36mm Mikuni to 38mm Air Striker - 2003 CR250

joliver722
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joliver722
I apologize in advance if this question is out there and i've been unable to find it through the search option.

Making the switch to the Keihin and research suggested the 38mm was the size of choice. However, the insulator is of course 36mm and the 38mm Keihin does not want to fit in without force that i've been reserving applying.

In my research did I miss the section that discussed an adapter for the 36mm insulator? Do I instead need to apply a little more ass to make the 38mm fit?

That said, I apologize for the stupidity of this question, too.
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Bruce372
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Bruce372 2/8/2021 7:41pm
2/8/2021 7:41pm
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold.

Have you measured the carb spigot (the bit that sticks into plastic manifold). The new carb should fit, maybe that manifold has aged and hardened or something?
Mr. Robinson 2/8/2021 7:44pm
2/8/2021 7:44pm
I don't remember having any problem getting the Keihin on the CR. It's very possible that your manifold is just old hardened up. Might try warming it up a little or just getting a new one.
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jc34
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jc34 2/8/2021 8:50pm
2/8/2021 8:50pm
Recommend trying an S7 nozzle and go 27.5 pilot and 420 main before trying the air striker out. 74 needle, a tool-less air screw as well. I think I run the needle clip in the 2nd position. AV-gas only. Throw on a boyesen rad valve too. Stock expansion chamber with a PC titanium 2 silencer. Bike rips and is easily tuned for temperature changes with slight tweaks of air screw.
2
PNWRider
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PNWRider 2/8/2021 8:53pm
2/8/2021 8:53pm
Bruce372 wrote:
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold. Have you measured the carb spigot (the...
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold.

Have you measured the carb spigot (the bit that sticks into plastic manifold). The new carb should fit, maybe that manifold has aged and hardened or something?
Honda’s parts fiche calls it an insulator...probably where he got the term.

Agreed on hardening. They are a pain when the rubber has hardened.

OP, I believe I may have an 03 manifold (insulator) new in the bag if you’re interested. I’d have to look and let you know on a price. Bought it for my 02 and sold the bike without installing.

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Matt Fisher
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Matt Fisher 2/9/2021 8:35am
2/9/2021 8:35am
38 AS fits the 2003 OEM manifold just fine- this exact combo is sitting in my garage as I type this out.
joliver722
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joliver722 2/10/2021 5:30pm
2/10/2021 5:30pm
Bruce372 wrote:
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold. Have you measured the carb spigot (the...
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold.

Have you measured the carb spigot (the bit that sticks into plastic manifold). The new carb should fit, maybe that manifold has aged and hardened or something?
PNWRider wrote:
Honda’s parts fiche calls it an insulator...probably where he got the term. Agreed on hardening. They are a pain when the rubber has hardened. OP, I...
Honda’s parts fiche calls it an insulator...probably where he got the term.

Agreed on hardening. They are a pain when the rubber has hardened.

OP, I believe I may have an 03 manifold (insulator) new in the bag if you’re interested. I’d have to look and let you know on a price. Bought it for my 02 and sold the bike without installing.

PM sent.
PNWRider
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PNWRider 2/11/2021 12:52pm
2/11/2021 12:52pm Edited Date/Time 2/11/2021 12:52pm
Bruce372 wrote:
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold. Have you measured the carb spigot (the...
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold.

Have you measured the carb spigot (the bit that sticks into plastic manifold). The new carb should fit, maybe that manifold has aged and hardened or something?
PNWRider wrote:
Honda’s parts fiche calls it an insulator...probably where he got the term. Agreed on hardening. They are a pain when the rubber has hardened. OP, I...
Honda’s parts fiche calls it an insulator...probably where he got the term.

Agreed on hardening. They are a pain when the rubber has hardened.

OP, I believe I may have an 03 manifold (insulator) new in the bag if you’re interested. I’d have to look and let you know on a price. Bought it for my 02 and sold the bike without installing.

joliver722 wrote:
PM sent.
Doesn’t look like I got the PM
PNWRider
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PNWRider 2/18/2021 9:30am
2/18/2021 9:30am
Bruce372 wrote:
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold. Have you measured the carb spigot (the...
By insulator do you mean the black plastic piece between the carb and the cylinder. That's the carb manifold.

Have you measured the carb spigot (the bit that sticks into plastic manifold). The new carb should fit, maybe that manifold has aged and hardened or something?
PNWRider wrote:
Honda’s parts fiche calls it an insulator...probably where he got the term. Agreed on hardening. They are a pain when the rubber has hardened. OP, I...
Honda’s parts fiche calls it an insulator...probably where he got the term.

Agreed on hardening. They are a pain when the rubber has hardened.

OP, I believe I may have an 03 manifold (insulator) new in the bag if you’re interested. I’d have to look and let you know on a price. Bought it for my 02 and sold the bike without installing.

joliver722 wrote:
PM sent.
Found the PMs, they went to my junk folder for some reason. Reply sent.

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