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TTR125 Idle Setting (with a CRF150 carb)

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My TTR125 has a Honda CRF150 carb that I put in there because the stock Mikuni is junk. The bike runs 100% better now. There is one small complaint that I have with the CRF150 carb: there is no good setting for the idle RPM.

The problem is that if you set the idle screw so it idles at a nice reasonable RPM when the engine is cold, then once the engine warms up, the engine races when it is idling. But, if you set the idle screw so it idles nicely when the engine is hot, then when the engine is cold it idles at about 500 RPM or something and is barely running.

So there is a huge discrepancy in a good idle screw setting between when the engine cold and and when the engine is hot. The CRF150 carb has a simple choke for cold starting (instead of an enricher circuit as in the stock carb). Usually a choked carb likes to have a high-idle setting for when the engine is cold, but the CRF150 carb doesn't have this. Is there any good solution to this?

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I don't know of a solution, but I have the exact same set up and it does the same thing..

But the bike does run great.

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Hey thanks I appreciate the feedback. I just wanted to get a feel that there wasn't something wrong that needed attention. Like you said, it's not really a problem at all and the bike runs great, so the carb swap is totally worth it.

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What I used to do was either rev the bike a few times for about a minute or put the idle up higher (about 1/4 turn) until it gets warmed up. Then turn it back down. Kinda an obvious answer, but it became routine after a while. You can also try richen the fuel screw a bit.

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How do you mount a crf150 carb on a TTR? Does someone make a different intake boot? They mount 2 different ways. I agree that the stock carb is junk! I have never had so many issues with a carb before. I would like to do this to my daughters ttr but can't find out how you mount a crf carb on the stock boot.

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How do you mount a crf150 carb on a TTR? Does someone make a different intake boot? They mount 2 different ways. I agree that the stock carb is junk! I have never had so many issues with a carb before. I would like to do this to my daughters ttr but can't find out how you mount a crf carb on the stock boot.

im not sure if its the same carb but the vm24 carb is one many people have been trading in for and i havent heard any bad stuff about it yet

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How do you mount a crf150 carb on a TTR? Does someone make a different intake boot? They mount 2 different ways. I agree that the stock carb is junk! I have never had so many issues with a carb before. I would like to do this to my daughters ttr but can't find out how you mount a crf carb on the stock boot.

BBR makes an adapter you can use.

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BBR makes an adapter you can use.

I went on the BBR site. I can see the adapter but they don't have it listed seperately...only with the carb kit. Is it available seperately? I actually got the stock carb working pretty good...but I just need a bowl for it that isn't available seperately. The overflow tube has a hole it in and it constantly drips. (it isn't the float adjustment) I have it plugged for now and was looking for a parts carb with no luck. Everytime I find one the bid gets higher than I want to spend. So I was thinking about swapping for a 150 carb. The bike is bone stock. My 12 yo daughter rides it. Don't need any performance gains at this point. Do I keep looking for a parts carb or do the swap.

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im not sure if its the same carb but the vm24 carb is one many people have been trading in for and i havent heard any bad stuff about it yet

If I did a swap I was looking to put a Keihin on it. I have never had any issues with my many XR's or CRF's with these carbs. Unlike the junk one that is on the TTR.

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I went on the BBR site. I can see the adapter but they don't have it listed seperately...only with the carb kit. Is it available seperately?

Yes. Call BBR on the phone-- they will sell it separate.

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I am wanting to put the 150F carb on my 2003 ttr125. did it bolt right up? did the ttr cable slide and needle work? or do you have to get a new cable assembly?

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I think I am going to do this swap to. Whatis everything I need to do the swap, bolt it on and go? Jetting, adaptors, cables? Thanks

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