Any aftermarket replacement carbs for 1984 XT 600?
 

Hi All,

Are there any aftermarket replacement carbs for my 1884 XT 600? I can't get my XT 600 to rev out. It has good low end punch, but gets flat at the top end as if it's secondary carb is not opening up. I've done everything - carbs off many times to make sure they are clean, cleaned fuel petcock, opened up the air box, etc..... Every now and then, it will run hard at the top end for a moment as if it had a burst of fuel. I'm at a loss with what to do. Any ideas?

when you've had the carbs off have you checked that the butterfly in the second carb is opening OK, it can be adjusted on this screw, things can get a bit worn where the wheel makes contact as shown in second pic.
http://lh4.ggpht.com/_aJzSBN66Sc0/Sl...DSC04074.2.jpg

http://lh4.ggpht.com/_aJzSBN66Sc0/Sc...0/DSC04083.JPG

i dont think thats a good idea, if all the jets and exhaust are standard then the air supply needs to be as yamaha had it.

check for air leaks.
check float/fuel level. and get one of those carb repair kits which include o rings, needle valve etc.
http://lh3.ggpht.com/_aJzSBN66Sc0/Sl...0/DSC04306.JPG


yes you can get new carbs, one option is a pair of Keihin 31CR's (or 33). but not cheap.
but damn they are sexy
http://lh4.ggpht.com/_aJzSBN66Sc0/Sl...T600Carb02.jpg

http://lh3.ggpht.com/_aJzSBN66Sc0/Sl...T600Carb04.jpg




I dont think the standard set up is bad, I've had two previous early XT's and the carburation was perfect. but my '84 carbs like yours for sure don't work like they did 25 years ago. and unfortunately the carbs off a newer XT dont fit.

my next step is getting my carbs ultrasonic cleaned - anyone got any experience of having carbs ultrasonic cleaned?

cheers

XT 600 carbs
 

Thanks for the reply. I forgot to mention, I have a Supertrapp installed and aftermarket air filter. I've "upped" both main jets, which helped with overall performance, but you can still feel it "flat" at the top end. Yes, the secondary butterfly is opening and adjusted right, as well as the float levels. The secondary carb barrel is in very good condition. The only thing in question would be the rubber diaphram. It looks a little deformed, but doesn't show any signs of a pin hole. What does the diaphram do? The rubber boots that the carbs bolt onto are also in good condition. Who offers a carb rebuild kit? How much & who offers aftermarket replacement carbs?

Thanks again!

the rubber diaphram in the CV carb is attached to the slide. theres a hole through the slide from the bottom to the top chamber above the rubber. when the air flows it lifts the slide by the vacuum from the engine. so open the butterfly = air flows=slide goes up.

as far as i know on the early 600's (34L 55W 43F) they have an alloy piston instead of a rubber diaphram in the CV carb. what bike have you got, you said it was an '84?

carb repair kits are on ebay, and an internet search should show up some aftermarket carbs.

XT 600 carbs
 

I'm not very familiar with XT 600's, but I think mine is the 43F. I guess they made many different models in one year? It does have the alloy piston. I understand the diaphram now... that's what I thought it did. I think it would be best for me to get a carb rebuild kit from Ebay as you suggest. I think aftermarket carbs would be too much $$ to soak into such an old bike. I'm not much of a computer guy, but I did see rebuild kits on Ebay however, they didn't explain what is all included in the kits. I think the most important items I need would be the float/needle, diaphram and "o" rings.
Thanks for your help!
Baron

I've read a post somewhere of a guy that bought some FCR 33 and he didn't manage to fine tune it for his XT600 and said the a 31 might be the way to go for dual carb upgrade...


Btw, do you still have the carbs of your bike? I could use a few details, could ya help me out?


Vando :innocent:

http://lh3.ggpht.com/_aJzSBN66Sc0/Sl...4/DSC04306.JPG
Linkster - rebuild kit like this includes O rings, float bowl gasket, top gasket and complete float valve.

diaphram and slides are sold by Allens Performance or NRP carbs - but if yours has the alloy piston it doesn't have a diaphram in the CV carb. or are you talking about the one on the first carb, under the cover on the side?
http://lh4.ggpht.com/_aJzSBN66Sc0/Sl...%2C%282%29.jpg


one thing to watch is when you put the top of the CV carb back on, make sure the piston slides up and down freely - things can move as you tighten screws and stop the piston from sliding freely. or maybe thats just mine.

mr bacardi - the pics of the Keihins are off the net, sadly not mine, probably cost more than I paid for my complete bike.

XT 600 diaphram
 

The diaphram I was talking about is on the first carb as you have pointed out. I'll assume that diaphram has something to do with the second carb vacuum to lift the alloy piston. If it has a leak, then it might loose some of the vacuum needed to lift the piston all the way under full throttle? The piston has always moved freely after I assembled the carbs. Something funky must be happening with yours. I'll check out the 2 sources you recommend for the diapram.

Thanks, Baron

XT 600 carbs
 

To modify my XT with different carbs is too much to deal with. I don't have that kind of time anymore! I'll try to massage the old carbs best as possible without spending a fortune from the Yamaha dealership. I can't believe what they want $ for carb parts!
Thanks for your suggestions.

Baron

the diaphram on the first carb is part of a circuit that regulates (enriches) the mixture when you are coasting (I think). it has nothing to do with the second carb.

Why buy directly from yamaha when there is a lot of stuff on flebay? you can just research which bikes have which stock carbs and get them used..


I'm currently "guestimate" making my own carb-airbox joint rubber boot with my college Solidworks program.
I'll be using a software integrated feature that has fluid dinamics to improve the design so I have what I need in terms of airflow and shape to avoid the rear shock as well..

That's why I'm asking around for airbox dimensions, distance from engine cylinder to the rear shock, rear shock spring positioning and diameter...

So yeah, any help is appreciated :rofl:

Vando :Beach:

Could someone please translate the word "coasting" for me, thx.

hi there jens the coasting enricher diaphram richens the fuel in to the cylinder on the over run or when you are going down hill with the throttle closed (coasting) ,if it stops working the bike will pop and bang badly. it is genrally just the atached plunger that is stuck ,which is a easy fix . zigzag:thumbup1:

XT 600 measurments
 

Boy, you are too technical for me. I have a hard enough time making a paper airplane! I'd give you some dimesions, but it would be hard to pinpoint exactly where I'm measuring from point to point to you. Can't you measure from your own XT 600?

Good Luck!

Xt 600
 

Good explaination. Mine does the poping inconsistantly with closed throttle and sometimes mildly between gear shifts. I thought it was the pilot jet being too lean with the Supertrapp installed.
Any ideas why my bikes idle rpm increases sometimes after it's all warmed up after riding for a while? I've sprayed carb cleaner around the carb boots with no RPM difference. If there were a vacuum leak there, I'd think the RPM would drop, not increase all by itself. Could there be something funky in the choke area? I just LOVE Yamaha's duel carb set up:thumbdown: