Triumphrat

ResearchRat · 03-12-2007

I'll be honest that I'm fairly ignorant when it comes to carbs, but I'm having what I believe is a carb issue.

I notice that when I really crank on the throttle, there is a bit of initial hesitation, then response is great, and then at high(er) rpms-engine power just cuts out dramatically. (I noticed this even after I had my carbs tuned.)

I do have an aftermarket staintune 3-1 exhaust. Although, according to staintune-no jetting is needed, would jetting remedy this issue and provide more power at higher rpm? Are there any drawbacks to jetting?

From looking around the online shops-see a multitude of jet kits, jet sizes, etc. Anyone have any recos on specific sizes, etc?

Appreciate any feedback.
Thanks.
-RR

TechmanBD · 03-12-2007

Have you sinchronyzed the carbs? that could be your probalem as well. That is how my FZR felt when they were not sinchronyzed correctly.

ResearchRat · 03-12-2007

Hey TechmanBD,

Yes-previously did have the carbs synched. But the issues i mentioned still prevailed So perhaps the synching wasn't very good?

-RR

daytonacharlie · 03-14-2007

I installed a jet kit in my 96 Daytona 1200 and it made a huge difference. I had a flat spot around 4,000 rpm that lasted till 5,000, the jet kit cured that. The kit I used was from K&N specifically for my model bike. It came with two sets of jets, one for stock and one for aftermarket exhausts. No guess work. The only drawback I've experienced is about 5 mpg loss in fuel mileage.

You said you had the carbs tuned. What was done besides having them synchronized? Were the pilot air screws also adjusted (2-1/2 turns out works best)?
Even if both were done your bike could benefit from a jet kit but that may not be all... How many miles are on your bike? Has it ever sat for several months without being ridden (ever in it's life)? Have the carbs ever been rebuilt?
To see what's involved click here.

I suspect your carbs may need to have the float needles and seats inspected and or replaced. If the bike ever sat without being ridden for any extended period then you'll also need to have the pilot jets removed and poke a wire (or suitable poking devise) through the opening to remove varnish build up.

It's also possible you could have a vacuum leak, check the rubber boots between the carbs and the engine for cracks.
When was the last time the air filter was serviced or the fuel filter (if fitted) replaced? Have you ever replaced the coils? There are a lot of things it could be and sometimes it could be several things that all add up to a crappy running bike. You'll need to have each issue addressed one at a time to figure it out but when all is sorted it'll run sooo sweet.

good luck,
dc

[ This message was edited by: daytonacharlie on 2007-03-14 07:30 ]

ResearchRat · 03-14-2007

Daytona Charlie,

I purchased the Daytona last year via ebay. The bike was in meticulous condition-very well cared for and just a shade under 10,000 miles.

Last year, I did have the carbs synched at a shop-though can't specifically state if the steps you outlined below were followed. I do know the gas tank had rust-so was steamed and cleaned. I have yet to remove the carbs but can imagine that some rust and grime is gunked inside. Side note: right now the bike is gettiing around 120 mph to a full tank. Which I think is less than what some other T3 daytona owners have posted.

If I'm removing the carbs for cleaning, would it be recommended to rebuild as well?

New air filter (K&N) is on the way, unsure if a fuel filter was previously installed.

What exactly is replacing the coils?

Thanks.
-RR

__________________________________________________

I installed a jet kit in my 96 Daytona 1200 and it made a huge difference. I had a flat spot around 4,000 rpm that lasted till 5,000, the jet kit cured that. The kit I used was from K&N specifically for my model bike. It came with two sets of jets, one for stock and one for aftermarket exhausts. No guess work. The only drawback I've experienced is about 5 mpg loss in fuel mileage.

You said you had the carbs tuned. What was done besides having them synchronized? Were the pilot air screws also adjusted (2-1/2 turns out works best)?
Even if both were done your bike could benefit from a jet kit but that may not be all... How many miles are on your bike? Has it ever sat for several months without being ridden (ever in it's life)? Have the carbs ever been rebuilt?
To see what's involved click here.

I suspect your carbs may need to have the float needles and seats inspected and or replaced. If the bike ever sat without being ridden for any extended period then you'll also need to have the pilot jets removed and poke a wire (or suitable poking devise) through the opening to remove varnish build up.

It's also possible you could have a vacuum leak, check the rubber boots between the carbs and the engine for cracks.
When was the last time the air filter was serviced or the fuel filter (if fitted) replaced? Have you ever replaced the coils? There are a lot of things it could be and sometimes it could be several things that all add up to a crappy running bike. You'll need to have each issue addressed one at a time to figure it out but when all is sorted it'll run sooo sweet.

good luck,
dc

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Photos

bradtx · 03-14-2007

RR, DC, is referring to the ignition coils. It is quite easy for a weak coil(s) to be diagnosed as a carburation problem as the symptoms can be quite similar.

Generally a carb rebuild is easy, it's the removal/installation of all that stuff around them that's a PIA. Since there was rust found in the tank I'd have to suspect some in the carb's bowls also, in the least. You DO have a fuel filter, I hope. The rust in the tank also suggests, to me anyhow, that the bike has sat for some time without a full tank of gas. I think Eastwood made a product to coat the interior of the tank, if not there are likely others.

All this leads me (if the bike were mine) to rebuild the carbs, see how she runs and then look at the coils.

Brad

ResearchRat · 03-14-2007

DC,

I saw from the link that you rebuilt your cabs with OEM compenents- I imagine that OEM is considerably more costly than aftermarket. Does Mikuni offer replacement parts?

Also, how does one determine which carb parts need replaced? Is there a general rule-ie replace everything: seals, floats, etc. Or, other way of determining replacement need?

Thanks.
-RR

daytonacharlie · 03-15-2007

Quote:

On 2007-03-14 11:12, ResearchRat wrote:
DC,

I saw from the link that you rebuilt your cabs with OEM compenents- I imagine that OEM is considerably more costly than aftermarket. Does Mikuni offer replacement parts?

Also, how does one determine which carb parts need replaced? Is there a general rule-ie replace everything: seals, floats, etc. Or, other way of determining replacement need?

Thanks.
-RR

RR,
I looked around for a long time at online parts stores for carb parts including Mikuni's own site but in the final analysis the price difference was so small compared to what the dealer charged I just went ahead and bought my parts from Triumph. I'm a RAT member so after my discount it was pretty close to the price I could get elsewhere and if there was a problem my dealer would be a lot easier to deal with than some faceless e-store. I do buy a lot of parts off the internet but it just depends on what it is.

In my case I had 63,000 miles on the clock, had never done any carb work (apart from cleaning and a jet kit at 30,000 miles) and a considerable amount of rust had gotten past the fuel filter from my rusty tank so I opted for a large scale rebuild.

You'll need to take the carbs apart to assess what you'll need. But a general rule is with a bike as old as yours (and mine) the float needles probably need replacing but since the needles don't come separately you have to buy the whole float assembly ($43.00 ea.)! The thinking on replacing the whole assembly is that after about 8 to 10 years the floats just don't float like they used to and will cause the bike to run rich (low gas mpg). The seals and O rings are cheap so you may as well replace them too since you'll have everything torn apart anyway. In my case the carb boots were all cracked from heat and age and they're only $6.00 so again while you're there why not.?

And as bradtx said bad coils can produce the same symptoms as carb trouble so if in doubt get a competent mechanic to check them.

Here's a link to my carb rebuild post click here

good luck,
dc

[ This message was edited by: daytonacharlie on 2007-03-16 07:50 ]

ResearchRat · 03-16-2007

DC,

Can you go into more detail on physically cleaning the carbs. Did you use a solvent in combination with the dremel? And how did you clean the carb internals?

-RR

daytonacharlie · 03-16-2007

Quote:

On 2007-03-15 23:57, ResearchRat wrote:
DC,

Can you go into more detail on physically cleaning the carbs. Did you use a solvent in combination with the dremel? And how did you clean the carb internals?

-RR

Sure, I just used gasoline but a solvent of equal strength such as mineral spirits or a specific carb cleaner product from an auto parts store will do the trick too. I did all my cleaning work outside (in sub freezing weather I might add) and all the reassembly indoors. You can never be too careful with flammable liquids! I scrubbed off as much grime as possible with a toothbrush and gasoline then let that dry and used a wire brush attachment on my dremel to polish out the rust and crud that was still left. Because I had so much rust inside the carbs the dremel brush was necessary. Hopefully you don't have the rust issue and won't have to go to such lengths. If your float bowls just have the usual film left from gasoline then scrubbing with a toothbrush should be sufficient.

Taking apart the carbs completely to clean all the internals is a much more serious job than just taking off and cleaning the float bowls but done carefully, methodically and one at a time it's not that bad. I've been doing it for 20 years and I've made plenty of mistakes along the way. One time I installed the floats upside down in the carbs of a friend's Yamaha 750. It caused fuel to flood the cylinders so much that fuel ended up in the crankcase causing the oil to thin. The engine began to clatter and run rough. I immediately shut it off, checked the oil and discovered gasoline in the oil, drained and changed the oil, pulled the carbs back off, figured out the mistake with the floats, put it back together and all was fine but it could have been a disaster. Every time he changed the oil after that it still smelled of gasoline.

So what I'm saying is take things apart one piece at a time, clean them with a toothbrush and solvent, use an air compressor to blow out any orifice, through any passage or hole a part came out of after cleaning it with solvent then reinstall that part before moving on to the next. The only part you'll need to adjust is the air mixture screw. It has a spring located inside the carb and a washer that will get lost easily so watch out for that. Once cleaned and air blown through it's opening, thread it all the way back in till it bottoms out then turn it back out 2-1/2 turns.
Taking off the top plastic cap reveals the rubber diaphragm and slides. This assembly is very fragile so be careful. There is a needle (which in a jet kit would be replaced) and washer that will need to be removed and cleaned. The face of the slides and the mating surfaces inside the carbs need to be cleaned as this is a place where grime will build up and cause poor performance. When reassembling the slides make sure the diaphragm seats into it's recessed groove at the top of the carb (very important, don't ask how I know!) and be sure the spring goes back into it's proper position. Now move on to the next one... piece of cake!

Hope that helps, keep those questions coming,
dc

[ This message was edited by: daytonacharlie on 2007-03-16 15:00 ]