Plomb Posted September 4, 2006 Share Posted September 4, 2006 Hi, anyone tell me what is the standard main jet size for a UK XX. Jets in mine have 155 on them, standard exhaust airfilter etc. Reading around this would not appear to be standard. Also what is stock number of turns on pilot. Thanks, got to go, wife grumbling about carbs in kitchen! John Quote Link to comment Share on other sites More sharing options...
airborneXX Posted September 5, 2006 Share Posted September 5, 2006 Hi, anyone tell me what is the standard main jet size for a UK XX. Jets in mine have 155 on them, standard exhaust airfilter etc. Reading around this would not appear to be standard. Also what is stock number of turns on pilot. Thanks, got to go, wife grumbling about carbs in kitchen! John My book says 1 & 4 #140 main and 2 & 3 #142 main 49 states/Canada 2-3/4 turns out California 2-1/2 turns out Euro bikes may be different. Quote Link to comment Share on other sites More sharing options...
Plomb Posted September 5, 2006 Author Share Posted September 5, 2006 brett Thanks for the quick reply, the Euro setup might be slightly richer but will be up one size at most. (just checked 145 / 150) I bought this bike recently as a bit of a project & the high speed stutter is the only thing I cant sort. I had assumed as it has standard mufflers & filter that it wouldnt be jetted & only examined the carbs for damage & dirt. Felt a little thick looking at it again last night and spotting 155 stamped on the jet! I will buy a set of standard jets to replace these. I suppose I should also now check that the other parts are standard. The smaller jet says K42S (or possibly K425) which I think is standard. The needle has a stepped profile , is this standard? Thanks again John Quote Link to comment Share on other sites More sharing options...
airborneXX Posted September 5, 2006 Share Posted September 5, 2006 brett Thanks for the quick reply, the Euro setup might be slightly richer but will be up one size at most. (just checked 145 / 150) I bought this bike recently as a bit of a project & the high speed stutter is the only thing I cant sort. I had assumed as it has standard mufflers & filter that it wouldnt be jetted & only examined the carbs for damage & dirt. Felt a little thick looking at it again last night and spotting 155 stamped on the jet! I will buy a set of standard jets to replace these. I suppose I should also now check that the other parts are standard. The smaller jet says K42S (or possibly K425) which I think is standard. The needle has a stepped profile , is this standard? Thanks again John What RPM's are you noticing the stumbling? Around 5k? Mine does it around 5k, if it hasn't been run hard for a while. Example cruising along at 4500 to 5000 and hit the the throttle it will stumble for a second then go like hell. It seems to go away for a while after I run it good and hard. I'm waiting for the next foul weather weekend to pull them out and give them a good cleaning. Mine is running a little rich as it was set up for a 4 into 1 Yosh exhaust now it has a stock header with Micron slip ons. While I'm in there I want to see what I have and try to lean it out some. Edit to add: Looking the the microfiche it appears that the factory needles are a stepped profile. Quote Link to comment Share on other sites More sharing options...
Plomb Posted September 5, 2006 Author Share Posted September 5, 2006 brett 5K would be about right, though in my case almost unrideable. I have a full standard exhaust & airfilter so I am going to have to go back to standard. I pulled the needles out this evening & they are not original so I will replace them & the main jets. To get back to standard should I replace the emulsion tube the main jet screws into & the spring ontop of the diaphragm or will this make little diffrence?. The slide also looks like it has been drilled, it now has two holes, am I right in thinking one is standard? Thanks & apologies if the Questions are a little obvious, don't know much about jets etc. John Quote Link to comment Share on other sites More sharing options...
airborneXX Posted September 5, 2006 Share Posted September 5, 2006 brett 5K would be about right, though in my case almost unrideable. I have a full standard exhaust & airfilter so I am going to have to go back to standard. I pulled the needles out this evening & they are not original so I will replace them & the main jets. To get back to standard should I replace the emulsion tube the main jet screws into & the spring ontop of the diaphragm or will this make little diffrence?. The slide also looks like it has been drilled, it now has two holes, am I right in thinking one is standard? Thanks & apologies if the Questions are a little obvious, don't know much about jets etc. John No apologies needed, I'm learning as I go along myself. According to the Dynojet website (Dynojet is common here, I don't know what's standard over there) There is one hole in the slide that just gets enlarged. I've read where there's a 5k "flat spot" that is cleared up by installing a jet kit. Dynojet's kit supply's 2 different size mains, one for stock exhaust and one for aftermarket. Their jet numbers don't match the Keihin numbers, and I haven't figured out how to cross reference them yet. Actually I haven't really tried too hard either . Personnally I'm going to try adjusting the needles and maybe dropping the main down a size or 2 depending on what I find in mine. Mine runs great I just want to give them a cleaning and maybe lean it out a touch for better gas mileage. Quote Link to comment Share on other sites More sharing options...
Plomb Posted September 5, 2006 Author Share Posted September 5, 2006 Thats interesting, Maybe I would be better to look for that jet relevant to the standard exhaust (fairly sure it's a dynojet kit, clip on 3rd slot on needle), though it is almost easier here to order honda stuff & these type of bits are not so expensive. I don't want to tune this bike for more power , just rideability as I will use it through the winter. Thanks again & I will post back after I have it sorted. John Quote Link to comment Share on other sites More sharing options...
bajjer9 Posted September 5, 2006 Share Posted September 5, 2006 do a search for jets or factory pro by Maxx...he had his 98 tuned well and he told me the best peformance was from doing the european jetting Quote Link to comment Share on other sites More sharing options...
airborneXX Posted September 7, 2006 Share Posted September 7, 2006 Here's a listing of the Euro jets from one of MaXX's posts. UK is Carbs 1 and 4 = 142 Carbs 2 and 3 = 145 Here's the link to that post for more details. I think I'm going to pick up these jets sizes. Linky Quote Link to comment Share on other sites More sharing options...
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