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Discussion Starter · #1 ·
Ok, so i removed the snorkel and it made the bike sound way better. So here is the problem. Now when i'm getting on it around 4k and up it feels like it is falling on it's face. it no longer pulls in the higher rpm's, but rather loses most of it's power. Anyone know why this is? Also i noticed that from the dealer the little hex bolts on the bottom of the carbs one of them is really far out and one is screwed in most of the way. What should i do with them?
 

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Since removing the snorkel you've made it easier for the bike to breathe...yet nothing has changed for the fuel aspect of the equation. I would rejet...sound's like you need a larger main jet.

As for the screws in the carbs....tighten them.
 

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Those are the float bowl drain valves, they should be tight. If they're loose that means the drains are open and fuel could/will be running out of the bowls. Not good.

I'd recommend getting the D-shaped tool from newbonneville and messing with your idle mixture a little, that hole is located near the wires for the carb heaters, kind of centered on the float bowls (bottom of the carbs).

Also, you may need a bigger main and possibly may want to add a shim to your needles.

I'd tighten those float bowl drain screws and add a bigger main, and do the D-screw thing first, then maybe add a shim.
 

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If the gold screw's are what you are referring to, they are merely the drain valve's for your float bowls. I have since replaced my keihn's with mikuni's but seem to recall that one did stick out further than the other.

Just make certain they are snug and you'll be fine.


Do you know how your bike is presently jetted?
 

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Ok, you may want to make a minor adjustment to your idle setting, but you'll probably just need to rejet the bike swapping out the mains for something a bit larger....say 115/118

I wouldnt make a very large adjustment to your idle screw with the d-tool as it's better to be a little lean at idle rather than a little fat.
 

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Discussion Starter · #8 ·
sounds good. Also i'm going to be putting some epco stainless mufflers on it this winter. Should i go up some on the jets then as well? If so then i will just put the snorkel on and do both at the same time. Thanks for all the help.
TJ
 

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When you buy the new pipes I would assume they will come with new jet's for your carbs. Since you'll be removing the snorkel you may need to jet slightly heavier than what they send you.

Best thing to do is get the bike put on a dyno....preferably one close to home and conveniant to you so you can return to the same one when you do future mods for performance comparisons.


Dyno's eliminate guessing games regarding tuning.

Do you have a D-tool?
 

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do not worry about the float bowl drain bolts. One does stick out more than the other, I'd have to look to remember wich. The bolt just screws in and blocks the port for draining fuel. As long as the screw has hit bottom and there is no gas coming out, you are good. Do not try to tighten them anymore as you may damage them. If I remember right, both bolts are the same size and it is the float bowl that has a different depth hole.
 

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Discussion Starter · #12 ·
so i'm using that pat's jetting calculator program that i got off of this forum and it's saying that i need 127 main's if i have 42 pilot jets. I don't know what pilot jets come stock on the thruxton so i'm not sure if that's what i have. If i put in that i have size 48 pilot jets then it says that i need 125 main's which are listed on NewThruxton.com. so what Pilot Jets come in the Thruxton? I really appreciate all the help. Thanks again.
TJ
 

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the hole for the D tool is on the bottom of the carbs near the wires that hang down for the carb heaters, I usually have to disconnect the wires to get the tool in there. It's pretty centered on the float bowls, you'll have to get under the bike to see it.

I just poked around with the D tool until I found something that mated up.
 

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You should definitely rejet. It runs to lean. With TORs and K&Ns I installed 128 main jets and put one shim under the needle.

I ran this set-up for about 4 weeks and was quite satisfied.

Based on a recommendation in the German Thruxton Forum I enlarged the 2,5mm hole in the slider (is that the correct expression?) to 3mm. You would really be surprised what effect large holes have :razz:

Clearly more torque. The acceleration is amazing.

That's by far the best modification I've ever done! It's like a different bike.


And I put a specialy manufactured spacer between diaphragm and top cover. The diaphragm tend to swell due to agressive fuel. Hence, they space between them and the top cover isn't big enough and the slider can not be pulled up to full extend.
My bike was running really smooth. But I was missing top speed. It wouldn't run faster than 110 mph or so. With the spacer installed I'm back at 125.



Sailor
 

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You should definitely rejet. It runs to lean. With TORs and K&Ns I installed 128 main jets and put one shim under the needle.

I ran this set-up for about 4 weeks and was quite satisfied.

But:
In addition to the above described mods, and based on a recommendation in the German Thruxton Forum, I decided to enlarge the 2,5mm hole in the slider (is that the correct expression?) to 3mm. You would really be surprised what effect large holes have :razz:

Clearly more torque. The acceleration is amazing.

That's by far the best modification I've ever done! It's like a different bike.


And I put a specialy manufactured spacer between diaphragm and top cover. The diaphragms tend to swell due to agressive fuel. Hence, they space between them and the top cover isn't big enough and the sliders can not be pulled up to full extend.
My bike was running really smooth. But I was lacking top speed. It wouldn't run faster than 110 mph or so. With the spacers installed I'm back at 125.



Sailor

[ This message was edited by: streetsailor on 2006-11-28 07:01 ]
 

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On 2006-11-28 06:16, streetsailor wrote:
And I put a specialy manufactured spacer between diaphragm and top cover. The diaphragms tend to swell due to agressive fuel. Hence, they space between them and the top cover isn't big enough and the sliders can not be pulled up to full extend.
My bike was running really smooth. But I was lacking top speed. It wouldn't run faster than 110 mph or so. With the spacers installed I'm back at 125.



Sailor
Where did the spacers come from, sounds interesting.

Cheers,

Brett
 

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Discussion Starter · #17 ·
i actually just installed the epco stainless exhaust and i'm going to put some K&N pod filters on and i have a spare air box to cut up. I'm going to re-jet to 155 as per Pats Jet calculator. what hole do i enlarge?
 

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Brett wrote:
Where did the spacers come from, sounds interesting.

They were handmade by Classicbike Raisch in Germany. Rainer, the owner, came up with the theory of the 'swelling diaphragm'.

I was sort of the field tester for that spacer. Since it worked really well he is thinking about going into serial production...


Just contact him.



Streetsailor
 
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