1200cc engine, VM29 carbs, Pods, what jetting?

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Nessism wrote:

Problem one, can't find Jet Block Gaskets.  

It's really going to be a problem that Sudco is gone. Not good.

How about these?


376490546198

Yeah, there are some jet block gaskets out there that look homemade.  Kinda expensive.  I ordered a sheet of thin gasket paper.  The original gaskets are .005" thick.  Some thin paper would likely work as well.  In the past I made some out of thick velum drawing paper, after testing it in gasoline for a couple of days.

127.5/25 jets ordered from Niche

O-ring/gasket kit ordered from Joe's Carb.

Also, have gasket paper on order, as an experiment.

Thanks to all that contributed.

BTW, my house stinks like Berryman's carb dip.  ARG!!!  After dipping the carbs, rinsing in a bucket of water, soaking for an hour, I bought the bucket inside and did the final soap scrub in the kitchen sink.  MISTAKE!!  Just the random rinse off, after a soap scrub, stunk up my whole house!  Ha ha.  Good thing I'm a bachelor, or maybe I'm a bachelor because of crap like this?  Ha ha.  

Nessism wrote:

Yeah, there are some jet block gaskets out there that look homemade.  Kinda expensive.  I ordered a sheet of thin gasket paper.  The original gaskets are .005" thick.  Some thin paper would likely work as well.  In the past I made some out of thick velum drawing paper, after testing it in gasoline for a couple of days.


 

I am pretty sure I have a small roll of velum left over from my days on the board, even had a board here at the house for about 10 years before finally selling it when they were still in demand. The last time I saw a board was at Reproduction Decals office, he still does decal patterns at scale by hand.

As for the gas mileage on that particular type of engine, you maybe be around 30 MPG or lower. I know when I was running a big pilot jet on my 831cc engine with 33 flat slides it was horrible like that, at least 20 MPG down from stock.

Injected wrote:

What they don't give you there is the pilot air jet setting but that depends if it has the stock air screws, which have a tiny hole in the tip ends that lead to a cross drilled hole. Some owners replace those with normal VM air screws or solder up the holes. With the stock air screws you will find 1/8 turn out as a good start up point, I think max adjustment is 1/4 turn out (not like regular VM)



 

The carbs are going back together.  Still waiting on the jet block gaskets.  Anyway, setting the pilot air screws and rereading this.  1/8 of a turn is barely cracked open.  Is this correct?  Reading around, various sources, suggest roughly 1 turn open.  Please provide more feedback...

 

That was something wired George stated. I am not sue it is a hard and fast rule as such, I have always felt like since it has the hole (so do some of the 33 carbs air screws) depending upon where the hole lines up it allows more air to pass than a solid (without hole) air screw does. I think I have read some posts here and elsewhere where some have filled the holes and then used them like non-holed air screws

Damage on one slide.  Send it?  Or replace?  

EDIT: the photos make the other 3 slides look worse than they are.  All 4 have scuffs on that one side, but only one has wear through the chrome.  

Nessism post=921004 userid=14026

wrote:

What they don't give you there is the pilot air jet setting but that depends if it has the stock air screws, which have a tiny hole in the tip ends that lead to a cross drilled hole. Some owners replace those with normal VM air screws or solder up the holes. With the stock air screws you will find 1/8 turn out as a good start up point, I think max adjustment is 1/4 turn out (not like regular VM)






 

The carbs are going back together.  Still waiting on the jet block gaskets.  Anyway, setting the pilot air screws and rereading this.  1/8 of a turn is barely cracked open.  Is this correct?  Reading around, various sources, suggest roughly 1 turn open.  Please provide more feedback...
 

I think that may have been a typo on my part. I believe the maximum adjustment on those is 1 turn out if you do indeed have the stock screws (see pic of Sudco pages)

I started my 1200 up using 1/2 turn out on the air screws (stock type) and found black plugs, so I turned them down to 1/4 turn out. I still had black plugs, so I changed to a smaller pilot jet but have not restarted it yet.

I have a unusual setup as I am using a 4 into 2 exhaust with a air box, so I believe it needs a really lean idle jetting as the exhaust/filtration are restrictive. I confirmed the pilot jet/air screw setting with a Color Tune plug, but in the Spring I am switching to a handlebar AFR gauge.

Since I am not using pipe/pods the suggested jetting is way out of wack. I believe right now I have installed some #17.5 pilots and #127.5 mains. I started it on #22.5 pilot jets thinking better rich than lean. On that engine I have big valve full ported head and .425" lift cams.

They will work at 1/8 turn out, I read that on here when WiredGeorge chimed in on the VM33 thread. Just make sure you pass a guitar string thru the tiny end holes on the tips of the air screws before and after any cleaning.

Just realized that the slides on this set are 2.0's.  KZ bikes commonly use 1.5's.  Is this going to matter on a modded bike?  Any jetting compensation needed?  

Nessism wrote:

Just realized that the slides on this set are 2.0's.  KZ bikes commonly use 1.5's.  Is this going to matter on a modded bike?  Any jetting compensation needed?  

Sounds like they are Suzuki carbs. That cutaway will make them run slightly leaner all the way up to 1/2 throttle. You never want to run a modded engine on the lean side.

Your probably going to have to richen the jetting in those throttle ranges. I believe I have seen some Mikuni charts on this, they have charts on all those circuits.

I have a Sudco manual that shows that stuff specifically for VM33, will look it up and let you know.

I found these pages on throttle slides in Olav Aaen's carb tuning handbook :

 

Not sure if its going to help, the same mixture chart is in the Sudco Mikuni manual. It starts at 2.0 so you can't see any % difference to make jetting changes for the cutaway angle difference.

The new 1.5 slides came in.  When swapping them over, I noticed that the worn slide was secured with one screw that was allen head.  Not the stock screw.  Can't say this caused the problem, but it's suspicious. Maybe one of the original screws came loose, allowing the slide to flop around?  

Set the needle clips in the middle.  Someone stop me if this is wrong.  The owner also sprung for a brand new set of Mikuni brand float valves, so that should provide a solid foundation.

BTW, the Joe's carb kit seems nice.  I'm not a fan of rubber float bowl gaskets, but they are well executed.  The jet block gaskets look great.  I think the same material was used as I purchased separate.  I'm going to save that for a future project, not this one.