You might find this article interesting:

http://blog.jpcycles.com/the-great-oil-debate-synthetic-or-conventional/

Christof13T wrote on 03/03/18 at 02:16:08:



That makes sense then, keeping it easier.
47mpg is pretty good if you are running 70-75mph.
What is your needle setting ?
White spacer ?  Shaved ?  or washers ?

In case you are interested. The Suzuki standard slot width in the needle is .9mm, about .035". Our bikes sadly only have the one slot. But the measurement gives one an idea of how much to raise the needle when tuning.

Hope this will help your efforts.

Christof13T wrote on 03/01/18 at 17:59:38:



batman wrote on 03/05/18 at 10:11:56:

What makes you think he needs a main jet bigger than a #150?

Getting closer and closer...

I was pretty much convinced it was not getting enough air with that little RYCA pancake pod filter. I decided to play around with that big honking cone filter idea again...

I read the thread dood just posted about having too big of an air filter and the symptoms he described were exact mirrors of what mine was doing with the big cone filter installed.  His attempt to restrict airflow gave me the same idea. I pulled out my trusty roll of t-rex duct tape and proceeded to use it to block off about 3/4 of the filter element starting at the end, working back toward the mounting flange like opening. I started with just a single wrap of the full width tape and went to test it... it responded to the restriction and I got an extra 10mph out of 1st gear before it started stuttering.  Another overlapping wrap of tape to get to that 3/4 ish mark and tested it again... pure brilliance! She wraps all the way up through the rpm range with balls to the wall power without hiccups!

Next quest...

70+mph oomph!

I went ahead and threw in the 55 pilot... and after a test ride felt it could probably do with a bit more fuel at the top end. It would get to 70 and again just fall on its face...

So I huff and puff... just tired of opening that darn carburetor so much... and go out this morning to swap in the 155 main.

And boom goes the dynamite!

It now comfortably maintains 75 ish with room in the throttle.
I will have mileage numbers in the morning when we stop to fill up.
I'm already just assuming it will have dropped to the high 30's. It's added pep has enboldened the rider to more enthusiastic throttle control...

P.s.
Batz,
It is past the 1500 mile break in period. Back in service @ 4333.0, currently @5864.3.

I know it sounds ludicrous.  I would not have believed it myself until it worked. Without some restriction on the intake, the slide will not operate.
I have tried every jet combination I have with it unrestricted and get exactly the same result every time. As soon as I taped up the filter, problem was cured. So it seems for at least 2 of us, restriction at the intake is necessary.

I think it may be that the motor is to "free flowing " it hasn't got enough backpressure due to the muffler (or rather the lack of a decent muffler) that both these bikes share. neither of the bikes started their builds by first securing a proper exhaust system. both would benefit more from restricting the exhaust rather than the intake. while both bikes may run fine at higher speeds due to the increased vacuum in the carb pulling added fuel from the jets, what they don't understand is this will probably not work at all at lower speeds ,where they could be running dangerously lean, when there restrictors ,slides and throttles are all cracked open almost equally ,  there is no added vacuum to enrich the fuel mixture.while theywere busy trying to obtain the speed of 75 -80 they haven't considered what the bike is doing at 35-40 in town traffic.