Triumphrat

truebrit · 07-07-2007

Had a service at the dealer the other weekend and asked them to check and balance the carbs and take a look at the mixture settings for me as the pipe on the left (from behind) was much darker.

After handing me back another chunk of omissions metal (nice!), the tech said that all was good. The carbs were checked and "in-balance", and the mixture was a little off on the left carb. He said that after a test ride or two, the mixture screws are now out to 3 3/4 turns.

Since the service, the bike has been running ok (always does), but I do now feel that it is running a little rich. The roll-on throttle acceleration in higher gears seems chokey to me. I could change down, but the bike is so torquey and sounds so good - I do spend a lot of the time in the high gears.

Also, when I stop anywhere for a couple of minutes and try and start the bike when hot - it takes an effort to fire, and when it does - it just barely hangs on to the tickover. Give it 15+ mins and it seems fine.

Thoughts anyone?

gilligan · 07-07-2007

I'm running a similar set up on my 07 TBA (130's, stock 42's,TORS, Uni). I found that I was actually running a little lean at lower rpms with the snorkle removed and that the bike ran better (more tractable) with the snorkle left in.

Then, just this past week, i installed a thin washer shim under the needle jet to richen the mixture slightly and that made a huge difference. Still thinking of putting in the TBS needles which everyone says work well too.

Does your bike reach redline at full throttle or does it break up at higher rpms, as mine did during testing when running rich?

truebrit · 07-07-2007

Haven't tried the full throttle test ... i'll give that a try ... sounds like fun anyway

As for the mix, it shouldn't be too rich - and I don't think it is when it's up and running. When I first had the mods done, she was dyno'd and all was good - but the classic "lean through the mid range was evident". Hence the shims/tbs reccommendations from everyone.

With yet another piece of the emissions ***** removed - she must be breathing hard - so with no shims and the 130 - it should still be lean.

I think the isse might be with the 42s. Since putting them in, cold starting was much improved and I hardly use any choke. Conversely, more fuel is getting in at idle/low rpm/early throttle when warm/hot too and I wonder if it gets a little choked?

I am not much cop at all this a$$ dyno stuff as I am still a relatively new biker on the speedy - but it is getting "more sensitive" as the miles clock up.

ErwinM · 07-07-2007

Quote:

Still thinking of putting in the TBS needles

They did the trick for me. Bike runs great thru the range.

Erwin

speedblastr · 07-08-2007

Me too! TBS needles-1shim each! Far out! :-D

truebrit · 07-08-2007

Ok ... quick ride today with a couple of full throttle, high RPM runs.

Hitting the throttle hard in 1st/2nd, the bike pulled strongly all the way to 6K+ ... not sure I touched 7K ... but certainly no breaking up or running out of steam.

But ... starting the bike before the run was interesting. Again, it fired, ticked over, choked-up and stalled. I had to hold the throttle open at about 1500 - 2000 for about 20-30 secs to get the bike to hold a tickover. After literally 1/2 mile of riding - she was fine.

My instinct tells me that the new 3 3/4 turns on the mix coupled with the 42 pilots makes it all a little rich at idle - but I am no expert - so can't be sure.

The TBS or stock needles with shim(s) will definitely fill out that lean patch, but I am wondering if I need to drop back to the 40 pilots ... or turn the mixture back to 3 turns. The 42s made a big difference to cold/cool weather starting, so I would be reluctant to change them.

gilligan · 07-09-2007

I'm not a mechanic, but could the pilot jets be clogged or dirty?

truebrit · 07-09-2007

Me either ... but if they were clogged or dirty - wouldn't it be lean / fuel-starved - not chokey?

Anyway - I'll do some more riding/starting and see how it behaves over the coming weeks.

Something is definitely different about the bike since the service and it has to be either the extra 3/4 turn on the mix or the removal of the other bit of omissions ***** - and I'm looking at the mixture as a little rich at idle.

What I don't know is how uniform the mixture setting is across the rev range - from start/idel all the way to redline. If I turn back the mixture a half turn, am I likely to be leaner through the rev range or is there an idle mix and a wot mix?

My god - you can see I know nothing about this stuff - I just like to ride! I am going to have to get smarter about this stuff ...

gilligan · 07-09-2007

Maybe you are right and you just need to turn the mixture screws back in a little to lean it out at idle. The mixture screw isn't going to affect things at larger throttle openings. Go to the Bonneville America web site and look around in the tech vault. There is a lot of good info on carb tuning which explains how different mods affect these bikes at different throttle settings. Also a bunch of those guys have a rally up in NH in August. I don't think I can make it but, several of them helped me install 130 main jets and set my idle mixture screws last week here in CT. Overall a very good group of people.

ErwinM · 07-09-2007

Hey paul,

What kind of K&N filter do you have the single or the duals?
According to pats jetting calculator youre way to lean if you have anything other than the single filter.

Erwin