Bonneville America Forums Forums Technical Forums Performance Mods Dyno results

I just had the bike dyno`d.
It put out 64.1 hp.
The mechanic told me it isn't showing sign of running lean.
He thought it ran great & likes the Thunder pipes.
Told me bike was running fine & did not need to rejett.
Said if I check the spark plugs to look at the electrode for signs of running lean,not the ceramic.
I have the AI removed & the snorkel out.
I posted this on another forum.
Just wondered what you guys think.
I am running the stock jets for the Speedmaster.
Air screws are out about 4 turns.

thats actually very impresive i think. for only pipes and snorkle sounds about right. kind of funny how a 1450 harley puts out about the same hp as our lil 790's

Frank

Thanks for replying.
The ceramics on the plugs are a light gray color.
As I mentioned the mechanic told me the electrodes look good.
Not to pay to much attention to the ceramic unless it was black or starting to melt.
The dyno showed a good pull all the way to redline.
The bike runs a lot better with the snorkel out.
I had a sort of a flat spot from 3000-5500 rpm with it in.
I guess my only concern is that I am still running the stock jetting.
From what I have read everyone suggests rejetting.
Maybe I just read to much.
Thanks again.

Remember to read the ceramic insulator way up inside the plug, where it ends at the plug body. You may need some light to help you see up there.

Reading plugs was always the way to tell how your motor was running, but with "modern" gasoline, it has become very difficult to get plug coloring. Thanks, EPA.....

those thunderpipes must work well. the stock speedy jets were 120s in mine.

did he give you the hp when the snorkel was in?

be interested to se hp w/ a drilled a box and larger jets...

cat

No I only got the reading with the Snorkel out.
I am not sure what size the jets are in mine.
My bike was built on 1-04.
The service manual I bought<Part# T3850902 issue3,11.2002> says the AMERICA/SPEEDMASTER HAVE 110 MAIN JETS.
Maybe I have a old manual & they increased the jet size.
Do you know if this is true?

dowop,
My Speedmaster also came stock with the 110 mains.
Great results by the way. I guess those Thunderbike guys DO know what they're doing after all.
I am again playing with my jetting, I really need to get back on the dyno to dial it in when my buttdyno is done toying with it.

Dinqua,
I really do like the pipes.
I would like to know how to read the plugs for being to lean??
I have the link to the NGK chart.
But as I said the mechanic told me not to read the ceramic.
I will check them latter the way Papa Dean said.
Thanks

I would believe the NGK chart, no disrespect meant to your mechanic, but I would think that the plug manufacturer knows a little more about reading plugs. Even with the newer gas it is a little spazzy at times, but generally speaking about halfway or more down the ceramic is where I read mine. That's why I jetted again last night, mine was running too rich (black plugs) and my mileage sux, only about 30-35mpg. I went from 160 down to 150 mains to try and get a few more miles for my hard earned pence, but not at the cost of performance decreases either. Feels just the same as before. I can swap my jets in about 15 minutes now, getting really good at taking them apart by now.

Dinqua,
Re-jetted following your instructions, but need to open up the pilot screw a little to eliminate occassional backfiring. Tried to get the float bowels off while carbs still on, but my fat hands just couldn't get it done. I did replace the bolts with allen head cap screws, and thought it would be easy, but no such luck! Any secrets or do I just pull the carbs again?
Thanks

You do not need to pull the bowls to adjust the pilot screws. They are accessable from the outside of the carbs. They are the frontmost screw, up in the hole on the very front of the carbs. I cut off a little flathead screwdriver and it fits in there nicely. But I also replaced my pilot adjust screws with the big thumbwheel ones that I can adjust with my fingers with no tools. You might consider those, about $30 though for the set.
Check the pistures on my site again, you seem to be confusing the piolt jets with the pilot screws. They are different critters. Take another look. Measure twice, cut once I was always told.

Yes, yes, yes...you're right! Thanks! Seems like I get more confused every day! Where did you get the thumbwheel screws? By the way, your bike really looks sharp.
I had to put a flexible chrome strip along the bottom tank seam because during the re-jetting procedures, I removed the tank and chipped some paint along the seam, tried some touch-up, looked worse than the chip, so went the chrome route. I'll have to get one of my more computer literate daughters to help me post some pics.
Thanks again

BellaCorse Thumb Screws
If your bike is an 04/05, you may have the dreaded "D" screws in there now. If you do, you can use a piece of brake line, tapped on one side to form the D, to adjust/remove the ones in there now. Or, you can remove them and hacksaw a slot in them so you can adjust them with a small flathead screwdriver.

I guess the bottom line is.
I really like the way the bike is running.
But the ceramic is a gray color all the way down.
Should I be concerned?

Quote:

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the ceramic is a gray color all the way down.
Should I be concerned?

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short answer...no.

Thanks Pat,
I owe you a case of good beer.