Bonneville America Forums Forums Technical Forums Performance Mods Bike is running lean-need some advise

Hello-I have been subscribed to this board for 3 years and occassionally post.

I need some help. I read over all the rejetting information from Dinqua and the others and need some advise.

The bike has epco stainless pipes, air box removed, the freak kit with the K & N Filters. The current jets are 160 mains, 42 pilots and 1-2 shims. The carbs were synced but it was still not running good.

The plugs were showing ashy white, which is running hot and the pipes were getting golden.

I had this set up since I got the bike and there seemed to be a change in how it ran.

Now-I went to a local mechanic who re-jetted the mains to 172 and adjusted the air mixture.

In reading all your posts, this does not seem right.

It looks like I had the correct set up in the begining, but why was it running so lean?

Would changing the needles help?

Someone also said that the little rubber caps get old and should be replaced.

I was good and read previous posts, but need some advise here.

You have the same setup (intake/exhaust) as I do. Try this:

155 mains
45 pilots
TBS needles, no shims
3 turns out on the air mixture screws
balance the carbs last (!!!!!)

This ought to give you a good starting point.

You don't say where you are from so I cannot adjust for altitude. The above is for sea level to about a few hundred feet above.

Use Pat's Jetting Calculator and you will see that the setup I gave you is pretty much correct (for sea level).

Hi Phil/Bonnyusa-thank you. I live in California in the San Francisco Bay area.

Are the TBS needles stock on the Speedmaster?

I'm not sure what is on there now.

I had the dealer put in the freak, epcos and re-jet.

Do they change the needles also?

Is the stock set up different between the America and the Speedmaster.

What about using the Thruxton needles?

Thanks again.

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Are the TBS needles stock on the Speedmaster?

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Nope.. the Speedies carry the same as the Americas

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Do they change the needles also?

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Probably not unless you requested it

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Is the stock set up different between the America and the Speedmaster.

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Don't think so.. same carbs as far as I know

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What about using the Thruxton needles

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Needles are a midrange RPM kinda thing.. some people do but it's really more of a preference and how your bike accelerates through the whole power range.

Would I purchase the TBS or Thruxton needles from the dealer or??? I will do further research to find out.

So if I change my main and pilot jets and adjust the air mixtures, remove the shims and replace the stock needle with the TBS needle, hopefully it will run better.

Do you think that will remedy the leaness?

Is there anything else I should do???

Thanks for your assistance.

TBS needles part #T12410240) Youyr dealer will order them for ya.

Hey Deb, Is your Air Injection removed?
This could make a drastic difference in the overall setup and be a cause for your leanness ( sp?).

The lean condition can be caused by several things. Jets affect high and low RPM range and needles affect mid range. To find out where your problem lies would really require a dyno run.
I'm not the performance guru around here but hopefully he'll pick up on this and be able to offer some sound advice.

The A.I. is removed, that's the plugged holes next to the spark plug right? Yeah, they have been removed.

Well-maybe I should go and have a dyno test.

A mechanic put a 172 main, hopefully that will cool it down temporarily. But I just might go ahead and change the mains and pilots and put in a different needle and see how it runs and get new little caps for the carb. I'm hoping that will do it.

Have other folks with running with the Epcos, air box removed, ai removed, K & N filters and the 160 mains, 42 pilots and 1-2 shim and stock needles experienced leaness?

Would it be air holes or manifold leaks?

172!!! That sounds way too big. It could very possibly be leaks. I had 160 mains in mine well in Wendys too and they were still slightly too much. I run gutted stock pipes , Freak ,AI removed. Altitude plays a role as well I ride at mostly 1500 to 2000 above sea level.I also run 48 pilots but as I said in other posts I might bump that down 1 notch.

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The A.I. is removed, that's the plugged holes next to the spark plug right? Yeah, they have been removed.

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Yep.. thats a good thing.. pipes blue if you don't get rid of that.

172 jets are really big jets, shouldn't really need that much fuel.I think most with the freak set up go 160 max.
Yep, be sure to check the carb boots and manifolds for air intrusion between the carbs and head.

I talked to a guy and he'll charge $600 to run and dyno test and TUNE the bike using custom needles and jets. Its seems a bit much to me.

Maybe I'll just sell it and get another bike. I want to ride, don't have time to keep fixing or finding an honest capable mechanic.

Deb No need to go over the edge YET...your almost there... it doesn't say where you are...but I'm bettin there is some member near you that could lend a hand...

And most of us would just to get a chance to play with another bike!

$600 is way too much in my view shouldn't have to put that much time into it and the jets cost $3.

Hey Rob: I'm in the San Francisco Bay Area in California. I just posted the bike on the net. I love to ride, don't know enough to fix just yet, thinking of getting something more reliable like a Honda or Yamaha, but not as exciting.

More reliable? Than a 100,000 mile bike?

Well, mines got 25K on it and just about, the steering head bearings had to be replaced, the chain and sprocket were replaced, clutch cable replaced, two sets of tires, front wheel bearings.

I guess I could try and order the parts and just do it. The instructions are all there. I've taken a couple of classes and could do it. But I love to ride, and there are not very many mechanics that really know what they are doing. Or you can go to the dealer and pay an arm and a leg and they don't even know what they are doing.

I'll just be the person that will buy a bike, keep it maintained and serviced and when it gets lots of miles, I'll trade it in.

Riding is what makes me happy and if I have to take time to hastle and find someone to fix, its not worth it, its just stressful.

Triumph is a great and cool bike, but I can't afford for it to be in the shop or down all the time.

Triumphs are exotics and made for mechanics or people will lots of money to fix them.

I am a mechanic but most of what you just mentioned are standard wear items that need attention on every bike ever made. Unless you have a shaft drive bike but thats just the chain. I have very little money thats why I pay close attention to maintaining the bike. But obviously you do what you think you have to after all it's all about having a good time.

These are the most trouble free bikes I ever owned. I guess it just strikes me funny to hear anyone think otherwise that has one.

Do you know how to check for manifold leaks? Would that be a possibility do you think? Why wouldn't the mechanic have done that?

A good mechanic would have. One way is to spray carb cleaner on those areas and see if the idle changes or the engine dies but first visually inspect for things not seated or cracks in any rubber parts. Go over the clamps and make sure everything is tight. Be careful with the carb cleaner I don't know what it might do to any painted finishes on the bike.

Thank your for your advise. There is enough information on this website to troubleshoot anything. I'm going to try some things you suggested.

I really appreciate your advise, thanks again.