Bonneville America Forums Forums Technical Forums General Tech How to tell if I need a rejet?

I am new to Triumph and recently got an 07 Speedmaster. It had long TOR pipes on it but everything else was stock. I was told it had been rejetted when the stock pipes were swapped out. I found a pair of DC cocktail shakers used from the local Triumph dealorship I bought for a little more sound. I put them on and everything seems to run great but I noticed a little more popping when I pull in the clutch. I was told by 2 different guys at the dealorship I shouldnt need to rejet. I just dont want to hurt the motor at all if that isn't true. What do I need to be watching for to let me know if I do need to rejet my carbs?

A dyno run with an accompanying fuel/air readout would be a start. Carb tuning starts with the main jet. Your popping on decel could be remedied by something as simple as disconnecting your TPS or idle adjustments..

There's plenty of information available here. Check the vault and look for the section with intake and carbs. Find Dinqua jetting calculator input the specs and it should get you close. Don't be afraid to ask questions there are plenty of people who will be willing to help.

Here is the link to the jetting calculator.
http://www.bonnevilleamerica.com/dinqua/friar/
Removing the air injection system if yours is still in place also gets rid of most of the decel popping.

I did do the jetting calculator and that is why I was questioning the shop in not needing a rejet. I might try the ai removal and maybe tps and go from there. I haven't noticed any real difference inhow it runs but might take a trip in a few weeks and don't want a break down.

Make sure you have a good seal where the mufflers meet the headers, if you have a leak there that could cause popping. That being said, a correctly jetted engine with low restriction exhaust should pop a little. You can try reading your plugs but it is harder to do with ethanol treated gas. If the intake is stock you may get away with a bigger pilot and maybe a shim on the needle but a dyno run is the best way to see where you are now making it easier to judge what needs to be done. A dangerously lean engine will run great right up until you burn a valve.

I agree with the Dogg ^^

Reading plugs when you don't have cash for the dyno is the way to go.

Having a leak free exhaust makes the whole process easy. That a.I. is a big ole pipe leaner-outer.

I found the jetting calculator is good for + - 5 full jet sizes, to me, that's a fairly big range... And it tends to be liberal with the stock slow jet. But it gets you close.
I'd go up pilot jet size off the bat

This last weekend I did put a little gasket sealer on the connection to take care of any potential leak. After a ride this morning to work it seems to be the same way. My next step will be to remove the AI. I'm hoping that fixes my problem. The jet calculator is only calling for 5 sizes differences assuming my pipes are the same as bubs, Sceptre, or pretty much any aftermarket pipes. I don't think it is that bad as I don't have any dead spots in the throttle and the shop did tell me I would be good.

Oh, and is there a thread on how to read spark plugs? I did a quick search and didn't see anything.
Also for the poping I usually get one big pop only usually when I pull the clutch in and happens more often when warmed up.

That actually sounds like too much fuel loading up in the pipes.

That could make sense as it doesnt seem like I need to use the choke pulled out as much to start and keep running. So I could be overjetted??

Try unplugging your TPS, the plug is a hassle to get to. It is located atop the engine case beneath the carbs. But it's easy to put back together in the future, should you decide to. Eliminating the AI is just a plain good idea too, it serves no good purpose except to heat stain your headers or cause carbide precipitation, if you want the correct technical term. Both of these methods have reduced popping and backfires for many of us. One thing I question though, your dealer says your jets are correct, if so, can they actually tell you offhand, what size of jets are installed in your carbs without guessing? If you do change out the jets, pull your carbs, find the best fitting Phillips screwdriver you can for those (easy to bugger) soft alloy screws, remove them and replace with Allen cap screws (source from FastEddy), then you can do a jet change without having to pull them again the next time. The good news is that once you have them dialed in, your done, unless you change the in or out flow of your motor.

Well , TOR would probably be one pilot jet larger with mixture screw adjustment, nothing more. Less restrictive and you get into main jet adjustment along with pilot adjustment. Then intake mods and you get into even more of both.

If anyone is wondering about an update. I did an AI removal last week, rode it for a few days, and it hasn't popped once since.

Sweeet.. We like happy motorcycles here.. and we like to hear happy motorcycles. Coincidence? I think not..