Bonneville America Forums Forums Technical Forums Exhaust Bub Slash Cuts Now Harder to Start When Cold

Installed the Bub slash cut slip ons and now it is harder to start when it is cold and I have some popping on deceleration. I'm sure there are no leaks as I siliconed the slip ons and torqued the header pipes also. The bike is totally stock except that the AI system has been removed some time ago. Is this just a simple matter of adjusting the mixture screws or what? Any guidance appreciated.

anytime the out or the in is changed the carbs must be synched/adjusted. even a "minor" change like removing the snorkles requires carb adjustment/synch. hey you're down the road from me. are you gonna do the frosty balls poker run this sunday?

Thanks for the reply, however, I was looking for a little more detail in the adjustment department. I haven't heard anything about the frosty balls poker run but Sunday doesn't look good right now. Who is sponsoring the run anyway? HHmmm, maybe this post belongs in the Performance Mods section.

Make sure your carb heaters didn't become disconnected. If both are still attached to the bottom of the carbs, let them warm up for minute or two on cold days BEFORE firing the engine. Mine starts immediately with my previous long off-road pipes and the new Specialty Spares.
If you haven't adjusted the air/fuel screws, your carbs are probably set impossibly lean, guessing adding lower restriction pipes made that situation worse. If you are any where near Hagerstown, come up to my place and I'll adjust them for you.

Carb heaters are connected but I agree the mixtures (car talk) are probably lean. Unfortunately, you are very far away from me. The closest I get to you is the Hampstead area where my father lives around 15-20 miles south on Rt. 30. He lives in Fowblesburg, if you can find it on the map. I will buy the tool tonight from Brent to save time.

I would check first to make sure yours requires the tool. I purchased the tool for my 2004, only to find out that I had the older setup. Your 2005 most likely has the new setup, but it won't hurt to check. I just changed my pipes with some Specialty Spares long slash cuts and have similar problems. It starts and runs great, but it's a little harder to start. I have to run the starter a little longer and twist the throttle a little once it catches. It will also stall if it's not totally warmed up. It's popping a little but not too much. It has always popped a little. I'm still adjusting the screws out, I'm at 3.5 turns now. I need to get an 18MM spark plug wrench to check the plugs. Don't know how it would be in colder climates, it's been in the 80's here in NorCal.

80's huh? I'm jealous. A few weeks ago, it looked like an early Spring and then it got colder again. Maryland weather has always been fickle. Anyway, I guess I will pop off the mixture caps and check it out. Hopefully I won't need the tool. Does the popping get noticeably less as you back the screws out?

Don't be too jealous, it's starting to cool off now. We may have rain by the weekend. Yes, the popping and starting seem to be getting better. I started at 3 turns out and have since adjusted 1/2 turn, so it's still early. Hopefully another 1/2 turn will do it.

Hey loosend,
Your bike is breathing better now so you probably are running lean. A lean mix makes for hard starting. That's why you have a choke to richen things up. You probably could help the situation some by turning the air mix screws out a bit. Turn them out counter clockwise (richer) a quarter turn at a time and take a ride to see if it helps. The best thing to do is to turn them all the way in until they just hit bottom, not too tight though, don't damage them. Take note of how many turns it took to bottom out so you know where you were before you started adjusting. It should have been about 3 turns +/- 1/2. Turn them back out the same plus 1/4, or about 3 turns, which ever seems right. (This is seat of the pants stuff, not Sigma 6) The book says three turns. Make adjustments from there. Keep in mind though that the air-mix screws (and pilot jets) affect mostly the low end when you are just above idle or coming off throttle and decelerating. Air mix adjust and pilot jets have some but very little effect on the mid to high range.

A better solution is to re-jet. It sounds daunting, but it's not that bad, and it really helps you learn your way around your bike. The worst part is getting the airbox separated from the carbs. There are two hex screws under the rear fender that need to come loose. Dinqua has a great howto with pictures posted on his website. I'll put the link below, or you can find Dinqua's user profile and click on his homepage. He has gone to a lot of work to post some great information.

Your bike probably came from the factory with 120 main jets and 42 pilot jets. Going up to a 45 pilot jet might help both starting and popping on decel. Bigger main jets would help your top end (4500+ rpms).

My pipes are Staintunes, which are straight through absorber types with no baffles. I can see right through them like a telescope. I first tried 45 pilots and 135 mains and was fairly happy with that. I've tried several combinations and right now I'm running 45 pilots and 138 mains. Seems pretty good there.

Oh, by the way, I'm at about 800 ft in elevation. The higher you go the smaller the jets you need.

Hope this helps some.
John

Dinqua's "Everything you want to know about working on a Triumph" site

Did you get your carbs reset for the popping??? If not do what most suggest, go out 3.5 turns on the air screws, dont know if you have removed the snorkel, but do so! You dont necessiarly have to rejet with BUB pipes, after all you are talking about main jet. Remember-you are attempting to setup your bike like your riding style which isnt WOT, many overjet on the main quite often, it is a waste of fuel. All carb circuits overlap and unless you ride at 3/4 throttle you can setup your bike to perfrom well for now. If you decide to rejet, do not mess with the pilot 42 is fine (actually it is a 45 now - newer sized) so you dont need to mess with it. You can go up to a 130 main a bike will run very nicely.

i think you need to rejet. i never took the carbs off and rejetted w/ everything on the bike, and i'm pretty clumsy w/ my fat hands. if you rejet, you'll want brent's allen head carb screws, or you can take an old screw down to ace and match them up w/ some new lock washers.

i have one of those little mini rachet setups where you can turn the driver w/ a knurled head. they work great in tight spots. i got mine at ace in one of those cheapo bins for 4 bucks. boy are they handy, no pun intended.

get a reach mirror for a buck and see if you have the caps or the d screws.

some people here must have your pipes and they could recommend jet sizes.

cat

mini ratchet set

The D tool is on the way from Brent and I hope I get it by tomorrow. I will then see where the mixture (pilot) screws are from the factory and adjust them out to 3.5 turns or so a little at a time and see what happens. If it doesn't work, its on to the the jets. I kind of got into it with Bub's tech guy about fixing the popping. He did not want to give any guidance other than telling me to buy one of those aftermarket tuning kits. It kind of ticked me off. He had no advise on pilot screw adjustment or jetting and he said to call Dynajet!! A little trivia--My mixture screws do not have cover plates. I guess since I have the D screws. I will let everyone know if the adjustment works.

If your not getting the information your need from Bub, try contacting http://www.bellacorse.com. They sell the Bub pipes with jet kit. I have never dealt with them, but I've seen positive feedback regarding their technical knowledge about the products they sell.

loosend, I had to rejet when I put my Bub's on. The choke is still a bit finicky when I start her, but I think that is partly because I have modified my snorkel on the airbox more than the Bubs. I have decel popping too, and have tried the scilicone and turning out the screws, but not much change. Not too worried about it though. It's not much different than before when I had the stock exhaust.

Well, I received the D tool and found my mixture screws were close from the factory--right carb was 1.75 turns and left carb was 1.50 turns. I set mine to 3 turns out and it starts properly and there is a very minimal popping now. I would imagine what little popping (more like a crackle now) is probably normal for such an open exhaust.

Try pulling your snorkels as well. I pulled mine when installing the new exhaust.

I installed the bub slash cuts and had the air injectors removed, and the freak installed. rejetting was necessary. but i still get a loud backfire on decel. once in a while.

loosend, I have the popping on decel too, and have rtv'd the heck out of the inlets to the Bubs. I have my screws at 3 turns, but have tried 3 1/2 turns and 2 turns. All the 3 or 3 1/2 seems to do is make the exhaust tips build up soot, from what I can see. Am going to look around some more and see what I can find. Oh, and I had to go to 130 Mains when I went to Bubs. The dealer didn't change the Pilots though. Let us know what you find...