Triumphrat

peppington

Hello,
What should my '07 Thruxton idle setting be? My dealer says 1050 or so.
Short story...
I had dropped off my bike for excessive exhaust popping during acceleration ( I just had the TOR pipes put on, no re-jetting). Dealer said I must have fueled up with low grade/dirty fuel because my pilot jets was gunked up. I left the shop, after the bike warmed up the idle was at 2500k. I lowered it to the appropriate 1050k per dealer recommendation and all was fine. Today during deceleration I was getting the distinctive gurgling pop, but I also heard a sound like pffttttt coming from the top end carb area.
Question, did my setting the idle lower after they cleaned my jets cause me to have more exhaust problems?
Has anyone heard this sound before?
Long story short, I've ordered the Air-box removal kit, with appropriate jets. Dealer says this should fix my exhaust issues. Will it, or does this sound like an ongoing cash drain?
Thanks for any and all input. :???:

[ This message was edited by: peppington on 2007-06-29 18:57 ]

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Ski_rat

great question, naturaly the rpms will increase as the motor warms but the correct rpm is about 1000, really though it doesnt make too much of a differance.

now as you decelerate in gear your motor will be expelling alot of un burnt fuel this is the gurgling poping you hear as it burns up in your hot exhaust headers, also some times it wil poop out into your carbs and burn up making sharp poof sound, be assured your thrux is fine

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TCL

I don't know how the airbox removal kit is going to solve your problems. It makes the bike run stronger and is a good mod, but you should be able to dial it in with jets and shims without having to change the airbox. If they give the proper jets with the airbox, it may solve the problem, but like I said, the airbox is not the issue, it is the jets, idle mixture adjustment or gas. Somehow the fuel is not mixing right or getting enough to the engine. The airbox has nothing to do with your mix. You may get lucky and get the right jets with it, but don't think you need to spend $300 on an airbox to get the right $5 jets.

On to your idle question. Proper setting is 1050rpms regardless of jetting, pipes, or anything. New jets or pipes may require you to readjust your idle, but 1050 is correct. It takes the bike about 5-10 minutes of riding in normal weather to warm up to 1050, but that's where it should be when the bike is good and warm and running well.

Good luck with your issue. I caution you about relying on a dealer that thinks the airbox is to blame. You may want to get a second opinion or wait to someone on here with more knowledge than I chimes in.

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peppington

Excellent feedback people!
Thanks for responding. I was worried about riding with the popping/burn-off happening but my dealer said it'll bother me more than the bike.
And just to clarify, the dealer didn't say I 'needed' the Air box removal kit to reduce the problem, but if I went with that modification the new jets that come with it would really help. I'd been leaning towards getting this done, now I'll just do it sooner than I planned.
Once again, great feedback, Thanks

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TroyH

Haynes quotes correct idle at 1000 +/- 50 RPM.

Mecchanica

I figure the best idle speed is the lowest smooth and reliable idle. The only downside of a low idle is if you spend a lot of time in traffic, the alternator output might not keep up with the demand. Not really likely, but a potential problem.
If you're popping on the overrun, raise the idle speed slightly and/or lean out the idle mix a little.
Before fitting the Dynojet kit, the engine didn't make nearly as much torque down low, so the idle had to be set higher. Now, it can idle at a lower speed with no chattering or lurching and it pulls cleanly and strongly from idle.
I am doing the mods incrementally, as I like having a baseline to work from. So far, the only tuning mods have been the kit and drilling out both mufflers with six three eighths holes through the end cap AND the baffle plate inside, and picking out the packing. I also installed the extended idle screws. Total cost so far is about 125 dollars and the cost/benefit ratio is excellent.
My plan is to maximize the low to midrange torque of this engine, as opposed to maxing out the dyno. I find that it makes for a much more relaxing ride which is also more akin to the type of performance of the vintage Triumphs.

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peppington

Problem solved!
So it seems the reason I was getting all the trouble and back firing was a missing vacuum cap. I was inspecting the bike and noticed I had a missing cap, must have been from my AI removal.
Bottom line, bike idles fine when set, runs perfect, sounds great when decelerating. A 180 turn-around from earlier this week.
Thanks for all help and suggestions.

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