Dial A jet tuning??? Has anyone tried it?

[grizld1]

Re. boots--hotrdd, if you'd processed the reading you claim to have done you'd know how to check them, the procedure is in the XS650 Garage Carb Guide. OE boots were made by ARS, and they're still available from 650 Central and any dealer who sells parts from K&L Supply. They've held up to decades of 10% ethanol fuel here in Illinois.

 

[westonboege]

Agree with grizld1 - Get boots from 650 Central not Mikesxs... Ive had two or three sets from mikesxs and they disintegrate pretty quickly. Chinese rubber probably...

Not trying to hijack... the bars arent made for x-country... i have other bikes for that... this is just a bar hopper...

 

[hoffman900]

This dial-a-jet won't instantly fix your problem, in fact, it adds another level of complexity.
Properly tuned carbs work fine, you're still in the tuning zone, keep at it

+1

Also, depending on your exhaust and intake parameters, you could be causing the 'flat' spot. This is especially true for those not running mufflers or some sort of proper megaphone / reverse cone (megaphone mufflers are not this).

 

[hotrdd]

I've tested the boots and been through the Carb guid step by steps dozens of times. I'm now at the point where the bike runs good just not perfect and I'm trying to tune out some of these issues.

Thanks for all of the help guys.

 

[Bloody D]

i lost hope tuning my bs38's i have an innovate wideband tuner. have a tail pipe adapter i ran. my biggest problem was having a balanced tune. the closest i got them was with mismatched jetting and air mixture turns. swapped for a set of bs34's i overhauled, so far it idles way better. havent tuned yet.

is your plug black? im also going to say since u been messin with it u have your timing and valves adjusted proper?

 

[5twins]

There's just no tuning some of these perfectly if the combination of components you choose to run is way off from proven items that work. Things like straight pipes, pods, 2-1 this, 5-6 that, 10-12 something else, they all make tuning more difficult. And combine a bunch of them, well, good luck with that. Chances are, you pay that shop $500 and they won't be able to tune it either, lol. What you've got may be as good as it gets.

 

[DogBunny]

My two cents are that if the throttle plates aren't centered right, and/or their bores aren't well matched, you will never get the carbs to idle and pull in the low RPMs right, no matter what you do. What I mean is, back the idle and or synchro screws out until the plates can fully close, snap them shut, hold up to a strong light, and carefully look at where the light is shining through. Comparing the two carbs, the amount and placement of the light gaps should be very nearly identical.
The other thing I have seen more than once that will thwart all efforts to make carbs idle and pull in the low RPMs correctly is screwed up air mixture screw hole openings. If you shine a light in the air mix screw hole, you should see a tiny orifice at the end of it. If someone screwed up that orifice, than the carb is screwed.

 

[hotrdd]

So I tried a few different things this weekend. Mostly because I had a shop full of guys with nothing to do. So I put them to work and I played with the bike

1) Anyway I checked the plates with a bright light and a feeler gauge and they are dead on identical.

2) I pulled off the homemade 1-2 intake and replaced with individual filters.

3) Pulled the plugs and they showed black with Carb.

4) Pulled the mains and they are 127.5, so I looked through my stash of parts and of course I have 130, 132.5, 135, 137 BUT nothing smaller.


So right now I am running the straight pipes that have about 18" of Vance & Hanes baffles in them with uni filters on the BS38 carbs.

I'm running 127.5 in there right now and the majority of my riding is on the HWY at about 5K RPM and 5th gear. I'm assuming that if the plugs are black it means that the mains are too rich? Does 127.5 sound likes it's to BIG? What was stock for the BS38's?

 

[weaselbeak]

A new single carb and 2 into 1 manifold wouldn't run 500 bucks, and you'd have a new carb.

 

[itrguy]

My single vm36 runs Awesome!!

 

[grizld1]

Stock for which BS38's, hotrdd? I thought you wrote, twice, that you'd read the Carb Guide. Read it again--year-by-year jetting specs are there for every setup used in US models. Changes are due to emissions compliance and other factors, not to changes in engine demand.

Baffled straight pipes yield the worst of all possible worlds: heavy restriction and narrow power band. All you get is "the look" and lousy performance.