Mikes keihin carb kit

Thanks for the reply. I will do a test to see if this is a cause for the bike running rich. I ran two sets of spark plugs these BPR8EIX - Fits: 70-72 650's - Adds a solid 2 HP to your 650 (mike's) and Spark Plug NGK - BPR7ES.I was also going to try to change the exhaust and run straight or open pipes with no muffler or baffles. would that lean it up as well? I had the stock carbs on it and there was no rich/lean issues the plugs were spot on. this is my bike http://www.centralmotorcycles.com.au/shop/item/yamaha-tx650-03
 
very cool bike. Awesome hang in there, you can get this right----run the combustion chamber leak down test first. You can buy an adaptor to thread into the sparkplug to get shop air to. Make sure your valves and rings are in good condition first. You can try all kinds of stuff, but if the cylinders are weak, no adjustments, pipes, plugs, or ignition will ever pan out correctly. after the cylinder tests run the tempeture tests. is the ignition the old style points and origional coil?
 
My experience with these carbs....

Sealing on top of jet-block was not placed correct. :wtf: Re-assembly was no problem.:shrug:
2.jpg


Floatbowl broke while riding. :yikes:
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New floatbowl and thicker JJM needles arrives tomorrow in my mail.:thumbsup:

I dumped the suppled ugly green gaskets, and cut a groove in the alloy block for an O-ring.
I also blasted them for the same look as the engine. Now the supplyed bolts also fits :D.
DSCF0196.jpg

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Finish looks ok.
DSCF0200.jpg
 
Sweet love the o-ring, that's the way the stock adapters should seal too. Many other MC's use that system. Seems like a project for the one of the CNC whizzes around here......
 
rude said:
For the record, My chokes click and stay open, no splitting to the inlets evident at present, could it be a temperature thing? ambient temp over here is bloody warm at present. I do have issues with one (yes just one) carb slider that won't return fully even after reseating the cable in the slider, still fiddling.
cheers
Click to expand...

After spending the holiday riding and dialling in the Keihins it ran progressively worse to the point of back firing through the left carb, didn't take long to notice the split on the rubber carb holder running 180 deg around' same as wally's pic posted previously.
Naturally pissed off as I had some riding planned.
I can go and get the original carb holders, 3 hour drive, but I HAVE some riding planned (positive affirmation:bike::bike::bike:)
will these, the original carb holders, replace the mikes supplied ones?
or
do I go and find some rubber glue?
and no there are no machine shops open for at least a week, and I have some riding to do!:bike:
any help appreciated
merry christmas all
 
thanks wally, do those manifolds firm up and seal around the keihins body? it was running rich but nice all the same on the supplied jets but got distracted when it started coughing and spluttering, chased my tail for 10 minutes until I saw the splitting.
What jets and needle combo did you end up with? did you move the needle clip position from centre?
cheers
 
check your carb boots if you are running these, both of mine split, Mikes have kindly offered replacements
The carbs do vibrate a lot, I'll look to support the carbs when I fit them up again
cheers
 

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The problem with Mike's carb holders isn't vibrations or carb weight, it's gas. They don't hold up well to ethanol gas.
Try JBM Enterprises They sell good ones.
Leo
 
XSLeo said:
The problem with Mike's carb holders isn't vibrations or carb weight, it's gas. They don't hold up well to ethanol gas.
Try JBM Enterprises They sell good ones.
Leo
Click to expand...

XSLeo, my experience, I've only run 98 octane (overkill) no ethanol mix through these carbs, the splitting occured whilst it was being tuned up and run fairly hard, the carbs noticably wobble around a lot and there appears to be a weakness around the vacume nipple, both splits started at that same place.
I'll have a look at the JBM ones, Thanks
 
Closing this loop
I have used the original metal carb holders over the (second set) of PWK rubber manifolds, I used a few windings of vulcanising tape to fill the difference in the smaller diameter of the PWK manifold, along with some 1/2" wide clamps. No vacume leaks and very firm carbs.
Also improves throttle response with the carbs locked down

Having got off the bike yesterday arvo after a fair few miles with the standard carbs I got straight into it and replaced them (the old carbs) with the PWKs, did a simple tune and balance and off for a squirt, what a noticeable improvement over the standard carbs, great response and acceleration :thumbsup: worth the fiddlefucking around I think
cheers
 
I see that Mikes is now selling REAL Keihin carbs in addition to these. $$$ The VM34 kits, too.

Anyone tried the real thing, yet?

John
 
I'm still using twin vacume pet cocks, so I used the pretty pink lines for the petcock to manifold vacume nipples on both sides.
Also, don't hang the Carbs off the supplied rubber boots without support as they will split giving you grief when you least expect it, I used the original metal manifold outer "cage" over the provided rubber boots, clamped down this stops the carbs bouncing around and splitting the rubber manifold boots.
 
Ah yes that makes perfect sense now. I've had non vacuum petcocks on my '79 special since I purchased it so it's easy to forget they came with vacuum ones. And thanks for the metal cage idea. I've seen a ton of problems with those boots so I will defiantly take your advice. I'm thinking of using the pink lines as a carb boot vacuum line crossover. Can anyone think of a reason why not to do this?

thanks!
 
galt, for now you want to just plug the vaccum ports on the intake. Get every thing else spot on with the carbs, then as a last tuning step hook the vaccum ports together.
Leo
 
First, thank you to everyone who contributed to this thread...this wealth of information has really helped as I have worked through some of my challenges with these MikesXS carb kit.

My biggest issue is the slides sticking just above idle when I slowly get off the gas. If I go WOT and let go of the throttle, then the slides close properly (and you can hear the slide bottoming out). There is plenty of slack in the cable and the routing isn't an issue as they are currently off the bike.

So I plan to do three things to fix my issues:

1.) Source a new throttle cable. Given the design of the carbs, where do you recommend I go for a 2 into 1 carb cable that would fit?

2.) Install a stiffer slide spring. Any idea where to find one?

3.) Check the casting of the carb where the slide goes and rid the carb of any casting imperfections.

For anyone interested, here is how the project currently sits...the seat is getting appolstered.

IMG_0876.jpg

IMG_0885.jpg
 

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