Jetting advice for a new carb for the FXR

[F5 Dave]

but where can you hold it pinned in top gear for 20 seconds? Just jet it so it goes best without farting & then compare against other bikes & minor changes next kart day.

[hmurphy]

Ah fair enough, I will give that a go. Well it isn't legal but it's responsible where I have been testing. There are hardly any cars around at all and no houses also. So I am out of mostly everyone's space. Also it only does probably 90km/h max with the gearing in it at the moment so I don't go far in top gear with it pinned for 20 seconds haha. Hey cheers for the help Dave. Just need jets to test with now haha

[hmurphy]

Sorry for digging this thread up again, but I need help still haha.

Basically a van ran over the bowl of my carb while out testing a while ago and I have finally got a new carb bowl and it's all fixed. Long story, but some people must not like bikers or something..? This is why it has taken so long.

Testing was going well and now I have the bike running again, I just have no time to really test it and get things sorted. Too many assignments etc. How easy would it be to take it to a shop and get them to sort it? Would it cost much? All it needs is tuning (jets, needle, etc). Where is a decent shop in Wellington for this sort of thing?

At the moment it doesn't start easily at all (it did before the van hit the bowl) but once it is running, up to half throttle it's pretty good!! Main jet is shit and it doesn't like it when I wick the throttle fast. It was actually really close to being sorted before a van ran over the bowl (the rest of the carb was in my hand).

Also, it seems to only start with the choke, even when hot and I have to give it a really decent crash start. So it's fair to assume it needs more gas on start up?

Cheers

[Pumba]

well if you are talking about taking it to a shop you are talking Dyno time. Defently one of the best ways to tune the bike but it costs.

Wellington motorcycles is the only dyno shop down there I know of.

[F5 Dave]

I wouldn't know of any shop who has the experienced staff to do a from scratch jetting. They all seem to leave. It will end up being more expensive than you would stomach. If it doesn't start easily you don't need a dyno (won't help) to fix that. Get that sorted first. Check pilot jets aren't blocked. Or float height isn't crazy.

[richban]

I'm with Dave. There used to be people but they seem to have disappeared. Still might cost you $300 with the right person on the Dyno. Go See Andrew A and ask to look at his carb. I think it is the same as yours then at lease you will have a good start point. Failing that get yourself to the track and jet the main first. Work back from there. I would be happy to help out one weekend but I am away from this weekend until the next round. So know good to you really.

[hmurphy]

WAAHOO!! Found a major problem. The air fuel mix screw was completely missing! The bloody thing was running far far too lean for starting and idling. I have shut that whole valve off (I know it's not correct, I will have to find a proper valve) and it idles mint now, even when hot. It might be running a tad too lean though on the pilot circuit still, so I should really get a proper pilot jet but hey, it's not running too badly off the pilot. Also, I have the needle pretty spot on I believe and I just went out and tested the main jet.

THIS IS THE JET I WANTED TO TEST BEFORE A F*CKING VAN RAN OVER MY CARB BOWL!!

After this test, the carb is pretty much ready to race with. It was running MINT!! It pulls better for longer up top for sure. I think that I need a bigger jet still though. I am currently running a 165 standard Mikuni carb hex jet (the common one... MI-4/042) but I would like to know if anyone would want to lend me some others for testing? Maybe 170 ish?

I will most likely bring this to Slipway for testing, might as well.

Cheers!