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BBR 175 Jetting

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Alright, got this 150f bored to 175 by the prior owner. Hesitates on snap-open of throttle. I cleaned the carb and blew out all the ports with carb clean and compressed air, cleaned the mouse nest out of the airbox, filter is just a tad dusty but not terrible and the exhaust end cap has the cork removed. I also have a billet tip. Going to verify and update this post with my notes with exact jetting, but it looks pretty close to what's advised for the power-up thread. But I think the main is a 118. (will put again and verify) stupid me didn't write down everything and the stale gas got to me maybe. Plug installed is a BR8ES, manual calls out a completely different plug. What says readers about the ideal plug for use? 

 

Also possibly noteworthy, the only lines to the carb are fuel, the bottom bowl overflow, and the bowl vent. There are other nipples capped off that I presume were for emissions in a past life. I will be pulling the carb tomorrow and posting pictures as it's not too hard to do and may hopefully help others on their jetting quests. I got an 03 manual, I presume that's close enough to an 04 for government work. Looking to ride the crap out of it this weekend with some family on a fleet of XR100's with 125 kits. 

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That plug # is a 14mm 3/4 reach

Your bike is not stock so a colder plug is in order unless you just putt, putt at an idle all day.

I recommend an NGK 12mm J9A

Give us all a clue and help us to help you....

How much compression?

What cam?

What size carb? Brand?

Did you clean your air filter and re-oil it ANYWAY?

What silencer brand and header diameter?

How hard do you ride?

What elevation you riding at?

What's average weather temp range you ride in?

What fuel you running all the time?

You using a rev box? Brand?

Answer those to start, we can get you close....

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Stock carb, 04 150f, BBR 175 kit, BBR rev box, stock exhaust de-corked. Near sea level-1500'. Plan to add a Web cam & springs, but mostly talk. I'm 200+ and a back yard and hare scrambles adult rider. Fair weather rider, if it's cold or 100+, don't expect me out. Fuel is typically pump 93. I need to get some filter oil and plan to clean before riding it. It's only seen a few no helmet 100 yard rides, no action yet.

Edited by Spam16v

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Ok then:

Stock bore and stroke = 155cc

BBR bore kit is actually 170cc but increases compression to around 11-1 (claimed) (15cc more than stock)

sounds like every thing else is pretty much stock.

IMO: 45 pilot jet, needle clip 2nd from bottom (or 4th from the top)

Main jet - uncorked stock 110, yours 115

With your BBR rev box you are not making any more power at max revs than stock but at the lower revs there is a little more HP than the stock box.

There have been reliability concerns with the BBR box in the past so I would carry the stock one with you on long trail rides especially one far away from your truck (or carry a tow rope)

Also if you have BBR valve springs, they are known to break and bend your valves especially at max revs, so beware. (Tow rope again)

IMHO: If a larger cam is in your future, go with the WEB Cam 89a and use the WEB Cam valve springs!!! You will not be sorry and will be impressed!

On another note:

If you really want to wake up your engine even more, after you replace the cam;

Get the BBR 26mm carb kit, BUT use an intake manifold from an XR200r instead of the funky carb adapter that comes in the BBR carb kit.

(There carb kit carburetor is the same carb as an XR200r but comes jetted for your bike) (but IMO your stock carb needle should be used in it)

Since you got the BBR rev box, make sure you keep your valves adjusted and your oil clean. 11,000 + rpm is really tough on your engine! ( And does not make any more power than stock at that RPM either)

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I'm no pro motocrosser, I cruise the woods, rev-limiter is non-applicable. Tentatively going to get a Web 89a & springs. Do I need their rockers or to get them welded? Is there a carb I can upfit off eBay for less than $300? I see they list a lot of them for cheap and are likely China's finest... What part number NGK should I snag to use? Pulling the carb Wednesday to check jet sizes and looking I might have a larger carb already... Finding lots of Easter eggs.

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Yes you need a pair of new OEM rocker arms.

As stated before: NGK J9A

Any 26mm XR 200r carb will work, just get the XR200 intake manifold also.

Edited by adnohguy
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110 main, 42 pilot, needle labeled 18L on the 4th clip... Order a 115, 45 & which needle kit to get this right, done & over with?

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Installed currently: 110 main, 42 pilot, needle labeled 18L on the 4th clip and the air screw is out 4 turns (which I suspect is my bog)... So I should order a 115, 45 & which needle kit or is my 5 clip needle enough to get this right, done & over with once and for all?


fffffuuuuuuu, sorry for all 5 posted. stupid phone.... 

Edited by Spam16v

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Installed a 115 main, 45 slow jet, 4th clip, and around 2 turns on the air screw and it's much better. Couple turns on the air screw for abrupt off idle bog and it'll be dialed. Riding pending weather tomorrow if all goes well I'll report back. 

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