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Geoff, no apologies needed! I poured over the parts diagrams as well and believed that the slide vacum hole, spring, and jets differed from the sport model Keihins and the classic model keihins. I'm guessing that at some point Triumph changed things, at least as far as the Legend goes. I went ahead and ordered the correct spring for the sporty cam Keihins just in case (about 6 bucks apiece) and will change the carbs when they arrive. Seems to be a lot to learn! So far I've only spent the cost of a drill bit I didn't use, no biggie.

B
 

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Before you get too excited about changing the CVK bits you might want to try them without much fiddling.

I'd put a bone stock set of Keihin CVKs from a late Sprint on my Super III a while back and I am quite happy with the results. No flat spots, good off-idle, and gets better the more you twist. The bike has the stock airbox (split back cover for ease of pulling carbs), all the snorkels, intake canisters/silencer, K&N filter, and Yosh 3-1.

I had to use a late model Trident/Sprint throttle cable because I did not like the binding I was getting on the original cable regardless of routing and it had an odd bend at the elbow coming over the top of the engine that looked and felt pinched.

The only thing I did to the CVKs was pull the EPA caps and set the screws 3 turns out after checking everything else out. I talked to several guys working on CVKs on the other classic triples forums and they'd suggested the same after lots of fiddling with theirs. Three turns out may be just little rich since there's almost no choke required ever. I may end up eventually setting 1/2 turn less after checking plugs in a few months. FWIW, it runs perfect now.

The Super III's prior owner had diddled+ with the Mikunis until he ended up with a big flat spot and stop/go drivability issues. Setting the screws out to 2.5 solved about 50% of the flat spot, but not all of it. I had pulled these carbs to make sure there was nothing badly amiss when resetting the screws.

I plan to disassemble and debug the Mikunis eventually, more out of curiosity than anything, and probably return to stock OEM settings. I think there's bits of Dynojet parts in them but I have not bothered to look yet because they are probably never going back on as the Keihins are running perfectly.

I had also checked a while back that the Super III has a stock advance rotor plate and it does (folks have complained elsewhere that FactorPro advance rotors cause a flat spot on the dyno for T3s).

I still think my Trident's carbs are slightly crisper to respond. I'm told that Keihin slides have more mass (looks obvious when you take them apart) than the Mikunis, so more inertia and a bit slower slide response. So you Mikuni drivers may find this the case also if they're running well. My Trident seems to be my control sample and I would say they are in top form and very quick to respond, particularly at low revs.

The last bit I have learned through this project is that the full airbox is part of the equation, at least with my standard carb settings. I have experimented running without all of the airbox attached and it's horrible, barely will get out of its way. A forum member clued me to what a "Helmholtz resonator" was. :confused: Putting the full airbox on and it runs a treat.

Just thought I would pass this along so that others might benefit. It will be interesting hearing the opinions when everyone else gets their CVKs to their liking.
 

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Well I'm slowly getting there....I'm going for the full fat pods & all

Being me I couldn't let them be so Mottley'd them up a bit painting the float bowls with some solvent resistant engine paint & stainless lick me bolts all over..!



Removed witches hat filter at the fuel hose union and fitted micro inline jobbie, new thick walled vacuum hose & fuel line, new throttle cable, correct carb rubbers.

Rejetted as per Matt's thread for running pods so 152 mains & 42 pilots plus shimming the needles up 1mm (well the closest matching washers I could get were 1.07mm give or take so I hope that's close enough) pilot screws out 3 turns.



Old & new mains



Bang goes me fuel economy !!

Waiting for some stainless jubilee clips to arrive with me pods & crankcase breather, plus a fuel line splitter and quick release fuel line thingy.

Progess...yehaaaarrr ;-)
 

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Oh and my two tips of the day..

1. Blue Tack makes a great masking material, I simply pressed the carb bowl into a square of the stuff for a perfect seal around the base of it for painting.

2. Putting the new throttle cable on was a lot easier than I expected, I turned the carbs on their end, wound the lower lock nut off the bottom of the cable adjuster at the carb end and fed the cable end and lower nut into the carbs, located the cable end into the locating hole on the carbs and held it in place with a flat bladed screw driver gently levering against the carb bowls, then with another flat bladed driver pushed the cable around to seat itself in the slot and then pulled the far end of the cable to pull it home..





Ground a 10mm open ended spanner down so I hold the lower lock nut whilst winding the adjuster down into it....and bingo everyones a winner



 

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In regards to fuel economy then i`m finding this mod a vast improvement compared to my old Mikuni`s as the new Keihin carbs seem to only sip at the fuel compared to the mikuni gas guzzlers

Glad to see that Mott3 is hard at work with the camera and coming up with some good tips as per normal.

By the time i`d finished my R&D work then it seemed a bit late for me to start taking photos.

I`m looking forward to some feedback from folks who give this a try as i`ve been out playing on my bike most of this weekend and having a great time with the carb setup and a brand new set of Dunlop Roadsmarts. :motorbike2:
 

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Excellent thread. Can I ask about jets and sizes, the sizes mentioned are Keihin ones right? As Mikuni and Keihins use different sizing systems. Thought it worth an ask.

Never tried it but I keep seeing places on the net saying that M jets do physically fit into K carbs and vice versa, and others saying they don't...

As an aside I modified some old Keihins last year, drilling jets gradually, saved having to go shopping and wait around etc - used micro drills and an Archimedes drill. Cheap and goes easy on the soft brass. Say a 130 jet was a 1.3mm drill bit so it was easy to figure out what to use to get a certain size.
That said, I don't know if the same system applies to modern Keihins, but it would be a handy way to do small jet increments if so.
 

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Flying Custard...don't know what jets fit what but if you look back in this thread for a link to Allen's they list the dimensions of the Keihin jets so you might be able to compare..?

That aside I have fitted me carbs and gone for a run...although not too far before I encountered perhaps an unrelated problem..?

As the Keihin's have only one fuel hose I decides for the sake of clutter and ease of use to run one line to the reserve side of the tap and run the bike on reserve, blocking off the other outlet allowing me to fit a quick release fuel hose coupling to aid tank removal, later I shall be looking at getting rid of the vacuum tap altogether and maybe modifying one from a thunderbird or something. After all modern stuff only has a fuel light...so I'll go with that, I've always ridden it that way..light on fill up asap, plus I won't be reaching for reserve when I least want to.

I chose K&N pods because they look great and the way I see it you either stump your money up/up front or string it out over a period with junking cheaper pods (you pays ya money, ya takes ya choice ;-) )

I chopped the original fuel hose about to reroute, my now one, fuel hose around the back of the frame this also incorporates an inline fuel filter as I junked the witches hat at the hose junction on the carbs. I also chopped the original breather hose at a right angle to take the new breather filter (which I hope will tone down a bit once some oily air passes through it..!). I fitted a thick walled vacuum hose to safe kinking problems. Slightly rerouted the throttle cable...Matt you would have been able to run yours straight up the frame out and up to the throttle because the take off on the Keihin's is at the front right hand side (whereas the Mikunis take off os at the left hand side at the back) so therefore it gives you extra length on the cable to marry up to your higher bars..for my clip ons and lowered front end I had to take the cable left and then come back round to go through the same right hand hole at the top of the rad to loose some of the extra length.

Well she fired up second hit after priming the carbs and after a little tweek of the idle knob settled in to a tick over, low speed stuff is much more well mannered, also no popping banging when I shut the throttle..so far so good, very slightly different sound at this low speed stuff too..a bit more gruff.

On the open road pick up seemed very slightly sluggish but once the taps are open all seems good, one big difference here is the sound...!!! the old bus is now sucking, growling, bellowing, booming, wineing and sounds like a V8 tuned lump being given some gas. FFS this does sound bad..but in a good way !

So apart from my possible coil problem (other thread) and the fact that I haven't given the bike the oil change I planned or got the carbs balanced all I can say so far is the Mikunis seemd quicker and more frantic, the Keihins with pods sound blinding and are as quick top end but there is going to be more to this story yet as that was only about 15 miles of which 1/3 was town 1/3 was go for it/ish & a 1/3 was running on 2 !

I'll fix my gremlins balance them & whack a load more miles on to give a true idea, them back on the dyno a MOT time.

and pics if you like it or not ;-)





 

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Hey Mot, lovely job there old mate.

How is the support for the carbs without the airbox? Do they just hang on the rubbers?

Cheers,

Roden
 

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Yup pretty firm on the rubbers...they are new though...I will be looking for support, but it's not a straight forward thing to cure...kinda got to look for the right bodge if you know what I mean..
 

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Looking good and hopefully once your firing again on all cylinders then you`ll have some more fun.

I personally really like the "bite me!!" sound you get off the pods on full draw.

I was out playing today on a 150 mile charity run up here in Scotland
and even though it was chucking it down with rain most of the time then the bike didn`t miss a beat and i was having fun firing past the plastic rocket boys who don`t ever go out in the rain :D
 

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...all I can say so far is the Mikunis seemed quicker and more frantic...
My experience so far too with CVKs.

Very interested if you end up working this difference out and sharpen the response.
 

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Joined the CV club

Having read this thread I bought a set of carbs off flea-bay for my 92 Trophy. The chap I bought them off sent new inlet rubbers and carb to air box ones as well. What a nice supprise.
Ive not had a chance to test it yet. Im running 140 mains and 40 pilots.

I then bid on pods £20 winning bid. And im still waiting............

Mike.
 

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Here are some Super III dyno runs with CVK vs. BST carbs and sealed vs. non-sealed rear air plenum seams: http://www.moto-lab.com/gallery/view?itemid=150. Scroll down for the chart key. Click image for high res view. On the slides, I don't recommend drilling them. All it does is reduce the damping, so they flutter more, making things wear out sooner.

Regards,

Derek
 

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Well...eerrr no not yet..!

The old bus was spluttering onto what felt like only two cylinders after I gave it a good hand full (ie run it up to a Ton), it would get there ok but soon after go off the boil, if pulled over or easy on the throttle it would recover after a minute or so. Running it up to about 65-70 and town work was fine.

Swapped out the coils for new...same problem

So I changed to the uprated springs and put Thruxton needles (1 shim) sprayed the slides with a little ptfe and gave it a go...felt a bit sharper but same end result..

Thought it might be my fuel hose idea (1 hose etc) so routed it from the other side of the tap..same result.

Thought it could be over rich on full throttle and rejetted to 145's on the mains....felt just as good as the 152's but same end result..

Next I'm going to plumb both lines back in (need to get a splitter) and see what happens.

After that I'm going to have the carb bowls off again and have a good long hard look at the float valves...my gut feeling is that carb No. 2 has got a partially sticking float (as when I last drained them not too much came out of this one ?) could be that on low demand all is ok but giving some beans is ok for a while until it empties the float bowl..then problems while it plays catch up..?

Anyway...I'll keep you posted. Gardens are growing like a thing possessed at the moment so spare time is not in abundance as I single handedly take on mother nature !!!!

Cheers
Mot
 

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Well...eerrr no not yet..!

The old bus was spluttering onto what felt like only two cylinders after I gave it a good hand full (ie run it up to a Ton)

Thought it could be over rich on full throttle and rejetted to 145's on the mains.... but same end result..
Tried putting the full stock airbox & snorkels back on? Worked for me ;)

It would be an interesting data point.
 
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