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Jetting

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I'm at 3700' and it's 80 deg. I went to a 45 slow and 140 main . The fuel screw is at 1 1/2 turns . The bikes alot better than stock. Slow jet is a little fat, but cold weather is coming soon . The bike really felt better ( much smoother starting) . I'd like to know what everyone else is running .

The bike really felt and acted lean with the stock 40 slow and 135 main. It seems to pull much harder now. I left the needle in the stock position. The jets are really easy to work on. :thumbsup:

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I'm at 600 ft, about 70 degrees and maybe 50% RH. Stock 40 SJ is lean for sure - sometimes dies on idle and pops like a bowl of Rice Krispies on decel (no air leaks). Have FS out 2 1/2 turns, so need to go to a 42 or 45 SJ. Have not checked plug yet, but it feels and sounds lean on top also with stock 135 MJ. Tried to adjust that by dropping clip one position (4th from 3rd) but needle seems to have a pronounced taper and it was overkill (JD opportunity!). I don't think high speed circuit is far off - a 138 or 140 MJ should do it for fall. Will have new jets on Wednesday and will go from there. I am also going to check FS to see if it is compatible with the Zip-Ty style aftermarket FCR screws (that will be a must have accessory).

How about a sticky on this thread. We will all need to share experiences with jetting and tuning the FCR on this new red mini-rocket.

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45 Pilot

140 Main

Air Screw 2 1/2

Boyesen Quick Shot (the 32mm FCR Type carb uses the same accelerator pump cover as the bigger bikes)

This set up works really well. The Quick shot made a big difference.

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45 Pilot

140 Main

Air Screw 2 1/2

Boyesen Quick Shot (the 32mm FCR Type carb uses the same accelerator pump cover as the bigger bikes)

This set up works really well. The Quick shot made a big difference.

I thought that four stroke carbs had fuel screws :thumbsup:

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I thought that four stroke carbs had fuel screws :thumbsup:

Externally adjustable fuelscrews via a t-handle or similar knob.

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I would like to hear from someone in the Midwest about the jetting .Got a CRF150R yesterday have not had time yet to have my son ride it at the track , seems to run really good and very inpressive but it does die from idle alot.

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I took the bike to the track it's about 95 deg . bike worked best with about 1 1/2 turns out on the fuel screw. it gets pretty cold most of the winter , but i'm going to try a 42 pilot. The bike ran strong ,and I could leave it alone . It's so easy to get to the jets I'm going to try 42/138. R&D is doing a lot of testing on the bike . They say it has alot left in it. It makes me feel better with the stock bike.

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theres nothing close to being on the edge with any stock crf.

we run 40hp 250f's and 60hp crf 450f's that are dead reliable.

you will see 30hp 150r's

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it will be bit before i have a engine package ready.i dont release anything thats not fully developed.

i think if these little bikes are givin the attention they need they will serve people very well.

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our 150 also would die when you gave it gas or took the choke off. sometimes ran better with choke on. very aggervating..

i looked at the carb and my air/fuel screw was a 1/2 turn out so i took it to 1-1/2 out and it made a world of difference. i will have the local shop dyno tune it and jet it once white brothers has the alum pro out for it.

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I thought that four stroke carbs had fuel screws :devil:

My bad...... Fuel Screw

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The dealer should have the jets in stock . They are the same style my xr600 and xr650 used. My local dealer has a box full seperated by sizes.

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I would like to hear from someone in the Midwest about the jetting .Got a CRF150R yesterday have not had time yet to have my son ride it at the track , seems to run really good and very inpressive but it does die from idle alot.

our dealer tuned ours for us when i picked it up new. it would also die if you cracked the throttle from idle. replaced the stock slow jet with a 42(stock 40) and moved the needle jet clip up^ one notch from stock. idles great, starts easier than i imagined it would, no bog. its a blast :devil:

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Got the wife's bike last night and the sales guy had trouble starting it. I laughed. Told me they are like this when cold. Blah Blah.

I wasn't even kicking it and could see that it was lean on the pilot. He had to wick the throttle with the choke on to get it started.

Got home and started to change the jetts almost immediately. Found out the hard way I didn't have a 45 or 48 pilot jet in my stash anymore. I must have given them to someone at the track a while back. Threw in the 42 I had, but it didn't help, even with the fuel screw 2.5 turns out.

The wife is picking up the jets today, and I'll try again tonight. Damn this thing barks like a big bike. LOL

P.S. When I pulled the main jet, it was already clogged with something that looked like a very small piece of glass.

ben

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Trying to save a couple of bucks....does the 150R carb use the Keihin "13" series mains and "22" series pilot jets?

Denniskirk.com has them fairly cheap.

Thanks,

Rich

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I am in Ohio and found the stock jetting way lean, even at 75F. For temps around 40-50F I am at a 48 pilot(!) and 140 main with the FS at 2.0 turns out. I also tried 1-step richer on the stock needle and it was too much. I think a 1/2 step richer needle would be the best. Still have a slight hesitation just off idle if you slowly open the throttle (can't feel it on the track - just at idle). Sure is a fast little bike!

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