'98 CVK Carb settings

[fishnbiker]

Greetings from the We(s)t Coast of Canada. My '95 Tiger has been giving me some grief after a carb rebuild on my 1998 Mikuni CVK trio. I used the genuine Triumph kits for the rebuild. The centre exhaust pipe won't warm up, making it obvious of a problem. I first looked at spark plugs & coils but all seems to work there. I tried 3 spare coils & even exchanged the two others mounted (for a total of 5 tries) on the bike with no notable difference.

Seems the outside carbs were set about 2.5 turns out on the mixture screws while the centre was at 3.75 turns. Maybe sloppiness on my part, but now I'm left with wondering what the proper setting is for all 3 to start with. The main jets are #120 to accommodate my oversized air filter & ran great before the clean up & new parts, so I'm thinking that should still be OK. Pilot jets look to be either #38 or #58, unable to read completely, but have been fine for years. Floats are set all the same within specs with new needles.

Edit; I see the parts fiche shows #40 for the pilot jet on 1998 models, so am assuming mine reads #38, not #58. Shouldn't be an issue as they have worked great for 20+ years.

I have spent all of Covid shutdown tinkering on a restoral & am now at a standstill until I get the engine running smoothly, not wanting to damage new paint installing & removing a few times.

Thanks,
Ken/Fishnbiker

[London_Phil]

There is nothing to rebuild in a keihin

If the rubber diaphragms are good (not stretched out)
Scrub scrub scrub . Clean them
Take em apart and soak em in carb cleaner for a day or 4
Throw a couple new orings at em
Job done

While your in there......102 or 105 main jets
Replace the pilot jets with #40'S
And set the pilots at 2 turns out
Personally if you have a cracked box for 16 bucks diff. Go with oem

[fishnbiker]

Not all applicable as I have a custom air box that requires #120 jets to get a good mixture.I am wondering about a possibly blocked passageway or some other niggling little thing beyond the incorrect (now corrected but not yet tested) mixture screws. The diaphragms & slides have been traded with no effect.

[London_Phil]

Not you is it?

[IGP]

I also own a 1995 tiger 885. CVK carburetors are keihin, Mikuni are bst 36 flat slide CV. Mine has stock airbox with k&n panel (TB9091). Pilot jet 40, main jet 105. According to Triumph, pilot adjusting screws are 2, 2 1/4, 2 out.
After three years of idleness, I had been faced with the same problem, so i renew all pilot jets,   pilot adjusting screws, ignition coils, HT cables to spark plugs and then i visited local dealer to adjust the carburetors using gas analyzer. Since then i have not face any problem.
You cannot adjust carbs using only the fuel adjusting screws.
Using CO analyzer, unscrewing the three bolts (one at a time) onto downpipe, screwing or unscrewing, the fuel adjusting screw of the same cylinder, to set the correct mixture to 2.5%-4.5% CO at idle 950-1050 rpm, (for Europe, for the USA i think it is 1%), for each one cylinder.
 Old ignition coils, HT cables to spark plugs they  had been measured, out of engine within specs.

[fishnbiker]

If you are referring to the photo, The K&N airbox was made for the Mikuni but converted for the now fitted Keihins. Sorry, just another old photo. 

I built this airbox to get past the B.S. needed to service the OEM. Off & back on in under 3 minutes as it should be, removing just the airbox body covers. It passes about 15% more air thus explaining the larger main jets. I now use an oiled UNI foam filter overtop that catches enough dust that the oiled K&N rarely gets dirty, much easier to clean as well. Gives me more power above 4,000 RPM at a slight drop in torque under said 4,000 RPM. Smaller main jets bog at highways speeds on full throttle, so I now have the ones that give me best fuel mileage at the correct maximum flow. Been fine for some 16 years on existing settings. It was a great exercise in fabrications for me.

Thanks for the other hints, will check them out. I tried 5 different coils in the centre position with no discernible change. Upon taking the carbs apart (again) I found the spacer straddling the top of the centre needle was dislodged (sitting un the slide) & may have been a factor. Hopefully testing in the new few days.

[fishnbiker]

I also own a 1995 tiger 885. CVK carburetors are keihin, Mikuni are bst 36 flat slide CV. Mine has stock airbox with k&n panel (TB9091). Pilot jet 40, main jet 105. According to Triumph, pilot adjusting screws are 2, 2 1/4, 2 out.
After three years of idleness, I had been faced with the same problem, so i renew all pilot jets,  pilot adjusting screws, ignition coils, HT cables to spark plugs and then i visited local dealer to adjust the carburetors using gas analyzer. Since then i have not face any problem.
You cannot adjust carbs using only the fuel adjusting screws.
Using CO analyzer, unscrewing the three bolts (one at a time) onto downpipe, screwing or unscrewing, the fuel adjusting screw of the same cylinder, to set the correct mixture to 2.5%-4.5% CO at idle 950-1050 rpm, (for Europe, for the USA i think it is 1%), for each one cylinder.
 Old ignition coils, HT cables to spark plugs they  had been measured, out of engine within specs.

Just in case, any info on aftermarket suppliers on parts numbers for the coils & cables ? Will be looking there if carb remedies fail to work.

Thanks,
Ken / Fishnbiker

[London_Phil]

Just in case, any info on aftermarket suppliers on parts numbers for the coils & cables ? Will be looking there if carb remedies fail to work.

Thanks,
Ken / Fishnbiker

I fitted stick coils from  another Triumph to mine  TT600

https://tigertriple.com/forum/index.php/topic,14800.msg112716.html#msg112716

[nightrunner]

Did you get it sorted? I have a 98 with the Keihins plus larger jets ans him under needle. If you didn't have spark to one cylinder you would know it. It would run very rough and not even idle. The center pipe being cold would not be the most obvious problem. A quick test is to run it with and without the center plug cable connected. If there is no difference then you are dragging a cylinder.

Pretty much the same deal if you had the primary jet passage plugged and not getting fuel to one cylinder. From idle up to maybe 1/4 throttle, its running off the primary jet. But you said only that the center pipe is not getting as hot. Cool(er) exhaust gases mean its running very rich. And you did say that center screw is farther out than the other two.  Or are you saying the center pipe actually remains cool to the touch?

When you changed airbox and jetting, did you have the carbs, 1) balanced for air flow, and 2) set the mixture using a CO analyzer? [Or take to a shop that has a CO analyzer.]

[fishnbiker]

Now waiting on new OEM style coils & pilot jets. Likely nothing to be done until the "Silly Season" is done. Now filling in time doing winter maintenance on my Suzuki DR 790 (ex 650), also awaiting parts for it. 

[Beernard]

Phil,

  That was a fantastic vid. I have never messed at that level, but your vid gives a great amount of info and I have learned a lot from it. Well done and thanks.

[ssevy]

The video shows how awesome it would be to 3D print the float bowls in a transparent fuel proof plastic so that you could actually see the floats themselves.