Triumphrat

sbpark · 07-17-2008, 11:21 PM

dyno'd the bike this evening after installing the CR's and getting the jetting in a range that was suggested for my altutude. with the mods i had previously (predators, AI and airbod removed) i was pulling 63 hp on the dyno. after installing the CR's and nology coil, nology wires and iridium plugs and larger intakes, i was only pulling 60hp! also found out that my top end was way lean so i put in bigger mains and will dyno again soon, but am not really feeling any real difference after changing the jets.

also pulled the plugs and one plug was a touch lean while the other was a little rich. hooked the carbs up to the carb tuner and they are not in synch with each other; the carb on the side of the lean plug is reading higher than the carb with the side that has the rich plug. i looked and looked, and for the life of me cannot find the synch screw for these carbs, and neither could the guys at the shop. there is a screw with a nut and threadlock near the linkage, but adjusting that screw does absolutely nothing. do i need a pingle petcock to throw in more fuel? the bike is an 2007 thrux with 4200 miles, purchased new. all mods were done in stages so i could feel the difference and appreciate them over time. this mod seems to be a mistake.

any info or advice would be greatly appreciated. i have had nothing but problems with these carbs since buying them, and the vendor who actually sold them to me has not been any help and knows nothing about them so it's been trial and error so far.

thanks to everyone in advance!

RedBird · 07-18-2008, 12:02 AM

Do I need a Pingle petcock to throw in more fuel?

The stock petcock will empty the tank in less than 5 minutes. You would have to have a VERY BIG THIRSTY motor to need more than 4 gallons in 5 minutes!

Once you get the carbs balanced, you should be able to get the main jets sized correctly....then you will probably feel a big difference.

Good luck,

Baltobonneville · 07-18-2008, 01:09 AM

Thanks for being honest about the mods, instead of telling us that the butt dyno feels like you're riding a CBR1000 now.

sweatmachine · 07-18-2008, 01:16 AM

sounds like you have jetting and sync issues, as you already know. This will kill your hp, but the good news is that once you get it sorted out you will have some more power. CRs are actually smaller than stock, so I wouldn't expect astronomical gains with them, but they should really help throttle response. Certainly they shouldn't lose hp as they're roundslides vs the stock CV carbs.

All those electric parts you bought (coil, wires, etc) won't gain you any hp.

sbpark · 07-18-2008, 02:34 AM

i am tempted to just throw the stockers back on with the aftermarket manifolds and be happy. noticable on the meter (3/4 to one whole number difference.) when the carbtune is connected it's not a big difference in synch, but visible. with the stock carbs i didn't have to roll the throttle so it didn't bog down, i could wail on it if i wanted to with no issues, and it felt way better. this was the first mod i have done that i am starting to regret.

and i didn't expect any gains from the coil, wires and plugs, but i will say the bike runs much smoother since their installation.

amanger · 07-18-2008, 02:53 AM

For every day street use vacum operated carbs. are going to be smoother and better than cable operated slides. Unless you are racing there is no point in replacing the CV.s That is why they are there, the CRs would br cheaper to produce so if Triumph thought they would do a better job they would fit the bike with them standard.

wolverine · 07-18-2008, 05:29 AM

Quote:

Originally Posted by amanger

For every day street use vacum operated carbs. are going to be smoother and better than cable operated slides. Unless you are racing there is no point in replacing the CV.s That is why they are there, the CRs would br cheaper to produce so if Triumph thought they would do a better job they would fit the bike with them standard.

I don't agree with that. I have just installed a pair of Mikuni HSR42 on a stock truxton with open pipes and airbox eliminator kit. They are absolutely smooth in every day use. They have a rock steady idle, much more torque down low and not even one issue with driveability. Just you can't wack the throttle open from down low, but the feeling with the throttle is extreme (the throttle shaft return springs are strong so it's easy to accelerate smoothly). You can feel every little rotation and the response is much faster. What I like about them in the city traffic (I live in Rome) is that you need less shifting thanks to the more torque you can get from them down low.

The real problem is that, if you want to remove the stock carb with something else (CR, FCR, HSR...) you have to know how a carburator works and how to fine tune your new pair of carb. You cannot pretend to swich from stock to aftermarket carb without having to fine tune them, no matter how good the vendor was in dialing them for your configuration. Therefore you NEED to know how they work and how to get the best from them...or at least get close. Otherwise probably you are risking of spending the same money spent for the new carbs at a mechanic or at a dyno shop to get them dialed in.

To sbpark:

don't just throw the stockers back, surely some of the guys with CR will chime in and help you with some tips about jetting for your configuration.
Regarding the loss of power it's surely just a matter of main jets. Once they are right, you should get some more top end power from the CR due to the lack of butterfly valve.
However, the main reason to swich from stock CVK to CR is not top end power (CR are just 35mm venturi) but to improve throttle response and hopefully to get a little bit stronger acceleration. Venturi size is the same as stocker (35mm vs 36mm) but you are expecting a slight more torque due to the lack of butterfly valve which disturbs the flow and creates a restriction.

sweatmachine · 07-18-2008, 10:43 AM

Quote:

Originally Posted by amanger

For every day street use vacum operated carbs. are going to be smoother and better than cable operated slides. Unless you are racing there is no point in replacing the CV.s That is why they are there, the CRs would br cheaper to produce so if Triumph thought they would do a better job they would fit the bike with them standard.

I invite you to come ride my bike with HSR Mikuni flatslides on it and then try to maintain that viewpoint.

roxythruxton · 07-18-2008, 11:39 AM

You might need some time to fine tune those things . I certainly have more horsepower and torque by a landslide with my CRs . They can be a pain to perfectly tune them but when you find the right settings you'll know it . Don't give up on them just yet . Find the right settings first .

sbpark · 07-18-2008, 11:42 AM

where is the synch screw to synch these up on the carb tuner?!