylinder's pipe when accelerating, which looks to be fuel.

Also - some popping is back on deceleration. As I didn't touch the idle screws today, I believe they are off the setup again with the correct float level. But again, if popping means "too lean on idle", and I just added more fuel to the bowls... Then I don't get it.

I'm confused, need to think. And thanks if you help me notice what I'm missing here.

P.S. I forgot to pack my spark plug wrench, so didn't clean the sparks today for a test drive to see what's cooking inside. Another option is just to go for a new set of plugs - maybe the front ones got too much fossil on them. Or I just need to go back to stock main jets, and a half turn on the A/F screws and conclude, that jetting ends there :)
 

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Registered
1991 VT600 VLX
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61 Posts
Discussion Starter #22
Another update to my "rejet blog".

After riding for ~400 miles, the spark plugs in both cylinders look in very good shape and identical - white with some "chocolate". I guess the mixture is finally good. Motorcycle responds well in all range of RPM, slow or quick acceleration, doing it like on Sunday morning or spinning 2nd gear up to 60 mph. All is amazing! Well except some random popping on decel, but will fix that with another 1/4 or 1/2 screws out.

MPG is back at 4.2-5.2 liters/100 km, depending if it is 90 kmh or 110+ kmh.

Having all that in mind that it runs, why not starting messing up again, right. So I removed the baffles to regain some crazy decibels, and started playing with the lollipops. The first variant is eye bolt. Yes I know, the middle is open, but that is exactly what I want to test. It still limits ~1/3 to 1/4 of pipe diameter, so I want to start somewhere. The next step would be a small loop with closed middle. Let's see how it responds on low-mid range (so far no hesitation - it just flies!).

P.S. I do it because I like to experiment and learn. I guess I found the almost perfect tune for the current setup, but why not play a little more. At least I know how to come back to a well working state.

287434
 

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Registered
1991 VT600 VLX
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61 Posts
Discussion Starter #23
I stopped wasting time on the straight empty pipes, as it started hitting me back on my ears. Cobra baffles are in & I just enjoy the ride now.

And guess what after all the struggle - the MPG is back! I was doing 85-98 miles with those slim 7 liters of fuel before hitting reserve, on a 1000 miles trip a couple days ago around my country. I am yet to check the sparks, but anyways - I am happy with the MPG, and if sparks looks right - I will just continue riding it.

P.S. have you seen Chernobyl TV series? This is where it was filmed (along with other filming locations in my hometown) ;)

288400
 

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2007 VT750DC Spirit “chopper”
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673 Posts
As far as your plugs go the rear looks great, front is pretty darn close, just needs a tad less fuel. Factory jets in a lot of cases(Most) are tapered from front to rear with dual carbs, with the larger being in the rear to help facilitate cooling since it’s not directly in airflow, if it were me I’d change nothing but try 2-4 steps lower of a jet in the front, like a DJ111 or 112. Most all factory jetting is tapered a few sizes, I tried running dual 135’s in my 750 and had similar looking plugs, dropped to a 132 in the front and plugs almost match perfectly now.
 
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