Carb sync gauges to avoid??

[Steve]

On CV carbs these are different diameters; the vacuum plugs are 5mm, normal .80mm pitch.

It's the same on all GSes, regardless of carb type.

The carb drain plugs are 6mm, but an oddball fine pitch; I can't remember offhand the thread pitch used on these, but I suppose someone will be along soon who does know.

The bowl drains are M6 x 0.8. That is the standard "fine pitch" for M6. I need to order one of those taps. I have an M6 x 0.5 tap for chasing threads on the pilot screw, but it does not work for the drain screws.

The plastic adapters work fine, but it can be hard to grab hold of them. You can add a short piece of tubing to help reach and thread them in. The brass ones from Motion Pro are longer and somewhat easier to grab, so that's what I typically use.

I have heard that the reason the Carbtune uses the nylon adapters is to minimze the possibility of cross-threading the ports. I got my Carbtune used, and it came without adapters. Fortunately, I have some brass adapters for my mercury sticks, so there ws no problem.

MP also sells brass adapters that you could leave in place; the trouble here is that the crappy rubber caps they supply quickly deteriorate and fall off.

I don't know if they are the same thing, but I got some of those 'permanent' adapters from Z1. I installed them on my bike, then went for a ride. When I stopped for a break, I noticed that it was running a bit rough. I looked at the engine and saw that one of the caps was missing. I had some electrical tape in the trunk, so I covered the port and went to an auto parts store to get a vacuum port cap assortment. The next morning, I started the bike. While it was warming up, it did its usual hiccup back through the carb and I watched another cap disappear. I went through the selection of caps to install the absolutely TIGHTEST fitting ones. They got spit off, too. If your bike absolutely NEVER spits back during warm-up, the permanent adapters might work, but I removed them from my bike about a day after I installed them.

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[748cc]

"The bowl drains are M6 x 0.8. That is the standard "fine pitch" for M6."

I was assuming the drains were M6x0.75 due to another thread related to the plugs...need to confirm as I try sourcing some nipples. Nonetheless, if the adapters don't work there then so be it. Thanks again guys for everything!

[Steve]

I’ll check the thread pitch again.

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[748cc]

I based my thoughts on post no.3 of this thread:

https://www.thegsresources.com/_forum/showthread.php?222912-Float-bowl-drain-and-fuel-height-level-adapter

[Steve]

OK, I have checked a drain plug. I did not get a picture, but my 0.75 gauge did not fit.

I'm having a bit of difficulty trying to match up a 0.8 gauge because Harbor Freight strikes again.



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[Rob S.]

I'm having a bit of difficulty trying to match up a 0.8 gauge because Harbor Freight strikes again.
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Yeah, but look at the bright side. They probably sent you a coupon for $1 off a five-foot tape measure.

[Steve]

Hard to get $1 off when it's already free.



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[748cc]

Yeah, but you had to purchase the faulty thread gauge in order to get the free tape measure . . . see how it works? It's their apology to the skunked consumer.

[Tom R]

I like my carbtune but don't like the little plastic connectors. Buy the motion pro brass connectors and then you have a good setup. They make getting to the inside cylinders easy.

Mine came with brass connectors.... I don’t know why they vary on that.

[Andrew Vanis]

OK, I have checked a drain plug. I did not get a picture, but my 0.75 gauge did not fit.

I'm having a bit of difficulty trying to match up a 0.8 gauge because Harbor Freight strikes again.

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It IS 6 x 0.75

[748cc]

I'd have to wonder how accurate the HF's gauges are at this point... consider throwing them away (in fact dismantling them) and buying a quality set, Steve...for your own sanity . I should locate a set for myself soon. Starret would be best, no??

[fbody_mike]

20190909_185304.jpg

Got mine today, less than a week from Belfast to Los Angeles.
Oh mine came with brass adapters