Who's bored their stock TTR-125 carb?

[mikesbaron]

I'm getting set to do the 150cc kit and am considering keeping my stock carb and having it bored out. I've read alot of talk about various carbs and sizes and even recommendations to have theirs bored out. So...I'm looking for input from someone who has actually had it done to their stock carb.

If you haven't but have first hand knowledge please post your experience.

My reasoning is I think I'll get better low and midrange than trying to go to a bigger carb. Most of my riding is either single track or on my mini TT track with 2nd gear corners (stock gear). Just looking for more pull coming out of the corners really.

[john4ct]

hey mike,,,,,,,,,i havent done it....and the reason is that the overall design is flawed.......it has leaking issues and choke issues among other things....its nothing but trouble and boring a crappy carb would not solve the issues.....also the larger carb will somewhat cut out some low end.......due to larger air flow @ a lower velocity having less sucking action to pull fuel from the pilot circuit.

problem is if your boring it , you are making it a bigger carb and are doing the same thing. your cam also has alot to do with it. if doing the bbr kit, a honda 150f 24mm carb is cheap, dependable, and easy to convert. the stock carb jetted will do ok esp for low end but you need a bigger carb to get the most performance out of the bigger disp and cam. i can tell you from running the kit

and using stock 20mm , 24mm ,26mm. and 28mm , the 24mm was the best overall trail type performance to get the best of both worlds.....cranks out a little more witht the 26mmbbr but loses a little low end.....you will lose some with the kit period, as it moves the power band up some but youll still have plenty if you stay around 24mm on the carb .....youl lose some on the very bottom but gain alot on the low mid to hi midrange pull....the 26mm moves the power higher into the rev range..........the 24 mm is the trade off ... for what you want.........with a 14 /54 ratio you will pull those corners in 2nd gear with a smile on your face......good luck jls

[mikesbaron]

Very good! Sounds like the 24mm is what I need.

Any particular year of 150F I need and what type of adapters needed to fit it?

[john4ct]

i think any year will do......you need the bbr 26mm carb adapter......the 24 and 26 are identical and both use the same adapter....ive used it on both with no problems.......i just sold a whole setup to dad rider for his stock ttr with the adapter...........we had it running well in less than 30min........pm him and ask him about it. i still run it on both my modified crf 150f's.......both are bbr 175's but run so well with the stock carb i left them alone.......the ttr has a 26mm keihin [go figure] and im not really sure it improved anything but its runs pretty good on it as well......and its alot more expensive. i wouldnt do it again it i had it to do over.

[mikesbaron]

Ok so a CRF150 carb it will be.

I just purchased a nice carb on Ebay and ordered a CRF throttle cable. Any idea if my TTR throttle will work with this cable or if any pull setup will do? I think I have a few extras laying around.

The big problem now is the intake adapter....

I can't seem to find the BBR intake adapter on their website.?

[john4ct]

you wont. its sold in a carb kit but you can call them and they will sell it seperately. 25.00 i think . others have done it on here......i bought one off of ebay and the other came in the bbr carb kit......but many have bought them directly from bbr but you have to call because you wont find it on their web site as a single idem.......im not sure but the ttr throttle might work......the cable wont........but a throttle control can be gotten from pro motion and a lot of other sources..........i know the cr and crf will work......prob others as well but not sure.......what carb did you end up with?

[mikesbaron]

I ended up getting a nearly new 150F carb, ordered a new 150F cable and found a decent Vortex style throttle on Ebay. Also just bought a big bore BBR kit off there. Now I just need to get the adaptor.

Does the adaptor make the connection to the airbox hose or to the cylinder manifold? Cant I make it work with a dremel or a homemade adapter?

[john4ct]

I ended up getting a nearly new 150F carb, ordered a new 150F cable and found a decent Vortex style throttle on Ebay. Also just bought a big bore BBR kit off there. Now I just need to get the adaptor.

Does the adaptor make the connection to the airbox hose or to the cylinder manifold? Cant I make it work with a dremel or a homemade adapter?

air box makes up directly to the carb...you will have to cut about 1/2 to an inch off of the airbox boot where it makes up to the carb to make up for the adapter on the other side.......the adapter converts a 2 bolt flange to a sleeve that plugs into the intake manifold just like the oem 20mm did. honda uses a 2 bolt flange to connect to the manifold, yamaha uses a plugin sleeve with a clamp to seal it. the bbr 26mm carb is a new honda xr200 carb that also has a 2 bolt flange. thats why they make the adapter. so their carb can be used for this application. the carbs are identical to look at....you can hardly tell tha difference. it's just that one has a slightly different bore size.....both are keihin carbs of the same model style. you might call it a bbr upgrade for a stock bore but they can be jetted to work well with the 150 kit.

i still run them on my bbr175 /crf 150f's even though the 26mm is recommended for the bbk.......they run so well with the 24mm's i didnt change them.the only reason im running a 26mm on the ttr is because i bid on a new bbr carb kit for the ttr and won it for 100.00..and sold the 150f carb i had to a friend for a ttr conversion.....the only difference in the crf/bbr carb and the ttr/bbr carb is the adapter. you dont need it for the crf . it bolts right up. one day ill try the 26 on the crf 175.....if its better, ill used the 150 carb on it for the ttr i didnt notice alot of difference in the 2 on the ttr. i might on the crf.

..............good luck......if i can help any more just holler....i guarantee you will like this setup better that the pos that came on it.............jls:smirk:

[mikesbaron]

yeah I'll def. let you know and check back in. I'm sure I'll need help putting the head back on the bike after the big bore install.

[Hawker]

Sorry you spent all that money. I have bored out carbs on both my TTR's and 1 is a 150. The low end gain is great. The jetting was easy. And my bikes are run all year long in the dirt, on the asphalt, and the ice with no problems.