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Increasing pilot jet...How bid can I go?

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

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I installed a Dynojet stage 3 kit, K&N pods and a Supertrapp 4 into 1 on my 83' GS1100E. They main jets are DJ 138's, needles on 4th clip plus 1 shim and a/f screws 4 turns out and I'm still finding it lean on idle and on the bottom end so I'm going to try installing a larger pilot jet. The stock pilots are 47.5's and I wanted to order some 52.5's but the dealer said they were back ordered and would be a month but could get 50's or 55's. I told him to give me the next size (I meant smaller, he thought larger) so he ordered the 55's and since it's a special order, I'm stuck with them. It's not that bad because they're not that expensive but are these going to be way too large?
 
Three sizes up for the pilots, seems like a lot, but I've never tried that big of a jump. On size up makes starting easier. Usually no choke needed in the summer, less choke & quicker warm-ups in cooler weather.
 
I also have a 83 1100E, and the stock pilot jet size is 45. I have 47.5 in mine with pods and a pipe, and it seems to run fine on low end.

It takes a while to warm up, with full choke required, but after warmed up is no problem.
 
55 is a big increase. The 50 would probably be better. The pilot jets do make a big difference down low and right through the mid range. I went up only one size for mine, and it made all the difference.
 
The engine and carbs were a direct swap from a 82 Katana 1100 so that's why the stock pilot is 47.5. I'm a little pissed off that I'm being stuck with these 55 pilots when I wanted the 50's so I figure I'll give them a try anyway and see how it goes. With no airbox in the way, I can get the carbs out and back in in no time.
 
Does your kit instructions say to keep the pilots stock? Some Dynojet needles are meant to work with the stock pilots.
The needle has an effect much sooner than you think. Try removing the shim you have on top of your needle clips. Set the mixture screws back to 3 turns out. I assume you did a good job of drilling out your piston valves and you have all 4 carb vacuum levels within 1 cm of each other?
 
Since the jet ket kit didn't come with alternate pilots, I'm assuming it's meant to work with the stock ones. The only alternate jets that came with the kit other than some smaller mains were some larger pilot air jets but installing those would make my problem worse. I was very diligent in drilling out the slides but haven't checked the vacuum on the carbs yet. I plan to get back in them again this weekend and do a carb sync as well.
 
How do you spell gueni pig? Keep us imformed, cause now you've got me wondering.
 
rphillips said:
How do you spell gueni pig? Keep us imformed, cause now you've got me wondering.

It's official then, I don't mind being the guinea pig and I'm going to give the 55 pilot jets a shot. I really would have preferred some 52.5's or even 50's but since I have them, why not try them. Better to be too rich than too lean. Worse case scenario, I've wasted 1 1/2 hours of my life but then again, I do enjoy this sort of thing.
 
You say it's lean at idle and the bottom end. What's it doing? Any plug reads after low speed test? Have you removed the two floatbowl vent lines so the pilot jets can draw fuel easier? Also, make sure the float levels are set within range. I like to set them towards the "richer" end of their range.
Example: mine are supposed to be between .90 and .98", so I set mine at .96".
 
The float bowl vent lines have been removed. The carbs were out of the bike all winter and I had checked and double checked everything. The float heights are all within spec but the plugs are looking really quite white and it's very slow to warm up. It seems to be running fairly well but I'm getting tons of decel popping which I'm not sure is a sign of lean or rich but I've heard a larger pilot sometimes cures that also.
 
Yes, decel' popping is a lean sign. You can't always get rid of all of it, but as much as you describe is too much. I would FIRST try a good carb sinc' and test. If it's still lean I would also raise the needles 1/2 a position by removing the shims you installed and get some more plug reads. Your white plug colors I bet are at least partly related to the needles. You may have to go to the 5th position with a shim on top. Have you run the bike at a steady 70 mph for several miles and then immediately taken a plug read? I would have patience with the pilots and order the 50's or 52.5's if still needed. I think the 55's are too large and will just cause other problems.
 
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