Replaced Battery,Bogs at 5k;now Eureka!!!!

[ScottS2488]

just thought I should clarify a couple of things just so you know I'm not stubborn....

1) the carbs in my bike are from a 1980....they came with 110 main jets...the guys who worked on them put in 137.5s to match 78 specs...wonder why it's running rich..............

2) I am running a stock airbox with a K&N filter.....I tried individual filters 2 years ago I was describing my experience with those filters

3) I checked the advance wires....no stretch in them

4) the bike was idling rich and running a little bit rich with the old filter and the 110 mains......couldnt idle for crap but still got 35 mpg on the highway and could go about 190 kmh top end.....LAST MONTH

5)now the carbs have the needles all the way lean with the 137.5 mains......idles great, still a little rich.....top end is 140 kmh

6) the floats are sitting pretty close to 25 mm...they are black plastic and it looked like someone set them way too high...they have some really dorky pin on a wire setup to cut off the flow...they weren't seating worth crap so I set the floats using the 78E specs

so there's the story...all I'm trying to do now is find a logical way to select the proper mains and run the needles at centre position
instead of trying up to 11 different sets and going by trial and error.

TIA

[ScottS2488]

and wait! there's more.....checked the idle screws tonight....they were only out 1 1/2 turns.....set them out 2 1/2 turns and synched the carbs...can get up to 6000 rpm now

[TopCatGr58]

Alright, now we're getting somewhere!

Hey there Scotts,

That info is what you/we needed!!!! It doesn't matter what year the engine is, what matters is what year the carbs were!!! They changed from 78-79 to 80-81, the pilot/idle circuit gets its own supply thru a separate pilot jet, and it is controlled still by the pilot jet screws that you have turned out to 2 1/2.

Those 137mains are WAY TOO big for that year carb. With stock box and "assuming" stock pipes, the 110's were about what you needed to begin with!!! Perhaps you could go up to 115 or 120's, but that would be it, definitely not 137!!!!!

That little wire clip on the tang of the float was to keep the valve needle attached to the float tang so that when the float dropped it would PULL the valve open instead of relying on gravity pressure from the fuel lines to start the flow coming into the carbs, as well as keep it in position so as not to fall out!!

You stated with the 110's, that it was idling rich, but that was before you had adjusted the float height, and before you had adjusted the pilot/idle screws!!!

I would suggest you put the 110's back in, reset the needle jets to middle, then tweak the pilot screws, and see how it behaves. With your floats set lower/leaner, that may have been all you needed to do to reduce the richness of the idle, just hope you don't have them set too low so that you run the bowls dry on a long high rpm run?

And tell your mechanic to read the manual!!!! Geez, I've got a little big bore in my 81SH, 4-1 pipes, Indy filters, and I only have 117.5's in mine, want's to eat the redline in every gear!!!
T.C.

[ScottS2488]

ok..1 more thing....the pipes I run are 4 into 2 15" slash cut...with no restriction....baffles are like a perforated tube on the inside so the flow is unimpeded....would that call for a couple of sizes up from 112?

[TopCatGr58]

Hey Scotts,

According to the jetting guide, you would go up 2 sizes for the pipes, or 2 sizes for Indy filters, and if you had both, you add the two changes together, but subtract 1= 3 sizes.

You've got the stock box, but a nice K&N filter so that would breath a little better=leaner, along with the nonrestrictive pipes needing 2 sizes, so I would think 3 sizes would be a good point, starting from you stock 110's, going up to 117.5 should get you pretty near the ball park, then you can tweak your floats, your pilot screws and your needle jets depending on how it behaves in the three zones; idle, low-mid, and W.O.T. !! Good luck, keep us informed, we like to hear success stories!!
T.C.

[ScottS2488]

thanks so much.......it feels like I'm on the right track finally.....I'll let you know how it goes

[ScottS2488]

I put in 117.5s today and fired it up and went for a spin......local dangerous driving ordinances persuaded me to keep the revs at 8500 and 100 mphish......then I came home and synched the carbs..........

[TopCatGr58]

Awesome,

Amazing how much better both us drivers and our bikes behave when we don't GUZZLE the fluids too much!!!! Congrats!
T.C.