04 Raptor 350 - High Idle after strip & clean - Yamaha Raptor Forum
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post #1 of 4 (permalink) Old 06-24-2019, 10:12 PM Thread Starter
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04 Raptor 350 - High Idle after strip & clean

Working on getting a very under-used Raptor ready for sale and stripped the carb as it was running very lean, back-firing like crazy after essentially nil use for the last few years and very little use for ten years.

Clearly badly gummed up.

I've seen the other thread on this and I don't think I have a leak.

I cleaned it carefully, ensuring the slide is moving smoothly.

Firing it up, idle was very high, rpm increasing a shade after 10 secs or so. Throttle control operative, although it settle back higher still after blipping the throttle.

I made 2 mistakes that I've discovered so far, well three, starting work on something I didn't have maintenance docs for.

1. I didn't note the throttle linkage position before disassembly. I've adjusted at both ends in the closing direction as far as possible and backed off the idle setting stop, still too high. Does anyone have a photo or diagram of the carb end of the throttle mechanism so I can be sure that I've not done anything stupid there?

2. I didn't note how many turns I backed out the single adjustable part of the mechanism to clean it. (centre front, bottom when installed) I think it's the idle fuel setting and that fully in is lowest, but I don't know. Fully in did not have a perceptible effect on the very high idle. Can anyone please tell me what the "low" setting of that adjuster is and confirm the function.

What else stupid could I have done and what should I do to identify my failings?

I should add that I am competent at working on small mechanical stuff - I restore vintage audio stuff including tape recorders professionally, but I've no experience in working small engines and their carbs.
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post #2 of 4 (permalink) Old 06-25-2019, 08:27 AM
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Welcome to the forum,

I am wondering if you have an issue with the choke plunger? Have you looked over OEM schematics from parts places such as RMATV to confirm how things are situated? If I remember I can uncover ours and look it over to confirm a couple things for you.

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post #3 of 4 (permalink) Old 06-25-2019, 11:44 PM
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Motor stopped, hold the throttle open and let go quickly. You should hear the slide close with a thump/clunk. If not, your throttle cable may be to tight.

If the carb was gummed up it's likely the gas tank is/was gummed up. Something may have broken loose and went in the carb.

Lastly, check for vacuum leaks in the intake.


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post #4 of 4 (permalink) Old 06-29-2019, 03:23 PM Thread Starter
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Thanks both

I'll provide you guys with some free entertainment.

It was something quite dumb.

The throttle cable nipple at the carb end wasn't quite seated in the little brass holder, holding the throttle open at "idle"

With that fixed, I backed out the idle fuel adjuster two turns from fully in and it idled reasonably, then proceeded to bog down and refuse to start about 1/2 a mile from home (we can ride on the roads around home as the County never adopted them, no laws broken).

Fun towing it back on twisty hilly roads, then ran the idle fuel adjuster fully in and out one full turn. I got it warmed up, adjusted the idle throttle setting screw and ran it for 30 mins or so. All pretty good, just the occasional burble changing down and decelerating - a bit lean perhaps.

Given this is prep for sale, any other carb tweaking I should do?

I'm letting it cool and then going to check the cold starting to confirm idle fuel and throttle idle settings are good with a touch of choke.

Make sense?
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