1973 yamaha tx 650

[old bike nut]

Hi,another new guy with a bike problem.Got 1973 yam tx650 in trade for gt750 suzuki.The carbs were full of old gas and varnish.Took carbs off and cleaned 6 hours in carb cleaner.The bike runs fine but the idle is not that great and gas is leaking from what I think is the bowl overflowing.Advice?Thanks in advance!

 

[jayel]

well a couple of different things could be going on float level wrong, bad needle and seat, stand tube to overflow cracked ... search for the manual on this forum to find proper setting for the 73, try cleaning the fuel shut off needle/seat again, (if you have a yam dealer close by see if he's got any of the viton tipped needles around, they fit into my carbs) check those stand pipes while you clean the carbs again these are notorius for plugged idle circuits, there are 3 small holes hidden by the throttle plate make sure you can flow carb cleaner thru them

 

[gggGary]

That's the first I've heard that, can you sub the rubber tipped valves into 38's?

 

[jayel]

that's what I have in mine

 

[5twins]

Do you know what model they came from? Are they the 650 BS34 ones? And are they fitted into your original seats? Did you need to re-set your floats after installing them? Viton tipped needles would certainly be a nice upgrade for the 38s. This just sounds too simple.

 

[jayel]

here is a pic of the needles side by side, sorry my calipher battery is dead but viton tip appears maybe 1/2mm larger dia. but fit into my stock seats maybe they were worn, have to set float/fuel level anyway so not a problem, I set them using plastic hose in the bowl drain

 

[5twins]

But you don't know what model the viton ones are originally meant for? And I see you removed the little spring clip?

 

[jayel]

the needles are pretty much standard for all those carbs, spring just not on that needle, my local yam shop mech gave me some used needles out of his "junk drawer" that they had replaced re-building carbs

 

[jayel]

new battery in calipher solid needle measures 5.10mm dia., viton tip 5.24mm

 

[Fatman]

so which carb is best? 34's or 38's I have 2 sets of both and need to rebuild a set for bike(79 with elc' int'g) also sen new oem's for $358 on ebay, I can't find anyone one around here to rebuild them or i would just send them out. Small parts and old hands make my head hurt :O

 

[gggGary]

so which carb is best? 34's or 38's?
my head hurt :O

Less yr gone 4 spd either is fine. I think the 34's are a little easier to work on. Then again I'm insane. ihop
dfrnt mounts oc.

 

[Fatman]

Thanks, do you think a new set is worth 350+?

 

[gggGary]

Me? No, a rebuilt set is all you need, 20 or $30 in parts and some quality time at the bench. I like to guess 5 hours but that involves interruptions, uh where was I? and some polishing too.

 

[Fatman]

Iwould have them rebuilded if i could find someone who is good on them uncle arthur works hard at times LOL

 

[XSLeo]

I'm not sure if the Tech section has a link, Over at the Garage there is a carb guide. Authored by Grizld1 and 5twins. It covers how to tear down, clean and tune the carbs. A very good read. Even if you have someone else do the work, which is a bit insane, Reading the carb guide will help you understand just how they work.

 

[angus67]

i have 34's on my bike, synced easy, cleaned up easy.
currently working on a friend 71 with 38's, what a pain! dual throttle cables, extra passages, sheesh.
Im sure 38's are worth it to match the year they were used , but , I kinda like the 34's.
dont buy those new carbs. a couple hours, and that carb guide is all you need.
here it is...
http://xs650temp.proboards.com/index.cgi?board=carbfaq&action=display&thread=731

 

[old bike nut]

Thanks guys,I will recheck my carb cleaning.I also have to get my gas tank off and redkote it.Thanks!