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I have TORs on my Thruxton, but have an opportunity to get a set of British Custom "Predators".

I know that re-jetting is optimal for power, but I'm wondering if they can be run with stock jetting. My only mod is AI removed. Will the bike run lean without rejetting? I like the exhaust note from the Predators, and am not concerned about extra power--just don't want to run too lean. When I want speed and power I ride something else.

Thanks,

Karl
 

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Bike is somewhat lean right from the factory. I'd take the 110's up to 115 or 120 even. Jetting on the bike is easy -unless you have the dreaded factory carb screws which seem to be cast out of butter. Then you'll need the stainless steel carb screw kit sold by our vendors. Get the special "D" tool and adjust the air screw as well. Well worth the time and effort.

John

[ This message was edited by: Thrux-ton-up on 2007-02-17 05:53 ]
 

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+1

Yep, re-jet it. You'll take better advantage of the Predators abilities and get the cool sound you want at the same time.

JOHN
 

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I ran them for a short while before i Re-jetted. Your headers will go beyond blue into the purple zone. Your will prolly get some popping on decel. Its not going to destroy your bike but you will be very very lean at that point.

+2 for re-jetting.
 

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I now have Preds on with stock jets. I am also running a K&N air filter. Plugs are looking lean. Going to go to 125 mains and pull the snorkel. Unless I am missing something, Dinqua is set up for Speedmasters and Bonneville America, not Bonneville, T 100 or Thruxton. The Jenks Tools Tuning notes lay it out pretty well and have a Carb setting for various bikes and changes. This is down loadable from Jenks Tools.
 

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Running jetting that is too lean can definitely destroy your engine.

A moderately too lean jetting causes significant excess heat which can lead break down your engine oil and perhaps lead to detonation under heavy loads; a bit leaner and you've got an oxidizing flame that can burn holes in your piston and detonation is almost a given. Leaner still and you won't last one long full throttle run before severe detonation hammers your pistons and bearings to death. Now why would anyone want to do that to such a nice motor?
 

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OK, now you guys have me worried.

I'm getting a new house, with a garage, in about 10 days and was waiting to rejet the carbs until I moved into said house with garage.

The Predators have been on for about 3 weeks, still with the stock airbox. AIs have been removed all along. Hopefully, no lasting damage has been done.
 

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Hey Jimbonnie

Just in relation to the comments you made:

A moderately too lean jetting causes significant excess heat which can lead break down your engine oil

My Thruxton may be running a little on the lean side as I do get some popping on deacceleration, (AI has been removed)
I have only had the bike for about 4 months and in that time I have had to top up the engine oil twice which I have been advised is very unusual. I spoke with the Triumph dealer regarding the popping and they throught it was minimal and probably more that the cans I am using have very little backward pressure. Any thoughts???

Cheers mates.
 

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"OK, now you guys have me worried."

Be worried, be very worried!!!

"The Predators have been on for about 3 weeks, still with the stock airbox. AIs have been removed all along. Hopefully, no lasting damage has been done."

The stock airbox is probably saving your bacon. AI on or off has no impact on internal combustion and so the AI isn't an issue. I doubt any damage at all has been done, but rejet asap and definitely before you open up or replace the airbox.
 

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Icha:

Excess heat can increase oil consumption but you might have other issues. If your piston rings haven't fully seated yet (new bike with low milage?) combustion gases leaking past the rings might be pressurizing your crankcase and causing oil to be lost through the breather. In this case it will show up in your airbox and the oil collection tube beneath the airbox. If this is the case run it hard and try to get those rings to seat. This is the primary reason some folks like to break in a new motor hard.

If you have a more serious ring or valve guide problem you might smell the odor of burning oil as you decelerate after a hard run and the oil is sucked into the combustion chambers past the rings and guides. If you have this level of consumption I'd think you have a warrentee claim.

Popping in an exhaust system can be caused by over rich or over lean mixtures which fail to burn completely in the combustion chambers and collect in the exhaust system where they complete their combustion; too rich or too lean mixtures both burn more slowly. An air leak in your exhaust system introduces additional oxygen which helps burn any collected and unburned fuel. What kind of jets are you running and what else have you done to your intake system?
 

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OK, Jim, since you seem to know this stuff, **and** since you list NorCal as your location, wanna come to Seaside & help me out? :)
 

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On 2007-02-18 16:26, itcha wrote:
Hey Jimbonnie

Just in relation to the comments you made:

A moderately too lean jetting causes significant excess heat which can lead break down your engine oil

My Thruxton may be running a little on the lean side as I do get some popping on deacceleration, (AI has been removed)
I have only had the bike for about 4 months and in that time I have had to top up the engine oil twice which I have been advised is very unusual. I spoke with the Triumph dealer regarding the popping and they throught it was minimal and probably more that the cans I am using have very little backward pressure. Any thoughts???

Cheers mates.
Itcha, the predators will pop regardless of proper jetting, on decel anyway.

I doubt it has anything to do with oil consumption.
 

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On 2007-02-19 22:35, sweatmachine wrote:

Itcha, the predators will pop regardless of proper jetting, on decel anyway.
my preds don't pop at all on decel. my girlfriends Bonnie, on the other hand, with NH Togas, sound like the forth of july during decel.

[ This message was edited by: oregonthruxton on 2007-02-20 00:50 ]
 

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I tuned out the pop with the D shaped tool and idle mixture, but found that once the pop was tuned out, it was too rich at idle and up to 1/8 throttle once the bike warmed up. It was like being on choke; started great but ran like poop after 30 minutes.

I'm running 42 pilots 1 turn out now. It pops a little bit on decel but not a lot. with any more than 1.25 turns out it's so rich that rolling on the throttle from a stop bogs the motor.
 

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"OK, Jim, since you seem to know this stuff, **and** since you list NorCal as your location, wanna come to Seaside & help me out?"

Northern California is a big place; kind of like "New England", but if you'd like to come to Fairfield I'd absolutely help you to swap jets and anything else you'd want to take care of. PM me and we'll come up with a plan.

*warning*warning*warning*warning* I don't really know this stuff, though to the uninitiated it might occasionally seem so. Those who know me know otherwise.
 

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Sweatmachine: Your Predators pop because you live in Austin where the humidity is usually less than 20%. Oregonthruxton's don't pop because he lives in Oregon where the humidity is uaually greater than 120%. Those folks up there all have water injection whether they want it or not.
 

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On 2007-02-20 09:56, Jimbonnie wrote:
Sweatmachine: Your Predators pop because you live in Austin where the humidity is usually less than 20%. Oregonthruxton's don't pop because he lives in Oregon where the humidity is uaually greater than 120%. Those folks up there all have water injection whether they want it or not.
:razz: If you don't ride in the rain, you don't ride...
 
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