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Discussion Starter #1
I have a 790 Bonnie, all stock except A/I removed.
These things came out of the factory running WAY TOO LEAN and are a bitch to start in any weather below 70 f .
I want to re-jet it, but what size should I go with?
Any suggestions?

Thanks
 

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Try a 115 for the main jet. They come with 110.
 

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Discussion Starter #5
if its just hard to start,how about turning the mixture screws out 1/4 turn and see if that helps.
not just hard to start in cold? weather (anything less than 70) but I know it's too lean.
When engine is hot and I'm going down the road on a hot summer day, pulling out the choke should make the bike want to die, but it just runs stronger, telling me it wants a richer mixture.
The mixture screws are turned out already.
 

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Any air leaks? Doesn't sound right that your stock bike (the ai shouldn't affect mixture, right?) needs to be that much richer.
 

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Discussion Starter #8
no air leaks

Any air leaks? Doesn't sound right that your stock bike (the ai shouldn't affect mixture, right?) needs to be that much richer.
NO air leaks.
It was hard to start (COLD) from day one; I'm the original owner.
I know these bikes were set up very lean to meet USA EPA regulations.
That's the main reason the exhaust pipes turn blue so quickly.
 

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Try this....

First off, from my experience, removing the AI DOES make a difference to how the bike idles and starts - I have no proof of this other than my own experiences, but changing one thing in a set up must surely have SOME effect. Try putting it back on and see if it works for you - you can always remove it again;)

Secondly, if you're planning on staying almost stock (maybe adding TORs or other aftermarket exhausts and maybe a K&N or Unifilter) then can I suggest the best way forward is to get a DynoJet Stage 1 kit. This worked a treat on my otherwise completely stock 01 790cc Bonnie, so why not take advantage of the research DynoJet have done? I highly recommend it!

Dave
 

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Discussion Starter #10
First off, from my experience, removing the AI DOES make a difference to how the bike idles and starts - I have no proof of this other than my own experiences, but changing one thing in a set up must surely have SOME effect. Try putting it back on and see if it works for you - you can always remove it again;)

Secondly, if you're planning on staying almost stock (maybe adding TORs or other aftermarket exhausts and maybe a K&N or Unifilter) then can I suggest the best way forward is to get a DynoJet Stage 1 kit. This worked a treat on my otherwise completely stock 01 790cc Bonnie, so why not take advantage of the research DynoJet have done? I highly recommend it!
Dave

Put it (the AI system) back?
I bought the bike new (did you not read that), and it was HARD TO COLD START from day one.
Removing the AI didn't change its cold nature.
 

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Is this something specific to the 790 Bonnie's? I was talking to my dealer about cold starting and told him that I fired up the bike in -10C a few weeks ago and he said that it shouldn't be to much of a problem because they run a little rich anyway....

They did the TOR install before I bought the bike and they tuned it using the dyno to get everything right. It runs like a top despite any weather and starts better than my 05 FI Sprint ST. Go figure.
 

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What are the jet sizes in the stage one kit? I called bella corse and was told that for my bike which has the ai removed , pods and different mufflers that i should run 1 size up on the pilot and 125 mains and 1 shim on the stock needle for good gas mileage, 140s for max power. This is with a 19t countershaft sprocket.
 

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What are the jet sizes in the stage one kit? I called bella corse and was told that for my bike which has the ai removed , pods and different mufflers that i should run 1 size up on the pilot and 125 mains and 1 shim on the stock needle for good gas mileage, 140s for max power. This is with a 19t countershaft sprocket.
Sito is right, the info on jets sizes is on the DynoJet website, BUT bear in mind DJ use a different jet numbering to Keihin (there is a coversion on this site - do a search). However, the DJ kit also replaces the stock needle and spring (in the US) or airslide hole (Europe). DJ do not supply bigger pilots, but do suggest the airscrews are opened 3 turns ( 2.5 is stock).

The total effect is excellent if everything else is stock, and I've also had it working well with TOR's and a Unifilter. I don't think they would recommednd it for use if the airbox is removed though.

Dave
 

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Sito is right, the info on jets sizes is on the DynoJet website, BUT bear in mind DJ use a different jet numbering to Keihin (there is a coversion on this site - do a search). However, the DJ kit also replaces the stock needle and spring (in the US) or airslide hole (Europe). DJ do not supply bigger pilots, but do suggest the airscrews are opened 3 turns ( 2.5 is stock).

The total effect is excellent if everything else is stock, and I've also had it working well with TOR's and a Unifilter. I don't think they would recommednd it for use if the airbox is removed though.

Dave
That's right; you need a stage 3 kit with the airbox removed and they don't make them for triumphs--I called and talked to one of the guys there as I wanted an adjustable needle (at the time).
 

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Jets

If you are running stock 112.5 will work well. If you go with a K&N or Unifilter 115s will work well. If you still have a problem with starting go to 42 pilots. This set up will work with a debaffeled exhaust or TORS if you change out exhaust. Get a hex head stainless screw set for the carbs. Makes life easier.
 
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