Float set, 28.5mm suggested so what would 30 mm act like?

[Maxnewby]

Just got back from initial test run around the block, from start up this morning same as last evening weak idle, verified by touching header R-front cyl is the only one while idle. Add choke lever revs up normal. On road around block perfect!! V boost kicks in @ 6k and couldn't run better. Back to idle! weak. F/A screws make no diff on other 3 and very little on #4. Remember with sync gages hooked up L side sync screw barely moved gages between 1&2 and neither of 2 sync screws did anything on the R-side. I'm taking it on a shopping trip to find O rings for A/F prior to another take apart. Thank You all who gives your time or experience.

 

[Maxnewby]

Good old Harbor Freight 4.99

 

[Maxnewby]

365 views! half of ya must have said I will remember what that cheap sob used, or would you not use such stuff.

 

[Fire-medic]

If it fits and doesn't deteriorate then no reason not to use it, I suppose.

Problems like you complain about at idle are often due to not clean carburetor passages, and require an ultrasonic soak or sometimes two.

You say "at idle, 3 dead cylinders," I'm surprised that it even continues to run at that. I'd believe that the drag of three 'dead' cylinders not firing, would just kill the engine.

https://dn790009.ca.archive.org/0/i...ice-manual/yamahavmaxvmx12-service-manual.pdf

Use the factory service manual and give the carbs a disassembly and ultra-sonic bath, and then scrupulously rebuild the carburetors according to the manual. I know that sometimes I've had to throw the carbs back in the ultrasonic tank if they don't function properly. Rare, but it can happen.

I will use K&N carb parts but I would NOT use the 'all four carburetors in ONE giant package!' generic carb kits from Amazon or ebay. Order Yamaha parts from a dealership, or the K&N parts, All Balls has OK Yamaha replacement parts too.

 

[Maxnewby]

Thanks for that info the thing is it idled great prior to the disassemble wire out and blow out but would act up above idle. Now after idle is supper.. I will keep an eye open for a ultra sonic. I'm jazzed about the plumbing sleeve instead of the steep boots on the v boost manifold works great. Thanks for your guidence here.

 

[Fire-medic]

 

[CaptainKyle]

Anyone source these @ a o ring kit price? or know the size? Assuming its the correct part # Fuel air mix screw o ring.
View attachment 93151

O-RING​

93210-03119-00​

by Yamaha

$4.60 22% OFF
$3.58
View attachment 93150

Them orings are 1mm x 3mm I always keep them around the shop.

 

[Maxnewby]

Them orings are 1mm x 3mm I always keep them around the shop.

Yep 10 of them in $4.99 kit, are oem made of viton for the price?

 

[CaptainKyle]

Yep 10 of them in $4.99 kit, are oem made of viton for the price?

Yes they are Viton . I can send some much cheaper if the ones you bought don't work out.

 

[dannymax]

Thanks for asking and interest in my cluster! As I have removed and cleaned them they either got lost or just fell apart. They don't seem to matter that much I ordered a set from ghina still on the way. The carbs shown above by me and one showing the 128.5 mm ball park setting are upside down compared to installed so i guess wide open flow would be 15to17mm. If i can't get the sync proper I will be pulling them again so will check your measurement then. Thank You for taking the time to suggest or ask if there is a concern.

I don't measure the 15mm - 17mm....I use a pre-set gauge. Yamaha has a wet level gauge which is easy to make & usable with the carbs on the bike. Wet level check is the final word on your fuel levels.

 

[Maxnewby]

Final answer! Running awesomely. After the bitsy O rings which made some diff and resnugging the LOWES cheapskat V boost boots. (Maybe a problem) and getting the sync screws rite! Runaway idle and just wonkey results can be caused by the one L side screw being too far out, screw it in until it contacts the second carbs tab the sync will all come together. Runs stellar now and better than it ever has. Idle is solid, will stay at 1K with that hot cam lope sound, no hesitation and most of all no surging even when lugged. BTW compression all 4 was @ 150 on the nose with my new cheep Amson gages that has a 12mm adaptor. So I guess I was lucky with the float settings. Thanks all for your help..