Bonneville America Forums Forums Technical Forums Performance Mods Bike surges at speed since removing snorks

OK guys, I've asked Dinqua about this, looking for some ideas how to minimize or eliminate a slight occasional surging I notice at around 50-60mph (in 4th or 5th gears). Maybe it's always been there since 50-60 has always been where I notice the most vibration, but if I am cruising at a steady speed around 50-60, it seems like the bike surges back and forth, more noticeable downhill. Also a little under hard acceleration. What do you guys think? Anybody else out there see this. Have 130 Mains, 42 Pilots, 1 Shim on stock needles, Bub Slash Cuts and all Snorkels removed with a Unifilter.

On my bike, there was a flat spot right in the low to mid range RPM, which is where you are feeling this surging. My flast spot was cured with the TBS needles. I wonder if that's what you are feeling. It's cheap and fast to try.

Thanks Triumphant, I just went back and did a little further research, and found Deuces oringinal posts about the TBS needles, sounds like the ticket. Now to find some FAST!

gerg,

Call Bob at Palm Beach Triumph. I think I paid $7 apiece for them. I also know he can get them to you fast!!!

Ordered my needles from http://www.rideteamtriumph.com/intro.htm
Got them two days later with normal postage.

I noticed the same thing after adding more fibreglass to my Raask pipes, to quieten them down a bit. Once I did this, the bike seemed to accelerate faster, but had this surging at higher speeds. Thought at first it was just the wind buffeting me, but there is definately some surging going on. Thought I´d just have to get used to it, but maybe should try the TBS needles as well ?
/Tiv

It's called a "lean surge" and changing needles should cure it, as the others have said. This beats trying to fiddle with the main jet, especially when you are really close on jetting in the first place.

Thanks, now just waiting on the mail! Tick, tock, tick, tock....

Hey Papa, I have TBS needles and I still get a hint of that surging and another guy local to me is running sceptres and 160s and still gets it a teeny bit... Could it be possible we're still lean with the freak? Or is it something messing with the screws could cure?

benny,
When I put in the freak and the 160s I was very surprised to find white/slightly tan plugs after a plug chop.
I think this is very subjective to the pipes being used. Some are just more effecient and they all flow different.

Well I've got stock pipes with one baffle knocked out... I would think it anything I would still be rich!!

Ok I'll have to try to choke idea, I always forget once I get on the road!! It's really not THAT bad, and I think I might wait till next week when the Epcos arrive.

When you get your Epcos, be sure to use the jet kit that comes with them. Don't even bother starting it, it will run like crap untill you rejet. The exercise will be good for you anyway, you'll need the extra strength to hang on.

well, sadly, can't say the TBS needles made any noticeable difference in the midrange surging, and need to get a little more saddle time before I make a judgement on throttle repsonse (had stock needle with 1 shim) The only other thing I can think of that makes any sense (except for the fact that it seems most pronounced at one speed range, is maybe the chain being unevenly stretched. I'll throw it up on the floor jack in the morning and watch her go round and round and see what gives... Already checked the concentricity of the jackshaft sprocket, it looks good. Well, what the hell, i've already got an 18t on order, maybe a new chain will be next in line! Gee, glad it's only money...

Well, after reading Greybeards post somewhere about slack chains, and unevenly stretched chains (and seeing the wear on my front sprocket) I suspect my surge (a herky jerky motion) is more in the drivline. I am starting with the front sprocket, since I need a new one anyway and will go with the 18t at the same time. The rear sprocket looks ok, but I noticed with my bike on a lift and the engine running and in gear, that there is some "slapping" of the chain, and every so often it starts to bunch up where the chain feeds onto the bottom of the rear sprocket. So, I'll focus my attention there. Oh, and the TBS needles did seem to make the acceleration a little smoother and stronger, I'll have look at the plugs and see how they look.

Hey Greybeard, I already have 160's in there, did that when I did my freak this winter in anticipation of the pipes. They've been on order for a while, ,ong story, but they should be here this week sometime!!

Well Benny, you're right. The 18t was/is, what I was looking for!! I now cruise the strip in 4th with 5th in the back pocket, and it feels much more comfortable at 50 in 4th than before when I did it. Hard to believe what one tooth changes!! I'll be replacing my chain Sat and hopefully that'll be the end of the surge...

RE: "Hey Papa...."

What Greybeard said.

Also, and I've mentioned this before, there must be an intermediate circuit in these carbs somewhere. Enriching all the other circuits and not that one will give the result talked about here: a slight hesitation. Too low a float level setting will do that, too.

Guess I'd better get serious about looking at this carb from a design standpoint, that is, check out a cut-away drawing or something similar.

One last item on this hesitation business: something we have no controll over, but nonetheless affects acceleration, is spark timing. Advancing the spark timing helps! Maybe that trick of disconnecting the throttle position switch and locking it "open" should be done.

I was wondering about the pilots... I've parused the performance guide to see what other guys with my settings have for a setup, most of them have stock pilots, but hey, I'll give er a go!! Not that hard a job now that I've done it a few times. Some day I might even try it without removing the carbs!!

Glad you like it Greg!! Let me know how the chain works out. That one tooth is amazing...

Well, I was going to do the chain myself, until I looked at the cost of tools to do it (about $80-130!!!!) and so decided to call the dealer, "what's that, only $30 to do it, SOLD!!!" Seems our chains need a press to press fit the side plate onto the link pins, in addition to the chain breaker and riveting tool!!! DID sells a 1 in all tool for the 525 Series chain we use, but it's $129, OUCH!!! And they'll do it over the lunch hour, so I'll get in a free ride each way (20 miles)...